JP7265715B2 - secondary battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to a secondary battery in which an electrode assembly is housed inside an exterior body made of a laminate film.

In recent years, lithium-ion secondary batteries, nickel-hydrogen batteries, and other secondary batteries have become more important as power sources for vehicles, personal computers, and mobile terminals. In particular, lithium-ion secondary batteries are light and have high energy density, so they are preferably used as high-output power sources for vehicles. As an example of this type of secondary battery, there is a secondary battery in which an electrode body is accommodated inside a laminate film outer package (hereinafter also referred to as a “laminate battery”). When constructing such a laminate battery, the outer peripheral edges of a pair of laminate films are welded while the electrode body is sandwiched between the laminate films. As a result, an exterior body having a welded portion on the outer peripheral edge is formed, and the electrode body is housed inside the exterior body in a sealed state. Examples of such laminated batteries are disclosed in Patent Documents 1-5.

By the way, in a secondary battery, the internal pressure of the battery may change due to decompression processing during the manufacturing process, gas generation due to charging and discharging, and the like. In a laminated battery, deformation such as expansion/contraction may occur in the exterior body due to such a change in the internal pressure of the battery. When the amount of deformation of the armor increases, the welded portion of the armor may crack due to stress during deformation. For this reason, in the laminated battery, it has been proposed to house a protective member inside the exterior body, which restricts deformation of the exterior body due to changes in internal pressure and prevents cracking of the welded portion. Patent Literature 1 discloses a laminate battery provided with such a protective member (deformation restricting member).

JP 2005-317312 A JP-A-2001-57190 JP-A-2003-92132 JP-A-2001-283798 JP-A-2000-195475

However, when a protective member as in Patent Document 1 is provided inside the outer package, the frequency of manufacturing batteries with significantly reduced battery performance increases, and the problem of reduced production efficiency due to disposal of defective products becomes a problem. was there. The present invention has been made to solve such problems, and its main purpose is to prevent degradation of battery performance during the manufacturing process in a secondary battery provided with a protective member that prevents cracking of the welded portion. The purpose is to provide technology to

In order to achieve the above object, the present inventors have investigated the cause of significant deterioration in battery performance in the production of laminated batteries provided with protective members, and found the following findings.

As shown in FIG. 9 , in secondary battery 100 having protective member 140 , protective member 140 is arranged between side edge portion 120 a of outer package 120 and electrode assembly 110 . Since the protective member 140 can restrict the contraction of the exterior body 120 toward the center in the width direction X (see arrow A in the figure), it is possible to prevent the welded portion 126 of the exterior body 120 from cracking due to the stress during contraction. . However, in manufacturing the secondary battery, decompression processing may be performed to evacuate the inside of the exterior body 120 . In this decompression process, the exterior body 120 shrinks greatly and presses the protection member 140 toward the center in the width direction X, so that the protection member 140 moves to the center in the width direction X as indicated by an arrow B in the figure. may come into contact with the electrode body 110 as a result. The inventors of the present invention considered that damage to the electrode body 110 due to contact with the protective member 140 is the cause of deterioration in battery performance in the manufacturing process.

The secondary battery disclosed here is made based on the above-mentioned knowledge. Such a secondary battery is composed of an electrode body having a terminal connection portion in which a plurality of layers of current collector foils are mutually joined, and a pair of laminate films facing each other with the electrode body sandwiched therebetween, and the pair of laminate films are welded together. and a plate-shaped conductive member extending along the width direction, one end of which is connected to the terminal connection portion and the other end of which is exposed to the outside of the exterior body. terminals. The secondary battery disclosed herein has a terminal insertion hole through which an electrode terminal is inserted. It further includes a protection member that restricts shrinkage deformation of the facing exterior body, and a movement restricting means that restricts movement of the protection member toward the center in the width direction.

In the secondary battery disclosed herein, the movement of the protective member toward the center in the width direction (the electrode body side) is regulated by the movement regulating means. Contact between the member and the electrode body can be prevented. Therefore, according to the secondary battery disclosed herein, deterioration of battery performance due to breakage of the electrode assembly can be prevented in spite of the provision of the protective member.

Further, in a preferred aspect of the secondary battery disclosed herein, at least one engaging portion that engages the protective member and the electrode terminal is formed as the movement restricting means. As a result, the movement of the protective member toward the center in the width direction can be appropriately restricted, and damage to the electrode assembly due to contact with the protective member can be prevented.

In the aspect in which the engaging portion is formed as the movement restricting means, the engaging portion includes a convex portion protruding inward in the depth direction from the inner wall of the terminal insertion hole of the protective member, and a convex portion extending in the depth direction from both side edges of the electrode terminal. It is preferably formed by fitting an inward recess. Thereby, the movement of the protection member toward the center in the width direction can be appropriately restricted.

In the aspect in which the engaging portion is formed as the movement restricting means, the engaging portion includes projections protruding outward in the depth direction from both side edges of the electrode terminal and protrusions extending in the depth direction from the inner wall of the terminal insertion hole of the protective member. It is preferable that it is formed by fitting with an outward recessed portion. Also in this aspect, the movement of the protection member toward the center in the width direction can be appropriately restricted.

In the aspect in which the engaging portion is formed as the movement restricting means, the protective member includes a lower member having a stepped portion thinner than both end portions at the center portion in the depth direction, and upper surfaces of both end portions of the lower member. and an upper member having a flat lower surface in surface contact with the upper member. By using the protective member divided into two members in this manner, the protective member and the electrode terminal can be easily engaged inside the terminal insertion hole, which can contribute to the improvement of manufacturing efficiency. .

In another preferred aspect of the secondary battery disclosed herein, a locking member that locks the protective member to the terminal connecting portion is formed as the movement restricting means. In this way, even when the protective member is engaged with the terminal connection portion of the electrode body, it is possible to restrict the movement of the protective member toward the center in the width direction, thereby preventing deterioration of battery performance due to breakage of the electrode body. .

In the aspect in which the locking member is attached as the movement restricting means, it is preferable that a pair of locking members be attached to the outer end portions in the width direction of the terminal connecting portion so as to extend in the depth direction with the electrode terminals therebetween. . Thereby, the protective member can be appropriately locked to the terminal connection portion, and the movement of the protective member toward the center in the width direction can be restricted.

In addition, in a mode in which a pair of locking members are attached so as to sandwich the electrode terminal, the dimension _L1 from the end of one locking member to the end of the other locking member is the length of the terminal insertion hole in the depth direction. It is preferably longer than dimension L ₂ (L ₁ >L ₂ ). Thereby, the movement of the protective member toward the center in the width direction can be restricted more reliably.

In another preferred aspect of the secondary battery disclosed herein, an adhesive layer for adhering the protective member to the inner wall surface of the exterior body is provided as the movement restricting means. In this way, even when the outer casing and the protective member are adhered together, it is possible to restrict the movement of the protective member toward the center in the width direction, thereby preventing damage to the electrode assembly.

In another preferred aspect of the secondary battery disclosed herein, the protective member includes rib portions that sandwich the electrode terminals in the height direction. In a conventionally known secondary battery, when an external force along the height direction is applied to the electrode terminal exposed to the outside of the outer package, the electrode terminal reciprocates in the height direction, causing the electrode terminal and the electrode body to reciprocate. Connections may be damaged. In contrast, in this aspect, the reciprocating motion of the electrode terminal along the height direction can be restricted by the rib portion of the protection member that sandwiches the electrode terminal. Therefore, according to this aspect, it is possible to prevent the connecting portion between the electrode terminal and the electrode body from being damaged.

Further, in the aspect in which the electrode terminal is sandwiched by the rib portion of the protective member, it is preferable that the rib portion sandwiches the electrode terminal positioned inside the terminal insertion hole in the entire depth direction. As a result, the reciprocating motion of the electrode terminal due to an external force can be reliably restricted, and damage to the connecting portion between the electrode terminal and the electrode body can be suitably prevented. In addition, in this aspect, since the terminal insertion hole is closed by the rib portion, foreign matter (such as fine active material particles) is prevented from being released to the outside of the battery when the welded portion of the outer package is opened. can.

Further, in the embodiment in which the electrode terminal is sandwiched between the rib portions of the protective member, it is preferable that the pressure inside the exterior body is reduced by 10 kPa or more as compared with the standard atmospheric pressure. As a result, the protection member is pressurized from the outside of the exterior body, so that the electrode terminal can be more preferably held between the rib portions.

In another preferred aspect of the secondary battery disclosed herein, the protective member is formed with an internal cavity that communicates with the internal space of the exterior body. In the secondary battery, the internal pressure of the exterior body tends to increase due to the generation of gas from the electrode body. Therefore, if a secondary battery that has exceeded the warranty period is used for a long period of time, the increase in internal pressure may cause the exterior body to expand and the welded portion to crack. On the other hand, in this aspect, since the protective member is formed with an internal cavity that communicates with the internal space of the exterior body, the volume that can accommodate gas inside the exterior body is increased. As a result, it is possible to extend the period until the outer package expands, which contributes to extending the warranty period of the battery.

In another preferred aspect of the secondary battery disclosed herein, a gap is formed between the end surface of the protective member on the electrode assembly side and the electrode assembly. In a conventional secondary battery, in order to prevent damage due to contact between the protective member and the electrode body, the end face of the protective member on the electrode body side is shaped so as to follow the electrode body, and the end face of the protective member on the electrode body side and the electrode body are in contact with each other. It was necessary to make contact with On the other hand, in the secondary battery disclosed herein, since contact between the protective member and the electrode body can be prevented, a gap can be formed between the end surface of the protective member on the electrode body side and the electrode body. As a result, the volume inside the exterior body increases, so that cracking of the welded portion due to expansion of the exterior body can be suppressed.

1 is a plan view schematically showing a secondary battery according to a first embodiment of the invention; FIG. FIG. 2 is a cross-sectional view taken along the line II-II in FIG. 1; FIG. 2 is a plan view schematically showing the internal structure near the electrode terminals of the secondary battery according to the first embodiment of the present invention; FIG. 4 is a plan view for explaining the secondary battery movement restricting means according to the first embodiment of the present invention. It is a bottom view which shows the upper part of the protection member in the 1st Embodiment of this invention. FIG. 4 is a plan view showing the lower portion of the protective member according to the first embodiment of the present invention; FIG. 10 is a plan view for explaining a secondary battery movement restricting means according to a second embodiment of the present invention; FIG. 11 is a plan view illustrating a secondary battery movement restricting means according to a third embodiment of the present invention; FIG. 11 is a cross-sectional view illustrating a secondary battery movement restricting means according to a fourth embodiment of the present invention; FIG. 2 is a cross-sectional view schematically showing an internal structure near electrode terminals of a conventional secondary battery. FIG. 10 is a cross-sectional view schematically showing the internal structure near the electrode terminals of a secondary battery according to a fifth embodiment of the present invention; FIG. 11 is a perspective view illustrating the dimensional relationship between electrode terminals and holding members in a secondary battery according to a fifth embodiment of the present invention; FIG. 11 is a cross-sectional view schematically showing the internal structure near the electrode terminals of the secondary battery according to the sixth embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing an internal structure near electrode terminals of a conventional secondary battery.

A lithium ion secondary battery will be described below as an example of the secondary battery disclosed herein. Note that the secondary battery disclosed here is not limited to a lithium ion secondary battery, and may be, for example, a nickel metal hydride battery. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention (e.g., electrode bodies, exterior bodies, electrode terminals, electrolyte materials, etc.) can be found in the prior art in the field. It can be grasped as a design matter of a person skilled in the art based on.

In addition, in the drawings shown in this specification, members and portions having the same function are denoted by the same reference numerals. Also, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect the actual dimensional relationships. Further, the symbol X in each figure indicates the "width direction", the symbol Y indicates the "depth direction", and the symbol Z indicates the "height direction". Note that these directions are determined for convenience of explanation, and are not intended to limit the installation mode of the secondary battery disclosed herein.

The secondary battery disclosed herein has a movement restricting means that restricts the movement of the protection member housed inside the exterior body toward the center in the width direction (toward the electrode body). As a result, even if the outer package shrinks significantly during the depressurization process, the protection member and the electrode assembly can be prevented from coming into contact with each other, thereby preventing deterioration in battery performance due to breakage of the electrode assembly.
Various structures corresponding to the structure of the secondary battery and the like can be employed for such movement restricting means. In the following, secondary batteries according to first to fourth embodiments will be described as examples of secondary batteries having movement restricting means.

1. First Embodiment FIG. 1 is a plan view schematically showing a secondary battery according to a first embodiment. FIG. 2 is a sectional view taken along line II--II in FIG. Also, FIG. 3 is a plan view schematically showing the internal structure near the electrode terminals of the secondary battery according to the first embodiment (in other words, FIG. state plan view). FIG. 4 is a plan view for explaining the secondary battery movement restricting means according to the first embodiment (in other words, FIG. 4 is a plan view of a state in which the exterior body 20 and the upper member 42 in FIG. 2 are removed). Figure).

As shown in FIGS. 1 to 3, the secondary battery 1 according to this embodiment includes an electrode assembly 10, an outer package 20, an electrode terminal 30, and a protection member 40. As shown in FIGS. Each member will be described below. In the secondary battery 1 according to the present embodiment, substantially the same structure is provided on the right side and the left side in the width direction X, but for convenience, the structure near the electrode terminal 30 on the left side will be mainly described below. .

(1) Electrode body As shown in FIGS. 2 to 4, a terminal connection part 14 is formed by mutually bonding multiple layers of current collector foils on the side edge of the electrode body 10 in the width direction X. . Although detailed illustration is omitted, the electrode assembly 10 includes an electrode sheet composed of a positive electrode and a negative electrode. Each electrode sheet includes a collector foil, which is a foil-shaped metal member, and an electrode mixture layer coated on the surface of the collector foil. On one side edge of each electrode sheet, an uncoated portion is formed where the collector foil is exposed without being coated with the electrode mixture layer. Then, the positive and negative electrode sheets are arranged so that the uncoated portion of the positive electrode sheet protrudes from one side edge and the uncoated portion of the negative electrode sheet protrudes from the other side edge. The electrode assembly 10 is formed by stacking a plurality of layers of . A core portion 12 is formed in the central portion of the electrode body 10 in the width direction X, in which the electrode mixture layers of the positive electrode and the negative electrode are stacked. Then, on both side edges in the width direction X, regions where a plurality of layers of uncoated portions (current collector foil) are overlapped are formed. The terminal connection portion 14 is formed by sandwiching the ends of the region where the current collecting foils are overlapped and joining the current collecting foils together. As shown in FIG. 2, between the core portion 12 and the terminal connection portion 14, a converging portion 13 is formed in which the unbonded collector foil converges toward the terminal connection portion 14. As shown in FIG.

The detailed structure of the electrode body is not particularly limited as long as the terminal connecting portion is formed. For example, the electrode body may be a wound electrode body obtained by winding a long electrode sheet, or may be a laminated electrode body obtained by laminating a plurality of rectangular electrode sheets. In addition, materials that can be used for this type of secondary battery can be used without particular limitation for the materials of each member (for example, current collector foil, electrode mixture layer, etc.) that constitutes the electrode body, and the technology disclosed herein is not limited, detailed description is omitted.

(2) Exterior Body The exterior body 20 is composed of a pair of laminated films 22 and 24 facing each other with the electrode body 10 interposed therebetween. As shown in FIG. 1, the outer peripheral edge of the exterior body 20 is formed with a welded portion 26 to which the pair of laminate films are welded. As a result, the electrode body 10 is housed inside the exterior body 20 in a sealed state.

(3) Electrode Terminal The electrode terminal 30 is a plate-shaped conductive member extending along the width direction X. As shown in FIG. One end 32 of the electrode terminal 30 is connected to the lower surface 14 a of the terminal connection portion 14 of the electrode body 10 . Also, the other end 34 of the electrode terminal 30 is exposed to the outside of the exterior body 20 . The electrode terminal 30 is sandwiched between a pair of laminate films 22 and 24 at the portion where the electrode terminal 30 penetrates the exterior body 20, and the laminate films 22 and 24 are welded to the surface of the electrode terminal 30. there is Specifically, as shown in FIG. 3, a welding film 36 extending along the depth direction Y is provided near the center of the electrode terminal 30 in the width direction X. As shown in FIG. The welding film 36 is made of a heat-welding resin material such as polypropylene. The laminate films 22 and 24 can be preferably welded to the surface of the electrode terminal 30 by arranging each member so that the welding film 36 and the outer peripheral edge portions of the laminate films 22 and 24 overlap each other and performing the welding process. can.

(4) Protective Member As shown in FIG. 2 , in the secondary battery 1 according to the present embodiment, a protective member 40 is housed inside the exterior body 20 . A terminal insertion hole 46 is formed in the protective member 40 , and the electrode terminal 30 inserted through the terminal insertion hole 46 is exposed to the outside of the exterior body 20 . In addition, the protective member 40 is arranged between the side edge portion 20a of the exterior body 20 and the electrode body 10 in the width direction X. As shown in FIG. Since the protective member 40 can restrict the contraction deformation of the exterior body 20 toward the center in the width direction X, it is possible to prevent the welded portion 26 of the exterior body 20 from cracking due to the stress during contraction. In addition, it is preferable that the protective member 40 is made of a resin material having a predetermined strength. Thermoplastic resins such as polypropylene, polyethylene, and polyphenylene sulfide, and thermosetting resins such as phenolic resins and epoxy resins can be preferably used as the resin material forming the protective member 40 .

Also, the protective member 40 in this embodiment is divided into two members, an upper member 42 and a lower member 44, and is constructed by combining these members. A bottom view of the upper member 42 of the protection member 40 is shown in FIG. 5A, and a plan view of the lower member 44 is shown in FIG. 5B. As shown in FIGS. 5A and 5B, the shape of the upper member 42 and the lower member 44 in plan view (bottom view) is substantially U-shaped. Circular depressions 42 a are formed at both ends of the bottom surface of the upper member 42 . On the other hand, circular projections 44a are formed on both ends of the upper surface of the lower member 44. As shown in FIG. The protective member 40 is constructed by bringing the upper surface of the lower member 44 into surface contact with the bottom surface of the upper member 42 so that the projection 44a of the lower member 44 is inserted into the recess 42a of the upper member 42. . At this time, since the lower member 44 has a stepped portion 44b thinner than both ends in the central portion in the depth direction Y, the lower member 44 and the upper member 42 are combined to form the protective member 40. When constructed, a terminal insertion hole 46 is formed at a position corresponding to the stepped portion 44b. In the protection member 40 having such a configuration, the structure in which the electrode terminals 30 are inserted into the terminal insertion holes 46 can be easily formed simply by assembling the upper member 42 after placing the electrode terminals 30 on the stepped portion 44b of the lower member 44. can build.

(5) Movement Restricting Means As described above, the secondary battery disclosed herein includes movement restricting means for restricting the movement of the protective member to the center in the width direction. As shown in FIG. 4, in the secondary battery 1 according to the present embodiment, an engaging portion E for engaging the protective member 40 and the electrode terminal 30 is formed as the movement restricting means. Specifically, recesses 38 recessed inward in the depth direction Y are formed on both side edges of the electrode terminal 30 in this embodiment. On the other hand, a protrusion 46c protruding inward in the depth direction Y is formed on the inner wall 46a of the terminal insertion hole 46 of the protective member 40. As shown in FIG. In the present embodiment, the engaging portion E is formed by fitting the concave portion 38 of the electrode terminal 30 and the convex portion 46c of the protective member 40 together. As described above, the electrode terminal 30 is connected (fixed) to the terminal connection portion 14 and therefore does not move with respect to the electrode assembly 10 . Since the protection member 40 is engaged with the electrode terminal 30, which is a member fixed in this way, the movement of the protection member 40 to the center side in the width direction X (the electrode body 10 side) can be preferably restricted. Therefore, according to the present embodiment, even if the exterior body 20 shrinks significantly during decompression processing or the like, the electrode body 10 can be prevented from being damaged due to contact with the protective member 40, thereby preventing deterioration of battery performance in the manufacturing process.

Moreover, in the secondary battery 1 according to the present embodiment, the protective member 40 is formed by combining two members, the upper member 42 and the lower member 44 . Therefore, the projection 46 c formed on the inner wall 46 a of the terminal insertion hole 46 can be fitted into the recess 38 of the electrode terminal 30 . Therefore, according to the present embodiment, the assembly of the terminal insertion hole 46 and the electrode terminal 30 can be facilitated, which contributes to improving the manufacturing efficiency.

The dimensions of the concave portion 38 and the convex portion 46c are not particularly limited as long as the protective member 40 and the electrode terminal 30 can be engaged with each other, and can be appropriately changed as necessary. At this time, it is preferable to adjust the respective dimensions so that the gap (clearance) between the concave portion 38 of the electrode terminal 30 and the convex portion 46c of the protective member 40 is 1 mm or more. Thereby, the concave portion 38 of the electrode terminal 30 and the convex portion 46c of the protective member 40 can be easily fitted. From the viewpoint of preventing damage to the electrode body 10 (terminal connecting portion 14) due to contact with the inner wall 46a of the terminal insertion hole 46 of the protective member 40, the upper limit of the clearance is preferably 2 mm or less. For example, when the depth of the concave portion 38 of the electrode terminal 30 is 3 mm, it is preferable that the projection dimension of the convex portion 46c of the protective member 40 is 1 mm to 2 mm.

Further, in the conventional secondary battery 100 as shown in FIG. and the electrode body 110 must be brought into contact with each other. On the other hand, as shown in FIG. 2, in the secondary battery 1 according to the present embodiment, since the movement of the protective member 40 in the width direction X can be restricted, the end surface 40a of the protective member 40 on the electrode body side and the electrode body 10 A gap S can be formed between the converging portion 13 of . As a result, the internal volume of the exterior body 20 is increased, so that cracking of the welded portion 26 due to expansion of the exterior body 20 can be suppressed.

2. Second Embodiment In the secondary battery 1 according to the first embodiment described above, the engaging portion E is formed by fitting the concave portion 38 of the electrode terminal 30 and the convex portion 46c of the protective member 40 together. there is However, the structure of the engaging portion is not limited to the above-described embodiments. FIG. 6 is a plan view for explaining the secondary battery movement restricting means according to the second embodiment.

As shown in FIG. 6, in the secondary battery 1A according to the second embodiment, the projections 37 formed on both side edges of the electrode terminals 30 and the inner walls 46a of the terminal insertion holes 46 of the protective member 40 are formed. An engaging portion E1 is formed by fitting the concave portion 46b. As described above, in the second embodiment, the members in which the concave portions and the convex portions are formed are reversed from those in the first embodiment. Even with such a structure, the electrode terminal 30 and the protection member 40 are engaged with each other to restrict the movement of the protection member 40 toward the center in the width direction X, so that deterioration of battery performance due to breakage of the electrode assembly 10 can be prevented.

In addition, in the above-described first and second embodiments, the electrode terminal and the protective member are engaged by one engaging portion. However, the number of engaging portions is not particularly limited as long as at least one is formed. As the number of engaging portions is increased, the electrode terminal and the protection member are firmly engaged, and the movement of the protection member tends to be restricted. On the other hand, as the number of engaging portions is reduced, assembly of the electrode terminal and the protective member becomes easier, and production efficiency tends to improve. From these points of view, the number of engaging portions formed between the electrode terminal and the protective member is preferably about 1 to 3 (for example, 2).

3. Third Embodiment In the above-described first and second embodiments, the engaging portion that engages the electrode terminal and the protective member is formed as the movement restricting means. However, the specific structure of the movement restricting means is not limited to such an engaging portion, and various structures can be employed. A secondary battery according to the third embodiment will be described as an example of a secondary battery having movement restricting means other than the engaging portion. FIG. 7 is a plan view for explaining the secondary battery movement restricting means according to the third embodiment.

As shown in FIG. 7, in a secondary battery 1B according to the third embodiment, locking members 52 and 54 for locking the protection member 40 to the terminal connection portion 14 are provided. In the third embodiment, the locking members 52 and 54 function as movement restricting means to restrict the movement of the protection member 40 inward in the width direction X. As shown in FIG. Specifically, a pair of locking members 52 and 54 are attached to the outer end portions in the width direction X of the terminal connection portion 14 so as to sandwich the electrode terminal 30 therebetween. The locking members 52 and 54 extend outward in the depth direction Y. As shown in FIG. In this embodiment, the dimension _L1 from the end 52a of one of the locking members 52 to the end 54a of the other locking member 54 is longer than the dimension _L2 of the terminal insertion hole 46 in the depth direction Y ( That is, the dimensions of each member are adjusted so that L ₁ >L ₂ . As a result, the protective member 40 is locked to the terminal connection portion 14, and movement of the protective member 40 toward the center in the width direction X is restricted. As a result, it is possible to prevent damage to the electrode body 10 (the core portion 12 and the converging portion 13 ) due to contact with the protective member 40 even when the exterior body shrinks significantly due to depressurization or the like.

The locking member is not limited to the structure described above as long as it can lock the protective member to the terminal connecting portion. Another example of such a locking member is a locking member having a thickness greater than the height dimension of the terminal insertion hole of the protective member. That is, by attaching a locking member having a dimension not to be inserted into the terminal insertion hole to the terminal connecting portion, it is possible to restrict the free movement of the protective member with respect to the terminal connecting portion. damage can be prevented.

4. Fourth Embodiment Next, a secondary battery according to a fourth embodiment will be described as an example of a secondary battery having movement restricting means other than the engaging portion and the locking member. FIG. 8 is a cross-sectional view for explaining the secondary battery movement restricting means according to the fourth embodiment. In the secondary battery 1C according to the fourth embodiment, adhesive layers 62 and 64 for adhering the protective member 40 are provided on the inner wall surface 20b of the exterior body 20, and these adhesive layers 62 and 64 act as movement restricting means. function as In this embodiment, the protection member 40 is adhered to the inner wall surface 20b of the exterior body 20 via the adhesive layers 62 and 64, so movement of the protection member 40 toward the center in the width direction X is restricted. Therefore, in the present embodiment as well, it is possible to prevent deterioration of battery performance due to breakage of the electrode assembly 10 . For the adhesive layers 62 and 64, the same resin material as the welding film 36 (see FIG. 3) of the electrode terminal 30 can be used.

5. Fifth Embodiment The movement restricting means in each embodiment described above restricts the movement of the protection member 40 in the width direction X. FIG. The secondary battery disclosed herein may have a structure that restricts the reciprocating motion of the electrode terminal 30 in the height direction Z, in addition to such movement restricting means. FIG. 10 is a cross-sectional view schematically showing the internal structure near the electrode terminals of the secondary battery according to the fifth embodiment. FIG. 11 is a perspective view explaining the dimensional relationship between the electrode terminal and the holding member in the secondary battery according to the fifth embodiment. Also, FIG. 13 is a cross-sectional view schematically showing the internal structure near the electrode terminals of a conventional secondary battery.

Specifically, as shown in FIG. 13, in the conventional secondary battery 100, the other end 134 of the electrode terminal 130 exposed to the outside of the package 120 is exposed to high voltage due to connection with an external device or vibration during use. An external force C1 along the longitudinal direction Z may be applied. In this case, one end 132 of the electrode terminal 130 connected to the terminal connection portion 114 of the electrode body 110 reciprocates along the height direction Z (see symbol C2 in FIG. 13). If the reciprocating motion C2 along the height direction Z is repeated, there is a possibility that the connecting portion between the one end 132 of the electrode terminal 130 and the terminal connecting portion 114 will be damaged.

On the other hand, as shown in FIGS. 10 and 11, the protective member 40 of the secondary battery 1D according to the fifth embodiment includes rib portions 48 that sandwich the electrode terminal 30 in the height direction Z. . Specifically, the rib portion 48 according to the present embodiment is a projection projecting from the upper member 42 of the protective member 40 toward the lower member 44 . Since the electrode terminal 30 inserted into the terminal insertion hole 46 is sandwiched between the rib portion 48 and the lower member 44, reciprocating motion along the height direction Z is restricted. As a result, even if the external force C1 in the height direction Z is repeatedly applied to the other end 34 of the electrode terminal 30, damage to the connecting portion between the electrode terminal 30 and the electrode body 10 can be preferably prevented.

Moreover, in this embodiment, it is preferable to set each dimension shown in FIG. 11 according to the following formula (1). As a result, the reciprocating motion of the electrode terminal 30 along the height direction Z can be reliably regulated, and damage to the connecting portion between the electrode terminal 30 and the electrode body 10 can be prevented.
F×X ₁ /Y ₁ <P×R×r/Y ₂ (1)
F: Load (N) of external force C1 in assumed height direction Z
X ₁ : Distance (mm) from the end of the electrode terminal 30 to the center of the welded portion 26
Y ₁ : width of electrode terminal 30 (mm)
P: Differential pressure (MPa) between the inside and outside of the exterior body 20
R: Width (mm) of the holding member 40 in contact with the exterior body 20
r: distance from the center of the welded portion 26 to the center of the rib portion 48 (mm)
Y ₂ : width of protective member 40 (mm)

In addition, the thickness t1 of the electrode terminal 30 in the present embodiment is such that the electrode terminal 30 bends and deforms with the portion sandwiched between the rib portion 48 and the lower member 44 as a fulcrum, and the welded portion 26 between the electrode terminal 30 and the exterior body 20 is obtained. is preferably set from the viewpoint of preventing a load from being applied to the As an example, when aluminum (Young's modulus: 70 GPa) is used for the electrode terminal 30, the thickness t1 of the electrode terminal 30 is preferably 0.2 mm or more, more preferably 0.3 mm or more, and even more preferably 0.4 mm or more. In addition, when using a metal material other than aluminum (copper, nickel, etc.), find the ratio of the Young's modulus ratio (X GPa) of the metal used and the Young's modulus of the above aluminum, and use the Young's modulus ratio It is preferable to adjust the thickness t1 of the electrode terminal 30 based on (see formula (2) below).
t1=0.2 mm×(X/70) (2)

Moreover, it is preferable that the rib portion 48 is formed so as to sandwich the electrode terminal 30 positioned inside the terminal insertion hole 46 in the depth direction (perpendicular to the plane of FIG. 10). As a result, the electrode terminal 30 can be held more firmly, and the reciprocating motion of the electrode terminal 30 inside the exterior body 20 can be reliably restricted. Further, when the rib portion 48 is formed to sandwich the electrode terminal 30 over the entire depth direction, the terminal insertion hole 46 is closed by the rib portion 48 . As a result, it is possible to prevent foreign matter (such as fine active material particles) from being released to the outside of the battery when the welded portion 26 of the outer package 20 is opened.

Furthermore, when the ribs 48 are formed in the protection member 40 and the electrode terminals 30 are sandwiched by the ribs 48 as in the present embodiment, the pressure inside the exterior body 20 is the standard atmospheric pressure (101.325 kPa). It is preferable that the pressure is reduced by 10 kPa or more. In other words, the internal pressure of the exterior body 20 is preferably 90 kPa or less. By depressurizing the interior of the exterior body 20 in this manner, the protective member 40 can be pressurized from the outside to the interior of the exterior body 20 (see arrow A1 in FIG. 10). As a result, the rib portion 48 can more preferably sandwich the electrode terminal 30 and prevent damage to the connecting portion between the electrode terminal 30 and the electrode body 10 . From the viewpoint of further improving the terminal holding force of the rib portion 48, the internal pressure of the exterior body 20 is preferably reduced by 50 kPa or more from the standard atmospheric pressure, and more preferably by 100 kPa or more.

In addition, the rib portion is not limited to the structure shown in FIG. 10 as long as it can clamp the electrode terminal and regulate the reciprocating motion along the height direction. For example, the rib portion 48 shown in FIG. 10 directly sandwiches the electrode terminal 30 . However, the rib portion may be formed so as to sandwich the electrode terminal via the electrode body (typically, the terminal connecting portion). Further, in the structure shown in FIG. 10 , a rib portion 48 is formed on the upper member 42 of the protective member 40 . However, the rib portion may be formed on the lower member.

6. Sixth Embodiment FIG. 12 is a cross-sectional view schematically showing the internal structure near the electrode terminals of a secondary battery according to a sixth embodiment. As shown in FIG. 12 , it is preferable that an internal cavity 49 communicating with the internal space of the exterior body 20 is formed in the protective member 40 . A general secondary battery tends to increase the internal pressure of the exterior body with use due to the generation of gas from the electrode body. Therefore, if a secondary battery that has exceeded the warranty period is used for a long period of time, the increase in internal pressure may cause the exterior body to expand and the welded portion to crack. On the other hand, in the present embodiment, since the protective member 40 is formed with the internal cavity 49 that communicates with the internal space of the exterior body 20, the volume in which the gas is accommodated inside the exterior body 20 is increased. . As a result, it is possible to extend the period until the outer package 20 expands and the welded portion 26 splits, which contributes to extending the warranty period of the battery.

The volume of the internal cavity 49 of the protection member 40 is preferably 1.5 mm ³ or more. Forming the internal cavity 49 with such a volume makes it possible to prevent the weld from tearing due to pressure build-up for a sufficiently long period of time. According to the predictions of the present inventors, by forming the internal cavity 49 of 3 mm ³ or more (more preferably 4.5 mm ³ or more), it is possible to prevent cracking of the welded portion due to expansion of the exterior body for a longer period of time. can be expected.

Further, when the internal cavity 49 is formed in the protective member 40 as in the present embodiment, the rib portion 48 is formed in the protective member 40 and the interior of the exterior body is formed as in the fifth embodiment. It is more preferable if the pressure is reduced. As described above, from the viewpoint of more preferably holding the electrode terminals 30 by the ribs 48, it is preferable that the interior of the exterior body 20 is decompressed. At this time, if the internal cavity 49 is formed in the protective member 40, the state in which the interior of the exterior body 20 is decompressed can be maintained for a long period of time. damage can be prevented for a longer period of time.

7. Application Target An example of the technology disclosed herein has been described above. Note that the technology disclosed herein can be applied to secondary batteries of various structures without particular limitation. That is, the technology disclosed herein is applicable to all-solid batteries using a solid electrolyte as the electrolyte, polymer batteries using a polymer electrolyte, and non-aqueous electrolyte secondary batteries using a non-aqueous electrolyte. be able to. Among these secondary batteries, the technology disclosed herein can be particularly suitably applied to all-solid-state batteries and polymer batteries. In a battery that uses a liquid electrolyte, such as a non-aqueous electrolyte secondary battery, there is excess electrolyte inside the battery, and the excess electrolyte functions as a buffer material. significant contraction is suppressed. On the other hand, in all-solid-state batteries and polymer batteries, there is no surplus electrolyte inside the battery, and the exterior body shrinks significantly during depressurization processing or the like, so the electrode assembly is likely to be damaged due to contact with the protective member. According to the technology disclosed herein, even in such an all-solid-state battery or polymer battery, it is possible to suitably prevent damage to the electrode body due to contact with the protective member.
Also, in non-aqueous electrolyte secondary batteries, the amount of electrolyte to be injected has decreased due to the recent demand for cost reduction, and there is a tendency for the electrode body to be damaged due to contact with the protective member. According to the technique disclosed herein, even in such a non-aqueous electrolyte secondary battery in which the amount of injected electrolyte is small, it is possible to suitably prevent damage to the electrode assembly due to contact with the protective member. Specifically, when the volume ratio of the surplus electrolytic solution to the total volume of the empty space inside the exterior body is 20% or less, damage to the electrode assembly is particularly likely to occur during decompression processing. The technique disclosed herein can suitably prevent damage to the electrode assembly due to contact with the protective member even in such a non-aqueous electrolyte secondary battery in which the volume ratio of the surplus electrolyte is 20% or less.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

1, 1A, 1B, 1C, 100 Secondary batteries 10, 110 Electrode body 12 Core part 13 Convergence part 14 Terminal connection part 14a Lower surface of terminal connection part 20, 120 Armor body 20a, 120a Side edge parts 22, 24 of the armor body Laminate films 26, 126 Welded parts 30, 130 Electrode terminals 36 Welded films 37, 46c Protrusions 38, 46b Recesses 40, 140 Protection member 42 Upper member 42a Recess 44 Lower member 44a Projection 44b Step 46 Terminal insertion hole 46a Terminal insertion Inner wall 48 of hole Rib portion 49 Internal cavities 52, 54 Locking members 62, 64 Adhesive layer E Engaging portion

Claims (9)

an electrode body having a terminal connection portion in which multiple layers of current collector foils are joined together;
an exterior body composed of a pair of laminated films facing each other with the electrode body sandwiched therebetween, and having a welded portion formed by welding the pair of laminated films on an outer peripheral edge thereof;
A secondary battery comprising a plate-shaped conductive member extending along the width direction, an electrode terminal having one end connected to the terminal connection portion and the other end exposed to the outside of the exterior body,
It has a terminal insertion hole through which the electrode terminal is inserted, is arranged between the side edge of the exterior body and the electrode body in the width direction, and shrinks and deforms the exterior body toward the center in the width direction. a protective member that regulates
a movement restricting means for restricting movement of the protection member to the center in the width direction ,
At least one engaging portion for engaging the protective member and the electrode terminal is formed as the movement restricting means,
The engaging portion engages a convex portion projecting inward in the depth direction from the inner wall of the terminal insertion hole of the protective member and a concave portion recessed inward in the depth direction from both side edges of the electrode terminal. A secondary battery formed by letting The engaging portion engages a projection projecting outward in the depth direction from both side edges of the electrode terminal and a recess recessed outward in the depth direction from the inner wall of the terminal insertion hole of the protective member. 2. The secondary battery of claim 1, wherein the secondary battery is formed by allowing an electrode body having a terminal connection portion in which multiple layers of current collector foils are joined together;
an exterior body composed of a pair of laminated films facing each other with the electrode body sandwiched therebetween, and having a welded portion formed by welding the pair of laminated films on an outer peripheral edge thereof;
a plate-shaped conductive member extending along the width direction, an electrode terminal having one end connected to the terminal connection portion and the other end exposed to the outside of the exterior body;
A secondary battery comprising
It has a terminal insertion hole through which the electrode terminal is inserted, is arranged between the side edge of the exterior body and the electrode body in the width direction, and shrinks and deforms the exterior body toward the center in the width direction. a protective member that regulates
movement restricting means for restricting movement of the protection member toward the center in the width direction;
is further equipped with
At least one engaging portion for engaging the protective member and the electrode terminal is formed as the movement restricting means,
The engaging portion engages a projection projecting outward in the depth direction from both side edges of the electrode terminal and a recess recessed outward in the depth direction from the inner wall of the terminal insertion hole of the protective member. A secondary battery formed by letting The protective member includes a lower member having a stepped portion thinner than both ends at the center in the depth direction, and an upper member having a flat lower surface that makes surface contact with the upper surfaces of both ends of the lower member. The secondary battery according to any one of claims 1 to 3 , comprising: The secondary battery according to any one of claims 1 to 4 , wherein said protective member includes a rib portion sandwiching said electrode terminal in the height direction. 6. The secondary battery according to claim 5 , wherein said rib portion sandwiches said electrode terminal located inside said terminal insertion hole over the entire depth direction. 6. The secondary battery according to claim 5 , wherein the internal pressure of said exterior body is reduced by 10 kPa or more compared to standard atmospheric pressure. The secondary battery according to any one of claims 1 to 7 , wherein the protective member has an internal cavity that communicates with the internal space of the exterior body. The secondary battery according to any one of claims 1 to 8 , wherein a gap is formed between the end surface of the protective member on the electrode body side and the electrode body.

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