CN1828979A - battery pack - Google Patents

Abstract

The present invention discloses a box-shaped or plate-shaped battery pack. The battery pack has a hard outer jacket member, a box-shaped or plate-shaped battery element, a cover, and a circuit board. The hard outer jacket member is formed with a first opening and a second opening at both ends. The box-shaped or plate-shaped battery element is accommodated in the housing member and has electrode terminals. The cover is molded from resin and is mounted to the first opening. The circuit board is connected with the electrode terminal leads and accommodated in the cover. At least the electrode terminal lead extends from the first opening. The cover has concave portions at both ends of one longer side. The housing member has a cutout portion exposing at least the concave portion of the cover. At least the longer side of the cover is thermally bonded to the housing member.

Description

battery pack

technical field

The present invention relates to a battery pack, wherein the battery element is covered with an outer jacket member.

Background technique

In recent years, with the widespread application of portable electronic devices such as notebook personal computers, mobile phones and personal digital assistants (PDAs), lithium-ion batteries with high voltage, high energy density and light weight have been widely used as power sources for these electronic devices. .

When a battery uses a liquid electrolyte, there occurs a problem that the liquid electrolyte tends to leak outside the battery. In order to solve this problem, a lithium ion polymer secondary battery in which a gel-type polymer film impregnated with a polymer in a nonaqueous electrolyte solution and a lithium ion polymer secondary battery using a solid electrolyte have actually been used.

The lithium ion polymer secondary battery has a cell structure. The unit cell is composed of a cell element and a housing part made of aluminum laminate. The battery element is composed of negative electrode, positive electrode and polymer electrolyte. The battery element has electrode terminals extending from the negative electrode and the positive electrode. The battery element is covered with a case member. The unit cells and the wiring board on which the circuit part is mounted are accommodated in a box-shaped mold case composed of an upper case and a lower case. Patent Document 1 below describes an example of such a lithium ion polymer secondary battery.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 2002-260608.

Contents of the invention

In the prior art structure in which the battery element is housed in the molded case, the wall thickness of the molded case is about 0.3 mm to 0.4 mm. When the fixed double-sided tape and tolerances are considered, the cell thickness increases by about 0.8mm to 1mm. In addition, a shape is required that allows the upper and lower molded shells of the unit to be ultrasonically welded. For this, the wall thickness is increased by about 0.7 mm. Thus, the volume of the battery pack is increased by 1.3 to 1.4 times compared to the volume of the cells.

Furthermore, when the battery cells are housed in the molded case, the heat dissipation capability becomes poor. As a result, battery performance decreases and/or heat is generated.

In order to solve such a problem, the inventors of this patent application proposed a battery pack having the following structure. The battery pack consists of a hard outer jacket member and battery elements. The rigid shell member has a first opening and a second opening at both ends. The battery element is accommodated in the housing part. First and second covers molded of resin are attached to the first opening and the second opening, respectively. The circuit board is accommodated in the first cover mounted to the first opening. The circuit board has electrode terminals connected to the battery element.

This battery pack contributes to improved battery performance due to its excellent volumetric efficiency (capacity per unit volume/one battery pack) and high heat dissipation. In addition, the battery pack can be easily assembled and a high yield can be achieved. However, due to the simple shape of the battery pack, the inventors realized that there is a danger of reverse polarity connection of the battery pack to the electronic device. In order to solve this problem, a protruding portion may be added at the edge surface of the battery pack. However, the protruding portion reduces the volumetric efficiency of the battery pack.

In addition, when using the above-mentioned battery pack, it is important to protect the battery pack from external impact because of its simple structure. In the battery pack having the above structure, as shown in FIG. 1A, a soft outer jacket member 101a is spin-molded to form a concave portion for accommodating a battery element. After the battery element is accommodated in the concave portion, the hard case member 101b is placed on the flexible case member 101a such that the hard case member 101b covers the opening portion of the concave portion. Thermally bond the perimeter of the battery element. Thereafter, as shown in FIG. 1B , the rigid housing part 101b and the flexible housing part 101a are folded. Thus, the resulting structure has an elliptical cross-section. The ends of the housing members 101a and 101b are bonded. Thus, a battery cell was obtained. Covers with an oval cross-section are fitted to the openings at the top and bottom of the battery cell. Thus, a battery pack was obtained.

However, as shown in FIG. 2, in the battery pack having such a structure, the rigid case member 101b and the flexible case member 101a are along the left side surface portion and the right side surface portion connecting the battery element 104 and the opening for accommodating the battery element 104. Partial straight folds. Thus, the radius of curvature of these folded portions is smaller than the radius of curvature of the portion connecting the left and right surface portions of the battery element 104 and the bottom surface portion of the battery element 104 . Thus, the cross-section of the battery element 104 is not elliptical.

This is because the concave portion housing the battery element 104 is formed by spin molding, and the end portion 108 of the concave portion can be easily folded. When trying to fit a cover having a substantially elliptical cross-section to the opening portion of the battery element 104, the hard case member 101b does not match the shape of the cover. Because of their reduced contact, they cannot thermally bond adequately. Therefore, when the battery pack is dropped on the floor or an impact is applied to the battery pack, the hard case member 101b is easily detached.

Another problem with the above battery pack is that when the battery pack is designed to have an elliptical cross section, it is difficult to align the battery pack with the battery pack socket portion of the electronic device because the side surfaces are curved. In addition, after the battery pack is connected to the electronic device, the battery pack is easily detached from the slot portion.

In the battery pack described above, the circuit board 103 is accommodated in the top cover 102 constituted by the upper frame 102a and the lower frame 102b. The top cover 102 is attached to one opening portion of the case member 101 . At this time, as shown in FIGS. 3A and 3B , the electrode terminals 105 connected to the circuit board 103 are folded and housed in the battery pack. In this case, when there is a sufficient space between the battery element 104 and the top cover 102, the folded electrode terminal 105 does not interfere with the portion 109 in the upper holder 102a opposite to the electrode terminal wire portion. However, such a structure contradicts the fundamental purpose of designing battery packs with high volumetric efficiency.

When the space between the battery element 104 and the top cover 102 is narrow, the thermally bonded portion of the electrode terminal lead portion placed in the upper holder 102a and the case member 101 becomes very small due to the structure of the electrode terminal lead portion. Thus, the thermal bonding strength between the top cover 102 and the case member 101 becomes insufficient. In addition, when the battery thickness is relatively small, as shown in FIG. 3B , the portion 110 opposite to the electrode terminal wire portion and on the bottom surface of the lower bracket 102 b presses the electrode terminal 105 . Thus, the electrode terminals protrude and fold in the thickness direction of the battery element. Thus, the thickness of the electrode terminal portion becomes thicker than other portions. In this case, the battery pack may not match the battery pack slot of the electronic device.

In addition, the inventors of the present patent application proposed a battery pack having the same structure as the above-mentioned battery pack except that hot-melt resin or the like is injected into the first cover to fix the circuit board accommodated therein.

However, in this battery assembly, the resin was not sufficiently injected into the first cover and the cover had a cavity. Thus, the circuit board is not sufficiently fixed. When the battery pack fell to the floor, the circuit board deformed. Sometimes the circuit is damaged.

In view of the above, it would be desirable to provide a battery pack that prevents reverse polarity connection to the device without sacrificing volumetric efficiency.

In addition, it is desirable to provide a battery pack that is excellent in volumetric efficiency and external impact resistance, and that can be easily aligned with a battery pack slot.

In addition, it is desirable to provide a battery pack which frees the electrode terminals from being interfered by the top cover, and which does not require the electrode terminals to protrude and bend, and which does not make the electrode terminal part thicker than other parts of the battery pack, and which Production can be increased.

In addition, it is desirable to provide a battery pack that sufficiently injects a hot-melt resin into a cover that holds a circuit board and that allows the injected resin to securely hold the circuit board and that improves the mechanical strength of the battery pack.

According to an embodiment of the present invention, there is provided a box-shaped or plate-shaped battery assembly having a rigid case member, a box-shaped or plate-shaped battery element, a cover, and a circuit board. The rigid shell member has first and second openings formed at both ends. A box-shaped or plate-shaped battery element is accommodated in a case member and has electrode terminals. The cover is molded from resin and fitted to the first opening. The circuit board is connected with electrode terminal leads and accommodated in the cover. At least the electrode terminal wire extends from the first opening. The cover has concave portions at both ends of one longer side. The housing part has a cut portion exposing at least the concave portion of the cover. At least the longer side of the cover is thermally bonded to the housing part.

According to an embodiment of the present invention, there is provided a battery pack having a case member, a battery element, and at least one resin-molded cover. The housing part is composed of a first laminated part and a second laminated part. The first laminated part has a concave portion. The battery element is accommodated in the concave portion formed in the first laminated part. The first laminated member and the second laminated member are laminated such that the second laminated member covers the opening of the concave portion. The perimeter of the opening of the first laminate part is sealed. Both ends of the second laminated part are connected outside the bottom of the concave part of the first laminated part. Both sides of the second laminate member protrude and are formed in a substantially oval shape. At least one resin-molded cover is attached to the opening portion formed by the housing member. Corner portions are formed on the two shorter sides of the cover. The radius of curvature of the corner portion from the opening of the concave portion of the first laminated member to the curved surface of each shorter side is smaller than the curved surface from the outer surface of the bottom of the concave portion of the first laminated member to the curved surface of each shorter side The radius of curvature of the corner.

According to an embodiment of the present invention, there is provided a box-shaped or plate-shaped battery assembly having a rigid case member, a box-shaped or plate-shaped battery element, a first cover, and a second cover. The rigid shell member has a first opening and a second opening at both ends. A box-shaped or plate-shaped battery element is accommodated in a case member, and has electrode terminal leads connected to a circuit board. The first cover and the second cover cover the first opening and the second opening. The first cover is mounted to the first opening. The circuit board is accommodated in the first cover. The first cover has at least an upper bracket molded of resin and holding the circuit board on opposite sides of the battery element and a lower bracket molded of resin holding the circuit board on the side of the battery element. The upper bracket and the lower bracket are bonded or mechanically connected. The upper bracket has cutout portions corresponding to electrode terminal wire portions of the electrode terminals extending from the battery element.

According to an embodiment of the present invention, there is provided a box-shaped or plate-shaped battery assembly having a rigid case member, a box-shaped or plate-shaped battery element, a first cover, and a second cover. The rigid shell member has a first opening and a second opening at both ends. A box-shaped or plate-shaped battery element is accommodated in a case member, and has electrode terminal wires connected to a circuit board. The first cover and the second cover cover the first opening and the second opening. The first cover is mounted to the first opening. The circuit board is accommodated in the first cover. The first cover has at least an upper bracket molded of resin and holding the circuit board on opposite sides of the battery element and a lower bracket molded of resin holding the circuit board on the side of the battery element. The upper bracket and the lower bracket are bonded or mechanically connected. The upper bracket has a through hole through which resin is injected into a space formed between the battery element and the first cover. The lower bracket has protruding portions at both ends, the protruding portion has a cutout portion at a central portion, and the lower bracket has at least one substrate supporting protrusion protruding on the circuit substrate side near the central portion. Resin is injected into a space formed between the battery element and the first cover.

Preferably, one end of the housing member protrudes from one end of the battery element by about the thickness of the cover through the opening fitted to the cover. Preferably, the thermal bonding layer is provided in the raised portion of the housing part.

Preferably, the housing part is formed from a first laminate part and a second laminate part having substantially the same dimensions. Preferably, the first laminated part has a concave portion for accommodating the battery element, and the first laminated part and the second laminated part are laminated such that the second laminated sheet part covers the opening of the concave part, and the first laminated part The periphery of the opening is sealed, the electrode terminal leads connected to the battery element extend from the sealed portion, the ends of the first laminated part and the second laminated part are connected at the bottom outside of the concave part of the first laminated part, the first laminated part Both sides of the component and the second laminated component protrude and are formed in an oval shape.

As described above, according to an embodiment of the present invention, the cover has a concave portion at both ends of one longer side, and the housing member has a cutout portion exposing at least the concave portion of the cover. Thus, it is possible to provide a battery pack having an excellent volumetric efficiency having a structure that prevents reverse polarity connection of the battery pack.

Furthermore, according to another embodiment of the present invention, since the contact property of the mounting portion of the cover and the case member is improved, it is possible to prevent the thermally bonded portion from coming off. Thus, when the battery pack is dropped or impacted, the battery pack can be prevented from being damaged. In addition, since the battery pack can be easily aligned with the battery pack slot of the electronic device, and misalignment of the battery pack and the battery pack slot can be avoided, the quality of the battery pack can be improved.

Furthermore, according to another embodiment of the present invention, since the cover accommodating the circuit board has the cutout portion, the cutout portion can accommodate the bent electrode terminal when the cover is mounted to the case member. Thus, the thickness of the battery pack does not increase after the cover is thermally bonded to the case member. In addition, since the thermally bonded portion is prevented from falling off, the quality of the battery pack is improved.

Furthermore, according to the embodiments of the present invention, since the holder that does not prevent the flow of the injected resin is used, the resin can be sufficiently injected into the top cover, and the circuit board can be reliably held. In addition, the mechanical strength of the battery pack can be improved.

Furthermore, according to the present invention, since the ribs at both ends of the lower bracket have protruding portions in the longitudinal direction of the battery pack, when resin is injected, the flow of resin can be simplified. Thus, the resin can be sufficiently injected into the top cover.

In addition, according to another embodiment of the present invention, since the lower bracket has the protruding portion, when the upper bracket and the lower bracket are installed, since the through hole is opposite to the protruding portion, even if a metal pin is inserted into the through hole, it is possible to avoid metal The pins make contact with the battery element. Thus, accidents such as short circuits can be avoided.

These and other objects, features and benefits of the present invention will become more apparent from the following detailed description of preferred embodiments of the invention as shown in the accompanying drawings.

Description of drawings

From the following detailed description in conjunction with the accompanying drawings, the present invention will be more fully understood. In the accompanying drawings, the same reference numerals represent the same components. In the accompanying drawings:

1A and 1B are cross-sectional views showing the structure of a related art battery cell;

FIG. 2 is a schematic diagram showing the structure of a prior art battery cell;

3A and 3B are cross-sectional views showing the structure of a related art battery cell;

4 is an exploded perspective view showing an example of the structure of the battery pack according to the first embodiment of the present invention;

5 is a perspective view showing an example of the shape of one end of the battery pack according to the first embodiment of the present invention;

6A and 6B are a perspective view and a cross-sectional view showing an example of the structure of a battery element according to a first embodiment of the present invention, respectively;

7A, 7B and 7C are a plan view, a shorter side sectional view and a longer side sectional view showing a first example of a housing member;

8 is a cross-sectional view showing an example of the structure of a flexible laminate member constituting a case member;

FIG. 9 is a perspective view showing a second example of a housing member;

10 is a perspective view showing an example of the shape of an upper bracket;

11 is a perspective view showing an example of the appearance of a battery element covered with a case member;

12 is an enlarged cross-sectional view showing a case member covering a battery element;

13 is a perspective view illustrating a method of producing a battery pack according to a first embodiment of the present invention;

14 is a perspective view illustrating a method of producing a battery pack according to a first embodiment of the present invention;

15 is a perspective view illustrating a method of producing a battery pack according to a first embodiment of the present invention;

16 is a perspective view illustrating a method of producing a battery pack according to a first embodiment of the present invention;

17 is a perspective view illustrating a method of producing a battery pack according to a first embodiment of the present invention;

18 is a perspective view showing the external shape of the battery pack according to the first embodiment of the present invention;

19 is a perspective view showing an external shape of a battery pack according to a first comparative example;

20 is a perspective view showing an external shape of a battery pack according to a second comparative example;

21 is a perspective view showing an external shape of a battery pack according to a third comparative example;

22 is a schematic diagram showing the structure of a battery pack according to a second embodiment of the present invention;

23 is a schematic diagram showing a top cover structure used in a battery pack according to a second embodiment of the present invention;

24 is a schematic diagram showing a state in which a top cover produced according to a second embodiment of the present invention is mounted to a battery unit;

25 is a schematic diagram showing a state in which a top cover produced according to a second embodiment of the present invention is mounted to a battery unit;

26 is a schematic diagram showing a state in which a top cover produced according to a second embodiment of the present invention is mounted to a battery unit;

27A, 27B and 27C are a perspective view, a front view and a perspective view showing a top cover produced according to a second embodiment of the present invention;

28 is a schematic diagram showing the structure of a battery pack in the prior art;

29 is a schematic view showing the structure of a top cover and a battery cell used in a battery pack in the prior art;

30 is a perspective view showing the structure of an upper bracket of a top cover used in a battery pack according to a third embodiment of the present invention;

31 is a perspective view showing an example of the structure of a battery pack according to a third embodiment of the present invention;

32 is a plan view showing an electrode terminal lead portion of a battery cell in a state where a top cover used in a battery pack according to a third embodiment of the present invention is mounted to the battery cell;

33 is a schematic diagram showing the structure of a lower bracket constituting a top cover used in a battery pack according to a third embodiment of the present invention;

34A and 34B are perspective views showing wiring of electrode terminals in a battery pack according to a third embodiment of the present invention;

35 is a perspective view of a structure of an upper bracket, a lower bracket, and a battery unit according to a third embodiment of the present invention;

36 is a perspective view showing a state in which a top cover produced according to a third embodiment of the present invention is attached to a battery unit;

37 is a perspective view showing a state in which a top cover produced according to a third embodiment of the present invention is attached to a battery unit;

38 is a perspective view showing a state in which a top cover produced according to a third embodiment of the present invention is attached to a battery unit;

39A, 39B, 39C and 39D are cross-sectional views showing a state in which a top cover produced according to a third embodiment of the present invention is mounted to a battery cell;

40 is a perspective view showing a state in which an upper bracket is mounted to a battery unit according to a fourth embodiment of the present invention;

41 is a perspective view showing a first example of a lower bracket according to a fourth embodiment of the present invention;

42 is a perspective view showing a mounted state of an upper bracket and a lower bracket according to a fourth embodiment of the invention;

43 is a perspective view showing details of an upper bracket and a lower bracket mounting portion according to a fourth embodiment of the present invention;

44 is a perspective view showing a state where an upper bracket and a lower bracket are inserted into openings of end faces of battery cells according to a fourth embodiment of the present invention;

45 is a perspective view showing a second example of a lower bracket according to a fourth embodiment of the present invention;

46 is a perspective view showing a third example of a lower bracket according to a fourth embodiment of the present invention;

47 is an enlarged perspective view showing the vicinity of the through hole of the lower bracket in a state where the upper bracket and the lower bracket are installed according to the fourth embodiment of the present invention;

48 is a perspective view of an example of the shape of a lower bracket according to a fourth embodiment of the present invention;

49 is a perspective view showing an example of the shape of a lower bracket used in a related art battery pack;

FIG. 50 is a perspective view showing an example of the shape of the lower bracket having a plurality of circuit board supporting protrusions.

Detailed ways

Next, a first embodiment of the present invention will be described with reference to the drawings. 4 is an exploded perspective view showing an example of the structure of the battery pack according to the first embodiment of the present invention. 5 is a perspective view showing an example of the shape of one end of the battery pack according to the first embodiment of the present invention. The battery assembly is a battery assembly of a box-shaped or plate-shaped lithium ion polymer battery. As shown in FIG. 4 , the battery pack has a case part 1 (having an open end), a battery element housed in the case part 1 , and a top cover 2 and a bottom cover 3 mounted on both open ends of the case part 1 . In the following description, the open end to which the top cover 2 is mounted is referred to as the top end, and the open end to which the bottom cover 3 is mounted is referred to as the bottom end.

The battery element is, for example, a box-shaped or plate-shaped roll type battery element. The housing part 1 is in the shape of a plate. The housing part 1 is rectangular when viewed from the main plane. The case member 1 has cutout portions 10 a and 10 b exposing at least the concave portions 6 a and 6 b formed at both ends of the longer side of the top cover 2 . The opening at the end of the housing part 1 is rectangular. The two shorter sides of each opening protrude in the shape of an elliptical arc.

Furthermore, the top cover 2 and the bottom cover 3 are shaped such that they fit into openings at both ends of the case member 1 . When viewed from the front of the top cover 2 and the bottom cover 3, they are rectangular and their shorter sides protrude in the shape of an elliptical arc. As shown in FIG. 5, concave portions 6a and 6b are formed at both ends of one longer side of the top cover 2, thereby preventing reverse polarity connection of the battery pack with the battery pack slot of the electronic device. In addition, through holes 26 a and 26 b are formed on the front surface of the top cover 2 .

Next, referring to FIGS. 6 to 10 , the battery element 4 , the case member 1 , the top cover 2 and the bottom cover 3 will be described.

<battery element>

6A and 6B are a perspective view and a sectional view showing an example of the appearance of the battery element 4 according to the first embodiment of the present invention. FIG. 6B shows the structure of the end portions where the negative electrode 8 and the positive electrode 9 are wound. The battery element 4 is composed of a negative electrode 8 formed in a strip shape and wound in its longitudinal direction, a separator 19a, a positive electrode 9 disposed opposite to the negative electrode 8, and a separator 19b. Both surfaces of each of the negative electrode 8 and the positive electrode 9 are coated with a polymer electrolyte 20 . As shown in FIG. 6B , polymer electrolyte 20 is completely applied to both surfaces of each of negative electrode 8 and positive electrode 9 such that polymer electrolyte 20 completely covers the end portions of negative electrode 8 and positive electrode 9 . A negative terminal 5a connected to the negative electrode 8 and a positive terminal 5b connected to the positive electrode 9 protrude from the battery element 4 (the negative terminal 5a and the positive terminal 5b are simply referred to as electrode terminals 5 unless the electrode terminals are specifically indicated). The respective two surfaces of the negative terminal 5a and the positive terminal 5b are coated with resin sheets 7a and 7b to improve the adhesive performance of the laminated film (which will be described below as case member 1) (hereinafter, the resin sheets 7a and 7b are referred to as sealing agent (sealant)).

The negative electrode 8 is composed of a negative electrode current collector in a strip shape, a negative electrode active material layer formed on the negative electrode current collector, and a polymer electrolyte layer formed on the negative electrode active material layer. The negative electrode current collector is made of metal foil such as aluminum (Al) foil, nickel (Ni) foil, or stainless steel foil. The positive electrode 9 is composed of a strip-shaped positive electrode current collector, a positive electrode active material formed on the positive electrode current collector, and a polymer electrolyte formed on the positive electrode active material. The positive electrode current collector is made of metal foil such as copper (Cu) foil, nickel (Ni) foil, or stainless steel foil. The electrode terminals 5a and 5b of the negative electrode 8 and the positive electrode 9 are connected to a negative electrode current collector and a positive electrode current collector, respectively. For the negative electrode active material, positive electrode active material and polymer electrolyte, those already proposed can be used.

The negative electrode active material of the negative electrode 8 may be a metal oxide, a metal sulfide, or a predetermined polymer according to the type of the battery. When the battery component is a lithium ion battery, the negative electrode active material can be, for example, lithium composite oxide Li _x MO ₂ (wherein M represents one or more transition metals; X represents a value ranging from 0.05 to 1.10, which depends on battery charge/discharge status). The transition metal constituting the lithium composite oxide is preferably cobalt (Co), nickel (Ni), manganese (Mn) or the like.

The negative electrode active material layer is composed of, for example, a negative electrode active material, a conductive agent, and a binder. These are mixed equally and form a negative electrode mixture. The negative electrode mixture is dispersed in a solvent. Thus, a slurry of the negative electrode mixture was obtained. The negative electrode mixture slurry is evenly coated on the negative electrode current collector by, for example, a doctor blade method. The negative electrode current collector is heated at high temperature to volatilize the solvent. Thus, the negative electrode active material is obtained. In this case, the mixing ratio of the negative electrode active material, conductive agent, binder, and solvent is not limited as long as they are uniformly dispersed in the solvent.

Specific examples of lithium ion multi-oxides are LiCoO ₂ , LiNiO ₂ , LiNi _y Co _1-y O ₂ (where 0<y<1), and LiMnO ₄ . Alternatively, a solid solution in which a part of the transition metal is replaced by another metal may be used as the lithium ion composite oxide. Examples of such solid solutions are LiNi _0.5 Co _0.5 O ₂ and LiNi _0.8 Co _0.2 O ₂ . These lithium composite oxides are capable of generating high voltage and have high energy density. Alternatively, the negative electrode active material may be lithium-free metal sulfide or metal oxide, such as TiS ₂ , MoS ₂ , NbSe ₂ or V ₂ O ₅ . The negative electrode can be made of various types of these negative electrode active materials. When the negative electrode is made of these negative electrode active materials, a conductive agent and/or a binder may be added.

A carbon material such as carbon black or graphite is used as the conductive agent. For example poly(vinylidene fluoride), poly(tetrafluoroethylene) or polyvinylidene fluoride (PVDF) is used as binder. As a solvent, for example, N-methylpyrrolidone (methylpyrrolidone) is used.

The negative electrode 8 has the negative electrode terminal 5a spot-welded or ultrasonically welded to a part of the current collector. The negative terminal 5a is preferably a mesh-type metal foil. However, the negative terminal 5a may be made of a conductive non-metallic substance as long as the substance is electrochemically or chemically stable and conductive. The material of the negative electrode terminal 5 a is, for example, aluminum (Al).

The positive electrode active material layer is composed of, for example, a positive electrode active material and, if necessary, a conductive agent and a binder. These are mixed equally and form a positive electrode mixture. This positive electrode mixture is dispersed in a solvent. Thus, a slurry of the positive electrode mixture was obtained. The slurry of the positive electrode mixture is uniformly applied to the positive electrode current collector by, for example, a doctor blade method. The positive electrode current collector is heated at high temperature to volatilize the solvent. Thus, a positive electrode active material is obtained. In this case, the mixing ratio of the positive electrode active material, conductive agent, binder, and solvent is not limited as long as they are uniformly dispersed in the solvent.

As the material of the positive electrode 9 , for example, a material capable of intercalating (dope) or deintercalating (dedope) lithium can be used. Examples of such substances are non-graphitizable carbon carbon substances and graphite-type substances. More specifically, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, organic polymer sintered bodies (phenolic resin or furan resin sintered at an appropriate temperature carbide), carbon fiber, activated carbon, etc. As a substance that intercalates or deintercalates lithium, for example, polymers such as polyacetylene, polypyrrole, and oxides (eg, SnO ₂ ) can be used. When the positive electrode 9 is made of these substances, a binder or the like may be added.

Examples of substances capable of forming an alloy with lithium are various types of metals such as tin (Sn), cobalt (Co), indium (In), aluminum (Al), silicon (Si), and alloys thereof. When metallic lithium is used, it is not always necessary to coat its powder with a binder. Alternatively, rolled lithium metal plates may be used.

Examples of binders are polyvinylidene fluoride and styrene-butadiene rubber (SBR). Examples of solvents are N-methylpyrrolidone and methyl ethyl ketone.

Like the negative electrode 8, the positive electrode 9 has the positive terminal 5b spot-welded or ultrasonically welded to a part of the current collector. The positive terminal 5b is preferably a mesh-type metal foil. However, the positive terminal 5b may be made of a conductive non-metallic substance as long as the substance is electrochemically or chemically stable and conductive. The material of the positive terminal 5 b is, for example, copper (Cu) or nickel (Ni).

Preferably, the negative terminal 5 a and the positive terminal 5 b extend from the same opening of the battery element 4 . Alternatively, the negative terminal 5a and the positive terminal 5b may extend from any opening of the battery element 4 as long as no short circuit occurs and battery performance is not degraded. In addition, the negative terminal 5a and the positive terminal 5b may be connected at any position by any method as long as the negative terminal 5a and the positive terminal 5b are in electrical contact with the negative electrode 8 and the positive electrode 9, respectively.

Polymer electrolytes consist of polymer substances, electrolytes, and electrolyte salts. They are mixed and the gelled electrolyte is polymerized. The polymer substance is dissolved with an electrolyte. Examples of polymer substances are silicone gel, acrylic gel, acrylonitrile gel, polyphosphazen modified polymers, polyethylene oxide, and polypropylene oxide. As examples of these conjugated polymers, these crosslinked polymers, modified polymers, and fluorinated polymers, polymer substances such as poly(vinylidene fluoride), poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-hexafluoropropylene), polyvinylidene fluoride co-trifluoroethylene) and mixtures thereof.

An example of the electrolyte component is, for example, an aprotic solvent capable of dispersing the above-mentioned polymer substance. Examples of aprotic solvents are ethylene carbonate (EC), propylene carbonate (PC) and butylene carbonate (BC). Electrolyte salts are dissolved in solvents and consist of cations and anions. As examples of cations, alkali metals and alkaline earth metals are used. As examples of anions, Cl ⁻ , Br ⁻ , I ⁻ , SCN ⁻ , ClO ₄ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ and CF ₃ SO ₃ are used. Specific examples of the electrolyte salt are lithium hexafluorophosphate (LiPF ₆ ) and lithium hexafluoroborate (LiBF ₄ ) which are soluble in the electrolyte solution to a certain concentration.

The electrolyte solution, which is a mixture of the above electrolyte and electrolyte salt, forms a gel with a matrix polymer. Thus, a gel electrolyte is obtained. The matrix polymer is not limited as long as it dissolves in a non-electrolyte solution in which an electrolyte salt is dissolved in a non-aqueous solvent and forms a gel. Examples of matrix polymers are poly(vinylidene fluoride), polyethylene oxide, polypropylene oxide, polyacrylonitrile and/or poly(methacrylonitrile) repeatedly contained in predetermined units (in predetermined units). )) polymers. The polymer can be one of these components or a mixture thereof.

<Case parts>

7A , 7B and 7C show a first example of a housing part 1 . As shown in FIGS. 7A to 7C, the housing member 1 is composed of a soft laminate member (softlaminate member) 1a having a concave portion 15 for accommodating the battery element 4, and a hard laminate member (hard laminate member) 1b. The part 1b covers the concave portion 15 on the rigid laminate part 1b. The concave portion 15 is spin molded into the shape of the battery element 4 . On the bottom outer surface of the concave portion 15, a thermal bonding sheet 15a is provided.

The flexible laminated part 1a is formed in a rectangular shape. The flexible laminated part 1a has a top longer side 11a, a bottom longer side 12a, a left shorter side 13a and a right shorter side 14a. The length of the top longer side 11a is the same as the length of the bottom longer side 12a. The length of the left shorter side 13a is the same as the length of the right shorter side 14a. Similarly, the rigid laminated part 1b is formed in a rectangular shape. The rigid laminate part 1b has a top longer side 11b, a bottom longer side 12b, a left shorter side 13b and a right shorter end 14b. The length of the top longer side 11b is the same as the length of the bottom longer side 12b. The length of the left shorter side 13b is the same as the length of the right shorter side 14b. The left and right sides of the flexible laminated part 1a and the rigid laminated part 1b are based on the position when viewed from the top of Fig. 13A.

The length of the longer sides 11b and 12b of the rigid laminate 1b is such that the shorter sides 13b and 14b contact each other or are spaced a small distance apart when the concave portion 15 accommodating the battery element 4 is covered by the rigid laminate 1b. The length of the longer sides 11a and 12a of the flexible laminated part 1a is smaller than the length of the longer sides 11b and 12b of the rigid laminated part 1b. The lengths of the longer sides 11a and 12a of the flexible laminate 1a are such that the shorter sides 13a and 14a contact each other or are spaced a small distance apart when the concave portion 15 housing the battery element 4 is covered by the flexible laminate 1a. The distance between the shorter sides 13a and 14a of the flexible laminated part 1a is not limited to a small distance, but may have a certain distance.

The length of the shorter sides 13a and 14a of the flexible laminated part 1a is smaller than the length of the shorter sides 13b and 14b of the rigid laminated part 1b. Thus, the flexible laminated part 1 a and the rigid laminated part 1 b can be laminated such that only the rigid laminated part 1 b appears on top of the housing part 1 . In this case, the periphery of the top cover 2 provided at the top opening of the housing part 1 can be thermally bonded through the polypropylene layer of the rigid laminate part 1b. Similarly, the adhesive layer of the rigid laminate part 1b may be exposed at the bottom of the shell part 1, so that the periphery of the bottom cover 3 provided at the bottom opening of the shell part 1 may be sealed by the polypropylene layer of the rigid laminate part 1b. Perform thermal bonding.

One longer side of the rigid laminated member 1b has cutout portions 10a and 10b. The cutout portions 10a and 10b are formed at least at positions where the concave portions 6a and 6b of the top cover 2 are exposed when the battery element 4 is covered by the case member 1 and the top cover 2 is mounted to the top opening of the case member 1 . The cutout portions 10a and 10b are shaped such that when the top cover 2 is mounted to the top opening of the case member 1, at least the concave portions 6a and 6b of the top cover 2 are exposed.

The flexible laminated part 1a is adapted to form a concave portion 15 accommodating the battery element 4 by spin molding. The flexible laminated part 1a is softer than the rigid laminated part 1b.

FIG. 8 is a cross-sectional view showing an example of the structure of the flexible laminated member 1 a constituting the case member 1 . The flexible laminated part 1a has a laminated structure in which a polypropylene (PP) layer 16a as an adhesive layer, a flexible aluminum layer 17a as a metal layer, and a nylon layer or polyethylene terephthalate as a surface protection layer are sequentially laminated in this order. Polyethylene glycol ester (PET) layer 18a. The polypropylene layer 16a is the innermost layer (in contact with the rigid laminate part 1b).

One function of the flexible aluminum layer 17a is to prevent denaturation of the polymer electrolyte. As the polypropylene layer 16a, cast polypropylene (CPP) is used, for example. The thickness of the polypropylene (PP) layer 16a is, for example, 30 μm.

One function of the flexible aluminum layer 17a is to prevent moisture from entering the interior. An example of the material of the flexible aluminum layer 17a is annealed aluminum (JIS A8021P-O) or (JIS A8079P-O). The thickness of the flexible aluminum layer 17a is in the range of 30 μm to 130 μm. The function of the nylon or PET layer 18a is to protect the surface. The thickness of the nylon layer or PET layer 18a is in the range of 10 μm to 30 μm.

The rigid laminated part 1b can maintain a shape bent against external deformation. The rigid laminated part 1b has a laminated structure in which a polypropylene layer as an adhesive layer, a rigid aluminum layer as a metal layer, and a nylon layer or PET layer as a surface protection layer are sequentially laminated in this order.

The polypropylene layer and the nylon or PET layer of the rigid laminated part 1b are the same as those of the flexible laminated part 1a. The hard aluminum layer is made of non-annealed aluminum (JIS A3003P-H18) or (JIS A3004P-H18). The thickness of the rigid aluminum metal is in the range of 30 μm to 130 μm. The thickness of each layer of the flexible laminated part 1a and the rigid laminated part 1b is selected by considering the overall thickness of the battery assembly.

FIG. 9 shows a second example of a housing part 1 . In FIG. 9 , a laminated battery element 50 is covered by a case member 1 . The top cover 2 and the bottom cover 3 are provided on both end faces of the laminated battery element 50 .

The case member 1 is a rigid laminated member having an adhesive layer, a metal layer, and a surface protection layer sequentially laminated in this order. The material of the layers of the second example of the shell part 1 is the same as that of the layers of the first example of the rigid laminate part 1b.

Electrode terminals 5 a and 5 b extend from the laminated battery element 50 . The battery element 4 is covered by a flexible laminate. The perimeter of the flexible laminate is thermally bonded and sealed. Preferably, the flexible laminate preferably has a housing portion for housing the battery element 4 . The receiving portion is formed by spin molding a flexible laminated member into a predetermined shape. The flexible laminated part has an adhesive layer, a metal layer, and a surface protection layer laminated in this order. The material of each layer of the flexible laminated part of the second example is the same as the material of each layer of the flexible laminated part 1a of the first example.

The case member 1 is formed in a rectangular shape. The housing part 1 has a top longer side 31a, a bottom longer side 31b, a shorter side 32a and a shorter side 32b. The length of the top longer side 31a is the same as the length of the bottom longer side 31b. The shorter side 32a has the same length as the shorter side 32b. The top longer side 31 of the housing member 1 has cutout portions 10a and 10b. The cutout portions 10a and 10b are formed at least at positions that expose the concave portions 6a and 6b of the top cover 2 when the battery element 4 is covered by the case member 1 and the top cover 2 is mounted to the top opening of the case member 1 . The cutout portions 10 a and 10 b are shaped such that at least the concave portions 6 a and 6 b of the top cover 2 are exposed when the top cover 2 is mounted to the top opening of the case member 1 .

The case member 1 covers the laminated battery element 50 in the following manner, for example. First, the electrode terminals 5 a and 5 b extending from the top of the laminated battery element 50 are connected to the circuit board housed in the top cover 2 . The laminated battery element 50 is placed in the central portion of the case member 1 such that the upper surface of the top cover 2 almost matches the top longer side 31 a of the case member 1 . Thereafter, the bottom cover 3 is placed on the end face of the bottom of the laminated battery element 50 .

Subsequently, the shorter side 32 a and the shorter side 32 b of the case part 1 are folded in the direction of the laminated battery element 50 . The surface protective layer of the laminated battery element 50 and the adhesive layer of the case member 1 are subjected to thermal bonding, for example. Thereafter, the laminated battery element 50, the top cover 2, and the bottom cover 3 are held and thermally bonded using predetermined jigs. In other words, heater parts made of metal such as copper are placed above and below the top end of the housing part 1 . The heater member pressurizes the top end of the housing member 1 so that the periphery of the top cover 2 is thermally bonded to the adhesive layer on the inner surface of the rigid laminate member 1b. Similarly, heater parts are placed above and below the bottom end of the housing part 1 . The heater member pressurizes the bottom end of the housing member 1 so that the periphery of the bottom cover 3 is thermally bonded to the adhesive layer on the inner surface of the rigid laminate member 1b.

Subsequently, molten resin is injected into the space formed between the battery element 4 and the top cover 2 through the through holes 26 a and 26 b of the top cover 2 . Thereafter, the molten resin is solidified. Then, molten resin is injected into the space formed between the battery element 4 and the bottom cover 3 through the through hole of the bottom cover 3 . Thereafter, the molten resin is solidified.

After the laminated battery element 50 is covered with the case member 1 and top and bottom openings are formed at both end faces of the case member 1, the top cover 2 and the bottom cover 3 can be attached to the top and bottom openings, respectively.

<top cover>

The top cover 2 is composed of an upper frame 2a and a lower frame 2b. Fig. 10 is a perspective view showing an example of the shape of the upper bracket 2a. The top cover 2 closes the top opening of the housing part 1 . When viewing the top cover 2 from the front, the upper bracket 2a is rectangular and the two shorter sides protrude in an elliptical arc. The upper bracket 2a has concave portions 6a and 6b at the corners of one longer side and two shorter sides. The concave portions 6a and 6b are used to prevent reverse polarity connection of the battery pack and the electronic device. The housing member 1 has cutout portions 10a and 10b corresponding to the concave portions 6a and 6b of the upper bracket 2a. Therefore, it is possible to prevent the reverse polarity connection between the battery pack and the electronic device, and at the same time improve the volumetric efficiency of the battery pack.

Although the shapes of the concave portions 6a and 6b formed on both ends of one longer side of the upper bracket 2a are not limited, they are preferably formed in consideration of flexibility in design on the electronic device side. For example, the concave portions 6a and 6b are depressed in a stepped shape toward the shorter sides of the upper bracket 2a.

The upper bracket 2a has through holes 26a and 26b. The through-holes 26a and 26b penetrate the upper frame 2a from the surface adjacent to the battery element 4 to the surface opposite thereto. Although the number of through holes is not limited, at least one through hole is required. Preferably, two or more through holes are required. In the case where there are two or more through holes, at least one through hole can be used to discharge air from the space formed between the battery element 4 and the top cover 2 when injecting the resin. Therefore, the injection performance of the resin can be improved.

Furthermore, the top cover 2 has a circuit board. Electrode terminals 5a and 5b extending from the battery element 4 are connected to a circuit board.

The circuit board has a protection circuit including a temperature protection device (for example, a fuse), a positive temperature coefficient (PTC) circuit, a thermistor, and an ID resistor for identifying a battery pack. Furthermore, the circuit board has a plurality (for example three) of contact portions. The protection circuit includes an IC that monitors the battery element 4 and controls field effect transistors (FETs) and charge/discharge control FETs.

The PTC circuit is connected in series with the battery element 4 . When the temperature of the battery element 4 becomes higher than the set temperature, the resistance of the PTC circuit increases sharply and substantially prevents current from flowing in the battery element 4 . A fuse and a thermistor are also connected in series with the battery element 4 . When the temperature of the battery element 4 becomes higher than the set temperature of the fuse and the thermistor, they cut off the current flowing in the battery element 4 . A protection circuit including an IC that monitors the battery element 4 and controls FETs and a charge/discharge control FET monitors the voltage of the battery element 4 . When the voltage of the battery element 4 exceeds 4.3V to 4.4V, since a dangerous situation such as heat generation may occur in the battery element 4, the protection circuit turns off the charging/discharging control FET to prohibit charging of the battery element 4. When the battery element 4 is over-discharged, the terminal voltage of the battery element 4 drops to the discharge prohibition voltage, the voltage of the battery element 4 becomes 0V, and the battery element 4 can become an internal short-circuit state in which the battery element 4 cannot be recharged. . Thus, the protection circuit monitors the voltage of the battery element 4 . When the voltage of the battery element 4 becomes lower than the discharge inhibiting voltage, the protection circuit turns off the discharge control FET to inhibit the battery element 4 from discharging.

<Bottom cover>

The bottom cover 3 closes the bottom opening of the housing part 1 . When viewed from the front of the bottom cover 3, it is rectangular and the two shorter sides protrude in an elliptical arc. The bottom cover 3 has side walls on its surface adjacent to the battery element 4 . The side walls are adapted to the bottom opening of the housing part 1 . The side walls are formed along part or the entire outer periphery of the bottom cover 3 . The side wall is formed at a position spaced apart from the outer periphery of the bottom cover 3 by the length of the case member 1 .

The bottom cover 3 has through holes. The through hole passes through the bottom cover 3 from the surface adjacent to the battery element 4 to the surface opposite thereto. Although the number of through holes is not limited, at least one through hole is required. Preferably, two or more through holes are required. In the case where there are two or more through holes, at least one through hole can be used to exhaust air from the space formed between the battery element 4 and the bottom cover 3 when the resin is injected. Therefore, the injection performance of the resin can be improved.

The bottom cover 3 may be formed by directly injecting hot-melt resin (for example, polyamide type resin) into the bottom opening of the case member 1 .

Next, a method of manufacturing a battery element according to a first embodiment of the present invention will be described.

<Battery element manufacturing steps>

A positive electrode, a separator, a negative electrode, and a separator are sequentially laminated in this order. A laminate is thus formed. The positive and negative electrodes have gel electrolyte layers on both surfaces thereof. The laminate was wound around a flat core several times in the transverse direction of the core. Thus, a wound battery element 4 was produced.

<Procedure for covering the casing parts>

The concave portion 15 accommodating the battery element 4 is formed by deep spin molding the flexible laminated part 1a. At this point, as shown in FIG. 7A , a concave portion 15 accommodating the battery element 4 is formed at a position slightly to the right from the central position of the flexible laminated member 1 a. The battery element 4 is placed in the concave portion 15 formed in the flexible laminated part 1a.

Thereafter, as shown in FIG. 7A, the rigid laminated part 1b and the flexible laminated part 1a are laminated so that the rigid laminated part 1b is slightly to the right from the flexible laminated part 1a. Thus, when the flexible laminated part 1a and the rigid laminated part 1b are laminated as shown in FIG. 7A, the left non-laminated area of the flexible laminated part 1a, and the right non-laminated area of the rigid laminated part 1b appear. . As will be described later, after the ends of the flexible laminate 1a and the rigid laminate 1b are folded outside the bottom surface of the concave portion 15 of the flexible laminate 1a, these areas make the polypropylene of the flexible laminate 1a The layers are bonded to the polypropylene layer of the rigid laminate 1b at a predetermined width.

In the layout shown in FIG. 7A, the four sides of the opening of the concave portion 15 are thermally bonded under reduced atmospheric pressure. In this case, the overlapping portions of the polypropylene layers can be thermally bonded. When the periphery of the concave portion 15 is thermally bonded, the battery element 4 is sealed.

Thereafter, as shown in FIG. 7A , a thermal bonding sheet 15 a of a predetermined shape is placed outside the bottom surface of the concave portion 15 . The thermal bonding sheet 15a is an auxiliary part for thermally bonding the nylon layer or the PET layer of the flexible laminated part 1a. In consideration of the overall thickness of the battery assembly, it is preferable that the thermal bonding sheet 15a has a thickness in the range of 10 μm to 60 μm and a melting point of about 100° C. It is preferable that the melting point of the thermal bonding sheet 15 a has no thermal influence on the battery element 4 .

Thereafter, as shown in FIG. 11, the ends of the flexible laminated member 1a and the rigid laminated member 1b are folded outside the bottom surface of the concave portion 15 of the flexible laminated member 1a. That is, the shorter sides 13a, 14a of the flexible laminated part 1a and the shorter sides 13b, 14b of the rigid laminated part 1b are folded inwardly. Subsequently, the ends of the flexible laminated part 1a and the rigid laminated part 1b are thermally bonded. Furthermore, the flexible laminated member 1 a is thermally bonded to the outside of the bottom surface of the concave portion 15 . Thus, the flexible laminated part 1 a and the rigid laminated part 1 b seal the concave portion 15 accommodating the battery element 4 . Thereby forming a top opening and a bottom opening.

As shown in FIG. 12, when the rigid laminated part 1b wraps the battery element 4, the shorter sides 13b and 14b of the rigid laminated part 1b contact or appear a joint L1 where the shorter sides 13b and 14b of the rigid laminated part 1b The end faces face each other with a short gap. In the rigid laminated part 1b, the shorter sides 13a and 14a of the flexible laminated part 1a contact or present a junction L2 where the end faces of the shorter sides 13a and 14a face each other with a short gap. In FIG. 12, reference numeral 16b denotes the polypropylene layer of the rigid laminated part 1b. Reference numeral 17b denotes a hard aluminum layer. Reference numeral 18b denotes a nylon layer or a PET layer. In this example, the shorter sides 13a and 14a are in contact or their end faces are opposed with a small gap. Alternatively, the end faces of the shorter sides 13a and 14a may face each other with a gap of a predetermined width.

As shown in Figure 12, the nylon layer or PET layer 18a of the flexible laminate 1a is placed over the heat bonding sheet 15a. Thus, the thermal bonding sheet 15a is sandwiched between the nylon layer or the PET layer 18a. Thus, when the nylon layer or the PET layer 18a is heated from the outside, they can be bonded. Furthermore, since the polypropylene layers 16a and 16b of the flexible laminated part 1a and the rigid laminated part 1b are in contact, the polypropylene layers 16a and 6b can be bonded when they are heated from the outside.

Therefore, it is possible to manufacture a battery pack covered with a laminated member serving as a case member without requiring a box-shaped resin case and right and left resin frames.

<Top cover installation procedure>

Thereafter, as shown in FIG. 13 , the electrode terminals 5 a and 5 b are connected to the circuit board 22 by, for example, resistance welding or ultrasonic welding. Thereafter, as shown in FIG. 14 , the circuit board 22 is inserted into the open space of the upper frame 2 a so that the upper frame 2 a covers the circuit board 22 . The upper bracket 2a is a resin molded part produced by, for example, various injection molding steps.

A hold member that holds the circuit board 22 horizontally is provided in the upper bracket 2a. Three openings 21 are formed on the upper surface of the upper bracket 2 a at positions corresponding to the contact portions 23 of the circuit board 22 . The contact portion 23 extends to the outside through the opening 21 . The width of the upper bracket 2a is slightly smaller than the inner dimension of the top opening in the housing part 1 .

Thereafter, as shown in FIG. 15, the lower bracket 2b is attached to the upper bracket 2a. The lower bracket 2b is a resin molded part produced by, for example, various injection molding steps. Ribs 25a, 25b and 25c are provided at both ends and at the center of one longer side of the lower frame 2b. The ribs 25a, 25b and 25c face the upper bracket 2a. The end surfaces of the ribs 25a, 25b and 25c receive the circuit board 22 of the upper bracket 2a. Thus, the ribs 25a, 25b, and 25c can support the circuit board 22 reliably.

Thereafter, as indicated by the arrow R shown in FIG. 16 , the upper bracket 2 a and the lower bracket 2 b that have been installed are rotated by 90 degrees in the counterclockwise direction by hand or a jig. The orientation of the circuit board 22 is thus changed by 90 degrees. The circuit board 22 is held by the upper frame 2a and the lower frame 2b without being exposed to the outside. Thus, when the circuit board 22 is turned, the circuit board 22 can be prevented from being soiled or damaged by hands or jigs.

Thereafter, as shown in FIG. 17, the upper bracket 2a and the lower bracket 2b are pushed into the top opening of the case member 1 (in the direction of arrow S1) while folding the electrode terminals 5a and 5b. The top cover 2 is thus mounted to the top opening of the housing part 1 . As described above, since the width of the top cover 2 is slightly smaller than the inner dimension of the top opening of the case member 1, the upper bracket 2a and the lower bracket 2b holding the circuit board 22 can be accommodated near the end surface of the case member 1 in a rigid laminate part 1b formed in the top opening.

<Bottom cover installation procedure>

Thereafter, as shown in FIG. 17 , the side wall of the bottom cover 3 is pushed into the bottom opening of the case member 1 (in the direction indicated by arrow S2 ). The side walls of the bottom cover 3 are thereby fitted to the bottom opening of the housing part 1 . Furthermore, the bottom cover 3 covers the bottom opening of the housing part 1 . The bottom cover 3 is a resin molded part made by different injection molding steps.

<Thermal bonding step>

Thereafter, with a predetermined jig, the case member 1, the top cover 2, and the bottom cover 3 are held and thermally bonded. In other words, heater parts made of metal such as copper are placed above and below the top end of the housing part 1 . The top end of the housing member 1 is pressurized by a heater member to thermally bond the periphery of the top cover 2 to the adhesive layer on the inner surface of the rigid laminate member 1b. Similarly, heater parts are placed above and below the bottom end of the housing part 1 . The bottom end of the housing part 1 is pressurized with the heater part, so that the periphery of the bottom cover 3 is thermally bonded to the polypropylene layer of the inner surface of the rigid laminate part 1b.

<Resin injection step>

Thereafter, molten resin is injected into the space formed between the battery element 4 and the top cover 2 through the through holes 26a and 26b. The resin is then allowed to cure. The top cover 2 is thus bonded to the end face of the battery element 4 .

Thereafter, molten resin is injected into the space formed between the battery element 4 and the bottom cover 3 through the through hole of the bottom cover 3 . The resin is then allowed to cure. The bottom cover 3 is thereby bonded to the end face of the battery element 4 . The injected resin is not limited to a specific type as long as the resin has low viscosity when injected into the top and bottom openings of the case member 1 . Examples of the resin are polyamide-type hot-melt resin, polyolefin-type hot-melt resin, nylon, polypropylene (PP) resin, polycarbonate (PC) resin, and acrylonitrile-butadiene-styrene resin (ABS).

In these steps, the battery pack according to the first embodiment of the present invention can be manufactured.

According to the first embodiment of the present invention, the following effects can be obtained.

The battery pack has a square or rectangular case part 1 including an open end, a battery element 4 accommodated therein, a top cover 2 and a bottom cover 3 attached to the open end of the case part 1 . The top cover 2 has concave portions 6a and 6b on both sides of one longer side. The case member 1 has cutout portions 10 a and 10 b exposing at least the concave portions 6 a and 6 b of the top cover 2 . Thus, reverse polarity connection of battery packs can be prevented without sacrificing volumetric efficiency.

The housing part 1 is composed of a flexible laminate part 1a and a rigid laminate part 1b, the shorter sides 13a and 14a of the flexible laminate part 1a being slightly smaller than the shorter sides 13b and 14b of the rigid laminate part 1b. The flexible laminated part 1 a and the rigid laminated part 1 b are stacked such that only the rigid laminated part 1 b exists on top of the housing part 1 . Thus, the top cover 2 is aligned and mounted on the shorter sides of the flexible laminated part 1a and the rigid laminated part 1b. The periphery of the top cover 2 is thermally bonded to the flexible laminate part 1a and the longer sides of the rigid laminate part 1b with the polypropylene layer of the rigid laminate part 1b.

Next, a first embodiment of the present invention will be specifically described. The present invention is not limited to the following examples. Next, a first embodiment and a comparative example will be described with reference to the drawings.

first embodiment

Fig. 18 is a perspective view showing the appearance of the battery pack according to the first embodiment of the present invention. Concave portions 6a and 6b are formed at both ends of one longer side of the top cover 2 . The case member 1 has cutout portions 10 a and 10 b exposing the concave portions 6 a and 6 b of the top cover 2 .

First comparative example

Fig. 19 is a perspective view showing the appearance of a battery pack according to a first comparative example. The structure of the battery pack according to the first comparative example is the same as that according to the first embodiment, except that the battery pack according to the first comparative example omits the cutout portions 10 a and 10 b of the case member 1 .

Second comparative example

FIG. 20 is a perspective view showing the appearance of a battery pack according to a second comparative example. The structure of the battery pack according to the second comparative example is the same as that of the battery pack according to the first embodiment except that the battery pack according to the second comparative example has protruding portions 51a and 51b for distinguishing the negative electrode from the positive electrode on the top end face of the battery pack , instead of the concave portions 6a and 6b of the top cover 2 and the cutout portions 10a and 10b of the case member 1.

Third comparative example

Fig. 21 is a perspective view showing the appearance of a battery pack according to a third comparative example. The structure of the battery pack according to the third comparative example is the same as that of the battery pack according to the first embodiment, except that the end face of the top cover 2 protrudes from the top opening of the case member 1 instead of the cutout portions 10a and 10b of the case member 1, Thus, the concave portions 6 a and 6 b of the top cover 2 are not covered by the housing part 1 .

According to the first embodiment and the comparative example, the following results were obtained.

In the battery pack according to the first comparative example, since the entire periphery of the top cover 2 is covered by the case member 1, the electronic device side does not have the flexibility to design protrusions suitable for the concave portions 6a and 6b. When the case member 1 covering the concave portions 6a and 6b is dented at the concave portions 6a and 6b due to an external impact such as when the battery pack is dropped on the floor, the battery pack can be prevented from being connected to the electronic device.

In the battery pack according to the second comparative example, although the protruding portions 51a and 51b provided on the end face of the top cover can distinguish the negative electrode from the positive electrode, the external size of the battery pack becomes large. In addition, the shape of the protruding portions 51a and 51b needs to match the shape of the battery device side. In this way, the battery pack loses its versatility. Furthermore, when the protruding portions 51a and 51b are damaged by external impact such as in the case where the battery pack is dropped to the floor, the negative and positive electrodes cannot be distinguished.

In the battery pack according to the third comparative example, since the space for thermal bonding of the top cover 2 and the case member 1 is large, it is necessary to increase the height of the top cover 2 . Therefore, the volumetric efficiency of the battery pack cannot be improved.

In contrast, in the battery pack according to the first embodiment of the present invention, since the top cover 2 has the concave portions 6a and 6b on both sides of one longer side, and the case member 1 has at least the concave portion of the top cover 2 6a and 6b expose the cutout portions 10a and 10b, so the problems in the first comparative example to the third comparative example do not occur. In other words, in the battery pack according to the first embodiment, volumetric efficiency does not decrease. In addition, the battery pack according to the first embodiment provides the advantages of no deformation of the case member 1 due to external impact such as in case the battery pack is dropped to the floor, excellent versatility, and excellent volumetric efficiency.

Next, a second embodiment of the present invention will be described. According to a second embodiment, the housing parts are molded to have elliptical cross-sections with different radii of curvature. In the following description, the same parts as those of the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

According to the second embodiment, when covering the battery element with the case member, the flexible laminated part 1a and the rigid laminated part 1b are bent along the shape of the battery element. Since the flexible laminated part 1a is spin molded, the top and bottom open ends of the rigid laminated part 1b can be easily bent. When the flexible laminated part 1a is molded, the radius of curvature from the bottom surface portion of the battery pack to the respective side portions thereof becomes small. On the other hand, the radius of curvature from each side portion of the battery pack to its upper surface is larger than the radius of curvature from the bottom portion to each side portion because of the rigidity of the metal layer of the laminated film. The flexible laminated part 1 a and the rigid laminated part 1 b are molded such that their elliptical cross-sections have different radii of curvature, as in the battery cell 29 shown in FIG. 22 . Thereafter, the CPP layers of the rigid laminate part 1b and the flexible laminate part 1a are thermally bonded. A battery assembly in which the battery element 4 is protected by the rigid laminated member 1b as the outermost layer is thus obtained.

In this case, it is preferable to place the adhesive sheet 15a outside the bottom surface of the concave portion 15 formed in the flexible laminated member 1a. The bonding sheet 15a is an auxiliary part for thermally bonding the nylon layer or the PET layer of the flexible laminated part 1a.

Thereafter, resistance welding or ultrasonic welding is performed on the negative terminal 5a and the positive terminal 5b extending from the top of the battery cell 29 molded into a predetermined shape and the protection circuit mounted on the circuit board. As shown in FIG. 23, the circuit board connected to the battery element 4 is inserted into the space of the top cover 27, in which the upper bracket 27a and the lower bracket 27b have been molded and installed.

Next, the processing steps are described with reference to FIGS. 24, 25 and 26, starting with the circuit board contained in the top cover and ending with the connection of the top cover to the rigid laminate part 1b as the housing part . 24, 25, and 26 are perspective views showing steps of mounting the top cover to the housing part.

As shown in FIG. 24 , the upper bracket 27 a is placed over the circuit board 22 connected to the battery unit 29 such that the upper bracket 27 a covers the circuit board 22 . Thereafter, as shown in FIG. 25, the lower bracket 27b and the upper bracket 27a are aligned and mounted so that the circuit board 22 is accommodated therebetween. As shown in FIG. 26 , the orientation of the top cover 27 is changed so that the lower bracket 27 b faces the battery unit 29 . Thereafter, the top cover 27 is attached to one opening portion of the battery unit 29 . When the top cover 27 is attached to the opening portion of the battery cell 29 , the electrode terminal 5 is folded and accommodated in the battery cell 29 .

The top cover 27 is thermally bonded together with the bottom cover 28 mounted to the bottom of the battery cell 29 to the rigid laminated part 1b as the housing part. As shown in FIG. 27A, the upper bracket 27a of the top cover 27 is composed of an end surface R portion 33 mounted to the inside of the battery unit 29, an upper surface portion 34 as a part of the battery pack casing, and a thermal bonding portion 34a, wherein the thermal bonding The knot portion 34a is provided at the side portion on the longer side of the upper surface portion 34, and is thermally bonded to the rigid laminated member 1b.

When the top cover 27 is mounted to the battery unit 29, contact between the upper bracket 27a and the hard laminated part 1b may be degraded. In order to avoid this problem, the end face R portion 33 is molded to have corner portions having different radii of curvature R and r. In addition, the upper surface portion 34 is molded to have a corner portion having the same radius of curvature as the end surface R portion 33 . Thus, as shown in FIG. 27C , the shape of the top cover 27 and the shape of the battery cell 29 become the same. Thereby, the contact property of the battery unit 29 with the top cover 27 is improved and the top cover 27 is prevented from coming off due to impact.

The upper surface portion 34 has flat surface portions F on left and right side surfaces. The flat portion F makes it easy to align the battery pack with the battery pack socket of the electronic device. In addition, the plane portion F prevents the battery pack from being misaligned with the battery pack slot of the electronic device.

For easy understanding of this embodiment of the present invention, FIG. 28 shows a state where a top cover 35 having an elliptical cross-section used in the prior art is attached to a battery cell. In this case, since the radius of curvature of the top cover 35 is larger than that of both ends of the bottom surface portion of the battery cell 29 , there is a gap at both ends of the bottom surface portion of the battery cell 29 as indicated by a dotted line 30 . Therefore, contact between the top cover 35 and the battery cells 29 becomes insufficient. Thus, insufficient contact can lead to failure of the battery pack.

As shown in FIG. 22 , a bottom cover 28 made of an injection-molded resin molded part is attached to the bottom opening portion of the battery cell 29 . The bottom cover 28 and the case member of the battery cell 29 are thermally bonded. The bottom cover 28 may have an approximately elliptical cross section. Alternatively, the bottom cover 28 may have corner portions having different radii of curvature r and R, like the top cover 27 . In this case, the contactability of the bottom cover 28 is improved. In addition, the bottom cover 28 can be prevented from coming off. When the bottom cover 28 has flat portions F on the left and right sides of the portion that is part of the case member, the battery pack can be easily aligned with the battery pack slot of the electronic device and misalignment can be prevented.

Thereby, a battery pack having excellent volumetric efficiency, strong external impact resistance, and easy alignment of battery pack slots can be obtained.

Next, test results of a drop test (drop test) performed on the battery pack according to the second embodiment of the present invention will be described.

A test battery pack having the structure shown in FIG. 22 was dropped from a height of 1.5 m onto a concrete floor, and then the state of separation of the top cover from the battery pack was checked. The portion of the end face R attached to the upper bracket constituting the top cover has corner portions such that the radius of curvature at both ends of the bottom surface portion of the battery pack differs from the radius of curvature at both ends of the upper surface of the battery pack. The upper surface portion of the upper bracket has a concave portion that distinguishes the negative electrode from the positive electrode at a corner portion with a large radius of curvature, and has a flat portion on a side formed between the corner portion with a large radius of curvature and the corner portion with a small radius of curvature . The drop test was performed under the following conditions.

(1) The battery pack fell with the top cover facing down.

(2) The battery pack fell with one side facing down.

As battery packs for performing the drop test, 50 test battery packs A and 50 test battery packs B were produced, wherein the battery pack A had such a cover that the radius of curvature of both sides of the mounting portion was 1 of the thickness of the battery pack. /2, the battery pack B has such a top cover that the radius of curvature from the opening portion of the concave portion accommodating the battery element to the side is smaller than the radius of curvature from the surface outside the bottom surface of the concave portion to the side. Each battery pack is tested 30 times. In the drop test (2), each side of each battery pack was tested 15 times.

The states of the battery packs after 30 tests were classified into three types. Calculate the number of battery components divided into each type.

State A: The top cover is detached from the case member by less than 1/4 area of the outer periphery of the top cover.

State B: The detachment of the top cover from the housing part is 1/4 to 3/4 area of the outer periphery of the top cover.

State C: The top cover is detached from the case member beyond 3/4 of the outer periphery of the top cover (including the state where the cover is removed from the case member).

Table 1 shows the test results of the drop test (1).

Table 1 battery pack type Installation error rate Measurement results (pieces) State A State B State C Test battery pack A 0.50% twenty one 26 3 Test battery pack B 0.02% 35 15 0

Table 2 shows the test results of the drop test (2).

Table 2 battery pack type Measurement results (pieces) State A State B State C Test battery pack A 11 32 7 Test battery pack B 30 18 2

The test results of the drop test (1) showed that in the test battery assembly A using the top cover A used in the prior art, when assembling the battery assembly, the installation error rate of the case parts and the top cover was high, and the top cover and the top cover The shedding frequency of housing parts is relatively high. In contrast, in the test battery assembly B having the top cover B according to the embodiment of the present invention, when assembling the battery assembly, the installation error rate of the case parts and the top cover was very low, and the frequency of falling off of the top cover and case parts was low. Thus, it can be clearly seen that the battery assembly B having the top cover B has higher external impact resistance than the battery assembly A having the top cover A.

The test results of the drop test (2) showed that, in the test battery assembly A using the top cover A used in the prior art, the frequency of the top cover and case parts falling off was high. In the test battery assembly B having the top cover B according to the embodiment of the present invention, the frequency of drop-off was low. In the test battery assembly A having the top cover A, the outer dimensions of the case member and the top cover A were largely different. In the test battery pack B having the top cover B, the equality of the shapes of the side portions was high. This will result in a difference in damping performance.

Next, a third embodiment of the present invention is described. In the battery pack used in the related art, the circuit board 103 is accommodated in the top cover 102 constituted by the upper frame 102a and the lower frame 102b. The top cover 102 is attached to one opening portion of the case member 1 . In this way, as shown in FIGS. 3A and 3B , the electrode terminals 105 connected to the circuit board 103 are folded and housed in the battery pack.

For easy understanding of the third embodiment of the present invention, FIG. 29 shows the arrangement of the electrode terminal lead portion and the upper bracket 102a of the battery pack used in the prior art. In the electrode terminal lead portion indicated by the dotted line shown in FIG. 29, the electrode terminal extends from the vicinity of the end portion of the rigid laminated member as the case member. Thus, when the top cover is mounted to the rigid laminated part, the opposing portion of the upper bracket 102a indicated by the solid line shown in FIG. 29 presses the electrode terminal 5 of the electrode terminal wire portion.

In order to prevent the opposing portion from interfering with the folded electrode terminal 105, it is necessary to provide a space between the top cover 102 and the battery element or reduce thermal bonding to the mounting portion of the case member. However, in the former structure, the volumetric efficiency decreases. In the latter structure, the thermal bond strength of the top cover and the rigid laminate part is insufficient.

Thus, as shown in FIG. 30, according to the third embodiment of the present invention, a cutout portion 37a is formed at a part of the upper bracket 36a. The cutout portion prevents the upper bracket 36 a from interfering with the electrode terminal 5 . FIG. 31 shows an example of the structure of a battery pack according to a third embodiment of the present invention. In this battery pack, a top cover (described later) constituted by an upper bracket 36a and a lower bracket 36b is attached to the opening portion of the rigid laminated member. Thus, extrusion of the electrode terminals and increase in thickness of the battery pack can be avoided. In the following description, the same parts as those of the first and second embodiments are denoted by the same reference numerals and their descriptions are omitted.

Fig. 32 shows the state of the electrode terminal lead part in the case where the upper bracket 36a shown in Fig. 30 is attached to the flexible laminated part 1a. As shown in FIG. 32, the mounting portion of the upper bracket 36a is inserted into the end portion of the flexible laminated member 1a. However, since the upper bracket 36 a has the cutout portion 37 a, the upper bracket 36 a does not interfere with the electrode terminal 5 . Thus, since the upper bracket 36a has the cutout portion opposed to the electrode terminal 5, the space formed between the top cover 36 and the battery element 4 can be reduced. Thus, a battery assembly in which the electrode terminal 5 does not interfere with the top cover 36 can be manufactured with sufficient thermal bonding strength.

When the thickness of the battery pack is small, the electrode terminal 5 interferes with the lower frame and protrudes in the thickness direction of the battery pack. In order to avoid this, as shown in FIG. 33, cutout portions 37b and 37c are formed on the bottom surface of the top cover 36 so that the cutout portions 37b and 37c correspond to the wiring of the electrode terminals. Thus, the electrode terminal 5 is folded and accommodated in the cutout portions 37b and 37c.

In this case, since the cutout portions 37b and 37c are formed on the side portions of the bottom surface of the lower bracket 36b, the area of the bottom surface having the cutout portions becomes small. Thus, the strength of the lower bracket 36b decreases. In addition, when the lower bracket 36b is molded of resin, the lower bracket 36b is easily twisted. In order to avoid this problem, as shown in FIG. 33, it is preferable to form a protruding wall in the longitudinal direction of the bottom surface portion of the lower bracket 36b having a thickness equal to or greater than the bottom thickness, thereby maintaining the strength and formability of the lower bracket 36b.

34A and 34B show the arrangement of the lower bracket 36b and the electrode terminal 5 in a state where the top cover is attached to the rigid laminated part. FIG. 34A shows the arrangement of the lower holder 36b and the battery element 4 in a state where the electrode terminal lead portion of the battery cell faces downward. FIG. 34B shows the arrangement of the lower holder 36b and the battery element 4 in a state where the electrode terminal lead portion of the battery cell faces downward. The lower bracket 36b is positioned close to the battery element 4 when the top cover is mounted to the rigid laminate. In FIGS. 34A and 34B , the lower bracket 36b and the battery element 4 are separated for clarity.

34A and 34B show that cutout portions 37b and 37c formed at predetermined positions of the lower bracket 36b provide space for the electrode terminal 5 and prevent the upper bracket 36a from pressing the electrode terminal 5 and preventing the thickness of the battery pack from increasing.

FIG. 35 shows structures of an upper bracket 36a, a lower bracket 36b, and a battery unit 29 according to a third embodiment of the present invention. When the thickness of the battery pack is small, as shown in FIG. 35, by virtue of the top cover 36 having the cutout portion 37a and the lower bracket 36b having the cutout portions 37b and 37c, these cutout portions can more effectively prevent the top cover 36 and the lower bracket 36b from Squeeze the electrode terminals.

When the thickness of the battery pack is relatively large, the same effect as the cutout portions 37b and 37c of the lower bracket 36b can be obtained by virtue of the lower bracket 36b having a bottom surface portion having a thickness smaller than that of the upper bracket 36a. Thus, the cutout portions 37b and 37c of the lower bracket 36b can be omitted. When the thickness of the battery pack is large, since the thickness of the upper bracket 36a is large, even if the upper bracket 36a and the lower bracket 36b are designed so that the thickness of the lower bracket 36b is smaller than the thickness of the upper bracket 36a, it will not affect the strength of the battery pack. cause adverse effects. Even if the thickness of the battery pack increases, the position of the electrode terminal lead portion does not change as long as the structure of the battery element according to this embodiment is adopted. Thus, the upper bracket 36a needs to have the cutout portion 37a.

Next, referring to FIGS. 36, 37, 38, 39A, 39B, 39C, and 39D, processing steps are described, starting with the circuit board contained in the top cover and mounted with the top cover Up to the rigid lamination part 1b is the final step. 36 to 38 are perspective views showing the steps of mounting the top cover 36 to the rigid laminated part 1b. 39A to 39D are sectional views showing the top cover 36 and the electrode terminal 5 folded.

First, as shown in FIG. 36 , the upper bracket 36 a is placed above the circuit board 22 connected to the battery unit 29 . Thereafter, as shown in FIGS. 37 and 39A, the lower bracket 36b and the upper bracket 36a are aligned and mounted so that the circuit board 22 is accommodated therebetween. Thereafter, as shown in FIGS. 38 and 39B , the orientation of the top cover 36 is changed so that the lower bracket 36 b approaches the battery unit 29 . After the top cover 36 is attached to one opening portion of the battery cell 29 (see FIGS. 39C and 39D ), the top cover 36 and the case member of the battery cell 29 are thermally bonded. When the top cover 36 is mounted to the opening portion, the electrode terminal 5 is folded and accommodated in the cutout portions 37b and 37c.

39D shows that the cutout portions 37a, 37b and 37c of the upper bracket 36a and the lower bracket 36b prevent the upper bracket 36a and the lower bracket 36b from pressing the electrode terminal wire portion of the battery cell 29. Thus, an increase in the thickness of the battery pack can be effectively prevented. Furthermore, since the cutout portion 37b of the lower bracket 36b accommodates the folded electrode terminal 5, the cutout portion 37b of the lower bracket 36b needs to have a space for the folded electrode terminal 5 coated with the sealant 7. In contrast, since the cutout portion 37 c corresponds to the wiring of the electrode terminal 5 , the cutout portion 37 c needs to have a space for the electrode terminal 5 coated with the sealant 7 .

As shown in FIG. 31 , a bottom cover 39 , which is a resin molded part manufactured in a different injection molding step, is attached to an opening portion opposite to the opening attached to the top cover 36 . The bottom cover 39 and the rigid laminated member 1 b are thermally bonded as a case member of the battery cell 29 . Alternatively, the bottom cover 39 and the case member may be connected by injecting a thermal resin material (hot melt) into the opening. When injecting thermal resin, it is necessary to prevent thermal deformation and/or damage to the circuit board.

In this way, a battery assembly having high quality, high yield, high volumetric efficiency, and pressure resistance of electrode terminals can be realized without increasing the thickness of the battery assembly.

Next, test results of tests performed on the battery pack according to the third embodiment will be described.

A test cell assembly having a structure as shown in FIG. 31 and a thickness of 3.97 mm was fabricated. After thermal bonding of the top cover and housing components, the thickness of the thermally bonded portion of the battery assembly was measured. Ten test battery assemblies were manufactured under each of the following conditions.

(1) The upper bracket and the lower bracket each have a cutout portion.

(2) The upper bracket has a cutout portion, while the lower bracket has no cutout portion.

(3) The upper bracket has no cutout portion, while the lower bracket has a cutout portion.

(4) Neither the upper bracket nor the lower bracket has a cutout portion.

Each battery pack is designed to have a maximum thickness of 4.00mm. After thermal bonding of the top cover and housing components, each test assembly was determined to be good or bad. Table 3 shows the thickness measurements for each of the test cell assemblies with the top cover and case components thermally bonded.

table 3 Cutout part of the upper bracket o o x x Cutout part of the lower bracket o x o x Battery thickness (mm) battery 1 3.97 3.97 3.97 3.97 battery 2 3.97 3.97 3.97 3.97 battery 3 3.97 3.97 3.97 3.98 battery 4 3.97 3.97 3.98 3.98 battery 5 3.97 3.98 3.98 3.98 battery 6 3.97 3.98 3.98 3.99 battery 7 3.97 3.98 3.99 3.99 battery 8 3.97 3.99 3.99 4.00 battery 9 3.98 3.99 4.00 4.01 battery 10 3.98 3.99 4.00 4.02

The test results indicated that the thickness of some battery modules of type (4) (ie, neither the upper bracket nor the lower bracket had the cutout portion) exceeded the designed maximum thickness. However, the thickness of battery assemblies of types (1), (2) and (3) did not exceed the designed maximum thickness. In particular, the battery pack of type (1) does not deviate in its thickness.

Next, a fourth embodiment of the present invention will be described with reference to the drawings. According to a fourth embodiment of the present invention, a cutout portion is formed in the central portion of the mounting rib of the lower bracket. In addition, trapezoidal circuit board support protrusions are provided parallel to or perpendicular to the longitudinal direction of the lower bracket. Thereby, the resin can be sufficiently and uniformly injected into the top cover. In this embodiment, the same parts as those of the first embodiment, the second embodiment, and the third embodiment are denoted by the same reference numerals and their descriptions are omitted.

In addition, the lower bracket 41 may be expressed as a lower bracket 41a, a lower bracket 41b, a lower bracket 41c, a lower bracket 41d, or a lower bracket 41e as described later. In the following description, when there is no need to identify the lower brackets 41 a , 41 b , 41 c , 41 d , and 41 e , they are simply indicated as the lower bracket 41 .

As shown in FIG. 40, the circuit board 22 is inserted into the free surface of the upper bracket 40a. The upper bracket 40 a is mounted on the circuit board 22 such that the upper bracket 40 a covers the circuit board 22 . The upper bracket 40a has a holding portion that holds the circuit board 22 horizontally. A plurality of (for example, three) openings 21 are formed on the upper bracket 40 a at positions corresponding to the contact portions 23 of the circuit board 22 . The contact portion 23 extends to the outside through the opening 21 . The width of the upper bracket 40 a is slightly smaller than the width of the opening on the top end face of the battery unit 29 .

Through-holes 26 a and 26 b are formed near both ends of the upper bracket 40 a such that the through-holes 26 a and 26 b do not interfere with the circuit board 22 . The diameters of the through holes 26a and 26b are in the range of Φ0.8mm to Φ1.5mm.

The lower bracket 41a is, for example, a resin molded part manufactured in various injection molding steps. In FIG. 41, reference numeral 41a denotes a first embodiment of the lower bracket. Ribs 42a and 42b are formed at both ends of the lower bracket 41a. Ribs 42a and 42b are mounted to upper bracket 40a. Cutout portions are formed at central portions of the ribs 42a and 42b.

In addition, a circuit board supporting protrusion 43a is formed near the center of the lower bracket 41a. The substrate support protrusion 43a has a surface parallel to the longitudinal direction of the lower bracket 41a. When the upper bracket 40a and the lower bracket 41a are installed, the circuit board support protrusion 43a holds the circuit board 22 disposed therebetween.

Fig. 42 shows a state where the upper bracket 40a and the lower bracket 41a are attached. The lower bracket 41a is mounted to the upper bracket 40a such that the circuit board 22 is interposed therebetween. According to the fourth embodiment, the upper bracket 40a and the lower bracket 41a are mounted by mechanical connection means. In other words, as shown in FIG. 43, the upper bracket 40a has fixing holes 44a and 44b. A hook 45a formed at the edge of the rib 42a of the lower bracket 41a is inserted into the hole 44a. A hook 45b formed at the edge of the rib 42a of the lower bracket 41a is inserted into the hole 44b. Thereby, the upper bracket 40a and the lower bracket 41a are installed.

Rotate the installed upper bracket 40a and lower bracket 41a by 90 degrees in the counterclockwise direction by hand or a jig, as indicated by the arrow R shown in FIG. 44 . Thus, the orientation of the circuit board 22 is changed by 90 degrees. The circuit board 22 is held by the upper bracket 40a and the lower bracket 41a, and is not exposed to the outside. Thus, when the circuit board 22 is turned, it is possible to prevent the hand or the jig from staining and damaging the circuit board 22 .

Thereafter, the installed upper bracket 40 a and lower bracket 41 a are inserted into the battery unit 29 . Thereafter, hot-melt resin is injected into the battery cell 29 through the through holes 26a and 26b. The injected hot-melt resin holds the circuit board 22 and improves the mechanical strength of the battery pack.

In FIG. 45, reference numeral 41b denotes a second example of the lower bracket. The lower bracket 41b has a circuit board supporting protrusion 43b integrally formed thereon. The circuit board support protrusion 43b has a surface perpendicular to the longitudinal direction of the lower bracket 41b. The circuit board supporting protrusion 43b is formed in a trapezoidal shape in which the edges of the circuit board supporting protrusion 43b are tapered. Thus, since the circuit board supporting protrusions reduce the resistance of the hot-melt resin, the injectability of the resin can be improved.

Next, a third example of the lower bracket will be described. As a third example, as shown in FIG. 46, projecting portions 46a and 46b protrude from ribs at both ends of the lower bracket 41c in the longitudinal direction of the lower bracket 41c. The lower bracket 41c improves the injectability of the hot-melt resin more than in the foregoing examples.

In other words, when the upper bracket 40a and the lower bracket 41c are mounted, the protruding portions 46a and 46b face the through holes 26a and 26b of the upper bracket 40a, respectively. FIG. 47 is a bottom perspective view showing the vicinity of the through hole 26a in a state where the upper bracket 40a and the lower bracket 41c are installed. As shown in FIG. 47, since the lower bracket 41c and the upper bracket 40a are mounted such that the protruding portion 46a of the lower bracket 41c covers the through hole 26a of the upper bracket 40a, hot melt resin can be equally injected. Therefore, the injectability of resin can be improved.

The protrusions 46a and 46b prevent the metal pin from contacting the battery element 4 when the metal pin is inserted into the battery pack through one of the through holes 26a and 26b. Thus, short circuiting of the protruding portions 46a and 46b can be prevented.

Next, test results of a drop test performed on the battery pack according to the fourth embodiment will be described. A drop test was performed by dropping the battery pack from a height of 1.5 m onto a concrete floor with the top cover 40 facing down, and then the top cover 40 and case components were checked for abnormality and drop-off.

Fifty battery assemblies each having a lower holder 41a, a lower holder 41b, a lower holder 41c, a lower holder 41d shown in FIG. 48, and a lower holder 41e shown in FIG. 49 were produced and tested. The lower bracket 41d has ribs 42a and 42b at both ends in the longitudinal direction. Ribs 42a and 42b are mounted to top cover 40a. Cutout portions are formed at central portions of the ribs 42a and 42b. Cutout portions are formed at central portions of the ribs 42a and 42b. The circuit board support protrusion 43c is integrally formed on the lower bracket 41d. The circuit board supporting protrusion 43c has a rectangular surface. The rectangular surface is formed near the center of the lower bracket 41d. The rectangular surface is formed perpendicular to the longitudinal direction of the lower bracket 41d.

The lower bracket 41e is used in prior art battery packs. Ribs 42a' and 42b' mounted to the top cover 40a are formed at both ends of the lower bracket 41e. The circuit board support protrusion 43c is integrally formed on the lower bracket 41e. The circuit board supporting protrusion 43c has a rectangular surface. The rectangular surface is formed near the center of the lower bracket 41e. The rectangular surface is formed perpendicular to the longitudinal direction of the lower bracket 41e. Table 4 shows the test results of the drop test.

Table 4 Type of lower bracket Number of battery packs with circuit abnormalities state A B C 41a 0/50 0/50 6/50 44/50 41b 0/50 5/50 12/50 33/50 41c 0/50 1/50 8/50 41/50 41d 0/50 8/50 20/50 22/50 41e 7/50 12/50 23/50 15/50

"Number of battery assemblies in which circuit abnormality occurred" indicates the number of battery assemblies in which abnormality of the circuit board 22 was detected. "Status" indicates the number of battery assemblies in which the top cover 40 is deformed. The "state" is subdivided into "state A" to "state C" according to the degree of detachment of the top cover 40 from the housing components. "Status A" indicates the number of battery assemblies in which the top cover 40 came off to a degree of 3/4 or more of the outer periphery (including removal of the top cover 40 ). "State B" indicates the number of battery assemblies in which the top cover 40 is detached from 1/2 to 3/4 of the outer periphery. "Status C" indicates the number of battery assemblies whose top cover 40 is detached to less than 1/2 of the outer periphery. In Table 4, " ^* /50" indicates that in the drop test of 50 battery assemblies manufactured with the lower holders 41a to 41e, the number of battery assemblies in which a circuit board abnormality occurred or one of "state A" to "state C" occurred quantity. In the battery pack using the lower holder 41a to the lower holder 41d, abnormality of the circuit board did not occur. Seven of the 50 battery modules using the lower bracket 41e had circuit board abnormalities. In the drop test of the battery pack using the lower bracket 41a, the degree of detachment of the top cover 40 from the case components of "state A" did not occur. "State B" occurred in 6 out of 50 battery packs using the lower bracket 41a. "State C" occurred in 44 out of 50 battery packs using the lower bracket 41a.

As a result of the drop test, in the battery pack using the lower bracket 41a, the circuit board 22 showed no abnormality. Also, "State A" does not appear. In the battery pack using the lower brackets 41b and 41c, no abnormality occurred in the circuit board 22 . "Status A" occurred in 1 or several of the 50 battery packs. The other battery components came off to a lesser extent.

In the battery pack using the lower bracket 41d, no abnormality occurred in the circuit board 22. The degree of detachment of the top cover 40 is greater in the battery pack using the lower bracket 41d than in the battery pack using the lower brackets 41a to 41c. In some battery packs using the lower bracket 41e, abnormality occurred in the circuit board 22. The degree of detachment of the top cover 40 in the battery pack using the lower bracket 41e is greatest in the battery packs using the other lower brackets 41a to 41d.

The battery pack using the five types of lower brackets 41 was disassembled, and then the inside of the battery pack was inspected. In the battery pack using the lower holder 41e, the resin was not sufficiently injected into the battery pack, and many of them had large voids.

The first, second, third, and fourth embodiments of the present invention have been described. However, the present invention is not limited to these Examples. Rather, various modifications can be made according to the spirit of the present invention.

For example, the numerical values used in the foregoing first embodiment, second embodiment, third embodiment, and fourth embodiment are merely examples. Other values may be used as necessary.

The aluminum (Al) foils used for the rigid and flexible laminates are not limiting to the foregoing examples. Alternatively, various materials may be used. In particular, for rigid laminated parts, other rigid aluminum materials such as Group 2000, Group 5000, and Group 6000 may be used in addition to JIS 1100H group.

In addition, a plurality of substrate supporting protrusions 43a and 43b may be formed as necessary. As shown in FIG. 50, when a plurality of substrate supporting protrusions 43a and 43b are formed, they can support the circuit board 22 reliably.

It should be understood by those skilled in the art that various changes, combinations, sub-combinations and substitutions may be made depending on design requirements and other factors within the scope of the appended claims or the equivalents thereof.

The present invention includes Japanese Patent Application No. 2005-013862 filed on January 21, 2005, Japanese Patent Application No. 2005-013863 filed on January 21, 2005, and Japanese Patent Application No. 2005 filed on January 21, 2005. 2005-014616 and Japanese Patent Application No. 2005-014758 filed Jan. 21, 2005 are hereby incorporated by reference in their entirety for subject matter.

Claims (14)

1. A box-shaped or plate-shaped battery assembly, comprising: a rigid housing member having first and second openings formed at both ends; A box-shaped or plate-shaped battery element housed in a housing part and having electrode terminals; a cover molded from resin and fitted to the first opening; and A circuit board connected to the electrode terminal wires and housed in the cover, Wherein, at least the electrode terminal lead extends from the first opening; wherein the cover has a concave portion at both ends of one longer side; wherein the housing member has a cutout portion exposing at least the concave portion of the cover, and Wherein at least one longer side of the cover is thermally bonded to the housing part. 2. A battery pack according to claim 1, wherein one end of the housing member protrudes from one end of the battery element by about the thickness of the cover through an opening fitted to the cover, and Wherein, the thermal bonding layer is arranged in the protruding part of the housing part. 3. A battery pack according to claim 1, wherein the housing part consists of a first laminated part and a second laminated part having substantially the same dimensions, Wherein, the first laminated part has a concave part for accommodating the battery element, and the first laminated part and the second laminated part are laminated so that the second laminated sheet part covers the opening of the concave part, and the opening of the first laminated part Peripheral sealing of the battery element, the electrode terminal wires connected to the battery element extend from the sealing part, the ends of the first laminated part and the second laminated part are connected at the bottom outside of the concave part of the first laminated part, the first laminated part Both sides of the component and the second laminated component protrude and are formed in an oval shape. 4. A battery pack, comprising: a housing part consisting of a first laminated part and a second laminated part, the first laminated part having a concave portion; The battery element accommodated in the concave portion formed in the first laminated part, the first laminated part and the second laminated part are laminated such that the second laminated part covers the opening of the concave part, and the first laminated part The periphery of the opening is sealed, both ends of the second laminated part are connected outside the bottom of the concave part of the first laminated part, and both sides of the second laminated part protrude to form a substantially oval shape; and at least one resin molded cover mounted to the opening portion formed by the housing member, wherein corner portions are formed on the two shorter sides of the cover, and Wherein, the radius of curvature of the corner portion of the curved surface from the opening of the concave portion of the first laminated member to each shorter side is smaller than that from the outer surface of the bottom of the concave portion of the first laminated member to each shorter side The radius of curvature of the corners of the surface. 5. A battery pack according to claim 4, Wherein, the cover is at the corner portion from the opening of the concave portion of the first laminated part to each shorter side and from the bottom outer surface of the concave portion of the first laminated part to the corner of each shorter side There are flat parts between the parts. 6. A battery pack according to claim 4, Wherein, the concave portion is formed at the corner portion of the curved surface from the bottom outer surface of the concave portion of the first laminated member to the shorter side. 7. A box-shaped or plate-shaped battery assembly, comprising: a rigid housing member having a first opening and a second opening at both ends; A box-shaped or plate-shaped battery element housed in a case member and having electrode terminal wires connected to a circuit board; and a first cover and a second cover covering the first opening and the second opening, the first cover is mounted to the first opening, the circuit board is accommodated in the first cover, Wherein, the first cover has at least an upper bracket and a lower bracket, the upper bracket is molded of resin and holds the circuit board on the opposite side of the battery element, the lower bracket is molded of resin and holds the circuit board on the side of the battery element, and the upper bracket The bracket and lower bracket are bonded or mechanically connected, and Wherein, the upper bracket has a cutout portion corresponding to an electrode terminal wire portion of an electrode terminal extending from the battery element. 8. A battery pack according to claim 7, Wherein, the lower bracket has cutouts on both sides of the bottom end, the cutouts formed on the first side correspond to the lead wires of the electrode terminals, and the cutouts formed on the second side correspond to the wires of the electrode terminals. 9. A battery pack according to claim 8, Wherein, the lower support has a protruding part at the bottom of the circuit board side and a protruding wall in the longitudinal direction of the lower support, the protruding part supports the circuit board, and the height of the protruding wall is lower than that of the protruding part. 10. A battery pack according to claim 8, Wherein, the first cover is fitted to the first opening of the case member such that the electrode terminal is folded and accommodated in the cutout portion of the lower bracket. 11. A box-shaped or plate-shaped battery assembly, comprising: a rigid housing member having a first opening and a second opening at both ends; A box-shaped or plate-shaped battery element housed in a case member and having electrode terminal wires connected to a circuit board; and a first cover and a second cover covering the first opening and the second opening, the first cover is mounted to the first opening, the circuit board is accommodated in the first cover, Wherein, the first cover has at least an upper bracket and a lower bracket, the upper bracket is molded of resin and holds the circuit board on the opposite side of the battery element, the lower bracket is molded of resin and holds the circuit board on the side of the battery element, and the upper bracket Bracket and lower bracket bonded or mechanically connected, wherein the upper bracket has a through hole through which resin is injected into a space formed between the battery element and the first cover, wherein the lower bracket has protruding portions at both ends, the protruding portion has a cutout portion at a central portion, the lower bracket has at least one substrate supporting protrusion protruding on the circuit substrate side near the central portion, and Among them, the resin is injected into a space formed between the battery element and the first cover. 12. A battery pack according to claim 11, Wherein, the substrate supporting protrusion has a surface parallel to the longitudinal direction. 13. A battery pack according to claim 11, Wherein, the substrate supporting protrusion has a surface perpendicular to the longitudinal direction, and the surface has a tapered trapezoidal shape. 14. A battery pack according to claim 11, Wherein, the lower bracket has extensions extending from the protrusions at both ends.

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