WO2020071362A1 - Secondary battery - Google Patents

Abstract

Provided is a secondary battery having an electrode assembly equipped with a positive-electrode tab connection part where tabs respectively provided for multiple positive electrodes are interconnected and a negative-electrode tab connection part where tabs respectively provided for multiple negative electrodes are interconnected. If the secondary battery is envisaged as having four battery sections defined by a first bisecting imaginary line and a second bisecting imaginary line in a plan view, the tab connection parts are arranged such that both a positive-electrode tab connection part and a negative-electrode tab connection part are not present in the same section or in adjoining sections.

Description

Rechargeable battery

The present invention relates to a secondary battery. In particular, the present invention relates to a secondary battery including an electrode assembly including an electrode constituting layer including a positive electrode, a negative electrode, and a separator.

Rechargeable batteries are so-called storage batteries that can be repeatedly charged and discharged, and are used for various purposes. For example, secondary batteries are used in mobile devices such as mobile phones, smartphones, and laptop computers.

で は In such various applications, the secondary battery is often used for a relatively long time, and the secondary battery is often exposed under severe conditions.

JP 2018-14194 A

発 明 The inventor of the present application has noticed that there is still a problem to be overcome in the conventional secondary battery, and has found that it is necessary to take measures for that. Specifically, the present inventor has found that there are the following problems.

The secondary battery has an electrode assembly in which a positive electrode, a negative electrode and an electrode constituent layer including a separator are stacked therebetween, but when an impact is applied to the secondary battery and the electrode assembly is divided, the An internal short circuit may occur due to the division.

The safety of the secondary battery based on the viewpoint of the division can be evaluated by a “collision test”. However, the present inventor has found that the secondary battery is particularly likely to generate heat and / or ignite due to an internal short circuit at the time of the division. I found that it could be.

Specifically, it has been found that when the electrode assembly is divided by an impact or the like, an excessively high temperature is caused in the internal short-circuit portion caused by the division, and the secondary battery may generate heat and / or ignite. Was. This is because all layers of the positive electrode and the negative electrode of the electrode assembly are connected so as to contribute to the battery reaction, and such connection causes a large current to flow into the internal short-circuit portion and generate a large amount of Joule heat. (See FIG. 15).

二 A secondary battery that may be a problem in a collision test is a battery that easily generates heat and / or fires due to a similar internal short circuit even in an actual use environment, and there is a concern in terms of safety.

The present invention has been made in view of such problems. That is, a main object of the present invention is to provide a secondary battery in which excessive heat generation and / or ignition is less likely to be caused at the time of division, and thus safety in an actual use environment is improved.

発 明 The inventor of the present application tried to solve the above-mentioned problem by taking measures in a new direction instead of taking measures on an extension of the prior art. As a result, the invention of a secondary battery in which the above main object has been achieved has been attained.

In the present invention, a secondary battery including a positive electrode, a negative electrode, and an electrode assembly including a separator disposed between the positive electrode and the negative electrode,
A tab provided for the plurality of positive electrodes is connected to each other, and a positive electrode tab connection portion, and a tab provided for the plurality of negative electrodes is provided with a negative electrode tab connection portion connected to each other,
In a plan view of the secondary battery, when four battery sections divided by a first virtual equal bisecting line and a second virtual equal bisecting line that are orthogonal to each other are imagined, a positive electrode tab connection portion is provided in the same section and an adjacent section. And the tab connection portion where both the negative electrode tab connection portion does not exist,
A secondary battery is provided in which at least one of the positive electrode tab connection portion and the negative electrode tab connection portion has no lead and is not provided to an external terminal of the secondary battery.

(4) The secondary battery of the present invention is a battery in which excessive heat generation and / or ignition hardly occurs when the secondary battery is divided, and thus has improved safety in an actual use environment.

Specifically, in the secondary battery of the present invention, for four virtual plane sections, a tab connection section in which both the positive electrode tab connection section and the negative electrode tab connection section do not exist in the same section and adjacent sections. Therefore, even if the electrode assembly is cut off by a collision test or the like, an undesirable short circuit that generates a large amount of Joule heat hardly occurs. In particular, even if the electrode assembly is split or broken, as represented by a collision test, all layers are not electrically connected in the split or broken body and an internal short-circuit occurs partially. However, it is difficult for all layers to be short-circuited. Therefore, in the secondary battery of the present invention, an unfavorable phenomenon such as generation of a large amount of Joule heat due to a large current flowing through the short-circuit portion is unlikely to occur.

Sectional view schematically showing the electrode constituting layer Schematic plan view of an electrode assembly for explaining four virtual battery compartments FIG. 3 is a schematic plan view and a cross-sectional view of an electrode assembly showing an arrangement relationship between a positive electrode tab connection portion and a negative electrode tab connection portion according to one embodiment of the present invention. FIG. 3 is a schematic plan view of an electrode assembly for describing a first virtual equal bisecting line and a second virtual equal bisecting line. Schematic diagram for explaining a collision test FIG. 2 is a plan view and a cross-sectional view schematically illustrating an electrode assembly according to an embodiment of the present invention. Schematic plan view and cross-sectional view of an electrode assembly showing a reference example compared with the present invention Schematic plan view of an electrode assembly showing a reference example compared with the present invention FIG. 2 is a plan view and a cross-sectional view schematically showing an electrode assembly according to the first embodiment of the present invention. FIG. 4 is a plan view and a sectional view schematically showing an electrode assembly according to a second embodiment of the present invention. Plan view and sectional view schematically showing an electrode assembly according to a third embodiment of the present invention. Plan view and sectional view schematically showing an electrode assembly according to a fourth embodiment of the present invention. Schematic diagram for explaining “non-rectangular shape” (“partially notched shape”) Schematic diagram for explaining the phenomenon of preventing the inflow of large current Schematic diagram for explaining a phenomenon in which a large current flows into a short-circuited portion due to disconnection, resulting in excessive heat generation and ignition (s).

Hereinafter, a secondary battery according to an embodiment of the present invention will be described in more detail. Although description will be made with reference to the drawings as necessary, various elements in the drawings are shown only schematically and exemplarily for understanding of the present invention, and the appearance and dimensional ratio may be different from the real ones .

方向 The direction of “thickness” described directly or indirectly in the present specification is based on the lamination direction of the electrode materials constituting the secondary battery. For example, in the case of a “secondary battery having a plate-like thickness” such as a flat battery, the “thickness” direction corresponds to the thickness direction of such a secondary battery. In the present specification, “sectional view” is based on a virtual cross section of an object obtained by cutting along the thickness direction of the secondary battery. In addition, the “plan view” used in this specification is based on a sketch when the object is viewed from above or below along the direction of the thickness.

Furthermore, the terms “vertical direction” and “lateral direction” used directly or indirectly in this specification correspond to the vertical direction and the horizontal direction in the drawings, respectively. Unless otherwise specified, the same reference numerals or symbols indicate the same members or the same meanings. In a preferred embodiment, the downward direction in the vertical direction (that is, the direction in which gravity acts) corresponds to “downward”, and the opposite direction corresponds to “upward”.

[Basic configuration of secondary battery]
As used herein, the term “secondary battery” refers to a battery that can be repeatedly charged and discharged. Therefore, the secondary battery according to the present invention is not limited to its name, and may include, for example, a power storage device.

二 The secondary battery according to the present invention has an electrode assembly in which electrode constituent layers including a positive electrode, a negative electrode, and a separator are stacked. FIG. 1 illustrates an electrode assembly 100. As shown in the figure, the positive electrode 3 and the negative electrode 4 are stacked with a separator 5 interposed therebetween to form an electrode constituting layer 8, and at least one or more such electrode constituting layers 8 are laminated to constitute an electrode assembly. I have. In a secondary battery, such an electrode assembly is enclosed in an outer package together with an electrolyte (for example, a non-aqueous electrolyte).

The positive electrode includes at least a positive electrode material layer and a positive electrode current collector. In the positive electrode, a positive electrode material layer is provided on at least one surface of the positive electrode current collector, and the positive electrode material layer contains a positive electrode active material as an electrode active material. For example, the plurality of positive electrodes in the electrode assembly may each have a positive electrode material layer provided on both surfaces of the positive electrode current collector, or may have a positive electrode material layer provided only on one surface of the positive electrode current collector. . From the viewpoint of further increasing the capacity of the secondary battery, the positive electrode preferably has a positive electrode material layer provided on both surfaces of the positive electrode current collector.

The negative electrode is composed of at least a negative electrode material layer and a negative electrode current collector. In the negative electrode, a negative electrode material layer is provided on at least one surface of the negative electrode current collector, and the negative electrode material layer contains a negative electrode active material as an electrode active material. For example, the plurality of negative electrodes in the electrode assembly may each have a negative electrode material layer provided on both surfaces of the negative electrode current collector, or may have a negative electrode material layer provided only on one surface of the negative electrode current collector. . From the viewpoint of further increasing the capacity of the secondary battery, the negative electrode is preferably provided with a negative electrode material layer on both surfaces of the negative electrode current collector.

The electrode active material contained in the positive electrode and the negative electrode, that is, the positive electrode active material and the negative electrode active material are materials directly involved in the transfer of electrons in the secondary battery, and are the main materials of charge and discharge, that is, the positive and negative electrodes responsible for the battery reaction. is there. More specifically, ions are brought to the electrolyte due to the “positive electrode active material included in the positive electrode material layer” and the “negative electrode active material included in the negative electrode material layer”, and the ions are generated between the positive electrode and the negative electrode. And transfer of electrons is performed to perform charging and discharging. The positive electrode material layer and the negative electrode material layer are particularly preferably layers capable of inserting and extracting lithium ions. That is, a non-aqueous electrolyte secondary battery in which lithium ions move between the positive electrode and the negative electrode via the non-aqueous electrolyte to charge and discharge the battery is preferable. When lithium ions are involved in charge and discharge, the secondary battery according to the present invention corresponds to a so-called lithium ion battery, and the positive electrode and the negative electrode have layers capable of inserting and extracting lithium ions.

と こ ろ Where the positive electrode active material of the positive electrode material layer is made of, for example, a granular material, a binder may be included in the positive electrode material layer for more sufficient contact between particles and shape retention. Further, a conductive auxiliary may be included in the positive electrode material layer in order to facilitate the transfer of electrons for promoting the battery reaction. Similarly, when the negative electrode active material of the negative electrode material layer is made of, for example, a granular material, it is preferable that a binder is included for more sufficient contact between particles and shape retention, and the transfer of electrons for promoting a battery reaction is smoothly performed. In order to achieve this, a conductive auxiliary may be included in the negative electrode material layer. As described above, because of the configuration including a plurality of components, the positive electrode material layer and the negative electrode material layer can also be referred to as a positive electrode material layer and a negative electrode material layer, respectively.

The positive electrode active material is preferably a material that contributes to the insertion and extraction of lithium ions. From this viewpoint, the positive electrode active material may be, for example, a lithium-containing composite oxide. More specifically, the positive electrode active material may be a lithium transition metal composite oxide containing lithium and at least one transition metal selected from the group consisting of cobalt, nickel, manganese, and iron. That is, in the positive electrode material layer of the secondary battery according to the present invention, such a lithium transition metal composite oxide is preferably contained as a positive electrode active material. For example, the positive electrode active material may be lithium cobaltate, lithium nickelate, lithium manganate, lithium iron phosphate, or a material in which some of these transition metals are replaced with another metal. Although such a positive electrode active material may be contained as a single species, two or more thereof may be contained in combination.

The binder that can be included in the positive electrode material layer is not particularly limited, but includes polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, and polytetrafluoroethylene. And at least one selected from the group consisting of The conductive auxiliary agent that can be included in the positive electrode material layer is not particularly limited, but includes carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples thereof include at least one selected from carbon fibers such as carbon fibers, metal powders such as nickel, aluminum and silver, and polyphenylene derivatives. For example, the binder of the positive electrode material layer may be polyvinylidene fluoride, and the conductive additive of the positive electrode material layer may be carbon black.

The negative electrode active material is preferably a material that contributes to the insertion and extraction of lithium ions. From this viewpoint, the negative electrode active material may be, for example, various carbon materials, oxides, lithium alloys, silicon, silicon alloys, and / or tin alloys.

Various carbon materials for the negative electrode active material include graphite (natural graphite, artificial graphite), MCMB (mesocarbon microbeads), non-graphitizable carbon, easily graphitizable carbon, surface decorative graphite, hard carbon, soft carbon, and / or Or diamond-like carbon. In particular, graphite is preferable because of its high electron conductivity and excellent adhesion to the negative electrode current collector. As the oxide of the negative electrode active material, at least one selected from the group consisting of silicon oxide, tin oxide, indium oxide, zinc oxide, lithium oxide, and the like can be given. The lithium alloy of the negative electrode active material may be any metal that can form an alloy with lithium, and examples thereof include Al, Si, Pb, Sn, In, Bi, Ag, Ba, Ca, Hg, Pd, Pt, Te, Zn, It may be a binary, ternary or higher alloy of lithium and a metal such as La. Such an oxide is preferably amorphous in its structural form. This is because deterioration due to non-uniformity such as crystal grain boundaries or defects is less likely to occur.

The binder that can be contained in the negative electrode material layer is not particularly limited, but is at least one selected from the group consisting of styrene butadiene rubber, polyacrylic acid, polyvinylidene fluoride, polyimide resin, and polyamideimide resin. Can be mentioned. For example, the binder contained in the negative electrode material layer may be styrene butadiene rubber. The conductive auxiliary agent that can be included in the negative electrode material layer is not particularly limited, but includes carbon black such as thermal black, furnace black, channel black, Ketjen black, and acetylene black, graphite, carbon nanotube, and vapor phase growth. Examples include at least one selected from carbon fibers such as carbon fibers, metal powders such as copper, nickel and silver, and polyphenylene derivatives. In addition, the negative electrode material layer may contain a component derived from a thickener component (for example, carboxymethylcellulose) used during battery production.

正極 The positive electrode current collector and the negative electrode current collector used for the positive electrode and the negative electrode are members that contribute to collecting and supplying electrons generated in the active material due to a battery reaction. Such a current collector may be a sheet-shaped metal member, and may have a perforated or perforated form. For example, the current collector may be a metal foil, a punched metal, a net or an expanded metal, or the like. The positive electrode current collector used for the positive electrode is preferably made of a metal foil containing at least one selected from the group consisting of aluminum, stainless steel, nickel, and the like, and may be, for example, an aluminum foil. On the other hand, the negative electrode current collector used for the negative electrode is preferably made of a metal foil containing at least one selected from the group consisting of copper, stainless steel, nickel, and the like, and may be, for example, a copper foil.

セ パ レ ー タ The separator used for the positive electrode and the negative electrode is a member provided from the viewpoint of preventing short circuit due to contact between the positive electrode and the negative electrode, and maintaining the electrolyte. In other words, the separator can be said to be a member that allows ions to pass while preventing electronic contact between the positive electrode and the negative electrode. Preferably, the separator is a porous or microporous insulating member and has a membrane form due to its small thickness. By way of example only, a microporous polyolefin membrane may be used as the separator. In this regard, the microporous membrane used as the separator may contain, for example, only polyethylene (PE) or only polypropylene (PP) as the polyolefin. Furthermore, the separator may be a laminate composed of a “PE microporous membrane” and a “PP microporous membrane”. The surface of the separator may be covered with an inorganic particle coat layer and / or an adhesive layer. The surface of the separator may have adhesiveness. In the present invention, the separator is not particularly limited by its name, and may be a solid electrolyte, a gel electrolyte, and / or an insulating inorganic particle having the same function.

で は In the secondary battery according to the present invention, an electrode assembly including an electrode constituting layer including a positive electrode, a negative electrode, and a separator is enclosed in an outer package together with an electrolyte. When the positive electrode and the negative electrode have a layer capable of inserting and extracting lithium ions, the electrolyte is preferably a “non-aqueous” electrolyte such as an organic electrolyte or an organic solvent (that is, the electrolyte is preferably a non-aqueous electrolyte). preferable). In the electrolyte, metal ions released from the electrodes (positive electrode / negative electrode) will be present, and therefore, the electrolyte will assist the movement of the metal ions in the battery reaction.

The non-aqueous electrolyte is an electrolyte containing a solvent and a solute. A specific solvent for the non-aqueous electrolyte may include at least carbonate. Such carbonates may be cyclic carbonates and / or chain carbonates. Although not particularly limited, examples of the cyclic carbonate include at least one selected from the group consisting of propylene carbonate (PC), ethylene carbonate (EC), butylene carbonate (BC), and vinylene carbonate (VC). be able to. Examples of the chain carbonates include at least one selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dipropyl carbonate (DPC). Although it is only an example, a combination of a cyclic carbonate and a chain carbonate may be used as the non-aqueous electrolyte, and for example, a mixture of ethylene carbonate and diethyl carbonate may be used. As a specific non-aqueous electrolyte solute, for example, a Li salt such as LiPF ₆ and / or LiBF ₄ is preferably used. The non-aqueous electrolyte may be made of a chemical gel.

The outer package of the secondary battery wraps the electrode assembly in which the electrode constituent layers including the positive electrode, the negative electrode, and the separator are laminated, but may be in the form of a hard case, or may be in the form of a soft case. Good. Specifically, the exterior body may be a hard case type corresponding to a so-called metal can or a soft case type corresponding to a so-called pouch made of a laminate film.

[Features of the secondary battery of the present invention]
The secondary battery of the present invention is characterized by the structure of the electrode assembly. In particular, the arrangement of the tab connection portions of the positive electrode and the negative electrode in a plan view of the electrode assembly is characterized. That is, the secondary battery of the present invention has a positive electrode tab connection portion in which tabs provided for a plurality of positive electrodes are connected to each other, and a negative electrode tab connection portion in which tabs provided for a plurality of negative electrodes are connected to each other. It has a characteristic in the arrangement relation of the parts.

Specifically, in a plan view of the secondary battery, when four battery sections divided by a first virtual equal bisecting line and a second virtual equal bisecting line that are orthogonal to each other are imagined, a positive electrode tab is placed in the same section. Both the connecting portion and the negative electrode tab connecting portion do not exist, and the positive electrode extends so as to straddle sections adjacent to each other (in other words, to straddle sections having a horizontal relationship). The tab connection portion is arranged so that the tab connection portion and the negative electrode tab connection portion do not exist separately.

In other words, while the positive electrode tab connection is disposed in one of the four battery cells, the negative electrode tab connection is disposed in another cell, and the positive electrode tab connection is disposed. The section where the negative electrode tab connection portion is arranged is not adjacent to the section where the negative electrode tab connection portion is disposed, that is, such sections do not have a horizontal relationship in plan view. That is, it can be said that, typically, the section in which the positive electrode tab connection section is disposed and the section in which the negative electrode tab connection section is disposed obliquely oppose each other in plan view of the secondary battery. .

説明 This will be described with reference to FIG. FIG. 2 shows a plan view of the square or rectangular rectangular electrode assembly 100. In the present invention, four battery compartments (100A, 100B, 100C, and 100D) divided by the first virtual equal bisecting line 1 and the second virtual equal bisecting line 2 in plan view of the electrode assembly 100 are assumed. . With respect to these four virtual sections, the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20 have an arrangement relationship shown in FIGS. 3 (A) to 3 (D).

As shown in FIG. 3A, when the positive electrode tab connection portion 10 is arranged in the first battery compartment 100A, the negative electrode tab connection portion 20 is provided in the third battery compartment 100C obliquely facing the first battery compartment. Are located. Similarly, as shown in FIG. 3B, when the positive electrode tab connection portion 10 is disposed in the second battery compartment 100B, the negative electrode tab connection portion 20 is obliquely opposed to the fourth battery compartment. It is arranged in the battery compartment 100D. Further, as shown in FIG. 3 (C), when the positive electrode tab connection portion 10 is arranged in the third battery compartment 100C, the negative electrode tab connection portion 20 is provided in the first battery compartment obliquely facing the third battery compartment. 100A. Then, as shown in FIG. 3D, when the positive electrode tab connection portion 10 is arranged in the fourth battery compartment 100D, the negative electrode tab connection portion 20 becomes the second battery compartment obliquely facing the fourth battery compartment. 100B.

て も The same applies if the positive electrode side and the negative electrode side are reversed. When the negative electrode tab connection part 20 is arranged in the first battery section 100A, the positive electrode tab connection part 10 is arranged in the third battery section 100C that is located in the oblique direction (see FIG. 3C). When the negative electrode tab connection part 20 is arranged in the second battery section 100B, the positive electrode tab connection part 10 is arranged in the fourth battery section 100D that is located in the oblique direction (see FIG. 3D). When the negative electrode tab connection part 20 is arranged in the third battery compartment 100C, the positive electrode tab connection part 10 is arranged in the first battery compartment 100A that is located in the oblique direction (see FIG. 3A). And when the negative electrode tab connection part 20 is arrange | positioned at the 4th battery section 100D, the positive electrode tab connection part 10 is arrange | positioned at the 2nd battery section 100B located in the diagonal direction (refer FIG. 3 (B)). ). As described above, in the secondary batteries according to FIGS. 3A to 3D, the section in which the positive electrode tab connection is provided and the section in which the negative electrode tab connection is provided are mutually separated in plan view. Except for an obliquely facing configuration, they are not adjacent to each other (not immediately adjacent to each other).

The first virtual equal bisecting line 1 and the second virtual equal bisecting line 2, which are orthogonal to each other, are particularly supposed to be used for a collision test of a battery, and respectively imaginarily divide the size of the battery or the battery assembly into two equal parts. Line. That is, assuming a typical battery shape in plan view as shown in FIG. 2, the first virtual equal bisecting line 1 substantially has a dimension along one direction (for example, a dimension along the lateral direction). Is an imaginary line equally divided into two, that is, a bisector having one dimension. Similarly, the second virtual equal bisecting line 2 is a virtual line that substantially equally divides a dimension along the other direction (for example, a dimension along the vertical direction) into two, that is, the other dimension. It is a bisector. Here, considering other shapes than the typical shape of the secondary battery, shapes as shown in FIGS. 4B to 4E are also conceivable. In such a case, the smallest rectangle 30 including all the shapes of the battery or the battery assembly in a plan view (excluding the tabs) is imagined, and the equal bisecting line having the horizontal and vertical dimensions is defined as the first virtual equal bisecting line 1. And the second virtual equally divided line 2. In summary, in the present invention, the “first virtual equal bisecting line” and the “second virtual equal bisecting line” all include the plan view shape (the plan view shape excluding the tabs and leads) of the battery or the battery assembly. In addition, when a square / rectangular rectangle having the minimum area is imagined in a plan view, it corresponds to a vertical bisector in each of the horizontal dimension and the vertical dimension of the rectangle (see FIG. 4).

In addition, the term “collision test” as used in this specification means a test in which a weight is naturally dropped and a collision is caused with a rod member placed on a battery as shown in FIG. Although not particularly limited, such a collision test may be a test based on UL1642 {Impact} Test.

The tab connection portion is a portion where tabs provided for a plurality of electrodes (particularly, a plurality of same electrodes) are connected to each other. Here, the "tab" in the present invention is a member (15, 25) corresponding to a part of an electrode current collector (for example, a current collector foil) protruding from a side surface of the electrode assembly (right side view in FIG. 3). reference). That is, in the secondary battery, the current collectors (for example, current collector foils) provided on the plurality of electrodes of the positive electrode or the negative electrode extend so as to protrude from the side of the electrode assembly. A portion where the protruding current collectors are integrated with each other corresponds to a tab connecting portion. Positive electrode tab connecting portion 10 is a member in which positive electrode tabs 15 provided for a plurality of positive electrodes are connected to each other. In one embodiment, all tabs of the plurality of positive electrodes are connected to each other. Similarly, the negative electrode tab connection part 20 is a member in which the negative electrode tabs 25 provided for the plurality of negative electrodes are connected to each other. In one embodiment, all the tabs of the plurality of negative electrodes are connected to each other. When the current collector is a current collector foil, the tab connection portion is referred to as a “foil collector portion” because the tab connection portion corresponds to a portion where such current collector foils are gathered together. Can also.

FIG. 6 shows one typical embodiment of the present invention. In the secondary battery of the present invention, the positive electrode tab connecting portion 10 in which tabs provided for a plurality of positive electrodes (for example, tabs provided for all positive electrodes) are connected to each other; The provided tabs (for example, tabs provided for all the negative electrodes) are connected to the negative electrode tab connecting portion 20 and the same and adjacent sections in the four battery sections (100A, 100B, 100C, and 100D). Is not provided. As can be seen from the illustrated embodiment, this means that the positive electrode tab connecting portion 10 and the negative electrode tab connecting portion 20 are provided in two sections obliquely facing each other.

(4) The secondary battery having such a unique arrangement of the tab connecting portions is unlikely to generate excessive heat and / or fire even if it is disconnected due to an external force such as a collision. That is, such a secondary battery is excellent in terms of safety in an actual use environment, and moreover, is also excellent in terms of safety as a used battery. In particular, even when the battery is accidentally or undesirably disconnected, the section in which the secondary battery is provided with the positive electrode tab connection section and the section in which the negative electrode tab connection section is provided are separately provided in plan view. The tendency to fragment increases. Here, in the case of such a division, there is a positive electrode tab connection on one side of the division and a negative electrode tab connection on the other side of the division. Therefore, the divided one and the other do not have a portion where all layers of the positive electrode and the negative electrode are electrically connected at the same time, and even if a part is internally short-circuited by the division, all the layers are separated. Can provide a highly safe battery without short circuit.

態 様 For better understanding of the present invention, the embodiments shown in FIGS. 7 and 8A to 8C will be described. FIG. 7 shows an embodiment having no arrangement of the tab connecting portions of the present invention. Specifically, a positive electrode tab connection portion (for example, a positive electrode tab connection portion in which all the positive electrode layers are electrically connected to each other) and a negative electrode tab connection portion (for example, a negative electrode in which all the negative electrode layers are electrically connected to each other) Tabs) are arranged in the same section of the four battery sections (100A, 100B, 100C and 100D). In the illustrated embodiment, both the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20 are arranged in the first electrode section 100A. In such a case, if an external force such as a collision acts to divide the portion indicated by the dotted line, both the positive and negative electrode tab connection portions 10 and 20 will be present simultaneously in one of the divided portions. Therefore, in one of the layers, all layers of the positive electrode and the negative electrode are electrically connected, so that when an internal short circuit occurs due to division, a large current eventually flows to the short circuit over all layers. . In other words, when a partial internal short circuit occurs, a discharge reaction proceeds between all the positive and negative electrodes facing each other, and the current flows into the short circuit portion via the connection tab, generating a large amount of Joule heat at the short circuit portion. (See FIG. 15). Therefore, in the embodiment shown in FIG. 7, excessive ignition and / or heat generation is likely to be caused in the divided secondary battery.

Similarly, in each of the embodiments shown in FIGS. 8A to 8C, there is a possibility that the same undesired internal short circuit may occur. For example, in the mode shown in FIG. 8A, the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20 are arranged in sections adjacent to each other, that is, in adjacent sections. When divided along the horizontal dotted line L1-L1 ', both of the divided portions include both the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20 at the same time. The same applies to the embodiment shown in FIG. When divided along the vertical dotted line L2-L2 ', both of the divided portions include both the positive electrode connection tab 10 and the negative electrode connection tab 20 at the same time. The shape of the battery in plan view is not limited to a square or a rectangle, and the same applies to the case of “non-rectangular” as shown in FIG. 8C, and the horizontal dotted line L3-L3 ′ or the vertical dotted line L4-L4 When it is divided by ', both the positive electrode tab connecting portion 10 and the negative electrode tab connecting portion 20 exist on one of the divided portions at the same time. Therefore, in all of the embodiments shown in FIGS. 8A to 8C, when an internal short circuit occurs due to division, a large current may eventually flow to the short circuit over all layers, and a large amount of Joule heat may be generated. As a result, excessive ignition and / or heat generation is likely to occur.

In contrast to the above-described embodiments shown in FIGS. 7 and 8A to 8C, according to the present invention, in one or the other of the divided portions, a portion where all the layers of the positive electrode and the negative electrode are electrically connected is formed. It is not held at the same time, and even if a part is internally short-circuited by division, all layers are not short-circuited. That is, even when such an internal short circuit occurs, an undesired phenomenon such as generation of a large amount of Joule heat due to a large current flowing in the short-circuit portion is unlikely to occur.

One preferred embodiment of the present invention is shown in FIG. As can be seen from FIG. 6, of the four battery compartments (100A, 100B, 100C and 100D), the first compartment 100A is connected to the positive tab connection 10 (for example, the positive tab connection where all the positive electrodes are electrically connected to each other). ) Is provided, while the third section 100C is provided with a negative electrode tab connection portion 20 (for example, a negative electrode tab connection portion in which all the negative electrodes are electrically connected to each other). The tab connection 20 is not provided in the “same and adjacent section”. Further, in the present invention, the leads (60, 70) preferably have a unique arrangement configuration in view of the tab connection portion.

Specifically, in the secondary battery of the present invention, at least one of the positive electrode tab connection portion and the negative electrode tab connection portion has no lead and does not form an external terminal of the secondary battery. That is, either one of the positive electrode tab connection part and the negative electrode tab connection part is not provided with a lead, or neither the positive electrode tab connection part nor the negative electrode tab connection part is provided with a lead. In other words, although one of the positive electrode tab connection portion and the negative electrode tab connection portion has a lead, both the positive electrode tab connection portion and the negative electrode tab connection portion do not have a lead at the same time.

As used herein, the term "lead" broadly refers to a battery member used for electrical connection, and narrowly refers to a battery used for electrical connection between an external terminal of the battery and an electrode assembly. Means a member. The lead is a member having conductivity. The lead is made of, for example, metal and preferably has a thin-walled form and / or an elongated form. Such a lead may be one commonly used in a secondary battery (for example, a lithium secondary battery).

電池 In the battery of the present invention, a first lead and a second lead may be provided as leads. Then, one of the first lead and the second lead may be connected to one of the positive electrode tab connection part and the negative electrode tab connection part. The tab connection portion connected to the lead becomes a member that directly contributes to the external terminal, and contributes to the design of a suitable secondary battery. In this regard, in the secondary battery of the present invention, the other of the first lead and the second lead is connected to one of the positive electrode and the negative electrode via another additional tab different from the tab at the positive electrode tab connection portion and the negative electrode tab connection portion. It is electrically connected to the electrodes. In such a case, the electrode to which the “other” lead is electrically connected corresponds to an electrode on a different polarity side from the electrode to which the “one” lead is electrically connected. That is, the electrode to which the “other” lead is electrically connected has a different polarity from the electrode at the positive electrode tab connection portion or the negative electrode tab connection portion to which the “one” lead is connected. In the present invention, the other of the first lead and the second lead can be provided at a position different from the installation position of the positive electrode tab connection portion and the negative electrode tab connection portion. The “further tab (another further tab different from the tab at the positive electrode tab connection portion and the negative electrode tab connection portion)” referred to in the present specification is the number of tabs electrically connected to each other at the positive electrode tab connection portion. And / or less than the number of tabs electrically connected to each other at the negative electrode tab connection. In other words, in each of the positive electrode tab connection part and the negative electrode tab connection part, it can be said that a larger number of electrode layers than the number of “further tabs” are electrically connected to each other (ie, the “further tabs”). Preferably more than a number of tabs).

In the example illustrated in FIG. 6, the first lead 60 of the first lead 60 and the second lead 70 is connected to the positive electrode tab connection unit 10. The second lead 70 is electrically connected to the negative electrode via another additional tab 80 different from the current collection tabs (15, 25) of the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20. As can be seen from the illustrated embodiment, the first lead 60 and the second lead 70 preferably have a positional relationship of being adjacent to each other in a plan view, and therefore are easily provided to external terminals of the secondary battery. .

The first lead and the second lead can work particularly advantageously for the secondary battery of the present invention having a unique arrangement of the positive electrode tab connection portion and the negative electrode tab connection portion. This is because the positive electrode tab connection portion and the negative electrode tab connection portion are not provided in the “same and adjacent section”, but if the leads are provided in both the positive electrode tab connection portion and the negative electrode tab connection portion, the arrangement of the leads This is because even the location is restricted to a positional relationship that is not such “same and adjacent section”. Therefore, in the above-described arrangement of the leads, the external terminals of the secondary battery can be arranged with a relatively high degree of freedom regardless of the arrangement of the positive electrode tab connection portion / negative electrode tab connection portion. In other words, it can be said that the external terminal of the secondary battery of the present invention can be provided at a desired position from the viewpoint of a control circuit (for example, a protection circuit and / or a charge / discharge control circuit) and space saving.

In the example illustrated in FIG. 6, the positive electrode tab connecting portion 10 has a configuration in which all the tabs 15 of the plurality of positive electrodes are connected to each other. Similarly, the negative electrode tab connection portion 20 has a configuration in which all the tabs 25 of the plurality of negative electrodes are connected to each other. Therefore, all layers of the positive electrode and the negative electrode contribute to the charge and discharge of the battery, that is, the battery reaction. Here, with respect to the embodiment of FIG. 6, even if an external force such as a collision acts to break the first virtual equal bisecting line 1, or the second virtual equal bisecting line 2 is orthogonal to the line. Even if it is divided along, all of the layers of the positive electrode and the negative electrode do not have a part electrically connected at the same time in both the divided one and the other, and when a part is internally short-circuited by the division Even in this case, all layers do not eventually short-circuit. In other words, even when such an internal short circuit occurs, an undesired phenomenon such as the generation of a large amount of Joule heat due to the flow of a large current through the short-circuit portion is unlikely to occur.

The present invention can be embodied in various modes.

(First aspect)
FIG. 9 shows a plan view of the electrode assembly according to the first embodiment. In such an embodiment, the plurality of negative electrodes are not all connected by the tab 25 in the negative electrode tab connection section 20. That is, some of the tabs provided on each of the plurality of negative electrodes are not provided for the negative electrode tab connection unit 20. In the secondary battery of the present invention, not all of the tabs need be connected to each of the positive electrode tab connection portion and the negative electrode tab connection portion.

In the illustrated embodiment of FIG. 9, although not all of the plurality of negative electrodes are connected by the tabs 25 in the negative electrode tab connection part 20, they are different from the tabs (15, 25) of the positive electrode tab connection part 10 and the negative electrode tab connection part 20. An additional tab 80 is provided so that all layers of the positive and negative electrodes contribute to the charging and discharging of the battery, ie, the battery reaction. In the embodiment shown in FIG. 9, one negative electrode also has another tab 80 connected to the lead, together with the tab 25 provided for the negative electrode tab connection portion 20, so that the negative electrode can be connected through such a layer. All layers will be electrically connected to each other.

Even if the secondary battery of the first aspect is divided along the first virtual uniform bisecting line 1 due to an external force such as a collision, or the second virtual equal bisecting line 2 orthogonal to the line. Even if it is divided along, all of the layers of the positive electrode and the negative electrode do not have the electrically connected part at the same time in both the divided one and the other. Even if it does, all layers do not eventually short-circuit. In other words, even when such an internal short circuit occurs, an undesired phenomenon such as the generation of a large amount of Joule heat due to the flow of a large current through the short-circuit portion is unlikely to occur.

(Second aspect)
FIG. 10 shows a plan view of the electrode assembly according to the second embodiment. In such an embodiment, there is one additional (ie, "single") additional tab 80 connected to the lead.

In the secondary battery of the present invention, the number of the additional tabs 80 connected to the leads (particularly, the number of the tabs provided as the additional tabs or the tabs electrically connected to each other as the additional tabs) is provided. ) May be smaller than the number of tabs (15, 25) in the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20. For example, when the positive electrode tab connecting portion 10 has a configuration in which the tabs 15 of all layers of the positive electrode are connected to each other, another additional positive electrode tab 80 may be provided in a smaller number than the number of the tabs 15. Further, in the case where the tabs 15 of only some layers of the positive electrode are connected to each other at the positive electrode tab connection portion 10, a smaller number of additional tabs 80 of the further positive electrode than the several layers are provided. May be provided. The same applies to the case of the negative electrode. Even if the number of the additional tabs 80 connected to the leads is small in this way, since the tabs of the positive electrode tab connecting portion 10 and the negative electrode tab connecting portion 20 exist, all the layers of the positive electrode and the negative electrode are formed. It can contribute to battery charge / discharge, that is, battery reaction.

If the number in "another further positive electrode tab 80" is small, the number of layers that ultimately short-circuit may be reduced even if the internal short-circuit occurs partially due to the division of the battery. In particular, in the embodiment shown in FIG. 10, since the number of “another additional positive electrode tab 80” is one, the number of short circuits can be minimized even when a part is internally short-circuited due to the division of the battery. can do. In other words, even when all layers are not short-circuited due to the division, if the number of “another additional positive electrode tab 80” is large, the number of layers finally short-circuited may increase accordingly. In this regard, if the number of “another additional positive electrode tab 80” is one, the number of such short-circuit layers can be minimized, so that a large amount of Joule heat is less likely to be generated, and A secondary battery in which the risk of excessive ignition and heat generation is more appropriately prevented can be provided. That is, a secondary battery with higher safety can be obtained.

(Third aspect)
FIG. 11 shows a plan view of the electrode assembly according to the third embodiment. In such an embodiment, neither the positive electrode tab connection part 10 nor the negative electrode tab connection part 20 is provided with a lead. That is, both the first lead and the second lead are electrically connected to the positive electrode and the negative electrode, respectively, via another additional tab different from the tab at the positive electrode tab connection portion and the negative electrode tab connection portion.

More specifically, the first lead 60 is electrically connected to the positive electrode via “another additional tab 80A” different from the positive electrode tab 15 in the positive electrode tab connection portion 10, and the second lead 70 is The negative electrode tab connection portion 20 is electrically connected to the negative electrode via “another additional tab 80B” different from the negative electrode tab 25.

In this aspect, since the so-called foil collecting section and the extraction section of the external electrode are completely separated on both the positive electrode side and the negative electrode side, the degree of freedom of the installation position of the external terminal of the secondary battery becomes higher. I have. That is, external terminals can be particularly preferably arranged from the viewpoint of a control circuit (for example, a protection circuit and / or a charge / discharge control circuit) and space saving.

(Fourth aspect)
FIG. 12 shows a plan view of the electrode assembly according to the fourth embodiment. In such an embodiment, the planar view of the electrode assembly is non-rectangular. That is, the planar shape of the secondary battery is “non-rectangular”.

As used herein, the term “non-rectangular shape” refers to a shape that is not normally included in the concept of a rectangular shape such as a square or a rectangular shape in plan view. It refers to the shape of a truncated part. Therefore, in a broad sense, “non-rectangular shape” refers to a shape in which the electrode shape in plan view viewed from above in the thickness direction is not square or rectangular, and in a narrow sense, the electrode shape in plan view is square / rectangular. While the base is partially cut away from the base (preferably, the base has a shape in which the square and rectangular corners of the base are cut out). Although merely an example, the “non-rectangular shape” means that the electrode shape in a plan view is based on a square and a rectangle, and a square, rectangular, semicircular, semielliptical, circular, It may be a shape obtained by cutting out a part of an oval or a combination thereof from the base shape (particularly, a shape obtained by cutting out from a corner of the base shape) (see FIG. 13).

Even in the “non-rectangular” electrode assembly, the tabs provided for the plurality of positive electrodes are connected to each other, and the tabs provided for the plurality of negative electrodes are connected to each other. The negative electrode tab connection section 20 is not provided in the same and adjacent sections in the four battery sections (100A, 100B, 100C, and 100D). In the illustrated embodiment, the positive electrode tab connection portion 10 and the negative electrode tab connection portion 20 are provided in two sections obliquely facing each other. Therefore, even if the battery is divided along the first virtual equal bisecting line 1 due to an external force such as a collision, or if the battery is divided along the second virtual equal bisecting line 2 orthogonal thereto. Also, in both the divided one and the other, all the layers of the positive electrode and the negative electrode do not have electrically connected portions at the same time. There is no eventual short circuit. In other words, even when such an internal short circuit occurs, an undesired phenomenon such as generation of a large amount of Joule heat due to a large current flowing in the short-circuit portion hardly occurs (see FIG. 14).

In the “non-rectangular” mode, the first virtual equal bisecting line 1 and the second virtual equal bisecting line 2 are considered to be lines based on a base square / rectangle assumed to be before the notch. Is also good. That is, the first virtual equal bisecting line 1 substantially has a dimension (for example, a dimension along the lateral direction) along one direction of a base square / rectangle assumed to be before the notch in the plan view shape. It may be a line that is equally divided into two. Similarly, the second virtual equal bisecting line 2 is a dimension along the other direction (for example, a dimension along the vertical direction) of the base square or rectangle assumed to be before the notch in the plan view shape. May be substantially equally divided into two lines.

態 様 In the embodiment shown in FIG. 12, the “another additional tab” to which the lead is connected is a tab provided for the electrode corresponding to the outermost layer of the electrode in the electrode assembly. Specifically, “another additional tab 80” of the outermost layer of the electrode is connected to the first lead 60. Thus, in the secondary battery of the present invention, the first lead or the second lead connected via another additional tab is electrically connected only to the electrode corresponding to the outermost layer of the electrode in the electrode assembly. May be. This is preferable in that when the battery is disconnected due to impact or the like, the outermost electrode is split relatively early. This is because if the outermost layer of the electrode is divided relatively quickly, the amount of heat generated during the time until the electrode is completely separated can be further suppressed, and as a result, a battery with higher safety This is because

From this point of view, it is preferable that the above-mentioned outermost electrode layer is the outermost electrode layer on the side that collides relatively early. That is, in the secondary battery of the present invention, such an electrode outermost layer may be only one of the two outermost layers in the stacking direction of the electrode assembly.

Although the embodiments of the present invention have been described above, they are merely typical examples. Therefore, those skilled in the art will easily understand that the present invention is not limited to this and various embodiments are conceivable.

For example, in the above description, the mode of the electrical connection between the outermost electrode layer and the lead is described based on the “non-rectangular” electrode assembly shown in FIG. 12, but the square or rectangular electrode assembly is used. It is the same as above. That is, the first lead or the second lead connected via “another additional tab” in the square / rectangular electrode assembly in plan view is electrically connected only to the electrode corresponding to the outermost layer of the electrode. May be.

二 The secondary battery according to one embodiment of the present invention can be used in various fields where power storage is assumed. By way of example only, secondary batteries are used in the fields of electricity, information and communication in which mobile devices are used (eg, mobile phones, smart watches, smartphones, laptops, digital cameras, activity meters, arm computers, and electronic devices). Mobile devices such as paper), household and small industrial applications (for example, electric tools, golf carts, home, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and harbor cranes) ), Transportation systems (eg, hybrid vehicles, electric vehicles, buses, trains, electric assist bicycles, electric motorcycles, etc.), power system applications (eg, various types of power generation, road conditioners, smart grids, general home-installed power storage systems) Fields, medical applications (earphone hearing aids, etc.) Medical equipment field), pharmaceutical use (fields such dosage management system), IoT art, and it can be utilized Space and deep sea applications (e.g., spacecraft, areas such as submersible), etc..

DESCRIPTION OF SYMBOLS 1 1st virtual equal bisecting line 2 2nd virtual equal bisecting line 3 Positive electrode 4 Negative electrode 5 Separator 8 Electrode constituent layer 10 Positive electrode tab connection part 15 tab (positive electrode tab matched mutually as a positive electrode connection tab)
20 negative electrode tab connection part 25 tab (negative electrode tab that can be combined with each other as negative electrode connection tab)
Reference Signs List 30 virtual rectangle 60 first lead 70 second lead 80 another additional tab 80A further positive electrode side tab 80B further negative electrode side tab 100 electrode assembly 100A first battery compartment 100B second battery compartment 100C third battery Section 100D 4th battery section

Claims (9)

A secondary battery comprising a positive electrode, a negative electrode, and an electrode assembly including a separator disposed between the positive electrode and the negative electrode,
A tab provided for the plurality of positive electrodes is connected to each other, and a positive electrode tab connection portion, and a tab provided for the plurality of negative electrodes is provided with a negative electrode tab connection portion connected to each other,
In a plan view of the secondary battery, when four battery sections divided by a first virtual equal bisecting line and a second virtual equal bisecting line that are orthogonal to each other are imagined, the positive electrode tab is placed in the same section and an adjacent section. Tab connection portion where both the connection portion and the negative electrode tab connection portion are not present,
A secondary battery, wherein at least one of the positive electrode tab connection portion and the negative electrode tab connection portion has no lead and is not provided to an external terminal of the secondary battery. The secondary battery according to claim 1, wherein all the tabs of the plurality of positive electrodes are connected to each other at the positive electrode tab connection portion. The secondary battery according to claim 1, wherein all the tabs of the plurality of negative electrodes are connected to each other at the negative electrode tab connection portion. A lead having a first lead and a second lead,
4. The secondary battery according to claim 1, wherein one of the first lead and the second lead is connected to one of the positive electrode tab connection part and the negative electrode tab connection part. The other of the first lead and the second lead is electrically connected to one electrode of the positive electrode and the negative electrode through another additional tab different from the tab of the positive electrode tab connection and the negative electrode tab connection. The secondary battery according to claim 4, which is connected. A lead having a first lead and a second lead,
Both the first lead and the second lead are electrically connected to the positive electrode and the negative electrode respectively via another additional tab different from the tab in the positive electrode tab connection part and the negative electrode tab connection part. The secondary battery according to any one of claims 1 to 3, wherein The secondary battery according to claim 5, wherein the number of the further tabs is smaller than the number of the tabs in each of the positive electrode tab connection part and the negative electrode tab connection part. The first lead or the second lead connected via the further tab is electrically connected to an electrode corresponding to an outermost layer of the electrode in the electrode assembly. The secondary battery according to any one of the above. 9. The secondary battery according to claim 1, wherein the electrode of the electrode assembly includes a positive electrode and a negative electrode capable of inserting and extracting lithium ions.

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