JP2017103219A - Current limiting structure and lithium ion battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current limiting structure for preventing heat evolution of a lithium ion battery under occurrence of internal short-circuiting with a simple configuration.SOLUTION: In the current limiting structure applied to a lamination type lithium ion battery in which a lamination type battery module is housed and sealed under reduced-pressure in a container, the lamination type battery module being configured by laminating lithium secondary single batteries in series so that the first and second surfaces of a pair of adjacent lithium secondary single batteries are adjacent to each other, and each lithium secondary single battery having a current collector of a first pole on the first surface and a current collector of a second pole on the second surface, the current collector of the first pole and/or the current collector of the second pole and the container on the outside of the lamination type battery module have contact surfaces that are in contact with one another, at least a part of the contact surface is a current drawing part to the outside of the lamination type lithium ion battery, the current drawing part has conductivity and flexibility, and when the pressure inside the container rises, the current drawing part is deformed by the pressure, whereby the current collector of the first pole and/or the current collector of the second pole and the current drawing part are spatially separated from each other.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a current limiting structure and a lithium ion battery.

  Lithium ion (secondary) batteries have been widely used in various applications in recent years as high-capacity, small and lightweight secondary batteries. In general lithium ion batteries, a positive electrode active material and a negative electrode active material are respectively provided on one surface of a substantially flat current collector constituting the positive electrode and the negative electrode, and then heat-treated to dry the positive electrode active material and the negative electrode active material. If necessary, a separator is interposed between the positive electrode active material and the negative electrode active material, and the positive electrode active material and the negative electrode active material are laminated to produce a substantially flat lithium secondary cell. Was configured by laminating a plurality of layers.

  In such a lithium ion battery formed by laminating a plurality of single cells, when an internal short circuit occurs, current may concentrate on the part where the internal short circuit occurs, and the lithium ion battery may generate heat. For the purpose of suppressing the heat generation of the lithium ion battery during a short circuit, a technique is disclosed in which a current collector is provided with first and second layer portions that can be spatially separated in the stacking direction (see Patent Document 1). ).

JP 2013-69549 A

  However, in the conventional technique described above, the first and second layered portions are provided on the current collector, so that the configuration of the entire lithium ion battery may be complicated.

  The present invention has been made in view of the above-described problems, and provides a current limiting structure and a lithium ion battery that prevent the lithium ion battery from generating heat when there is an internal short circuit with a simple configuration. It is one.

  The present invention provides a lithium secondary cell having a current collector of a first electrode on a first surface and a current collector of a second electrode on a second surface. The present invention is applied to a current limiting structure applied to a stacked lithium ion battery in which a stacked battery module formed by stacking in series so that the first surface and the second surface are adjacent to each other is housed in a container. A contact surface that contacts the container is provided on each of the current collector of the first electrode and the current collector of the second electrode outside the stacked battery module, and at least a part of the contact surface of the container is provided. As a current drawing part to the outside of the laminated lithium ion battery, this current drawing part has conductivity and flexibility, and when the pressure inside the container rises, the current drawing part is deformed by the pressure, and the current drawing part is laminated. At least one of the above-described problems is solved by spatially separating the current collector and the current collector of the first electrode and / or the second electrode of the battery module.

  Here, it is preferable that the current drawing portion is made of a film-like substrate made of a metal or a conductive polymer.

  In addition, the present invention solves at least one of the above-described problems by a lithium ion battery having the above-described current limiting structure.

  Here, the lithium secondary cell is preferably formed in a substantially flat plate shape as a whole.

  Furthermore, it is preferable that the current drawing portion is substantially equal to a contact surface where the container is in contact with the current collector of the first pole and / or the current collector of the second pole.

  According to the present invention, it is possible to provide a current limiting structure and a lithium ion battery that prevent the lithium ion battery from generating heat when there is an internal short circuit with a simple configuration.

It is sectional drawing and the partially broken perspective view which show the lithium secondary cell applied to 1st Embodiment of this invention. 1 is an exploded view showing a lithium ion battery having a current limiting structure according to a first embodiment of the present invention. It is sectional drawing and the partially broken perspective view which show the lithium ion battery of 1st Embodiment. It is sectional drawing and the partially broken perspective view which show the lithium ion battery of 1st Embodiment in the state which the current limiting structure functioned. It is sectional drawing which shows the example of the structure of the electric current extraction part of the lithium ion battery of 1st Embodiment. It is a perspective view which shows the lithium ion battery which has the current limiting structure which is 2nd Embodiment of this invention.

(First embodiment)
With reference to FIGS. 1-3, the lithium ion battery which is 1st Embodiment of this invention is demonstrated. FIG. 1A is a cross-sectional view showing a lithium secondary cell applied to the first embodiment of the present invention, and FIG. 1B shows a lithium secondary cell applied to the first embodiment. FIG. 2 is an exploded view showing a lithium ion battery having a current limiting structure according to the first embodiment of the present invention, FIG. 3A is a sectional view showing the lithium ion battery according to the first embodiment, FIG. 3B is a partially broken perspective view showing the lithium ion battery of the first embodiment.

  In these drawings, the lithium ion battery L of the present embodiment includes a stacked battery module 21 in which a plurality of substantially flat unit cells 1 are stacked in series in a hollow container 20 that forms the outer shell of the lithium ion battery L. It is housed and configured.

  As shown in detail in FIGS. 1A and 1B, the unit cell 1 has a positive electrode active material, an electrolytic solution, and a positive electrode current collector 7 on the surface of a substantially flat plate-shaped first electrode current collector. A negative electrode active material and an electrolyte solution on the surface of a negative electrode current collector 8 that is a substantially flat plate-like second electrode current collector, and a positive electrode 2 on which a substantially flat positive electrode composition layer 5 containing And a negative electrode 3 having a substantially flat negative electrode composition layer 6 formed thereon are similarly laminated with a substantially flat separator 4 interposed therebetween, and is formed in a substantially flat shape as a whole. Thereby, the unit cell 1 having the positive electrode current collector 7 and the negative electrode current collector 8 facing each other on the upper surface and the lower surface in the drawing is formed.

  As best shown in FIG. 1A, the positive electrode current collector 7 and the negative electrode current collector 8 are positioned so as to face each other at a predetermined interval by a seal member 9 formed at the end of the unit cell 1. Yes. Further, since the end portion of the separator 4 is embedded in the seal member 9, the separator 4 is supported and the positional relationship between the separator 4, the positive electrode current collector 7, and the negative electrode current collector 8 is determined. Yes.

  The distance between the positive electrode current collector 7 and the separator 4 and the distance between the negative electrode current collector 8 and the separator 4 are adjusted according to the capacity of the lithium ion battery L. The positive electrode current collector 7, the negative electrode The positional relationship between the current collector 8 and the separator 4 is determined so that a necessary interval is obtained.

  As shown in FIG. 2, the unit cell 1 shown in FIGS. 1A and 1B has an upper surface of the positive electrode current collector 7 and a lower surface of the negative electrode current collector 8 of the adjacent unit cells 1 adjacent to each other. A stacked battery module 21 is formed by stacking in series, and the stacked battery module 21 is sealed in a container 20 under reduced pressure and stored in the container 20 according to the present embodiment shown in FIGS. A lithium ion battery L is configured.

  As shown in detail in FIG. 2, the container 20 constituting the lithium ion battery L of the present embodiment is divided into an upper container 20a and a lower container 20b. The lower container 20b includes a substantially hollow box-shaped lower container body 20c whose upper surface is open, and a substantially rectangular frame-shaped lower container edge 20d formed on the upper peripheral edge of the lower container body 20c. On the other hand, the upper container 20a is formed in a substantially rectangular plate shape having the same size as the lower container edge 20d of the lower container 20b, and is arranged so as to cover the opening of the lower container body 20c of the lower container 20b.

  Then, the stacked battery module 21 is housed in the lower container body 20c, and the upper container 20a and the lower container 20b are sealed with a seal member (not shown) in a state where the lower container body 20c is decompressed. The lithium ion battery L of the present embodiment is configured.

  Here, on the lower surfaces of the upper container 20a and the lower container body 20c in FIG. 2 and FIG. 3, rectangular plate-shaped current extraction portions 22a and 22b having flexibility and conductivity are formed, respectively. The current drawing portions 22 a and 22 b are formed in substantially the same shape as the positive electrode current collector 7 and the negative electrode current collector 8 of the unit cell 1 located at the uppermost and lowermost portions of the stacked battery module 21. Since the stacked battery module 21 is housed in the container 20 under reduced pressure sealing, as shown in FIG. 3, the positive electrode of the unit cell 1 positioned at the top and bottom of the stacked battery module 21. The upper surface and the lower surface of the current collector 7 and the negative electrode current collector 8 are in electrical contact with each other by being in close contact with the current drawing portions 22a and 22b, respectively.

  In addition, since the current drawing portions 22a and 22b have flexibility, when the internal pressure of the container 20 rises to be equal to or higher than the atmospheric pressure, the container 20 including the current drawing portions 22a and 22b expands outward. Thus, the positive electrode current collector 7 and the negative electrode current collector 8 of the unit cell 1 are configured to be spatially separated from the upper surface and the lower surface.

The positive electrode active material includes positive electrode active material particles. As the positive electrode active material particles, composite oxides of lithium and transition metals (for example, LiCoO ₂ , LiNiO ₂ , LiMnO _2, and LiMn ₂ O ₄ ), transition metal oxides are used. Products (eg MnO ₂ and V ₂ O ₅ ), transition metal sulfides (eg MoS ₂ and TiS ₂ ) and conductive polymers (eg polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene and polycarbazole), etc. Can be mentioned.

The negative electrode active material includes negative electrode active material particles. As the negative electrode active material particles, graphite, non-graphitizable carbon, amorphous carbon, a polymer compound fired body (for example, a phenol resin, a furan resin, or the like is fired). Carbonized, etc.), cokes (eg, pitch coke, needle coke, petroleum coke, etc.), carbon fibers, conductive polymers (eg, polyacetylene, polyquinoline, etc.), tin, silicon, and metal alloys (eg, lithium-tin alloys) , Lithium-silicon alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), composite oxides of lithium and transition metals (for example, Li ₄ Ti ₅ O _12, etc.).

  In the unit cell 1, the positive electrode active material particles and / or the negative electrode active material particles are preferably coated active material particles in which at least a part of the surface is coated with a coating agent containing a coating resin.

  The coating material contains a coating resin. If the periphery of the active material particles is coated with the coating material, the volume change of the electrode accompanying the expansion of the active material particles that occurs during charge and discharge is alleviated, and the expansion of the electrode is suppressed. can do. Examples of the coating resin include vinyl resin, urethane resin, polyester resin, polyamide resin, epoxy resin, polyimide resin, silicone resin, phenol resin, melamine resin, urea resin, aniline resin, ionomer resin, polycarbonate, and the like. Among these, vinyl resin, urethane resin, polyester resin or polyamide resin is preferable.

  The coating agent may further contain a conductive auxiliary agent, and the conductive auxiliary agent contained in the coating agent is selected from materials having conductivity.

  Specifically, metal [aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.], carbon [graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, single layer Carbon nanotubes and multi-walled carbon nanotubes, etc.)], and mixtures thereof, but are not limited thereto.

  These conductive assistants may be used alone or in combination of two or more. Moreover, these alloys or metal oxides may be used. From the viewpoint of electrical stability, aluminum, stainless steel, carbon, silver, gold, copper, titanium and mixtures thereof are preferred, silver, gold, aluminum, stainless steel and carbon are more preferred, and carbon is more preferred. is there. These conductive assistants may be those obtained by coating a particulate ceramic material or resin material with a conductive material (metal among the conductive auxiliary materials described above) by plating or the like.

  It is also possible to use conductive fibers as the conductive auxiliary agent contained in the coating agent. Examples of conductive fibers include carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers obtained by uniformly dispersing highly conductive metal and graphite in synthetic fibers, and metals such as stainless steel. Examples thereof include fiberized metal fibers, conductive fibers in which the surface of organic fiber is coated with metal, and conductive fibers in which the surface of organic fiber is coated with a resin containing a conductive substance. Among these conductive fibers, carbon fibers are preferable.

  The coated active material particles are, for example, dropped into and mixed with a resin solution containing a coating resin over a period of 1 to 90 minutes in a state where the active material particles are put in a universal mixer and stirred at 30 to 500 rpm. It can be obtained by mixing, raising the temperature to 50 to 200 ° C. with stirring, reducing the pressure to 0.007 to 0.04 MPa, and holding for 10 to 150 minutes.

  As the electrolytic solution, an electrolytic solution containing an electrolyte and a non-aqueous solvent used for manufacturing a lithium ion battery can be used.

As the electrolyte, those used in ordinary electrolytic solutions can be used. For example, lithium salts of inorganic acids such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ and LiClO ₄ , LiN (CF ₃ SO ₂ ) ₂ and lithium salts of organic acids such as LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ . Among these, LiPF ₆ is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

  As the non-aqueous solvent, those used in ordinary electrolytic solutions can be used, for example, lactone compounds, cyclic or chain carbonates, chain carboxylates, cyclic or chain ethers, phosphates, nitriles. Compounds, amide compounds, sulfones, sulfolanes and the like and mixtures thereof can be used.

  A non-aqueous solvent may be used individually by 1 type, and may use 2 or more types together.

  Among the nonaqueous solvents, lactone compounds, cyclic carbonates, chain carbonates and phosphates are preferred from the viewpoint of battery output and charge / discharge cycle characteristics, and more preferred are lactone compounds, cyclic carbonates and chains. A carbonic acid ester is more preferable, and a mixed liquid of a cyclic carbonate and a chain carbonate is more preferable. Particularly preferred is propylene carbonate (PC) or a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC).

  The positive electrode composition layer 5 containing the positive electrode active material and the electrolytic solution and the negative electrode composition layer 6 containing the negative electrode active material and the electrolytic solution are each further in the form of a fiber from the viewpoint of improving the conductivity. It is preferable to include a conductive substance. As the fibrous conductive substance, the same conductive fibers as exemplified as the conductive auxiliary agent contained in the coating agent can be used.

  The positive electrode composition layer 5 and the negative electrode composition layer 6 are each composed of positive electrode active material particles or negative electrode active material particles and a fibrous conductive material to be used as necessary, based on the weight of the electrolytic solution or nonaqueous solvent. It can be obtained by providing a layer of a mixture obtained by mixing and dispersing with an electrolytic solution at a concentration of% by weight on the surfaces of the positive electrode current collector 7 and the negative electrode current collector 8.

  As the separator 4, polyethylene, polypropylene, etc., microporous membrane film made of polyolefin, multilayer film of porous polyethylene film and polypropylene, non-woven fabric made of polyester fiber, aramid fiber, glass fiber, etc., and silica on the surface thereof, Examples include those having ceramic fine particles such as alumina and titania attached thereto.

  As the positive electrode current collector 7 and the negative electrode current collector 8, a film-like base material made of a metal material such as copper, aluminum, titanium, stainless steel, nickel, and an alloy thereof, a conductive polymer material, or the like is used. Among them, a nonporous film-like substrate that does not transmit an electrolyte solution is preferable. Among them, the metal material is preferably aluminum and copper from the viewpoint of weight reduction, corrosion resistance, and high conductivity, and more preferably, the positive electrode current collector 7 is aluminum and the negative electrode current collector 8 is copper.

  When the positive electrode current collector 7 and the negative electrode current collector 8 are resin current collectors made of a conductive polymer material, the polymer material serving as the base material of the conductive polymer material may be a conductive polymer. It may be a polymer that does not have conductivity.

  Among the polymer materials, examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, and polyoxadiazole. Examples of the polymer material having no electrical conductivity include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyether nitrile (PEN), poly Tetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin or mixtures thereof Etc.

  Among polymer materials having no electrical conductivity, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferable from the viewpoint of electrical stability, and polyethylene is more preferable. (PE), polypropylene (PP) and polymethylpentene (PMP).

  When the positive electrode current collector 7 and the negative electrode current collector 8 are resin current collectors made of a conductive polymer material, the purpose is to improve the conductivity of the resin current collector containing the conductive polymer material, or For the purpose of imparting conductivity to a resin current collector containing a polymer material having no conductivity, it is preferable that a conductive filler is contained. The conductive filler is selected from materials having conductivity. Preferably, from the viewpoint of suppressing ion permeation in the current collector, it is preferable to use a material that does not have conductivity with respect to ions used as the charge transfer medium. Specific examples include, but are not limited to, carbon materials, aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, antimony, titanium, nickel, and the like. These conductive fillers may be used alone or in combination of two or more. Moreover, these alloy materials, such as stainless steel (SUS), may be used. From the viewpoint of corrosion resistance, aluminum, stainless steel, carbon material, nickel, and more preferably carbon material are preferred. In addition, these conductive fillers may be those obtained by coating the metal shown above with a plating or the like around a particulate ceramic material or resin material.

  Specific examples of the resin current collector based on a polymer having no conductivity include those obtained by dispersing 5 to 20 parts of acetylene black as a conductive filler in polypropylene and then rolling with a hot press. It is done. Moreover, the thickness is not particularly limited, and can be applied in the same manner as known ones or with appropriate changes.

  The material constituting the seal member 9 is not particularly limited as long as it is a material that has adhesiveness to the positive electrode and the negative electrode current collectors 7 and 8 and is durable to the electrolytic solution. A thermosetting resin is preferred. Specific examples include epoxy resins, polyolefin resins, polyurethane resins, and polyvinylidene fluoride resins. Epoxy resins are preferable because they are highly durable and easy to handle.

  As long as the material which comprises the container 20 is a material which can accommodate the laminated battery module 21 in the container 20, arbitrary materials are applicable suitably. However, in consideration of the possibility that the unit cell 1 and the container 20 are in contact with each other, the material constituting the container 20 is preferably an insulating material. In addition, since the container 20 is sealed under reduced pressure in a state where the stacked battery module 21 is housed therein, the material constituting the container 20 is preferably a material having flexibility and airtightness. As such a material, a laminate film, which is known as an exterior material for a lithium ion battery, for example, a film in which both sides of a metal foil are covered with a polymer film, a non-woven fabric imparted with airtightness, etc. A laminate film can be used.

  If the material which comprises the current drawing parts 22a and 22b is the material which has the electroconductivity which can extract the electric current which generate | occur | produced to the exterior which can deform | transform with the pressure when the pressure inside a container rises with the pressure, and the laminated battery module There is no special limitation. As such a material, the same thing as the same film-like base material as what was demonstrated as a material which can be used as the said positive electrode collector 7 and the negative electrode collector 8 can be used preferably. These materials have conductivity and flexibility, but it is preferable to use a film having a thickness of 20 to 80 μm from the viewpoint of current limiting ability.

  The position where the current drawing portions 22a and 22b are arranged is not particularly limited as long as the current drawing portions 22a and 22b are arranged at a position having a contact surface in contact with the container 20, but as an example, as shown in FIG. Conductive material may be doped into the corresponding part of the container 20 made of nonwoven fabric to impart conductivity to a part of the container 20, and as shown in FIG. 5B, the container 20 was made of a laminate film. The container 20 may be provided with an opening, and the current drawing portion 22a, which is a flexible conductive plate, may be attached. In addition, when providing the opening part in the container 20 and sticking the current drawing part 22a which is a flexible conductive plate, the current drawing part 22a is stuck inside the container 20 as shown in FIG. Alternatively, the current drawing portion 22a may be attached to the outside of the container 20.

  Here, when the current drawing portion 22 a is attached to the outside of the container 20, a gap derived from the thickness of the container 20 is generated between the container 20 and the stacked battery module 21, but the stacked battery module 21 is connected to the container 20. In the case of being housed inside and sealed under reduced pressure, the flexible current extraction portion 22a is deformed to fill the gap, and the positive electrode current collector 7 and the current extraction portion 22a are in electrical contact with each other. Can do. When the pressure inside the container rises, the current drawing part 22a is pushed outward from the inside of the container and bulges outside, but the current drawing part 22a that has been deformed at the same time has a gap with the positive electrode current collector 7, Stress is generated to return to the shape. Therefore, when the current drawing portion 22a is affixed to the outside of the container 20, it is considered that the current limiting ability due to the internal pressure change is further improved as compared with the case where the current drawing portion 22a is affixed to the inside of the container 20. It is done.

  In addition, the flexible current extraction part 22a may be installed not only on the positive electrode side but also on the negative electrode side. In this case, the current extraction part 22a and the negative electrode current collector 8 are in electrical contact.

  The unit cell 1 having the above configuration includes a positive electrode composition 5 containing a positive electrode active material and an electrolytic solution on each surface of the positive electrode current collector 7 and the negative electrode current collector 8, and a negative electrode active material and an electrolytic solution. A negative electrode composition 6 containing the positive electrode 2 and the negative electrode 3 is formed. The method of forming the positive electrode 2 and the negative electrode 3 is arbitrary, and the positive electrode current collector 7 is formed by applying the positive electrode composition 5 and the negative electrode composition 6 to the surfaces of the positive electrode current collector 7 and the negative electrode current collector 8, respectively. And various methods such as leveling with a spatula or the like so as to have a predetermined thickness after the positive electrode composition 5 and the negative electrode composition 6 are placed on the respective surfaces of the negative electrode current collector 8 through a nozzle or the like. Is mentioned. Then, the positive electrode 2 and the negative electrode 3 are laminated | stacked through the separator 4, the edge part of the positive electrode electrical power collector 7 and the negative electrode current collector 8, and also the edge part of the separator 4 are sealed with the sealing member 9, and the cell 1 is obtained. Can be manufactured.

  Next, the unit cell 1 manufactured by the above-described process is stacked in series so that the upper surface of the positive electrode current collector 7 and the lower surface of the negative electrode current collector 8 of the adjacent unit cell 1 are adjacent to each other, and the stacked battery module 21 is further formed, and the laminated battery module 21 is housed in the container 20, and the container 20 is degassed under reduced pressure and then sealed with a sealing member, whereby the lithium ion battery L of the present embodiment is manufactured. be able to.

  In the lithium ion battery L having such a configuration, one end of an unillustrated electrode terminal made of, for example, a strip-shaped metal foil is fixedly connected to the upper and lower surfaces of the current drawing portions 22a and 22b with a conductive adhesive or the like. The power supply voltage from the lithium ion battery L is supplied to the outside.

  And in the lithium ion battery L of this embodiment, when an internal short circuit etc. generate | occur | produce, a trace amount gas may generate | occur | produce from one of the single cells 1 with time. At this time, as a result, when the internal pressure of the container 20 including the current drawing parts 22a and 22b rises to be equal to or higher than the atmospheric pressure, the container including the current drawing parts 22a and 22b as shown in FIGS. 20 expands outward. As a result, at least a part of the current drawing portions 22a and 22b and the upper and lower surfaces of the positive electrode current collector 7 and the negative electrode current collector 8 of the unit cell 1 positioned at the uppermost and lowermost portions of the stacked battery module 21 are provided. The contact area between the current drawing portions 22a and 22b and the positive electrode current collector 7 and the negative electrode current collector 8 is decreased and the electrical resistance therebetween increases. Therefore, the current flowing through the unit cell 1 is suppressed, preferably interrupted, and heat generation of the entire lithium ion battery L is suppressed.

  Thus, according to this embodiment, the lithium ion battery that prevents the lithium ion battery L from generating heat in the event of an internal short circuit or the like by the simple configuration in which the container 20 is provided with the current drawing portions 22a and 22b. Can be realized.

  In particular, in the lithium ion battery L of the present embodiment, the stacked battery module 21 is sealed in the container 20 under reduced pressure to improve the adhesion between the stacked battery module 21 and the container 20, and as a whole lithium ion battery L Rigidity can be increased. In particular, when a resin current collector is used as the positive electrode current collector 7 and the negative electrode current collector 8 of the unit cell 1, the adhesion between the stacked battery module 21 and the container 20 is increased. This improves the adhesion with the current drawing portions 22a and 22b, and exhibits excellent current extraction efficiency even when using a resin current collector that does not have high conductivity compared to a metal current collector. it can. In addition, since the resin current collector does not have higher conductivity than the metal current collector, in order to efficiently extract the power supply voltage from the stacked battery module 21 to the outside of the lithium ion battery L, the container 20 side It is preferable that the current drawing portions 22a and 22b, which are power supply voltage extraction portions provided in, have a large area, preferably approximately the same area as the positive electrode current collector 7 and the negative electrode current collector 8. In the present embodiment, since the current extraction portions 22a and 22b having a large area are used for controlling the current when an internal short circuit occurs, the configuration is simplified compared to a configuration in which a separate electrode tab is provided in the container. Can be achieved.

(Second Embodiment)
Next, FIG. 6 is a perspective view showing a lithium ion battery having a current limiting structure according to the second embodiment of the present invention.

  The difference between the lithium ion battery of this embodiment and the lithium ion battery of the first embodiment described above is that the container 20 in which the laminated battery module 21 is housed is formed of a laminate film, and the current provided in the container 20 The lead portions 22a and 22b (only the current lead portion 22a is shown in FIG. 6) is a metal foil affixed to the inner surface of the container 20 which is this laminate film, or a conductive film formed on the inner surface of the container 20 by sputtering or the like. It is composed of parts.

  Similarly to the first embodiment, the current drawing portions 22a and 22b in the present embodiment are also the positive electrode current collector 7 and the negative electrode current collector of the unit cell 1 located at the uppermost and lowermost portions of the stacked battery module 21. 8 and substantially the same shape.

  Further, the upper container 20a and the lower container 20b constituting the container 20 of the present embodiment are formed in substantially the same shape, and the upper container body 20e and the lower container body 20f whose upper surfaces are opened, the upper container body 20e, In FIG. 6 of the lower container body 20f, a pair of upper container edge 20g and lower container edge 20h projecting laterally from the left and right ends are provided.

  The stacked battery module 21 is housed in an internal space formed by arranging the upper container 20a and the lower container 20b so as to face each other, and the upper container edge 20g and The lower container edge 20h is sealed with a seal member (not shown), whereby the lithium ion battery L of the present embodiment is configured.

  A part of the upper container edge 20g and the lower container edge 20h is further extended to the side, and the current drawing parts 22a and 22b are also extended to the extended parts of the upper container edge 20g and the lower container edge 20h. The electrode terminals 23 and 24 for taking out electricity from the lithium ion battery L are formed.

  Therefore, the present embodiment can achieve the same effects as those of the first embodiment described above.

(Modification)
In each of the above-described embodiments, the current extraction portions 22a and 22b are formed in the upper container 20a and the lower container 20b constituting the container 20, respectively, but the current extraction portion is provided in at least one of the upper container 20a and the lower container 20b. Even if 22a and 22b are formed, the object of the present invention can be achieved. Further, in each of the above-described embodiments, the current drawing portions 22a and 22b are formed to have substantially the same size as the positive electrode current collector 7 and the negative electrode current collector 8, but the current is suppressed, preferably interrupted when an internal short circuit occurs. There is no limitation on the size as long as it is possible.

L Lithium ion battery 1 Single cell 2 Positive electrode 3 Negative electrode 4 Separator 5 Positive electrode composition 6 Negative electrode composition 7 Positive electrode current collector 8 Negative electrode current collector 9 Seal member 20 Container 21 Stacked battery module 22a, 22b Current extraction part

Claims (5)

A lithium secondary cell having a current collector of a first electrode on a first surface and a current collector of a second electrode on a second surface is connected to the first surface of a pair of adjacent lithium secondary cells. And a current limiting structure applied to a stacked lithium-ion battery in which stacked battery modules stacked in series so that the second surface is adjacent are housed in a container,
The current collector of the first electrode and / or the current collector of the second electrode and the container on the outside of the stacked battery module each have a contact surface in contact with each other;
At least a part of the contact surface of the container is a current drawing part to the outside of the stacked lithium ion battery,
The current draw part has conductivity and flexibility,
When the pressure inside the container rises, the current drawing portion is deformed by the pressure, whereby the current collector of the first electrode and / or the current collector of the second electrode and the current of the stacked battery module. A current limiting structure characterized in that the lead part is spatially separated.   The current limiting structure according to claim 1, wherein the current drawing portion is made of a film-like substrate made of a metal or a conductive polymer.   A lithium ion battery comprising the current limiting structure according to claim 1. The lithium ion battery according to claim 3,
The lithium secondary cell is formed in a substantially flat plate shape as a whole. The lithium ion battery according to claim 3 or 4,
The current drawing part is a lithium ion battery substantially equal to the contact surface where the container contacts the current collector of the first electrode and / or the current collector of the second electrode.

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