JP7165880B2 - Laminated secondary battery - Google Patents

Description

The present disclosure relates to stacked secondary batteries.

The electrode body housed in the exterior body of the secondary battery may move inside the exterior body due to external vibration or impact. In Patent Document 1, a thermoplastic resin is inserted between the electrode body and the exterior body in order to suppress misalignment between the electrode body and the exterior body made of a laminate film, and the electrode body is fixed to the exterior body. A method for doing so is disclosed.

JP 2003-109667 A

By the way, it has been found that in a stacked secondary battery having a structure in which an electrode body is suspended and held by electrode tabs, there is a problem that the electrode tabs rub against each other due to external vibrations or shocks and are damaged. Patent Document 1 discloses a method of fixing an electrode assembly to a laminate film whose outer packaging is soft and easily deformable. Repeating this may deform the electrode body fixed to the exterior body and cause an internal short circuit.

An object of the present disclosure is to provide a stacked secondary battery that suppresses breakage of electrode tabs while suppressing deformation of an electrode body.

A laminated secondary battery according to one aspect of the present disclosure includes a laminated electrode body in which a plurality of electrode plates are laminated with a separator interposed therebetween and has a plurality of electrode tabs protruding from each of the plurality of electrode plates; and a laminated electrode body. A metallic rectangular outer body to be accommodated, one or a plurality of electrode body holders arranged in a gap between the stacked electrode body and the rectangular outer body to store the stacked electrode body, the stacked electrode body and the rectangular outer body and one or more spacers provided between the electrode body holders, wherein the spacers are provided between the stacked electrode body and the electrode body holder or between the electrode body holder and the rectangular exterior when the number of electrode body holders is one. When there are a plurality of electrode body holders, it is provided between at least one of the electrode body holders.

According to one aspect of the present disclosure, it is possible to provide a stacked secondary battery that suppresses damage to electrode tabs while suppressing deformation of an electrode body.

1 is a perspective view showing a layered secondary battery that is an example of an embodiment; FIG. 1 is a perspective view showing a stacked secondary battery that is an example of an embodiment, with the front surface of a rectangular outer package, the front surface of an electrode body holder, and a sealing plate removed. FIG. 1 is a perspective view showing a laminated electrode body that is an example of an embodiment; FIG. FIG. 2 is a cross-sectional view taken along line AA of FIG. 1; FIG. 5 is a diagram corresponding to FIG. 4 in another example of the embodiment;

An example of an embodiment will be described in detail below. In this specification, the vertical direction of the paper of FIGS. It is sometimes called "direction".

FIG. 1 is a perspective view showing a stacked secondary battery 100 that is an example of an embodiment. As shown in FIG. 1, a stacked secondary battery 100 includes a battery case 20 having a rectangular exterior body 1 with an opening and a sealing plate 2 that seals the opening. The square outer body 1 and the sealing plate 2 are each made of metal, and can be made of aluminum or an aluminum alloy, for example. The rectangular exterior body 1 has a bottom portion 1a, a pair of first side walls 1b and a pair of second side walls 1c. The rectangular exterior body 1 is a rectangular, bottomed cylindrical exterior body having an opening at a position facing the bottom portion 1a. The sealing plate 2 is connected to the edge of the opening of the rectangular exterior body 1 by laser welding or the like. In FIG. 1, the rectangular exterior body 1 has a wide shape in which the first side wall 1b is larger than the second side wall 1c. It may have a shape that is thicker in the direction.

The sealing plate 2 has an electrolyte injection hole. The electrolyte injection hole is sealed with a sealing plug 10 after injecting an electrolyte, which will be described later. The sealing plate 2 also has a gas exhaust valve 11 . This gas exhaust valve 11 operates when the pressure inside the battery reaches a predetermined value or higher, and exhausts the gas inside the battery to the outside of the battery.

A positive electrode terminal 7 is attached to the sealing plate 2 so as to protrude outside the battery case 20 . Specifically, the positive electrode terminal 7 is inserted into a positive electrode terminal mounting hole formed in the sealing plate 2, and an external insulating member 9 disposed outside the battery in the positive electrode terminal mounting hole and an external insulating member 9 disposed inside the battery. It is attached to the sealing plate 2 in a state of being electrically insulated from the sealing plate 2 by the inner side insulating member 12 (see FIG. 4). The positive electrode terminal 7 is electrically connected to the positive current collector inside the battery case 20 . The positive electrode current collector is provided on the sealing plate 2 with the inner insulating member 12 interposed therebetween. The outer insulating member 9 and the inner insulating member 12 are preferably made of resin.

A negative electrode terminal 8 is attached to the sealing plate 2 so as to protrude outside the battery case 20 . Specifically, the negative electrode terminal 8 is inserted into a negative electrode terminal mounting hole formed in the sealing plate 2. An external insulating member 9 is disposed outside the negative electrode terminal mounting hole of the battery, and an external insulating member 9 is disposed inside the battery. It is attached to the sealing plate 2 while being electrically insulated from the sealing plate 2 by the inner insulating member 12 (see FIG. 4). The negative terminal 8 is electrically connected to the negative current collector inside the battery case 20 . The negative electrode current collector is provided on the sealing plate 2 with the inner insulating member 12 interposed therebetween. The outer insulating member 9 and the inner insulating member 12 are preferably made of resin.

Next, the internal structure of the stacked secondary battery 100 will be described with reference to FIG. FIG. 2 is a perspective view showing a stacked secondary battery 100 that is an example of an embodiment, in which the front side surface of the rectangular exterior body 1, the front side surface of the electrode body holder 13, and the sealing plate 2 are removed. It is a diagram of a state in which The rectangular outer body 1 accommodates the laminated electrode body 3, the electrode body holder 13, the spacer 14, and the electrolytic solution. The laminated electrode body 3 includes a lower surface portion 3a facing the bottom portion 1a of the rectangular exterior body 1, a pair of first side surface portions 3b facing the first side wall 1b, a pair of second side surface portions 3c facing the second side wall 1c, and an upper surface facing the sealing plate 2 . In FIG. 2, the laminated electrode body 3 has a wide shape in which the first side surface portion 3b is larger than the second side surface portion 3c. It may have a shape that is thicker in the depth direction than . As will be described later, the laminated electrode body 3 has a laminated structure in which a positive electrode plate 30 and a negative electrode plate 31 are laminated with a separator 32 interposed therebetween. A positive electrode tab 4 and a negative electrode tab 5 protrude from the positive electrode plate 30 and the negative electrode plate 31, respectively, on the top surface of the laminated electrode body 3. The positive electrode tab 4 and the negative electrode tab 5 are positive current collectors and negative current collectors (not shown), respectively. It is connected to the body by welding or the like. Therefore, the laminated electrode body 3 is suspended from the sealing plate 2 via the positive electrode tab 4 and the negative electrode tab 5 (hereinafter, the positive electrode tab 4 and the negative electrode tab 5 may be collectively referred to as "electrode tab 6"). . Since the laminated electrode body 3 is smaller than the rectangular outer body 1 in the depth direction and the width direction and is positioned substantially in the center in a plan view, there is a space between the rectangular outer body 1 and the laminated electrode body 3 in the width direction and in the depth direction. There is a gap between the front and back of the direction. Therefore, when vibration or impact is applied from the outside, the electrode tab 6 may vibrate in the depth direction or the width direction with the electrode tab 6 as a fulcrum. The distance d1 of the gap between the laminated electrode body 3 (second side face portion 3c) and the second side wall 1c and the distance d2 of the gap between the laminated electrode body 3 (first side face portion 3b) and the first side wall 1b is between 0.5 mm and 3 mm, preferably between 0.75 mm and 2 mm. Note that the distance d1 between the left and right gaps and the distance d2 between the front and back gaps may not be the same.

The stacked secondary battery 100 includes an electrode body holder 13 arranged between the stacked electrode body 3 and the rectangular exterior body 1 . The electrode body holder 13 has, for example, a bottomed box-like or bag-like shape with an opening at the top, like the rectangular outer body 1 . Since the electrode body holder 13 has a bottomed box-like or bag-like shape with an opening at the top, the stacked electrode body 3 is inserted through the opening of the electrode body holder 13 and the stacked electrode body 3 is covered by the electrode body holder 13. be able to.

If the material of the electrode body holder 13 has electrical insulation, chemical stability that is not attacked by the electrolytic solution, and electrical stability that does not electrolyze against the voltage of the laminated secondary battery 100, It is not particularly limited. As the material of the electrode body holder 13, for example, resin materials such as polyethylene, polypropylene, and polyfluoroethylene can be used from the viewpoint of industrial versatility, manufacturing cost, and quality stability. It should be noted that the electrode body holder 13 is not limited to the case-like shape such as the box-like or bag-like shape described above. For example, a planar electrode body holder 13 may be wound around the laminated electrode body 3 . Thereby, the laminated electrode body 3 can be covered with the planar electrode body holder 13 .

The thickness of the electrode body holder 13 is preferably 0.01 mm to 1 mm from the viewpoints of ensuring electrical insulation, increasing the capacity of the laminated secondary battery 100, and workability of the electrode body holder 13. , 0.1 mm to 0.5 mm. When the electrode body holder 13 has a plurality of sheets, the total thickness of all layers is preferably 0.01 mm to 1 mm, more preferably 0.1 mm to 0.5 mm.

The spacer 14 fills a part of the gap between the laminated electrode body 3 and the rectangular exterior body 1, as will be described later. Therefore, when external vibration or impact is applied, the spacer 14 can narrow the width of vibration of the laminated electrode assembly 3, so that the electrode tabs 6 suspending the laminated electrode assembly 3 are rubbed and damaged. can be suppressed.

The electrolyte contains a solvent and an electrolyte salt dissolved in the solvent. Both non-aqueous solvents and aqueous solvents can be used as the solvent. When a non-aqueous solvent is used, the electrolytic solution becomes a non-aqueous electrolytic solution. Examples of non-aqueous solvents that can be used include carbonates, esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Carbonates include cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, vinylene carbonate; dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl propyl carbonate; , ethyl propyl carbonate, and methyl isopropyl carbonate. The non-aqueous solvent may contain a halogen-substituted product obtained by substituting at least part of the hydrogen atoms of the above solvent with halogen atoms such as fluorine. The electrolytic solution is not limited to a liquid electrolyte, and may be a solid electrolyte using a gel polymer or the like. Electrolyte salts include lithium salts. As the lithium salt, LiPF ₆ or the like, which is generally used as a supporting salt in the conventional laminated secondary battery 100, can be used. Additives such as vinylene carbonate (VC) can also be added as appropriate.

Next, the laminated electrode body 3, the positive electrode tab 4, and the negative electrode tab 5 will be described with reference to FIG. The laminated electrode body 3 has a laminated structure in which positive electrode plates 30 and negative electrode plates 31 are alternately laminated with separators 32 interposed therebetween. The positive electrode plate 30 has a positive electrode core made of metal and a positive electrode active material layer 30a containing a positive electrode active material formed on the positive electrode core. For the positive electrode core, a foil of a metal such as aluminum that is stable in the potential range of the positive electrode plate 30, a film having the metal on the surface layer, or the like is used. The thickness of the positive electrode core is, for example, 10 to 20 μm. The negative electrode plate 31 has a negative electrode core made of metal and a negative electrode active material layer 31a containing a negative electrode active material formed on the negative electrode core. For the negative electrode core, a foil of a metal such as copper that is stable in the potential range of the negative electrode plate 31, a film having the metal on the surface layer, or the like can be used. The thickness of the negative electrode core is, for example, 5 to 15 μm. In the laminated secondary battery 100 , the size of the positive electrode plate 30 is preferably slightly smaller than the size of the negative electrode plate 31 .

A positive electrode tab 4 protrudes from one end of the positive electrode plate 30 forming the laminated electrode body 3 , and a negative electrode tab 5 protrudes from one end of the negative electrode plate 31 . Since each positive electrode plate 30 has the positive electrode tabs 4 at approximately the same position, the plurality of positive electrode tabs 4 are arranged in a line in the stacking direction in the laminated electrode assembly 3 . Similarly, since each negative electrode plate 31 has the negative electrode tabs 5 at substantially the same position, the plurality of negative electrode tabs 5 are arranged in a row in the stacking direction in the laminated electrode assembly 3 . Since the laminated electrode body 3 shakes in the width direction and the depth direction due to the application of external vibrations and impacts, the plurality of electrode tabs 6 hanging the laminated electrode body 3 from the sealing plate 2 are separated from each other by the adjacent electrode tabs 6 . They may rub against each other, wear out, and break. If the electrode tab 6 is damaged, an electrode plate that cannot be charged and discharged will be produced, resulting in deterioration of battery characteristics.

In this embodiment, the positive electrode core extends to form the positive electrode tab 4 , and the negative electrode core extends to form the negative electrode tab 5 . It is also possible to connect another conductive member to the positive electrode core or the negative electrode core, respectively, to form the positive electrode tab 4 or the negative electrode tab 5 . It is preferable to provide an insulating layer or a protective layer having a higher electrical resistance than the positive electrode core at the root portion of the positive electrode tab 4 .

The positive electrode active material layer 30a contains a positive electrode active material, a conductive agent such as carbon, and a binder such as polyvinylidene fluoride (PVdF), and is preferably provided on both surfaces of the positive electrode core. The positive electrode plate 30 is formed by coating a positive electrode core with a positive electrode active material slurry containing a positive electrode active material, a conductive agent, a binder, and the like, drying the coating film, and then compressing the positive electrode active material layer with a roller or the like. It can be produced by forming 30a on both sides of the positive electrode core. The positive electrode active material layer 30a can also be provided only on one side of the positive electrode core.

For example, a lithium metal composite oxide is used as the positive electrode active material. Metal elements contained in the lithium metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, etc. are mentioned. An example of a suitable lithium metal composite oxide is a lithium metal composite oxide containing at least one of Ni, Co and Mn. Specific examples include lithium metal composite oxides containing Ni, Co and Mn, and lithium metal composite oxides containing Ni, Co and Al. Inorganic compound particles such as tungsten oxide, aluminum oxide, and lanthanide-containing compounds may adhere to the surfaces of the lithium metal composite oxide particles.

The negative electrode active material layer 31a contains a negative electrode active material, a binder such as styrene-butadiene rubber (SBR), and a thickener such as carboxymethyl cellulose (CMC), and is preferably provided on both sides of the negative electrode core. . The negative electrode plate 31 is formed by coating a negative electrode core with a negative electrode active material slurry containing a negative electrode active material, a binder, and the like, drying the coating film, and then compressing the negative electrode active material layer 31a with a roller or the like to turn the negative electrode active material layer 31a into a negative electrode active material layer 31a. It can be produced by forming on both sides of the core. The negative electrode active material layer 31a can also be provided only on one side of the negative electrode core.

As the negative electrode active material, for example, graphite such as natural graphite such as flake graphite, massive graphite, and earthy graphite, massive artificial graphite, and artificial graphite such as graphitized mesophase carbon microbeads is used. As the negative electrode active material, a metal such as Si or Sn that is alloyed with lithium, an alloy containing the metal, a compound containing the metal, or the like may be used, and these may be used in combination with graphite. Specific examples of the compound include silicon compounds represented by SiO _x (0.5≦x≦1.6).

A porous sheet having ion permeability and insulation is used for the separator 32 . The separator 32 is a porous substrate containing at least one selected from, for example, polyolefin, polyvinylidene fluoride, polytetrafluoroethylene, polyimide, polyamide, polyamideimide, polyethersulfone, polyetherimide, and aramid as a main component. with polyolefins being preferred, particularly polyethylene and polypropylene being preferred. The separator 32 may be composed only of a resin-made porous substrate, or may have a multilayer structure in which a heat-resistant layer containing inorganic particles or the like is formed on at least one surface of the porous substrate. . Moreover, the resin-made porous substrate may have a multi-layer structure such as polypropylene/polyethylene/polypropylene. The separator 32 has, for example, an average pore diameter of 0.02 to 5 μm and a porosity of 30 to 70%.

Next, with reference to FIG. 4, the internal structure of the stacked secondary battery 100 including the spacer 14 when the number of the electrode body holders 13 is one will be described in detail.

FIG. 4 is a cross-sectional view taken along line AA in FIG. 1, showing a case where the number of electrode body holders 13 is one. The laminated electrode body 3 is suspended from the sealing plate 2 via the electrode tabs 6, and there is a gap of distance d1 between the laminated electrode body 3 (second side surface portion 3c) and the second side wall 1c. there is An electrode body holder 13 is provided between the laminated electrode body 3 and the rectangular exterior body 1 , and the electrode body holder 13 accommodates the laminated electrode body 3 while covering the side and bottom surfaces thereof. The spacer 14 is provided between the laminated electrode body 3 (second side surface portion 3c) and the electrode body holder 13 in a direction perpendicular to the lamination direction of the laminated electrode body 3. The spacer 14 allows the laminated electrode body 3 and the electrode body holder 13 are connected to such an extent that they can move as one. The shape, number and position of the spacers 14 are not particularly limited. The shape of the spacer 14 is, for example, cylindrical or conical as shown in FIG. In addition, by setting the number of spacers 14 to an even number and arranging them on the left and right sides at the same height in the vertical direction, it is possible to improve the holding posture of the suspended laminated electrode body 3 . Furthermore, by arranging the spacers 14 in the upper part near the sealing plate 2 and in the lower part near the bottom part 1a, the vertical and horizontal balance of the laminated electrode assembly 3 can be improved. Of course, it is also possible to make the number of spacers 14 an odd number, make them left-right asymmetrical, or provide spacers 14 only on one of the opposing side surfaces.

For example, by sandwiching an elastic body between the laminated electrode body 3 and the electrode body holder 13 or bonding the laminated electrode body 3 and the electrode body holder 13 together, the laminated electrode body 3 and the electrode body holder 13 can be separated. and can be connected to the extent that they move as one. If the spacer 14 is installed only between the laminated electrode body 3 and the electrode body holder 13, the laminated electrode body 3 will not move to the distance of the gap when the laminated electrode body 3 vibrates due to vibration or impact from the outside of the elastic body. Since it moves by the distance obtained by subtracting the thickness of the spacer 14 from d1, damage to the electrode tab 6 can be suppressed in this embodiment compared to the case where the spacer 14 is not provided.

The spacer 14 may be provided between the electrode body holder 13 and the rectangular exterior body 1 . If the spacer 14 is installed only between the electrode holder 13 and the rectangular outer body 1, the electrode holder 13 is fixed to the rectangular outer body 1, so that when external vibration or impact is applied, The laminated electrode body 3 moves by a distance obtained by subtracting the thickness of the spacer 14 from the gap distance d1. Therefore, in the present embodiment, breakage of the electrode tabs 6 can be suppressed as compared with the case where the spacers 14 are not provided. In addition, since the side surface of the laminated electrode body 3 is not covered with the spacer 14, the electrolytic solution can easily spread uniformly over the entire laminated electrode body 3, which is preferable in terms of battery characteristics.

The spacer 14 is arranged between the laminated electrode body 3 (first side surface portion 3b) and the electrode body holder 13, or between the electrode body holder 13 and the rectangular exterior body 1 (first It can also be arranged between the side walls 1b). In this case, the width of the vibration of the laminated electrode body 3 in the lamination direction can be suppressed by the thickness of the spacer 14, so damage to the electrode tabs 6 can be suppressed.

The spacer 14 is arranged between the laminated electrode body 3 (the lower surface portion 3a and/or the upper surface portion) and the electrode body holder 13, or between the electrode body holder 13 and the rectangular outer body 1 in the direction perpendicular to the stacking direction of the stacked electrode body 3. (bottom part 1a and/or sealing plate 2). In this case, the width of vibration of the laminated electrode assembly 3 in the vertical direction can be suppressed by the thickness of the spacer 14, so damage to the electrode tab 6 can be suppressed.

Next, with reference to FIG. 5, the internal structure of the stacked secondary battery 100 including the spacers 14 when the electrode body holders 13 are plural will be described in detail. FIG. 5 is a diagram corresponding to FIG. 4 in another example of the embodiment, and shows a case where the number of electrode body holders 13 is two. Each electrode holder 13 may have a different shape. Hereinafter, when there are two or more electrode body holders 13, the electrode body holder 13 closest to the laminated electrode body 3 will be referred to as the innermost electrode body holder 13a, and the electrode body holder 13 closest to the rectangular exterior body 1 will be referred to as the innermost electrode body holder 13a. This is referred to as an outer electrode body holder 13b.

The laminated electrode body 3 is suspended from the sealing plate 2 via the electrode tabs 6, and there is a gap of distance d1 between the laminated electrode body 3 (second side surface portion 3c) and the second side wall 1c. there is An electrode body holder 13 is provided between the laminated electrode body 3 and the rectangular exterior body 1 , and the electrode body holder 13 accommodates the laminated electrode body 3 while covering the side and bottom surfaces thereof. The spacer 14 is provided between the innermost electrode holder 13a and the outermost electrode holder 13b, and the spacer 14 connects the innermost electrode holder 13a and the outermost electrode holder 13b. there is If the spacers 14 are placed only between the electrode body holders 13, the laminated electrode body 3 moves by the distance d1 of the gap minus the thickness of the spacers 14 when external vibration or impact is applied. Breakage of the electrode tabs 6 can be suppressed as compared with the case where the spacers 14 are not provided. The spacer 14 may be provided between the laminated electrode body 3 and the innermost electrode body holder 13a, or between the outermost electrode body holder 13b and the rectangular exterior body 1. FIG. Moreover, when the number of the electrode body holders 13 is three or more, it can be provided in at least one of the electrode body holders 13 .

The spacer 14 can also be arranged at least one between the electrode body holders in the direction parallel to the stacking direction of the stacked electrode body 3 . In this case, the width of the vibration of the laminated electrode body 3 in the lamination direction can be suppressed by the thickness of the spacer 14, so damage to the electrode tabs 6 can be suppressed.

The spacers 14 are preferably provided between the laminated electrode bodies 3 and the side surfaces of the rectangular exterior body 1 in a direction perpendicular to the lamination direction of the laminated electrode bodies 3 . In other words, the spacer 14 is preferably provided between the laminated electrode body 3 (second side surface portion 3c) and the second side wall 1c. In the direction perpendicular to the lamination direction of the laminated electrode body 3, the rate of expansion and contraction of the laminated electrode body 3 due to charging and discharging is smaller than that in the lamination direction of the laminated electrode body 3. Therefore, the spacers 14 are arranged in the direction perpendicular to the lamination direction. By providing it, the pressure applied to the laminated electrode body 3 during charging and discharging can be reduced, and deformation of the laminated electrode body 3 can be suppressed.

The spacer 14 is not particularly limited as long as it can connect the electrode body holder 13 and the laminated electrode body 3, the electrode body holder 13 and the square outer body 1, or the electrode body holders 13 to each other. Spacer 14 may include, for example, a thermosetting resin. Thermosetting resins include melamine resins, epoxy resins, unsaturated polyesters, silicone resins, and the like. The spacer 14 contains a thermosetting resin, and is inserted between the laminated electrode body 3 and the electrode body holder 13, between the electrode body holder 13 and the rectangular exterior body 1, or between the electrode body holders 13. In some cases, it can be in a gel-like form to facilitate insertion, and can be hardened and connected by a subsequent high-temperature treatment, such as a drying step. Since the spacer 14 is fixed at the provided position and does not move, a highly reliable stacked secondary battery 100 can be manufactured.

Also, the spacer 14 may contain a swelling resin that reacts with the electrolytic solution and exhibits swelling properties. When the swelling resin is immersed in the electrolyte, the electrolyte penetrates into the gaps in the network structure of the swelling resin, causing the swelling resin to expand. Examples of swelling resins include polyvinylidene fluoride, polystyrene (PS), polyvinyl alcohol, polyamide, polyacrylonitrile, polycarbonate, and polyethylene vinyl acetate due to their high affinity with the electrolyte (in particular, affinity with carbonate solvents). , polyamide, natural rubber, styrene-butadiene rubber (SBR), nitrile rubber, butyl rubber and the like are preferred. These may be used alone or in combination. The spacer 14 contains a swelling resin, so that after being inserted between the laminated electrode body 3 and the electrode body holder 13, between the electrode body holder 13 and the rectangular exterior body 1, or between the electrode body holders 13, electrolysis is performed. The spacer 14 can be easily installed because it swells when it comes into contact with the liquid and can be fixed at the provided position.

The thickness of the spacer 14 can be set to be half or more of the distance d1 of the gap between the laminated electrode body 3 and the rectangular exterior body 1. As shown in FIG. In this case, the range in which the laminated electrode body 3 moves due to external vibrations and impacts can be reduced, so that the electrode tabs 6 can be prevented from rubbing against each other and being damaged.

The spacers 14 preferably occupy 10% or more of the area of the surface on which the spacers 14 are arranged. By making it 10% or more, it is possible to stably connect with the spacer 14 . Moreover, from the viewpoint of facilitating uniform distribution of the electrolytic solution, it is more preferable to make it 10% or more and 50% or less.

From the viewpoint of suppressing the movement of the electrode tabs 6, the spacers 14 may be arranged on the upper side (the side closer to the electrode tabs 6) of the side surface (second side surface portion 3c) parallel to the stacking direction of the laminated electrode body 3. preferable.

EXAMPLES The present disclosure will be further described below with reference to Examples, but the present disclosure is not limited to these Examples.

<Example>
After mixing LiNi _0.5 Co _0.2 Mn _0.3 O ₂ as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, and carbon as a conductive material in a weight ratio of 92:4:4, N-methyl- A positive electrode mixture slurry was prepared by dispersing it in 2-pyrrolidone. After coating this slurry on an aluminum foil with a thickness of 15 μm as a positive electrode core, it is dried, compressed with a roller, and then cut into a predetermined electrode size to form a positive electrode mixture layer on both sides of the rectangular positive electrode core. A positive electrode was produced. A positive electrode tab was provided by exposing the positive electrode core at the end of the positive electrode.

Natural graphite as a negative electrode active material, styrene-butadiene rubber (SBR) and carboxymethyl cellulose as binders were mixed at a weight ratio of 96:2:2, and then dispersed in water to prepare a negative electrode mixture slurry. After coating a copper foil with a thickness of 10 μm as a negative electrode core with this slurry, it is dried, compressed with a roller, and then cut into a predetermined electrode size to form a negative electrode mixture layer on both sides of the rectangular negative electrode core. A negative electrode was fabricated. A negative electrode tab was provided by exposing the negative electrode core at the end of the negative electrode.

A laminated electrode body was prepared by laminating a plurality of negative electrode plates, polyethylene as a separator, and positive electrode plates in this order. Then, the produced laminated electrode body was inserted into one box-shaped electrode body holder having an opening at the top. Epoxy resin was applied between two side surfaces of the laminated electrode body parallel to the stacking direction and the electrode body holder so as to cover 10% of each of the side surfaces parallel to the stacking direction, and heated to 100°C. Epoxy resin was cured to form a spacer. The positive electrode tab and negative electrode tab of the laminated electrode body were welded to the positive electrode terminal and negative electrode terminal attached to the sealing plate, respectively. After that, the opening of the rectangular outer package was sealed with a sealing plate to fabricate a secondary battery.

In the present disclosure, a vibration test, which will be described later, was performed without injecting an electrolytic solution. When the electrolytic solution is not injected, the laminated electrode assembly is more likely to move against external vibrations and impacts than when the electrolytic solution is injected.

<Comparative example>
A secondary battery was fabricated in the same manner as in the example except that the epoxy resin was not inserted between the laminated electrode body and the rectangular exterior body and the spacer was not provided.

<Vibration test>
The vibration test was performed by vibrating the secondary batteries of Examples and Comparative Examples in the width direction. In the vibration test, the secondary battery was vibrated while changing the wave number by sweeping a sine wave logarithmically at 25 Hz for a predetermined time at a peak acceleration of 10 G in one vibration test cycle. After applying vibration, it was confirmed by transmitted X-ray whether the positive electrode tab and the negative electrode tab were damaged every 50,000 cycles, and the number of cycles at which damage was confirmed was evaluated.

Table 1 summarizes the results of the secondary batteries of Examples and Comparative Examples. The values shown in Table 1 are relative values when the number of cycles in which damage was confirmed in the comparative example was set to 1.

As can be seen from Table 1, the example in which the spacer was provided between the laminated electrode assembly and the rectangular outer package had 20.2 times the durability of the comparative example in which the spacer was not provided. Therefore, according to the laminated secondary battery of the present embodiment, it was confirmed that damage to the electrode tabs due to friction between the electrode tabs can be suppressed while suppressing deformation of the electrode body.

1 prismatic exterior body, 2 sealing plate, 3 laminated electrode body, 4 positive electrode tab, 5 negative electrode tab, 6 electrode tab, 7 positive electrode terminal, 8 negative electrode terminal, 9 external side insulating member, 10 sealing plug, 11 gas discharge valve, 12 inner side insulating member 13 electrode body holder 14 spacer 20 battery case 30 positive electrode plate 30a positive electrode active material layer 31 negative electrode plate 31a negative electrode active material layer 32 separator 100 laminated secondary battery

Claims (6)

a laminated electrode body in which a plurality of electrode plates are laminated with separators interposed therebetween, and which has a plurality of electrode tabs protruding from each of the plurality of electrode plates;
a metallic rectangular exterior body that houses the laminated electrode body;
a sealing plate that seals the opening of the rectangular exterior body;
one or a plurality of electrode body holders arranged in a gap between the stacked electrode body and the square outer body to accommodate the stacked electrode body;
one or more spacers provided between the laminated electrode body and the rectangular outer body,
The laminated electrode body is suspended from the sealing plate via the electrode tab,
The spacer isprovided between the laminated electrode body and a side surface of the rectangular outer body in a direction perpendicular to the lamination direction of the laminated electrode body,When the electrode body holder is one, it is provided between the stacked electrode body and the electrode body holder or between the electrode body holder and the square outer body, and the electrode body holder is provided with a plurality of electrode body holders. provided in at least one between the electrode holderscage,
The spacer contains a thermosetting resin, and the thermosetting resin is placed between the stacked electrode body and the electrode body holder, between the electrode body holder and the rectangular outer body, or between the electrode body holders. fixed to connect between , stacked secondary battery. 2. The stacked secondary battery according to claim 1, wherein the thickness of said spacer is half or more of the distance of said gap. 3. The stacked secondary battery according to claim 1, wherein said spacer occupies 10% or more of the area of the surface on which said spacer is arranged. The stacked secondary battery according to any one of claims 1 to 3 , wherein the number of the electrode body holder is one, and the spacer is provided only between the stacked electrode body and the electrode body holder. . The stacked secondary battery according to any one of claims 1 to 3 , wherein the number of the electrode body holder is one, and the spacer is provided only between the electrode body holder and the square outer body. . The stacked secondary battery according to any one of claims 1 to 5 , wherein the spacer contains a swelling resin.

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