JP2009187889A - Battery case and battery pack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a battery case and a battery pack in which an increase of an inner pressure of a battery can be prevented. <P>SOLUTION: The battery case 2 houses a battery 1 of which the volume can be changed according to a variation of an inner pressure, and a pushing pressure to a thin type battery by at least either an upper surface portion 22a and a bottom surface portion 21a becomes smaller toward a pressure releasing portion 17, at least when an inner pressure of a battery external case rises. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a battery case and an assembled battery.

In lithium-based batteries, lead acid batteries, and the like, gas may be generated from battery elements and the internal pressure of the battery may increase. In order to prevent this, it has been proposed to provide a safety valve on the exterior material (Patent Document 1).

On the other hand, there is also proposed a battery in which thin batteries are stacked to form an assembled battery, which is accommodated in a battery case and a lid is wound around (Patent Document 2).

However, if gas is generated inside the battery while the thin battery with the safety valve is stored in the battery case, the generated gas may not be smoothly discharged from the safety valve depending on the storage state of the thin battery in the battery case. It may not be possible to prevent the rise of

JP 2002-151020 A JP 2006-92984 A

The problem to be solved by the present invention is to provide a battery case and an assembled battery that can prevent an increase in internal pressure of the battery.

The present invention solves the above problem by reducing the pressing force applied to the thin battery by at least one of the upper surface portion and the lower surface portion of the battery case toward the pressure release portion at least when the pressure inside the battery exterior increases. .

  According to the present invention, since the gas generated in the battery can be smoothly guided toward the pressure release portion, an increase in the internal pressure of the battery can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
First, the battery 1 according to this embodiment will be described. The battery 1 described below can also be applied to the second to fourth embodiments, and will be described collectively here. However, the assembled battery that houses the battery case 2 and the battery 1 according to the present embodiment is not limited to the form of the battery 1 described below.

  1A is a plan view showing a battery according to this embodiment, FIG. 1B is a cross-sectional view taken along line 1B-1B of FIG. 1A, and FIG. 2A is a safety valve shown in FIGS. 1A and 1B and other welded portions. FIG. 2B is an enlarged cross-sectional view showing a state when the safety valve shown in FIGS. 1A and 1B is operated.

  FIG. 1A and FIG. 1B show one battery 1 (also referred to as a unit battery or a cell), and by stacking a plurality of the batteries 1 and connecting them in a desired electric circuit configuration, an assembled battery having a desired voltage and capacity can be obtained. Can be configured.

  A battery 1 according to the present embodiment is a lithium-based, flat plate, and laminated type thin secondary battery, and as shown in the figure, a power generation element 12, a positive electrode tab 13 as a positive electrode terminal, and a negative electrode The negative electrode tab 14 as an electrode terminal, a first exterior member 111, a second exterior member 112, and a safety valve 17 are configured. The first exterior member 111 and the second exterior member 112 are also collectively referred to as the exterior member 11.

  Although the detailed structure of the power generation element 12 is not shown, the power generation element 12 is composed of a positive electrode plate, a separator, a negative electrode plate, and an electrolyte, and a plurality of positive electrode plates and negative electrode plates (for example, three each) via the separator. They are stacked alternately. The three positive plates are connected to the positive electrode tab 13 made of metal foil via the positive current collector 15, while the three negative plates are connected to the negative current collector 16. Similarly, it is connected to the negative electrode tab 14 made of metal foil.

  An outline of the power generation element 12 is as follows.

The positive electrode plate constituting the power generation element 12 includes a positive electrode current collector 15 extending to the positive electrode tab 13 and a positive electrode layer formed on a part of both main surfaces of the positive electrode current collector 15. The positive electrode layer of the positive electrode plate is not formed over both main surfaces of the positive electrode side current collector 15, but when the power generation element 12 is configured by stacking the positive electrode plate, the separator, and the negative electrode plate. In addition, the positive electrode plate is formed only on a portion substantially overlapping the separator.

  The positive electrode side current collector 15 of the positive electrode plate is made of an electrochemically stable metal foil such as an aluminum foil, an aluminum alloy foil, a copper foil, or a nickel foil.

In addition, the positive electrode layer of the positive electrode plate may be, for example, a lithium composite oxide such as lithium nickelate (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), or lithium cobaltate (LiCoO ₂ ), chalcogen (S, Se, Te) A positive electrode active material such as a compound, a conductive agent such as carbon black, an adhesive such as an aqueous dispersion of polytetrafluoroethylene or polyvinylidene fluoride, and a solvent such as N-methyl-2-pyrrolidone are mixed. This is applied to a part of both main surfaces of the positive electrode side current collector 15 so as to have a thickness of 20 μm, for example, and dried and rolled.

  The negative electrode plate constituting the power generation element 12 includes a negative electrode side current collector 16 extending to the negative electrode tab 14 and negative electrode layers respectively formed on both main surfaces of part of the negative electrode side current collector 16. . The negative electrode layer of the negative electrode plate is not formed over the entire main surfaces of the negative electrode side current collector 16, but when the power generation element 12 is configured by stacking the positive electrode plate, the separator, and the negative electrode plate. In addition, the negative electrode plate is formed only in a portion substantially overlapping with the separator.

  The negative electrode side current collector 16 of the negative electrode plate is made of an electrochemically stable metal foil such as a nickel foil, a copper foil, a stainless steel foil, or an iron foil.

  Further, the negative electrode layer of the negative electrode plate is formed of, for example, a negative electrode active material that occludes and releases lithium ions of the positive electrode active material, such as amorphous carbon, non-graphitizable carbon, graphitizable carbon, or graphite. The main material is a carbon particle surface carrying carbonized styrene butadiene rubber by mixing an aqueous dispersion of styrene butadiene rubber resin powder as a precursor material of an organic fired body, drying and then grinding. This is further mixed with a binder such as acrylic resin emulsion or polyvinylidene fluoride and a solvent such as N-methyl-2-pyrrolidone, and this mixture is applied to a part of both main surfaces of the negative electrode side current collector 16. It is formed by applying, drying and rolling.

  In particular, when amorphous carbon or non-graphitizable carbon is used as the negative electrode active material, the flatness of the potential during charge / discharge is poor and the output voltage decreases with the amount of discharge. This is advantageous because there is no reduction in output.

  The separator of the power generation element 12 prevents a short circuit between the positive electrode plate and the negative electrode plate described above, and can also have a function of holding an electrolyte. This separator is, for example, a microporous film made of polyolefin such as polyethylene (PE) or polypropylene (PP). When an overcurrent flows, the pores of the layer are blocked by the heat generation to block the current. It also has a function.

  In addition, the separator according to the present embodiment is not limited to a single layer film such as polyolefin, but a three-layer structure in which a polypropylene film is sandwiched with a polyethylene film, or a laminate of a polyolefin microporous film and an organic nonwoven fabric may be used. it can. By forming the separator in multiple layers as described above, various functions such as an overcurrent prevention function, an electrolyte holding function, and a separator shape maintenance (stiffness improvement) function can be provided.

  Moreover, the positive electrode plate, the separator, and the negative electrode plate of the power generation element 12 according to the present embodiment are not limited to the above-described number, and for example, the power generation element 1 is composed of one positive electrode plate, three separators, and one negative electrode plate. The number of positive electrode plates, separators, and negative electrode plates can be selected as necessary.

  On the other hand, the positive electrode tab 13 and the negative electrode tab 14 are not particularly limited as long as they are electrochemically stable metal materials. As the positive electrode tab 13, for example, aluminum, for example, is used. A thin plate having a thickness of about 0.5 mm formed of aluminum alloy, copper, nickel, or the like can be used. Moreover, as the negative electrode tab 14, a thin plate having a thickness of about 0.5 mm formed of, for example, nickel, copper, stainless steel, iron, or the like can be used as in the case of the negative electrode current collector 16 described above.

The power generation element 12 is housed and sealed in the first exterior member 111 and the second exterior member 112. Each of the first exterior member 111 and the second exterior member 112 in the present embodiment is composed of a plurality of layers. For example, from the inside to the outside of the battery 1, an inner layer composed of a resin film excellent in electrolytic solution resistance and heat fusion properties such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer, and aluminum It has a three-layer structure of an intermediate layer composed of a metal foil and an outer layer composed of a resin film excellent in electrical insulation such as a polyamide resin or a polyester resin.

Therefore, in each of the first exterior member 111 and the second exterior member 112, one surface of the metal foil such as an aluminum foil (the inner surface of the battery 1) is a resin such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer. And the other surface (the outer surface of the battery 1) is laminated with a polyamide-based resin or a polyester-based resin, and is formed of a flexible material such as a resin-metal thin film laminating agent.

  Thus, when the exterior member 11 includes the metal layer in addition to the resin layer, the strength of the exterior member 11 itself can be improved. Further, by configuring the inner layer of the exterior member 11 with a resin such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer, the exterior members 111 and 112 and the exterior member 11 and a seal member described later It is possible to ensure a good fusing property.

  As shown in FIGS. 1A and 1B, since the positive electrode tab 13 and the negative electrode tab 14 are led out from one end portion of the sealed exterior member 11, the thickness of the electrode tabs 13 and 14 is increased. A gap is generated in the heat-sealed portion between the first exterior member 111 and the second exterior member 112. For this reason, a sealing member made of polyethylene, polypropylene, or the like can be interposed in a portion where the electrode tabs 13 and 14 and the exterior member 11 are in contact with each other, so that the sealing performance inside the thin battery 1 can be maintained. It is preferable from the viewpoint of heat-sealability that the sealing member is made of the same type of resin as that constituting the exterior member 11 in both the positive electrode tab 13 and the negative electrode tab 14.

  These exterior members 11 enclose the power generation element 12, a part of the positive electrode tab 13 and a part of the negative electrode tab 14, and perchloric acid in an organic liquid solvent in a space formed by the two exterior members 11. While injecting a liquid electrolyte having a lithium salt such as lithium, lithium borofluoride or lithium hexafluorophosphate as a solute, the space formed by the exterior member 11 is sucked into a vacuum state, and then the outer periphery of the exterior member 11 The ends are sealed by heat fusion (thermal welding) by hot pressing.

  In addition, as the organic liquid solvent of the electrolyte, an ester solvent such as propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), or methyl ethyl carbonate can be used. However, the present invention is not limited to this, and an organic liquid solvent obtained by mixing and preparing an ether solvent such as γ-butylactone (γ-BL) or dietoxyethane (DEE) in an ester solvent can also be used.

  In the battery 1 according to the present embodiment, gas may be generated due to decomposition of the electrolyte of the power generation element 12 or the like, and an abnormal state may occur such that the internal pressure increases and the exterior member 11 expands. The battery 1 of this example has a safety valve 17 in which the heat-sealed portion at the outer peripheral end of the exterior member 11 is partially narrowed to prevent the internal pressure from increasing. That is, as shown in FIGS. 1 and 2A, a part where the heat-sealed part is partially narrowed is formed on one side of the exterior member 11, and the adhesive strength of the outer peripheral end part is weakened compared to other general surfaces. ing. This portion is referred to as a safety valve 17 (pressure release portion).

  According to the battery 1 having the safety valve 17, when gas is generated inside, the non-heat-sealed portion extends and rises up and down as shown in FIG. 2B, and the exterior member 11 is adhered only by the narrow heat-sealed portion. However, the adhesive strength is weaker than that of the other outer peripheral edge, and as shown in FIG. (See arrow in diagram). As a result, the adhesion of the exterior member 11 is broken at the portion of the safety valve 17 so that the inside and outside of the battery 1 communicate with each other, and gas is released from this to release the pressure inside the battery 1 and prevent the internal pressure from rising. can do.

  In the battery 1 shown in FIG. 1, since the positive electrode tab 13 and the negative electrode tab 14 are led out from the side of the same exterior member, the safety valve 17 is provided on the side facing the positive electrode tab. A safety valve 17 may be provided at a portion between 13 and the negative electrode tab 14. In addition to the side shown in the figure, it can be provided on any of the side sides.

  FIG. 3 is a plan view showing another embodiment of the battery according to the present invention. The battery 1 according to the embodiment shown in the figure is led out from the side of the exterior member 11 where the positive electrode tab 13 and the negative electrode tab 14 face each other. In the battery 1 having such a configuration, for example, as shown in the figure, a safety valve 17 can be provided on any one of the sides.

  The safety valve 17 according to these embodiments corresponds to the pressure release portion of the present invention, and the side where the safety valve 17 is provided is referred to as “the one provided with the safety valve”.

  Now, a battery case 2 in which one or a plurality of the above-described batteries 1 are stacked to form an assembled battery, and this is accommodated will be described.

4A to 4C are cross-sectional views showing the battery case according to the first embodiment. FIG. 4A shows a state where the lid 22 is removed, FIG. 4B shows a state where the lid 22 is closed, and FIG. 4C shows a safety valve 17 of the battery 1. Each shows the state of operating.

The battery case 2 of this example has an approximately rectangular parallelepiped aluminum case body 21 having an opening at the top and a bottom surface 21a, and an aluminum lid 22 having an upper surface 22a for closing the opening of the case body. The case body 21 and the lid 22 are fixed by the coupling portion 23 after the battery 1 is accommodated therein.

The coupling portion 23 has a structure in which the opening end portion of the case body 21 and the outer peripheral end portion of the lid 22 are fixed by fastening means such as welding. In addition, the connection part 23 of the case main body 21 and the lid | cover 22 of the battery case 2 of this embodiment can also be fixed with what is called a winding fastening structure other than welding joining.

Further, in the illustrated battery case 2, the battery 1 is housed in the case body 21 and the lid 22 is closed, but the openings of the case of the same size are aligned with each other by welding or the like. It can also be a coupling part. Even in such a case, one means the case body 21 and the other means the lid 22.

In the battery case 2 of the present embodiment, as shown in FIG. 4A, recesses 211 and 221 facing the inside of the battery case 2 are formed on the bottom surface 21 a of the case body 21 and the upper surface 22 a of the lid 22.

The concave portion 211 (protruding portion) formed in the bottom surface 21a of the case body 21 has a depth (that is, a protruding amount toward the inside of the case) D1 on the side where the safety valve 17 of the battery 1 is provided, as shown in FIG. It is formed shallower than the depth D2 where the safety valve 17 is not provided, that is, where the electrode tabs 13 and 14 are provided (D1 <D2). Note that the recess 211 is horizontal with respect to the width direction of the battery 1 shown in FIG. 1A (the vertical direction shown in FIG. 1A).

Similarly, the concave portion 221 (protruding portion) formed on the upper surface 22a of the lid 22 has a depth D3 (that is, a protruding amount toward the inside of the case) where the safety valve 17 of the battery 1 is provided as shown in FIG. However, it is formed shallower than the depth D4 where the safety valve 17 is not provided, that is, where the electrode tabs 13 and 14 are provided (D3 <D4). The recess 221 is horizontal with respect to the width direction of the battery 1 shown in FIG. 1A (vertical direction shown in FIG. 1A).

Incidentally, the depth (the amount of protrusion into the case) and the inclination angle of the concave portion 211 provided on the bottom surface 21a of the case body 21 and the concave portion 221 provided on the upper surface 22a of the lid 22 can be the same size. Further, instead of forming the recesses 211 and 221 on the bottom surface 21 a of the case body 21 and the upper surface 22 a of the lid 22, a recess can be formed on only one of them. Furthermore, it can replace with the recessed parts 211 and 221 and can also be set as the convex part which goes to the exterior of the battery case 2 which has the surface of the same inclination direction as what is shown to FIG. 4A.

The recess 211 formed on the bottom surface 21 a of the case main body 21 and the recess 221 formed on the top surface 22 a of the lid 22 shown in FIGS. 4A to 4C are both sized to press the main surface of the battery 1. However, as in another embodiment shown in FIG. 5, the recesses 211 and 221 can be formed so as to remove a part of the main surface of the battery 1 around the safety valve 17.

FIG. 4B is a cross-sectional view showing a state in which the lid 22 is attached to the case main body 21 and the coupling portion 23 is welded. In this state, a plurality (three are shown in the figure) of the batteries 1 are pressed in the stacking direction by the recess 211 formed in the case body 21 and the recess 221 formed in the lid 22. For this reason, when the recesses 211 and 221 receive stress from the battery 1 inside, the case is elastically deformed, and the inclination of the recesses 211 and 221 may become substantially horizontal as shown in FIG.

Although details will be described later, when the battery 1 expands and the safety valve 17 is about to operate, a force for expanding the battery case 2 also acts in the stacking direction of the batteries 1. At this time, the direction in which the electrode tabs 13 and 14 of each battery 1 are provided is pressed more strongly by the two recesses 211 and 221 than the direction in which the safety valve 17 is provided (P1 in FIGS. 4B and 4C). <P2). Thereby, the gas generated inside the battery 1 can be guided toward the safety valve 17. Therefore, it is desirable that the depths D1 to D4 and the inclination angles or the sizes of the recesses 211 and 221 are appropriately selected according to the required operation responsiveness of the safety valve 17 and the like. In this sense, each of the concave portions 211 and 221 in this example corresponds to a means for generating a pressure difference in the pressing force according to the present invention.

Next, the operation will be described.

First, a plurality of batteries 1 (three in the example shown in FIG. 4A) are stacked in the thickness direction of the battery 1 so that the main surfaces (outer surfaces in the thickness direction of the battery 1) are aligned with each other, and each positive electrode tab 13 and each negative electrode. After connecting the tab 14 with a predetermined electric circuit configuration (illustration of this part is omitted), the tab 14 is housed in the case body 21, and the lid 22 is closed to fix the coupling portion 23. In addition, all the safety valves 17 of each battery 1 are located in the same direction of the left side shown to FIG. 4A. This state is shown in FIG. 4B.

At this time, the batteries 1 are strongly sandwiched between the recesses 211 of the case body 21 and the recesses 221 of the lid 22 so that the plurality of stacked batteries 1 do not vibrate. Thereby, even if there is a manufacturing variation in the thickness of the battery and the height of the battery case, the electrode tab 13 of the battery 1 is formed by the inclined recess 211 of the case body 21 and the inclined recess 221 of the lid 22. , 14 is pressed relatively stronger than the one provided with the safety valve 17. That is, P1 <P2 in FIGS. 4B and 4C.

In this state, when an abnormality occurs in any of the batteries 1 stored therein, gas is generated inside the battery and the exterior member 11 expands, the safety valve 17 side has a smaller pressing force than the other parts, so the generated gas Is guided toward the safety valve 17 having a small pressing force. In the battery 1 as in this example, when gas is generated and the exterior member 11 expands, the volume expands mainly in the thickness direction. This thickness direction, in other words, the stacking direction of the batteries 1 corresponds to the main volume change direction of the battery 1.

And if the gas which generate | occur | produced inside the battery 1 and was gathered toward the safety valve 17 exceeds predetermined amount, as shown to FIG. 4C, the safety valve 17 will act | operate and a hole will open and gas will be discharged | emitted from here. Thereby, the raise of the internal pressure of the battery 1 can be suppressed.

In the present embodiment, the safety valve 17 of the battery 1 can be operated without destroying the battery case 2.

<< Second Embodiment >>
FIG. 6 is a cross-sectional view showing a second embodiment of the battery case 2 according to the present invention, and shows a state where the lid 22 is closed. The states of the elastic members 24 and 24 before being stored in the battery case 2 are shown above and below the battery case 2.

  In 1st Embodiment mentioned above, the recessed part 211,221 formed in each of the bottom face 21a of the case main body 21 and the upper surface 22a of the lid | cover 22 was illustrated as an aspect of a means which a pressure difference with respect to the main surface of the battery 1 produces. However, in the present embodiment, instead of this, the elastic members 24 and 24 are provided between the bottom surface 21 a of the case body 21 and the battery 1 and between the upper surface 22 a of the lid 22 and the battery 1. The left side in FIG. 6 is the one provided with the safety valve 17.

  As shown in the upper and lower views of FIG. 6, the elastic member 24 of this example is a molded article such as an elastomer having a substantially uniform elastic force, and the thicknesses H <b> 1 and H <b> 3 on which the safety valve 17 is provided are electrodes. The tabs 13 and 14 are formed so as to be inclined so as to be thinner than the thicknesses H2 and H4. The inclined surfaces of the elastic members 24, 24 can be formed on the upper surface and / or the lower surface. The elastic member 24 of the present embodiment corresponds to a means for generating a pressure difference in the pressing force of the present invention.

  In addition, since the structure of the battery 1 and the battery case 2 is the same as 1st Embodiment mentioned above, a part of the detailed description is used.

  Also in the battery case 2 of the present embodiment, as shown in FIG. 6, elastic members 24 and 24 are interposed between the battery 1 and the bottom surface of the main body case 21 and between the battery 1 and the lid 22, and the lid 22 is provided. If it fixes by the coupling | bond part 23, the direction in which the electrode tabs 13 and 14 of each battery 1 were provided will be pressed more strongly than the direction in which the safety valve 17 was provided. In other words, the safety valve 17 side is pressed weaker than the other parts (P1 <P2 in FIG. 6).

Therefore, when gas is generated in any one of the batteries 1 and the exterior member 11 expands, the safety valve 17 side is pressed weaker than the other parts, so that the generated gas is directed to the safety valve 17 side with a small pressing force. Will be guided.

And if the gas which generate | occur | produced inside the battery 1 and was collected toward the safety valve 17 exceeds predetermined amount, the safety valve 17 will act | operate and a hole will be opened (refer FIG. 2B), and gas will be discharged | emitted from here. Thereby, the raise of the internal pressure of the battery 1 can be suppressed.

In the present embodiment, the safety valve 17 of the battery 1 can be operated without destroying the battery case 2.

The elastic member 24 can also be provided only between one of the bottom surface of the case body 21 and the battery 1 and between the lid 22 and the battery 1.

<< Third Embodiment >>
FIG. 7 is a cross-sectional view showing a third embodiment of a battery case according to the present invention.

  In the first embodiment described above, the concave portions 211 and 221 formed on the bottom surface 21a of the case body 21 and the top surface 22a of the lid 22 are exemplified as modes of means for generating a pressure difference in the pressing force against the main surface of the battery 1. In the second embodiment, the elastic members 24 and 24 having different main surface thicknesses are exemplified. In contrast, in the present embodiment, instead of or in addition to these, the first elastic member 25 and the second elastic member 26 having different elastic forces in the expansion direction of the battery 1 are replaced with the bottom surface 21a of the case body 21. Between the battery 1 and the battery 1 and between the upper surface 22 a of the lid 22 and the battery 1. In FIG. 7, the left side is the one provided with the safety valve 17.

  The first elastic member 25 and the second elastic member 26 have a relatively small elastic force in the first elastic member 25 compared to the second elastic member 26, and the first elastic member 25 is provided with the safety valve 17. The second elastic member 26 is interposed in the direction in which the electrode tabs 13 and 14 are provided. The elastic force mentioned here means the elastic force in the expansion direction of the battery 1, that is, the stacking direction of the battery 1, in other words, in the thickness direction of the first and second elastic members 25 and 26.

The first elastic member 25 and the second elastic member 26 having different elastic forces in the thickness direction can be made of rubber or elastomer having different elasticity, but can also be made of a fluid bag filled with liquid or gas, for example. In that case, the amount or pressure of the fluid enclosed in the first elastic member 25 is made smaller than the amount or pressure of the fluid enclosed in the second elastic member 26. The 1st elastic member 25 and the 2nd elastic member 26 of this embodiment are equivalent to the means which a pressure difference produces in the pressing force of this invention.

  In addition, since the structure of the battery 1 and the battery case 2 is the same as 1st Embodiment mentioned above, a part of the detailed description is used.

  Also in the battery case 2 of this embodiment, as shown in FIG. 7, the first elastic member 25 and the second elastic member 26 are arranged along the main surface of the battery 1, and the battery 1 and the bottom surface 21 a of the main body case 21 are arranged. When the lid 22 is fixed by the coupling portion 23 between the battery 1 and the upper surface 22a of the lid 22, the safety valve 17 is provided when the electrode tabs 13 and 14 of each battery 1 are provided. Will be pressed more strongly than the direction (P1 <P2 in FIG. 7). In other words, the safety valve 17 side is pressed weaker than other parts.

Therefore, when gas is generated in any of the batteries 1 and the exterior member 11 expands, the safety valve 17 side is pressed weaker than the other parts, so that the generated gas is led to the safety valve 17 with a small pressing force. Will be.

And if the gas which generate | occur | produced inside the battery 1 and was collected toward the safety valve 17 exceeds predetermined amount, the safety valve 17 will act | operate and a hole will be opened (refer FIG. 2B), and gas will be discharged | emitted from here. Thereby, the raise of the internal pressure of the battery 1 can be suppressed.

In the present embodiment, the safety valve 17 of the battery 1 can be operated without destroying the battery case 2.

The first and second elastic members 25 and 26 may be provided only on either the bottom surface of the case body 21 and the battery 1 or between the lid 22 and the battery 1.

<< 4th Embodiment >>
FIG. 8 is a cross-sectional view showing a fourth embodiment of the battery case according to the present invention.

  In the first embodiment described above, the concave portions 211 and 221 formed on the bottom surface 21a of the case body 21 and the top surface 22a of the lid 22 are exemplified as modes of means for generating a pressure difference in the pressing force against the main surface of the battery 1. In the second embodiment, the elastic members 24 and 24 having different main surface thicknesses are exemplified. In the third embodiment, the first elastic member 25 and the second elastic member 26 having different elastic forces in the expansion direction of the battery 1 are provided. Illustrated. In contrast, in the present embodiment, instead of or in addition to these, the first interposed member 27 and the second interposed member 28 having different melting points are connected to the bottom surface 21a of the case body 21 and the battery 1 with each other. And between the battery 22 and the upper surface 22 a of the lid 22. The left side in FIG. 8 is the one provided with the safety valve 17.

  The first intervention member 27 and the second intervention member 28 are made of a material having a relatively low melting point in the first intervention member 27 as compared with the second intervention member 28. Is interposed in the direction where the safety valve 17 is provided, and the second interposed member 28 is interposed in the direction where the electrode tabs 13 and 14 are provided.

  In the event of an abnormal gas generation inside the battery 1, heat is also generated. For example, it is known that the battery temperature during normal operation is 40 to 45 ° C. and about 70 ° C. at maximum, but reaches about 200 ° C. when gas is generated.

The material of the first intervention member 27 and the second intervention member 28 having different melting points in this example uses this characteristic, and has a melting temperature of, for example, 80 ° C. to 200 ° C. Select what you have. The first interposed member 27 can be made of a plastic material having a melting point of, for example, 80 to 100 ° C., and the second interposed member 28 can be made of a plastic material having a melting point of, for example, 180 to 200 ° C. The first intervention member 27 and the second intervention member 28 of the present embodiment correspond to the means for generating a pressure difference in the pressing force of the present invention.

  In addition, since the structure of the battery 1 and the battery case 2 is the same as 1st Embodiment mentioned above, a part of the detailed description is used.

  In the battery case 2 of the present embodiment, as shown in FIG. 8, the first interposed member 27 and the second interposed member 28 are arranged along the main surface of the battery 1, and the bottom surface 21 a of the battery 1 and the main body case 21. And the battery 22 and the upper surface 22a of the cover 22 are interposed between the battery 22 and the cover 22, and the cover 22 is fixed by the connecting portion 23. In this state, there is no difference between the pressing forces P1 and P2 acting on the battery 1.

And when gas will generate | occur | produce in the inside of any battery 1 and the exterior member 11 will expand | swell, battery temperature will also rise in connection with this. Therefore, since the first intervention member 27 starts to soften and melts first, the pressing force to the main surface of the battery 1 on the safety valve 17 side becomes weaker than the pressing force on the side where the electrode tabs 13 and 14 are provided ( In FIG. 8, P1 <P2), the generated gas is guided to the safety valve 17 side having a small pressing force.

And if the gas which generate | occur | produced inside the battery 1 and was collected toward the safety valve 17 exceeds predetermined amount, the safety valve 17 will act | operate and a hole will be opened (refer FIG. 2B), and gas will be discharged | emitted from here. Thereby, the raise of the internal pressure of the battery 1 can be suppressed.

In the present embodiment, the safety valve 17 of the battery 1 can be operated without destroying the battery case 2.

The first and second interposed members 27 and 28 can be provided only between either the bottom surface 21 a of the case body 21 and the battery 1 or between the top surface 22 a of the lid 22 and the battery 1.

In addition, the melting point of the first intervention member 27 is lower than the melting point of the second intervention member 28. However, since the pressing force on the side where the safety valve 17 is provided should be smaller in the event of an abnormality, the first intervention member 27 A material whose softening point is lower than the softening point of the second intervention member 28 can also be selected.

It is a top view which shows embodiment of the battery which concerns on this invention. It is sectional drawing which follows the 1B-1B line | wire of FIG. 1A. It is sectional drawing which expands and shows the safety valve shown to FIG. 1A and FIG. 1B and the other welding part. It is sectional drawing which expands and shows a mode when the safety valve shown to FIG. 1A and FIG. 1B operate | moved. It is a top view which shows other embodiment of the battery which concerns on this invention. It is sectional drawing (state which removed the lid | cover) which shows 1st Embodiment of the battery case which concerns on this invention. It is sectional drawing (state which closed the lid | cover) which shows 1st Embodiment of the battery case which concerns on this invention. It is sectional drawing (state in which the safety valve act | operated) which shows 1st Embodiment of the battery case which concerns on this invention. It is sectional drawing (state which removed the cover) which shows the modification of 2nd Embodiment of FIG. 4A-FIG. 4C. It is sectional drawing (state which closed the lid | cover) which shows 2nd Embodiment of the battery case which concerns on this invention. It is sectional drawing (state which closed the lid | cover) which shows 3rd Embodiment of the battery case which concerns on this invention. It is sectional drawing (state which closed the lid | cover) which shows 4th Embodiment of the battery case which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Battery 11 ... Exterior member 111 ... 1st exterior member 112 ... 2nd exterior member 12 ... Power generation element 13 ... Positive electrode tab 14 ... Negative electrode tab 15, 16 ... Current collector 17 ... Safety valve 2 ... Battery case 21 ... Case Main body 21a ... Bottom 211 ... Recess 22 ... Lid 22a ... Upper surface 221 ... Recess 23 ... Coupling part 24 ... Elastic member 25 ... First elastic member 26 ... Second elastic member 27 ... First intervention member 28 ... Second intervention member

Claims (11)

A bag-shaped battery exterior in which a power generation element is sealed inside by forming a joint portion that joins the outer peripheral edges of two sheet-shaped exterior members, and is electrically connected to the power generation element inside the battery exterior And a battery terminal led to the outside of the battery exterior, and when the pressure inside the battery exterior increases, a part of the joint is released to communicate the interior and exterior of the battery exterior. A battery case for storing a thin battery provided with a pressure release portion,
An upper surface portion and a lower surface portion that press the thin battery from both sides in the thickness direction of the thin battery;
The battery case according to claim 1, wherein a pressing force applied to the thin battery by at least one of the upper surface portion and the lower surface portion decreases toward the pressure release portion at least when the pressure inside the battery exterior increases. The battery case according to claim 1,
At least one of the upper surface portion and the lower surface portion is provided with a protruding portion that protrudes toward the inside of the battery case and presses the thin battery,
The battery case, wherein the protruding portion has a smaller amount of protrusion in the inner direction of the battery case toward the pressure release portion. The battery case according to claim 1,
An elastic member is interposed between at least one of the upper surface portion and the lower surface portion and the thin battery,
The battery case characterized in that a dimension of the elastic member in a direction corresponding to a thickness direction of the thin battery becomes smaller toward the pressure release portion. The battery case according to claim 1,
An elastic member is interposed between at least one of the upper surface portion and the lower surface portion and the thin battery,
The battery case, wherein the elastic member is formed of a plurality of elastic members, and the elastic force of the plurality of elastic members is smaller as the elastic member is closer to the pressure release portion. The battery case according to claim 1,
Between the at least one of the upper surface portion and the lower surface portion and the thin battery, a plurality of interposition members made of materials having different softening points or melting points are provided,
The battery case is characterized in that the interposition member is formed of a material having a lower softening temperature or melting point temperature closer to the pressure release portion. A bag-shaped battery exterior in which a power generation element is sealed inside by forming a joint portion that joins the outer peripheral edges of two sheet-shaped exterior members, and is electrically connected to the power generation element inside the battery exterior And a battery terminal led to the outside of the battery exterior, and when the pressure inside the battery exterior increases, a part of the joint is released to communicate the interior and exterior of the battery exterior. One or more thin batteries provided with a pressure relief portion to
An upper surface portion and a lower surface portion that press the thin battery from both sides in the thickness direction of the thin battery are provided. And a battery case that is reduced in size toward the pressure release portion. The assembled battery according to claim 6,
Inside the battery case, a plurality of thin batteries are stored in a stacked state in the thickness direction of the thin batteries,
The plurality of laminated thin batteries are laminated such that the pressure release portions of the thin batteries are arranged side by side in the lamination direction of the thin batteries. The assembled battery according to claim 6,
At least one of the upper surface portion and the lower surface portion is provided with a protruding portion that protrudes toward the inside of the battery case and presses the thin battery,
The assembled battery according to claim 1, wherein the protruding portion has a smaller amount of protrusion in the inner direction of the battery case toward the pressure release portion. The assembled battery according to claim 6,
An elastic member is interposed between at least one of the upper surface portion and the lower surface portion and the thin battery,
The assembled battery according to claim 1, wherein a dimension of the elastic member in a direction corresponding to a thickness direction of the thin battery becomes smaller toward the pressure release portion. The assembled battery according to claim 6,
An elastic member is interposed between at least one of the upper surface portion and the lower surface portion and the thin battery,
The assembled battery, wherein the elastic member is formed of a plurality of elastic members, and the elastic force of the plurality of elastic members is smaller as the elastic member is closer to the pressure release portion. The assembled battery according to claim 6,
Between the at least one of the upper surface portion and the lower surface portion and the thin battery, a plurality of interposition members made of materials having different softening points or melting points are provided,
The assembled battery is characterized in that at least one of a softening temperature and a melting point temperature is lower as the intervention member is closer to the pressure release portion.

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