JP6842889B2 - battery - Google Patents

Description

The present invention relates to a battery.

In recent years, reduction of carbon dioxide emissions has been urgently desired for environmental protection. In the automobile industry, expectations are high for reducing carbon dioxide emissions by introducing electric vehicles and hybrid electric vehicles, and batteries having stacked single cells have been proposed for extending the cruising range (for example, patent documents). See 1.).

In such a battery, in order to reduce the internal resistance of the single cell, it is necessary to apply a uniform pressing pressure (surface pressure) to the single cell.

U.S. Patent Application Publication No. 2014/03656651

However, for example, when the internal pressure of the single cell increases due to the expansion of the negative electrode and the single cell is deformed, the central portion bulges more than the outer peripheral portion of the single cell restrained by the seal portion. .. Therefore, non-uniform deformation may occur and the surface pressure distribution may deteriorate. As a result, the battery reaction becomes non-uniform and the battery performance deteriorates.

The present invention has been made to solve the problems associated with the above-mentioned prior art, and an object of the present invention is to provide a battery capable of maintaining a uniform surface pressure distribution.

The present invention for achieving the above object is a battery having a laminated body composed of at least a laminated single cell, a deformation absorbing portion, and an anisotropic stretched portion. The deformation absorbing portion is arranged between the lid member and the laminated single cell, and is configured to absorb the deformation of the single cell in the stacking direction. The anisotropic stretch portion is arranged on the side surface of the laminated body, and is configured to stretch in the stacking direction according to the deformation when the single cell is deformed in the stacking direction. The anisotropic stretched portion is formed of an elastic body, is compressed so as to be stretchable in the stacking direction, and is restricted from elastic deformation in the lateral direction intersecting the stacking direction. The elastic modulus in the stacking direction of the anisotropic stretched portion is smaller than the elastic modulus in the lateral direction.

According to the present invention, for example, when the internal pressure of a single cell increases due to the expansion of the negative electrode and the single cell is deformed, the deformation in the stacking direction of the single cell is absorbed, while the outer peripheral portion of the single cell is absorbed. By reducing the difference between the deformation of the central part and the deformation of the central part, the deformation of the single cell is made uniform. Therefore, the non-uniformity of the pressing pressure (surface pressure) applied to the laminated body (single cell) is suppressed. That is, it is possible to provide a battery capable of maintaining a uniform surface pressure distribution.

It is the schematic for demonstrating the battery which concerns on embodiment of this invention. It is the schematic for demonstrating use of a battery. It is sectional drawing for demonstrating the main body part shown in FIG. It is sectional drawing for demonstrating the shape of the lid member shown in FIG. 3 before decompression. It is sectional drawing for demonstrating the single cell shown in FIG. It is the schematic which shows an example of the structure of the anisotropic stretch part shown in FIG. It is sectional drawing for demonstrating the modification 1 of the Embodiment of this invention. It is sectional drawing for demonstrating the modification 2 of the Embodiment of this invention. It is sectional drawing for demonstrating the modification 3 of the Embodiment of this invention. It is a top view for demonstrating the shape of the lid member shown in FIG. 9 before decompression. It is a chart which shows the performance evaluation result about Examples 1 to 3 and Comparative Examples 1 and 2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

FIG. 1 is a schematic view for explaining a battery according to an embodiment of the present invention, FIG. 2 is a schematic view for explaining a use of the battery, and FIG. 3 is a main body portion shown in FIG. FIG. 4 is a cross-sectional view for explaining the shape of the lid member shown in FIG. 3 before decompression.

The battery 100 according to the first embodiment is applied, for example, as a power source for the vehicle 190 shown in FIG. 2, and has a main body 110, a decompression device 185, and a control unit 187 as shown in FIGS. 1 and 3. The vehicle 190 is, for example, an electric vehicle or a hybrid electric vehicle.

The main body 110 has a cell case 120, a lid member 170, and a cover plate 175.

The cell case 120 is made of a highly rigid material and has a substantially rectangular bottom surface 122 and a side wall portion 124 surrounding the bottom surface, the upper surface of which constitutes an opening. Inside the cell case 120, a laminated body 140 and a side regulation portion 168 are arranged.

The laminated body 140 has a plurality of single cells 10, high electric tabs 150 and 152, spacers 155 and 157, a deformation absorbing portion 160, and an anisotropic stretching portion 162. The single cells 10 are laminated, and the opening of the cell case 120 is positioned so as to face the upper surface (one of the surfaces intersecting the stacking direction S) 142 of the laminated body 140 with respect to the stacking direction S of the single cells 10. ing. The side surface of the laminated body 140 extending in the stacking direction S faces the side wall portion 124 of the cell case 120 extending along the stacking direction S. The reference numeral L indicates a lateral direction orthogonal to (intersects) the stacking direction S.

The high-power tabs 150 and 152 are, for example, substantially plate-shaped copper, which is used to draw a current from the laminated single cell 10, and is used for the single cell 10 located at the bottom layer and the single cell 10 located at the top layer. It is in contact.

The spacers 155 and 157 are preferably rigid bodies. The spacer 155 is in contact with the lid member 170 and is located outside the high electric tab 150. The spacer 157 is in contact with the bottom surface 122 of the cell case 120 and is located outside the high power tab 152. Spacers 155 and 157 can be omitted as appropriate, if necessary.

The deformation absorbing portion 160 is located between the high electric tab 150 and the spacer 155, and is in contact with the high electric tab 150. The anisotropic stretched portion 162 is located on the outer peripheral portion of the single cell 10 (the side surface extending in the stacking direction S in the laminated body 140), and also serves as a sealing portion for sealing the inside of the single cell 10. The side regulation portion 168 is arranged between the side wall portion 124 of the cell case 120 and the anisotropic extension portion 162.

The lid member 170 has an opening sealed and is formed of an elastic membrane in the first embodiment. The constituent material of the elastic film is not particularly limited, and for example, silicon rubber and urethane rubber can be applied.

The cover plate 175 has an opening 177 and is arranged so as to cover the lid member 170 to guard the lid member 170. The cover plate 175 is a backup plate made of a lightweight material having good rigidity such as aluminum. The cover plate 175 and the lid member 170 are fixed to the cell case 120 by using a fastening member such as a screw. The fastening member can also be used as a fastening member used for mounting the battery 100 on the vehicle 190.

The decompression device 185 is a pressure applying device composed of a vacuum pump, and is used to depressurize the inside of the cell case 120 to make the internal pressure of the cell case 120 lower than the atmospheric pressure (external pressure). The control unit 187 is used to control the decompression device 185.

The lid member 170 covering the opening is separated from the spacer 155 as shown in FIG. 4 before the inside of the cell case 120 is depressurized (when the internal pressure of the cell case 120 is the same as the atmospheric pressure). doing. Then, when the inside of the cell case 120 is decompressed by the decompression device 185, the lid member 170 is deformed while maintaining the hermeticity based on the differential pressure between the atmospheric pressure and the internal pressure of the cell case 120, and the spacer 155 is used. And apply pressure based on the differential pressure.

As described above, the lid member 170 can be deformed while the opening is sealed, and is deformed when the inside of the cell case 120 is depressurized (the internal pressure of the cell case 120 is lower than the atmospheric pressure) to form a spacer. It contacts 155 (upper surface 142 of the laminated body 140) and applies pressure based on the differential pressure to the contacted surface. That is, the lid member 170 is configured to apply surface pressure in the stacking direction S to one of the surfaces intersecting the stacking direction S of the laminated body 140.

Therefore, the pressing pressure of the laminated body 140 is composed of a pressure based on the differential pressure between the atmospheric pressure and the internal pressure of the cell case 120. For example, a decompression device (pressure applying device) 190 that reduces the pressure inside the cell case 120. Since the total pressing pressure increases as the area of the single cell (electrode) increases without increasing the size of the electrode, it is easy to apply an appropriate pressing pressure to the laminate 140 even when the electrode area is large. It is possible to give to.

As described above, the laminated body 140 is firmly fixed to the highly rigid cell case 120 by the pressure based on the differential pressure between the atmospheric pressure and the internal pressure of the cell case 120, so that the battery 100 is fixed to the vehicle 190. By doing so, the entire battery 100 becomes stable.

Further, the cell case 120 further includes an insulating film layer 128, strong electric connectors 130 and 132, an exhaust connector 134, a pressure release valve 136, a pressure sensor 138, and a light electric connector (not shown).

The insulating film layer 128 is formed on the inner wall of the bottom surface 122 and the side wall portion 124. A spacer 157 is positioned on the insulating film layer 128 on the bottom surface 122. The high-power connectors 130 and 132 are airtightly attached to the side wall portion 124 and are electrically connected to the high-power tabs 150 and 152. The exhaust connector 134 is airtightly attached to the side wall portion 124 and is connected to the pipe from the decompression device 185. Therefore, the decompression device 185 can exhaust the air inside the cell case 120 to reduce the pressure inside the cell case 120.

The pressure release valve 136 is airtightly attached to the side wall portion 124, and discharges the gas inside the cell case 120 when the internal pressure of the cell case 120 rises excessively due to an unexpected cause, for example. It is used to reduce the internal pressure of the cell case 120. The mechanism for discharging the gas in the pressure release valve 136 is not particularly limited, and for example, a thin metal film that cleaves at a predetermined pressure can be used.

The pressure sensor 138 is arranged inside the cell case 120 and is used to measure the internal pressure of the cell case 120. The light electric connector (not shown) is airtightly attached to the side wall portion 124, and is used for monitoring (detecting) the voltage of a single cell contained in the laminated body 140.

The decompression device 185 is controlled by the control unit 187 based on the internal pressure measured by the pressure sensor 138, and when the internal pressure measured by the pressure sensor 138 exceeds the upper limit value, it is operated and the cell is operated. The inside of the case 120 is configured to reduce the pressure.

The upper limit of the internal pressure is set in consideration of the differential pressure between the atmospheric pressure and the internal pressure of the cell case 120. Therefore, while the unexpected increase in the internal pressure of the cell case 120 is prevented, a good pressing pressure (pressure based on the differential pressure) is ensured. The upper limit of the internal pressure is set to, for example, 0.25 atm, and in this case, it is possible to obtain a sufficient pressing pressure.

The decompression device 185 is configured to stop the decompression inside the cell case 120 when the internal pressure measured by the pressure sensor 138 reaches the lower limit value. The lower limit of the internal pressure is set to, for example, 0.15 atm, and in this case, since it is at the same level as the degree of vacuum used for multiple purposes, it is used in another application (vehicle 190) in which the battery 100 is mounted. The decompression device (vacuum source) used in the above can also be used as the decompression device 185.

Next, the single cell 10 included in the laminated body 140 will be described in detail.

FIG. 5 is a cross-sectional view for explaining the single cell shown in FIG.

The single cells 10 included in the laminate 140 are connected in series, and as shown in FIG. 5, the positive electrode current collector layer 20, the positive electrode layer 30, the separator 40, the negative electrode layer 50, and the negative electrode current collector are collected. The body layer 60 and the body layer 60 are laminated in this order, and the peripheral portion thereof is sealed by an anisotropic stretched portion 162 that also serves as a sealing portion.

The positive electrode current collector layer 20 and the negative electrode current collector layer 60 are composed of a resin current collector mainly containing a conductive filler and a resin. This makes it possible to use a higher capacity active material by reducing the weight of the positive electrode current collector layer 20 and the negative electrode current collector layer 60 and improving the internal short circuit resistance.

The constituent materials of the conductive filler are, for example, aluminum, stainless steel, carbon such as graphite and carbon black, silver, gold, copper and titanium. Resins include, for example, polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, styrene butadiene rubber, polyacrylonitrile, polymethyl acrylate, polymethyl methacrylate, polyvinyl chloride, polyvinylidene fluoride, and the like. It is a mixture.

The positive electrode current collector layer 20 and the negative electrode current collector layer 60 are not limited to the form composed of the resin current collector, and can be composed of, for example, a metal or a conductive polymer material. The metal is, for example, aluminum, nickel, iron, stainless steel, titanium, copper. The conductive polymer material is, for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, polyoxadiazole, or a mixture thereof.

If necessary, only one of the positive electrode current collector layer 20 and the negative electrode current collector layer 60 can be configured by the resin current collector.

The positive electrode layer 30 is a sheet-like electrode located between the positive electrode current collector layer 20 and the separator 40, and contains positive electrode active material particles and fibrous material.

The positive electrode active material particles have a coating layer on at least a part of the surface thereof. The coating layer contained in the positive electrode active material particles is composed of a conductive auxiliary agent and a coating resin, and can alleviate the volume change of the positive electrode layer 30 and suppress the expansion of the electrode.

The constituent materials of the positive electrode active material particles are a composite oxide of lithium and a transition metal, a transition metal oxide, a transition metal sulfide, a conductive polymer, and the like. Composite oxides of lithium and transition metals are, for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ and LiMn ₂ O ₄ . Transition metal oxides are, for example, MnO ₂ and V ₂ O ₅ . Transition metal sulfides are, for example, MoS ₂ and TiS ₂ . Conductive polymers are, for example, polyaniline, polyvinylidene fluoride, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene and polycarbazole.

The coating resin is preferably a vinyl resin, a urethane resin, a polyester resin, or a polyamide resin, but if necessary, an epoxy resin, a polyimide resin, a silicon resin, a phenol resin, a melamine resin, a urea resin, an aniline resin, or an ionomer resin. , Polycarbonate and the like can also be applied.

The conductive auxiliary agent is, for example, a metal, carbon such as graphite or carbon black, or a mixture thereof. Metals include aluminum, stainless steel, silver, gold, copper, titanium, and alloys thereof. Carbon black includes acetylene black, ketjen black, furnace black, channel black, thermal lamp black and the like. Two or more types of conductive auxiliary agents can be used in combination, if necessary. From the viewpoint of electrical stability, the conductive auxiliary agent is preferably silver, gold, aluminum, stainless steel, or carbon, and more preferably carbon.

At least a part of the fibrous material forms a conductive passage of the positive electrode layer 30, and is in contact with the positive electrode active material particles around the conductive passage. Therefore, the electrons generated from the positive electrode active material (positive electrode active material particles) quickly reach the conductive passage and are smoothly guided to the positive electrode current collector layer 20.

The fibrous substance is composed of, for example, carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, metal fibers obtained by fiberizing a metal such as stainless steel, and conductive fibers. Conductive fibers are conductive fibers in which metals and graphite are uniformly dispersed in synthetic fibers, conductive fibers in which the surface of organic fibers is coated with metal, and the surface of organic fibers is coated with resin containing a conductive substance. Such as conductive fibers. Among the conductive fibers, carbon fibers are preferable from the viewpoint of electrical conductivity.

The negative electrode layer 50 is a sheet-like electrode located between the negative electrode current collector layer 60 and the separator 40, and contains negative electrode active material particles and fibrous material.

The negative electrode active material particles have a coating layer on at least a part of the surface thereof. The coating layer of the negative electrode active material particles is composed of a coating resin and a conductive auxiliary agent that can be used as needed, and alleviates the volume change of the negative electrode layer 50 and suppresses the expansion of the electrode. It is possible.

The constituent materials of the negative electrode active material particles are graphite, amorphous carbon, calcined polymer compound, coke, carbon fiber, conductive polymer, tin, silicon, metal alloy, composite oxide of lithium and transition metal, and the like. .. The fired polymer compound is, for example, a calcined phenol resin and furan resin that are carbonized. The cokes are, for example, pitch coke, needle coke, and petroleum coke. The conductive polymer is, for example, polyacetylene or polypyrrole. The metal alloy is, for example, a lithium-tin alloy, a lithium-silicon alloy, a lithium-aluminum alloy, or a lithium-aluminum-manganese alloy. The composite oxide of lithium and the transition metal is, for example, Li ₄ Ti ₅ O ₁₂ .

The coating layer, the coating resin, the conductive auxiliary agent, and the fibrous material of the negative electrode layer 50 have substantially the same configurations as the coating layer, the coating resin, the conductive auxiliary agent, and the fibrous material of the positive electrode layer 30, so the description thereof will be described. Omitted. At least a part of the fibrous material of the negative electrode layer 50 forms a conductive passage of the negative electrode layer 50 and is in contact with the negative electrode active material particles around the conductive passage.

The thickness of the positive electrode layer 30 and the negative electrode layer 50 is 150 to 1500 μm, preferably 200 to 950 μm, and more preferably 250 to 900 μm. As a result, it becomes possible to contain a large amount of active material, and the capacity can be increased and the energy density can be improved.

The separator 40 is a porous insulator located between the positive electrode layer 30 and the negative electrode layer 50. The separator 40 exhibits ionic permeability and electrical conductivity when the electrolyte permeates. The electrolyte is, for example, a gel polymer system and has an electrolyte and a host polymer.

The electrolytic solution contains an organic solvent composed of propylene carbonate and ethylene carbonate, and a lithium salt (LiPF ₆ ) as a supporting salt. As the organic solvent, other cyclic carbonates, chain carbonates such as dimethyl carbonate, and ethers such as tetrahydrofuran can be applied. As the lithium salt, other inorganic acid anion salts and organic acid anion salts such as _{LiCF 3} SO _{3 can be applied.}

The host polymer is PVDF-HFP (a copolymer of polyvinylidene fluoride and hexafluoropropylene) containing 10% of HFP (hexafluoropropylene) copolymer. As the host polymer, other polymers having no lithium ion conductivity or a polymer having ionic conductivity (solid polymer electrolyte) can also be applied. Other polymers having no lithium ion conductivity are, for example, polyacrylonitrile and polymethylmethacrylate. The polymer having ionic conductivity is, for example, polyethylene oxide or polypropylene oxide.

Next, with reference to FIGS. 3 to 6, the deformation absorbing portion 160, the anisotropic stretching portion 162, and the lateral regulating portion 168 will be described in detail. Note that FIG. 6 is a schematic view showing an example of the configuration of the anisotropic stretched portion shown in FIG.

As shown in FIGS. 3 and 4, the deformation absorbing portion 160 is located between the high electric tab 150 and the spacer 155, is in contact with the high electric tab 150, and is formed of an elastic body in the present embodiment. It is configured to absorb the deformation of the single cell 10 in the stacking direction S by elastically deforming and shrinking (thickness decreases).

As shown in FIG. 5, the anisotropic stretched portion 162 is located on the outer peripheral portion of the single cell 10 and also serves as a sealing portion for sealing the inside of the single cell 10, and the single cell 10 is deformed in the stacking direction S. When (expanding), it is configured to expand in the stacking direction S according to the deformation (expansion). In the present embodiment, the anisotropic stretched portion 162 is formed of an elastic body, and the elastic body is compressed so as to be stretchable in the stacking direction S and is orthogonal to the stacking direction S in the lateral direction L. Elastic deformation is regulated.

Therefore, for example, when the internal pressure of the single cell 10 increases due to the expansion of the negative electrode and the single cell 10 is deformed, the deformation absorbing unit 160 absorbs the deformation of the single cell 10 in the stacking direction S, while absorbing the deformation. The anisotropic stretched portion 162, which also serves as a seal portion that seals the inside of the single cell (constrains the outer peripheral portion of the single cell), is stretched in the stacking direction S in accordance with the deformation of the single cell 10 to achieve a single cell. The difference between the deformation of the outer peripheral portion and the deformation of the central portion of the cell 10 is reduced, and the deformation of the single cell 10 is made uniform. Therefore, the non-uniformity of the pressing pressure (surface pressure) applied to the laminated body (single cell 10) 140 is suppressed. That is, it is possible to maintain a uniform surface pressure distribution.

As shown in FIG. 6, the anisotropic stretched portion 162 has a base material 163 and an auxiliary material 164, and the elastic modulus in the stacking direction S of the single cell 10 is orthogonal to the stacking direction S in the lateral direction L. It is configured to be smaller than the elastic modulus of (it can be preferentially stretched in the stacking direction S as compared with the lateral direction L). The stacking direction S is a direction perpendicular to the drawing, that is, a direction of entering and exiting the paper surface.

The base material 163 has a substantially rectangular frame-shaped cross section, and is arranged so as to surround the outer peripheral portion of the single cell 10 (the side surface extending in the stacking direction S in the laminated body 140). The auxiliary material 164 is columnar, is mixed with the base material 163, is arranged so as to extend in the lateral direction L in the base material 163, and has an opening corresponding to the outer peripheral portion of the single cell 10 in the central portion. It forms a mesh-like structure. The auxiliary material 164 is selected from materials having an elastic modulus larger than that of the base material 163. The base material 163 may be formed from the same elastic body as the elastic body forming the deformation absorbing portion 160, or may be formed from different elastic bodies.

The auxiliary material 164 suppresses the deformation of the base material 163 in the lateral direction L. That is, the mixing of the auxiliary material 164 is set so that the elastic modulus in the lateral direction L of the anisotropic stretch portion 162 increases. From the viewpoint of suppressing the seepage of the electrolytic solution, the auxiliary material 164 is preferably coated with a material having the same elastic modulus as the elastic modulus of the base material 163.

The elastic modulus in the stacking direction S and the lateral direction L can be adjusted, for example, by changing the material, shape, arrangement, etc. of the auxiliary material 164.

The method of making the elastic moduli of the stacking direction S and the lateral direction L different is not particularly limited to the above configuration. For example, by applying a foam material as the elastic body forming the anisotropic stretched portion 162, the elastic moduli in the stacking direction S and the lateral direction L can be made different. In this case, the elastic moduli in the stacking direction S and the lateral direction L can be adjusted by changing the porosity, for example.

As shown in FIGS. 3 and 4, the side regulation portion 168 is arranged between the side wall portion 124 of the cell case 120 and the anisotropic extension portion 162, and comes into contact with the anisotropic extension portion 162. (The anisotropic extension portion 162 receives a reaction force) and regulates the elastic deformation of the anisotropic extension portion 162 in the lateral direction L.

The side regulation unit 168 is arranged so as not to interfere with the strong electric connector 130, 132, the exhaust connector 134, the pressure release valve 136, 136, and the pressure sensor 138, and to prevent the deformation of the lid member 170. There is.

At least a part of the contact surface of the anisotropic stretch portion 162 with respect to the side regulating portion 168 and / or at least a part of the contact surface of the side regulation portion 168 with respect to the anisotropic stretch portion 162 is a coating layer of a lubricant. It is preferable to have. In this case, since the slip of the anisotropic stretched portion 162 with respect to the lateral regulating portion 168 is improved, the anisotropic stretched portion 162 is smoothly stretched.

The inside of the cell case 120 is depressurized. Therefore, the lubricant that forms the coating layer is preferably one having a small vapor pressure under vacuum, and is, for example, silicon grease, fluoroether grease, or apiison.

The elastic material forming the deformation absorbing portion 160 and the anisotropic stretched portion 162 is, for example, silicon rubber, fluororubber, epichlorohydrin rubber, acrylic rubber, ethylene acrylic rubber, urethane rubber, nitrile rubber, hydride nitrile rubber, and the like. Chlorosulfonated polyethylene, chloroplane rubber, EPDM (ethylene-propylene-diene rubber), ethylene rubber, propylene rubber, butyl rubber, butadiene rubber, styrene butadiene rubber, natural rubber, polyisobutylene, polyethylene chloride, isoprene rubber, foamed polypropylene, foamed polyethylene , Contains at least a part of foamed polyurethane.

Next, Modifications 1 to 3 according to the first embodiment will be described in sequence.

FIG. 7 is a cross-sectional view for explaining a modified example 1 of the embodiment of the invention.

The side regulation unit 168 can be omitted if necessary. For example, as shown in FIG. 7, the anisotropic extension portion 162 and the side wall portion 124 of the cell case 120 are configured to be in contact with each other to regulate the elastic deformation of the anisotropic extension portion 162 in the lateral direction L. It is possible to do. That is, it is possible to replace the side regulating portion 168 with the side wall portion 124 of the cell case 120. In this case, at least a part of the contact surface of the side wall portion 124 with respect to the side regulating portion 168 and / or at least a part of the contact surface of the side side regulating portion 168 with respect to the side wall portion 124 is covered with a lubricant. It is preferable to have.

FIG. 8 is a cross-sectional view for explaining a modification 2 of the embodiment of the invention.

The high electric tab 150 is not limited to the form arranged between the deformation absorbing portion 160 and the single cell 10 located in the uppermost layer. For example, as shown in FIG. 8, it is also possible to arrange the high electric tab 150 between the spacer 155 and the deformation absorbing portion 160 so that the deformation absorbing portion 160 is brought into contact with the single cell 10 located at the uppermost layer. .. In this case, in order to allow the current from the single cell 10 to flow to the high electric tab 150 via the deformation absorbing unit 160, the deformation absorbing unit 160 needs to have conductivity. The conductivity can be imparted by, for example, mixing a conductive filler with the material constituting the deformation absorbing portion 160.

FIG. 9 is a cross-sectional view for explaining a modified example 3 of the embodiment of the invention, and FIG. 10 is a plan view for explaining the shape of the lid member shown in FIG. 9 before decompression.

The lid member 170 is not limited to a form composed of an elastic film. For example, for example, the lid member 180 shown in FIGS. 9 and 10 can be applied.

The lid member 180 has a flat plate-shaped portion 181 and a stretchable portion 182. The flat plate-shaped portion 181 has a shape substantially matching the deformation absorbing portion 160. The telescopic portion 182 has a bellows structure and surrounds the outer peripheral portion of the flat plate-shaped portion 181. When the inside of the cell case 120 is decompressed, the telescopic portion 182 expands so that the flat plate-shaped portion 181 comes into contact with the spacer 155 (upper surface 142 of the laminated body 140), and the pressure based on the differential pressure is applied to the spacer. It is configured to be applied to the stacked single cells 10 via the 155, the deformation absorbing portion 160 and the high electric tab 150.

Next, the performance evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2 will be described. The quality of the surface pressure distribution corresponds to the discharge capacity ratio of 100% when the facing area is 1: 1. The more uniform the surface pressure distribution, the better the discharge capacity ratio. Therefore, the performance was evaluated based on the discharge capacity ratio.

FIG. 11 is a chart showing the performance evaluation results of Examples 1 to 3 and Comparative Examples 1 and 2.

The common conditions of Examples 1 to 3 are shown below. The cell size of a single cell is 30 mm × 30 mm. Three single cells are stacked. The surface pressure [MPa] for the stacked single cells is 0.2. The anisotropic extension portion is regulated by the side wall portion of the cell case, the thickness (horizontal size) is 5 mm, and the elastic modulus in the stacking direction is 0.1 MPa. The deformation absorbing portion is made of expanded polypropylene, has a thickness (size in the stacking direction) of 10 mm, and has an elastic modulus of 0.1 MPa. The discharge capacity ratio is compared between the case where the height of the anisotropic extension portion (size in the stacking direction) is 500 μm and the case where the height is 1200 μm.

The individual condition of Examples 1 to 3 is the lateral elastic modulus of the anisotropic extension portion. Specifically, the lateral elastic moduli of the anisotropic stretched portions of Examples 1, 2 and 3 are 5 MPa, 10 MPa and 3.5 MPa. The anisotropic stretched portion is formed of expanded polypropylene, and the elastic modulus in the lateral direction is adjusted by changing the porosity.

Comparative Example 1 is generally different from Examples 1 to 3 in that it does not have an anisotropic extension portion and the elastic modulus of the deformation absorbing portion is 10 MPa. The elastic modulus of the deformation absorbing portion is adjusted by changing the porosity of the expanded polypropylene. In Comparative Example 2, the elastic modulus in the lateral direction of the anisotropic extension portion is 0.1 MPa, no surface pressure is applied, and the side surface of the anisotropic extension portion is not regulated by the side wall portion of the cell case. Therefore, it is generally different from Examples 1 to 3.

As shown in FIG. 11, the discharge capacity ratios of Examples 1 to 3 show larger values than the discharge capacity ratios of Comparative Examples 1 and 2, and show a good surface pressure distribution. Further, in Examples 1 to 3, the discharge capacity ratio also shows a larger value as the ratio of the elastic modulus in the lateral direction increases. That is, the anisotropic stretched portion shows a better surface pressure distribution when it is easier to stretch in the stacking direction than in the lateral direction (when the property of stretching in the stacking direction (anisotropic) is large).

As described above, in the present embodiment, for example, when the internal pressure of the single cell increases due to the expansion of the negative electrode and the single cell is deformed, the deformation absorbing portion deforms the single cell in the stacking direction. While absorbing, the anisotropic stretched part that also serves as a seal part that seals the inside of the single cell (constrains the outer peripheral part of the single cell) is stretched in the stacking direction according to the deformation of the single cell. The difference between the deformation of the outer peripheral portion and the deformation of the central portion of the single cell is reduced, and the deformation of the single cell is made uniform. Therefore, the non-uniformity of the pressing pressure (surface pressure) applied to the laminated body (single cell) is suppressed. That is, it is possible to provide a battery capable of maintaining a uniform surface pressure distribution.

When the deformation absorbing portion is formed from an elastic body and elastically deformed to shrink (thickness decreases) so as to absorb the deformation in the stacking direction of a single cell, the configuration can be simplified. Is.

When the anisotropic stretched portion is formed from an elastic body, the elastic body is compressed so as to be stretchable in the stacking direction, and elastic deformation in the lateral direction is regulated, the configuration can be simplified. is there.

The lateral elastic deformation of the anisotropic stretched portion can be easily regulated by using the lateral restricting portion or the side wall portion of the cell case.

When the elastic modulus in the stacking direction of the anisotropic stretched portion is made smaller than the elastic modulus in the lateral direction, the anisotropic stretched portion is easily stretched in the stacking direction (preferentially stretched in the stacking direction as compared with the lateral direction). It is possible to make it.

The anisotropic stretch portion is composed of a base material and an auxiliary material selected from a material having an elastic modulus larger than the elastic modulus of the base material, and the auxiliary material is provided so that the elastic modulus in the lateral direction is increased. When mixed with the base material, it is possible to easily achieve the elastic modulus in the stacking direction to be smaller than the elastic modulus in the lateral direction.

When the high electric tab is arranged between the lid member and the deformation absorbing part (outside the deformation absorbing part), the influence of the deformation of the single cell is buffered by the deformation absorbing part, so even if the single cell is deformed, the high electric power is generated. It is possible to keep the tab position constant.

The lid member can be deformed while the opening of the cell case is sealed, and the inside of the cell case is decompressed (the internal pressure of the cell case is lower than the atmospheric pressure (external pressure)). When the laminated body is configured to contact one of the surfaces intersecting with the stacking direction and apply a pressure based on the differential pressure to the contacted surface, the total pressing pressure against the laminated body is simply included in the laminated body. It increases as the area of the cell (electrode) increases. That is, even when the area of the electrode is large, it is possible to easily apply an appropriate pressing pressure without increasing the size of the decompression device (pressure applying device) that depressurizes the inside of the cell case, for example. is there.

The lid member may have a multi-layer structure having a gas barrier metal layer that suppresses the permeation of gas such as steam on the surface or inside of the elastic film. For example, one of the elastic films can be coated with a metal layer, or both sides of the metal layer can be arranged on the elastic films. The metal layer is composed of, for example, aluminum configured to be able to follow some expansion and contraction. It is also possible to coat both surfaces of the elastic membrane with a metal layer.

It is also possible to arrange a second lid member for applying a pressure based on the differential pressure between the atmospheric pressure and the internal pressure of the cell case also on the lower surface of the laminated body (the other side of the surface intersecting the stacking direction). Is. In this case, it is possible to omit the part (bottom surface) of the cell case that faces the lower surface of the laminated body.

The upper end surface of the side wall portion of the cell case to which the lid member is in close contact is preferably formed in a stepped shape. In this case, it is possible to achieve good airtightness.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims. For example, it is also possible to appropriately combine Modifications 1 to 3.

10 single cell,
20 Positive electrode current collector layer,
30 Positive electrode layer,
40 separator,
50 Negative electrode layer,
60 Negative electrode current collector layer,
100 batteries,
110 body,
120 cell case,
122 bottom,
124 side wall,
126,127 openings,
128 Insulation film layer,
130, 132 High power connector,
134 Exhaust connector,
136 pressure release valve,
138 pressure sensor,
140 laminate,
142 Top surface (one of the surfaces that intersects the stacking direction),
144 Bottom surface (the other side of the surface that intersects the stacking direction),
150,152 High power tab,
155,157 spacers,
160 Deformation absorber,
162 Anisotropic extension part (seal part),
163 base material,
164 mixed material,
168 Side Regulation Department,
170 lid member,
175 cover plate,
177 opening,
180 lid member,
181 flat plate,
182 Telescopic part,
185 decompressor,
187 Control unit,
190 vehicles,
L lateral direction,
S Lamination direction.

Claims (7)

A laminated body composed of at least a laminated single cell, a deformation absorbing portion, and an anisotropic stretched portion,
A cell case having a side wall portion extending along the stacking direction of the single cell, and the laminated body is arranged so that the side surface of the laminated body extending in the stacking direction faces the side wall portion. When,
To one of the surfaces intersecting the laminating direction of the laminated body, and a lid member configured to impart a surface pressure in the stacking direction,
The single cell is configured by laminating a positive electrode current collector layer, a positive electrode layer, a separator, a negative electrode layer, and a negative electrode current collector layer in this order.
The deformation absorbing portion is arranged between the lid member and the laminated single cell, and is configured to absorb the deformation of the single cell in the stacking direction.
The anisotropic stretched portion is arranged on the side surface of the laminated body, and is configured to stretch in the laminated direction according to the deformation when the single cell is deformed in the stacking direction .
The anisotropic stretched portion is formed of an elastic body, is compressed so as to be stretchable in the stacking direction, and is restricted from lateral elastic deformation intersecting the stacking direction.
A battery characterized in that the elastic modulus of the anisotropic stretched portion in the stacking direction is smaller than the elastic modulus in the lateral direction. The battery according to claim 1, wherein the deformation absorbing portion is formed of an elastic body and is configured to elastically deform and contract. It also has a high power tab for drawing current from the single cell.
The high electric tab is arranged between the lid member and the deformation absorbing portion, and is arranged.
The battery according to claim 1 or 2, wherein the deformation absorbing portion has conductivity. Further, it has a side regulating portion that is arranged between the side wall portion and the anisotropic extension portion of the cell case and comes into contact with the anisotropic extension portion.
The battery according to any one of claims 1 to 3, wherein the lateral regulating portion regulates the elastic deformation of the anisotropic stretched portion in the lateral direction. The anisotropic stretched portion is in contact with the side wall portion of the cell case, and is in contact with the side wall portion.
The battery according to any one of claims 1 to 3, wherein the cell case regulates elastic deformation of the anisotropic stretched portion in the lateral direction. The anisotropic stretched portion has a base material and an auxiliary material, and has a base material and an auxiliary material.
The auxiliary material is selected from materials having an elastic modulus larger than the elastic modulus of the base material, and is mixed with the base material so that the elastic modulus in the lateral direction of the anisotropic stretched portion is increased. The battery according to any one of claims 1 to 5, wherein the battery is provided. The cell case has an opening that is positioned relative to one of the surfaces of the laminate.
The lid member is
It can be deformed while the opening is sealed.
When the internal pressure of the cell case is the same as the external pressure of the cell case, the cell case is positioned so as to be separated from one of the surfaces of the laminate.
When the internal pressure of the cell case is lower than the external pressure of the cell case, it deforms and comes into contact with one of the surfaces of the laminated body, and the differential pressure between the internal pressure of the cell case and the external pressure of the cell case. The battery according to any one of claims 1 to 6 , wherein the pressure based on the above is applied to the abutting surface.