JP6861016B2 - Lithium ion battery - Google Patents

Description

The present invention relates to a lithium ion battery .

Lithium-ion (secondary) batteries have been widely used in various applications in recent years as high-capacity, compact and lightweight secondary batteries. In a general lithium ion battery, a positive electrode active material and a negative electrode active material are provided on one surface of a substantially flat current collector constituting the positive electrode and the negative electrode, and then heat treatment is performed to dry the positive electrode active material and the negative electrode active material. Then, if necessary, a separator is inserted between the positive electrode active material and the negative electrode active material, and these positive electrode active materials and the negative electrode active material are laminated to produce a substantially flat lithium secondary cell, and this cell is used. Was laminated in multiple layers.

In such a lithium-ion battery in which a plurality of layers of single batteries are stacked, if an internal short circuit or the like occurs, the current may be concentrated on the portion where the internal short circuit has occurred, and the lithium ion battery may generate heat. For the purpose of suppressing heat generation of a lithium ion battery at the time of a short circuit, a technique is disclosed in which a current collector is provided with first and second layered portions that can be spatially separated in the stacking direction (see Patent Document 1). ).

Japanese Unexamined Patent Publication No. 2013-69549

However, in the above-mentioned conventional technique, since the current collector is provided with the first and second layered portions, the configuration of the entire lithium ion battery may be complicated.

The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a lithium ion battery that prevents the lithium ion battery from generating heat when there is an internal short circuit by a simple configuration. ..

In the present invention, a lithium secondary battery having a first-pole current collector on the first surface and a second-pole current collector on the second surface is used as a second of a pair of adjacent lithium secondary batteries. This is applied to a laminated lithium-ion battery in which a laminated battery module in which one surface and a second surface are laminated in series so as to be adjacent to each other is housed in a container. Then, each of the first-pole current collector and the second-pole current collector on the outside of the laminated battery module is provided with contact surfaces that come into contact with the container, and at least a part of the contact surface of the container is provided. A current drawing part to the outside of the laminated lithium ion battery, and this current drawing part has conductivity and flexibility. The container is provided with an opening and the current drawing part is attached to the outside of the container to be inside the container. When the pressure rises, the current drawing part is deformed by the pressure, so that the current collecting body of the first pole and / or the current drawing part of the second pole of the laminated battery module is spatially separated from each other. This solves at least one of the above problems.

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

Here, it is preferable that the lithium secondary cell is formed in a flat plate shape as a whole.

Further, it is preferable that the current drawing portion is equal to the 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 lithium ion battery that prevents the lithium ion battery from generating heat when there is an internal short circuit due to a simple configuration.

It is sectional drawing and the partial breaking perspective view which shows the lithium secondary cell which applies to 1st Embodiment of this invention. It is an exploded view which shows the lithium ion battery which has the current limiting structure which is 1st Embodiment of this invention. It is sectional drawing and the partial breaking perspective view which shows the lithium ion battery of 1st Embodiment. It is sectional drawing and the partial breaking perspective view which shows the lithium ion battery of 1st Embodiment in the state which the current limiting structure functions. It is sectional drawing which shows the example of the structure of the current drawing 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)
The lithium ion battery according to the first embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1A shows a sectional view showing a lithium secondary battery applied to the first embodiment of the present invention, and FIG. 1B shows a lithium secondary battery applied to the first embodiment. A partially broken perspective view, 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, and FIG. 3A is a sectional view showing a lithium ion battery according to the first embodiment. And FIG. 3B is a partially cutaway perspective view showing the lithium ion battery of the first embodiment.

In these figures, the lithium-ion battery L of the present embodiment includes a laminated battery module 21 in which a plurality of substantially flat-shaped cell cells 1 are laminated in series in a hollow container 20 forming the outer shell of the lithium-ion battery L. It is stored and configured.

As shown in detail in FIGS. 1 (a) and 1 (b), the cell 1 has a positive electrode active material and an electrolytic solution on the surface of the positive electrode current collector 7, which is a substantially flat plate-shaped first pole current collector. Negative electrode active material and electrolytic solution on the surface of the positive electrode 2 on which the substantially flat plate-shaped positive electrode composition layer 5 containing the above is formed, and the negative electrode current collector 8 which is also the substantially flat plate-shaped second pole current collector. The negative electrode 3 on which the substantially flat negative electrode composition layer 6 including the above is formed is similarly laminated via the substantially flat separator 4, and is formed in a substantially flat shape as a whole. As a result, the 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 configured.

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 predetermined intervals by a seal member 9 formed at the end of the cell 1. There is. Further, by embedding the end portion of the separator 4 in the seal member 9, the separator 4 is supported, and the positional relationship between the separator 4 and the positive electrode current collector 7 and the negative electrode current collector 8 is determined. There is.

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, and the positive electrode current collector 7 and the negative electrode are adjusted. The positional relationship between the current collector 8 and the separator 4 is determined so that the required spacing can be obtained.

In the cell 1 shown in FIGS. 1A and 1B, as shown in FIG. 2, the upper surface of the positive electrode current collector 7 of the adjacent cell 1 and the lower surface of the negative electrode current collector 8 are adjacent to each other. The laminated battery module 21 is formed by being laminated in series, and the laminated battery module 21 is sealed in a container 20 under reduced pressure and stored, and the present embodiment shown in FIGS. 3 (a) and 3 (b) 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 main body 20c having an open upper surface, and a substantially rectangular frame-shaped lower container edge portion 20d formed on the upper peripheral portion of the lower container main body 20c. On the other hand, the upper container 20a is formed in a substantially rectangular plate shape having substantially 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 main body 20c of the lower container 20b.

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

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

In addition, since the current drawing portions 22a and 22b have flexibility, when the internal pressure of the container 20 rises to above atmospheric pressure, the container 20 including the current drawing portions 22a and 22b expands outward. As a result, the cells 1 are configured to be spatially separated from the upper and lower surfaces of the positive electrode current collector 7 and the negative electrode current collector 8.

The positive electrode active material contains positive electrode active material particles, and the positive electrode active material particles include composite oxides of lithium and a transition metal (for example, LiCoO ₂ , LiNiO ₂ , LiMnO ₂ and LiMn ₂ O ₄ ), and transition metal oxidation. Substances (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) Can be mentioned.

The negative electrode active material contains negative electrode active material particles, and the negative electrode active material particles include graphite, non-graphitizable carbon, amorphous carbon, and a fired polymer compound (for example, phenol resin and furan resin). Carbonized materials, etc.), cokes (eg, pitch coke, needle coke, petroleum coke, etc.), carbon fibers, conductive polymers (eg, polyacetylene and polyquinolin, etc.), tin, silicon, and metal alloys (eg, lithium-tin alloys). , Lithium-silicon alloy, lithium-aluminum alloy, lithium-aluminum-manganese alloy, etc.), composite oxide of lithium and transition metal (for example, Li ₄ Ti ₅ O ₁₂ etc.) and the like.

In the 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 agent contains a coating resin, and when the periphery of the active material particles is coated with the coating agent, the volume change of the electrode due to the expansion of the active material particles that occurs during charging and discharging 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 are 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, metals [aluminum, stainless steel (SUS), silver, gold, copper and titanium, etc.], carbon [graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, single layer) Carbon nanotubes, multi-walled carbon nanotubes, etc.), etc.], and mixtures thereof, etc., but are not limited thereto.

These conductive aids 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 preferable, silver, gold, aluminum, stainless steel and carbon are more preferable, and carbon is more preferable. is there. Further, these conductive auxiliaries may be those obtained by coating a conductive material (a metal one among the above-mentioned conductive auxiliary materials) around a particle-based ceramic material or a resin material by plating or the like.

It is also possible to use conductive fibers as the conductive auxiliary agent contained in the coating agent. The conductive fibers include carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers in which a metal having good conductivity and graphite are uniformly dispersed in synthetic fibers, and a metal such as stainless steel. Examples thereof include fibrous metal fibers, conductive fibers in which the surface of organic fibers is coated with metal, and conductive fibers in which the surface of organic fibers is coated with a resin containing a conductive substance. Among these conductive fibers, carbon fibers are preferable.

For the coating active material particles, for example, in a state where the active material particles are placed in a universal mixer and stirred at 30 to 500 rpm, a resin solution containing a coating resin is added dropwise over 1 to 90 minutes, and a conductive additive is further added. 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 then holding the mixture for 10 to 150 minutes.

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

As the electrolyte, those used in ordinary electrolytes 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. Lithium salts of organic acids such as LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) _{3 can be mentioned. Of 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, and for example, a lactone compound, a cyclic or chain carbonate, a chain carboxylic acid ester, a cyclic or chain ether, a phosphoric acid ester, or a nitrile can be used. Compounds, amide compounds, sulfones, sulfolanes and the like and mixtures thereof can be used.

One type of non-aqueous solvent may be used alone, or two or more types may be used in combination.

Among the non-aqueous solvents, lactone compounds, cyclic carbonates, chain carbonates and phosphate esters are preferable from the viewpoint of battery output and charge / discharge cycle characteristics, and lactone compounds, cyclic carbonates and chains are more preferable. A state carbonic acid ester, more preferably a mixed solution of a cyclic carbonate and a chain carbonate. 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 fibrous from the viewpoint of improving conductivity and the like. It preferably contains a conductive substance. As the fibrous conductive substance, the same conductive fibers as those 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 each contain 10 to 60 positive electrode active material particles or negative electrode active material particles and a fibrous conductive material used as necessary based on the weight of the electrolytic solution or non-aqueous 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.

The separator 4 includes a microporous film film made of polyolefin such as polyethylene and polypropylene, a multilayer film of a porous polyethylene film and polypropylene, a non-woven fabric made of polyester fiber, aramid fiber, glass fiber and the like, and silica on their surfaces. Examples thereof include those to which ceramic fine particles such as alumina and titania are attached.

As the positive electrode current collector 7 and the negative electrode current collector 8, a metal material such as copper, aluminum, titanium, stainless steel, nickel and an alloy thereof, and a film-like base material made of a conductive polymer material or the like are used. Of these, a non-porous film-like substrate that does not allow the electrolytic solution to permeate is preferable. Among them, as the metal material, aluminum and copper are preferable, and the positive electrode current collector 7 is aluminum and the negative electrode current collector 8 is copper from the viewpoint of weight reduction, corrosion resistance, and high conductivity.

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 used as the base material of the conductive polymer material may be a conductive polymer. It may be a polymer having no conductivity.

Among the polymer materials, examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, and polyoxadiazole. Examples of non-conductive polymer materials include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyether nitrile (PEN), and poly. Tetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethylacrylate (PMA), polymethylmethacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin or a mixture thereof. And so on.

Among the non-conductive polymer materials, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferable, and polyethylene is more preferable, from the viewpoint of electrical stability. (PE), polypropylene (PP) and polymethylpentene (PMP).

Further, 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 , It is preferable that the resin current collector containing the non-conductive polymer material contains a conductive filler for the purpose of imparting conductivity. 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 having no conductivity with respect to ions used as a charge transfer medium. Specific examples thereof include, but are not limited to, carbon materials, aluminum, gold, silver, copper, iron, platinum, chromium, tin, indium, antimony, titanium and nickel. These conductive fillers may be used alone or in combination of two or more. Further, 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 preferable. Further, these conductive fillers may be a particle-based ceramic material or a resin material coated with the metal shown above by plating or the like.

Specific examples of a resin current collector using a non-conductive polymer as a base material include those obtained by dispersing 5 to 20 parts of acetylene black as a conductive filler in polypropylene and then rolling it with a hot press. Be done. Further, the thickness thereof is not particularly limited, and the same as known ones or appropriately modified ones can be applied.

The material constituting the seal member 9 is not particularly limited as long as it has adhesiveness to the positive electrode and negative electrode current collectors 7 and 8 and is durable against the electrolytic solution, but is particularly limited to a polymer material. Thermosetting resins are preferred. Specific examples thereof include epoxy-based resins, polyolefin-based resins, polyurethane-based resins, and polyvinylidene fluoride resins, and epoxy-based resins are preferable because they have high durability and are easy to handle.

As the material constituting the container 20, any material can be preferably applied as long as the material can accommodate the laminated battery module 21 in the container 20. However, considering that the cell 1 and the container 20 may come into contact with each other, the material constituting the container 20 is preferably a material having an insulating property. In addition, since the container 20 is sealed under reduced pressure with the laminated battery module 21 housed inside, the material constituting the container 20 is preferably a material having flexibility and airtightness. As such a material, a film called a laminate film, for example, a film in which both sides of a metal foil are covered with a polymer film, a non-woven fabric to which airtightness is imparted, and the like are known as exterior materials for lithium ion batteries. A laminated film can be used.

The materials constituting the current extraction portions 22a and 22b are flexible materials that can be deformed by the pressure inside the container when the pressure rises, and conductive materials that can take out the current generated by the laminated battery module to the outside. There are no particular restrictions. As such a material, the same film-like base material as that described as the material that can be used as the positive electrode current collector 7 and the negative electrode current collector 8 can be preferably used. These materials have conductivity and flexibility, but from the viewpoint of current limiting ability and the like, it is preferable to use a film having a thickness of 20 to 80 μm.

The positions where the current drawing portions 22a and 22b are arranged are not particularly limited as long as they are arranged at positions having a contact surface in contact with the container 20, but as an example, as shown in FIG. 5 (a), there is no particular limitation. A conductive material may be doped into the corresponding portion of the container 20 made of the non-woven fabric to impart conductivity to a part of the container 20, and as shown in FIG. 5B, the container 20 is made of a laminated film. An opening may be provided in the container 20 and a current drawing portion 22a, which is a flexible conductive plate, may be attached. When the container 20 is provided with an opening and the current drawing portion 22a, which is a flexible conductive plate, is attached, the current drawing portion 22a is attached to the inside of the container 20 as shown in FIG. 5 (b). Alternatively, the current drawing portion 22a may be attached to the outside of the container 20.

Here, when the current extraction portion 22a is attached to the outside of the container 20, there is a gap between the container 20 and the laminated battery module 21 due to the thickness of the container 20, but the laminated battery module 21 is placed in the container 20. When the battery is housed inside and sealed under reduced pressure, the flexible current drawing portion 22a is deformed to fill the gap, and the positive current collector 7 and the current drawing portion 22a are in electrical contact with each other. Can be done. Then, when the pressure inside the container rises, the current drawing portion 22a is pushed from the inside of the container and swells outward, but at the same time, the deformed current drawing portion 22a 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 attached 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 attached to the inside of the container 20. Be done.

The flexible current drawing portion 22a may be installed not only on the positive electrode side but also on the negative electrode side. In that case, the current drawing portion 22a and the negative electrode current collector 8 come into electrical contact with each other.

The cell 1 having the above configuration includes a positive electrode composition 5 containing a positive electrode active material and an electrolytic solution on the surfaces of the positive electrode current collector 7 and the negative electrode current collector 8, and a negative electrode active material and an electrolytic solution. The negative electrode composition 6 containing the above is formed to form the positive electrode 2 and the negative electrode 3. The method of forming the positive electrode 2 and the negative electrode 3 is arbitrary, and the positive electrode current collector 7 is coated with the positive electrode composition 5 and the negative electrode composition 6 on the surfaces of the positive electrode current collector 7 and the negative electrode current collector 8. Various methods such as placing the positive electrode composition 5 and the negative electrode composition 6 on the respective surfaces of the negative electrode current collector 8 via a nozzle or the like and then leveling them with a spatula or the like so as to have a predetermined thickness. Can be mentioned. After that, the positive electrode 2 and the negative electrode 3 are laminated via the separator 4, and the ends of the positive electrode current collector 7 and the negative electrode current collector 8 and the end of the separator 4 are sealed by the sealing member 9, so that the cell 1 is used. Can be manufactured.

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

In the lithium ion battery L having such a configuration, one end of an electrode terminal (not shown) made of, for example, a strip-shaped metal foil is fixed and connected to the upper surface and the lower surface 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.

Then, in the lithium ion battery L of the present embodiment, when an internal short circuit or the like occurs, a small amount of gas may be generated from any of the cell 1 over time. At this time, as a result, when the internal pressure of the container 20 including the current drawing portions 22a and 22b rises to the atmospheric pressure or higher, as shown in FIGS. 4A and 4B, the container including the current drawing portions 22a and 22b 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 cell 1 located at the uppermost and lowermost portions of the laminated battery module 21 By separating the current drawing portions 22a and 22b from each other and reducing the contact area between the positive electrode current collector 7 and the negative electrode current collector 8, the electrical resistance between them increases. Therefore, the current flowing through the cell 1 is suppressed, preferably cut off, and the heat generation of the entire lithium ion battery L is suppressed.

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

In particular, in the lithium ion battery L of the present embodiment, the laminated battery module 21 is sealed in the container 20 under reduced pressure to improve the adhesion between the laminated battery module 21 and the container 20, and the lithium ion battery L as a whole The rigidity can be increased, and 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 cell 1, the adhesion between the laminated battery module 21 and the container 20 is enhanced. As a result, the adhesion to the current extraction portions 22a and 22b can be improved, and excellent current extraction efficiency can be exhibited even when a resin current collector whose conductivity is not higher than that of the metal current collector is used. it can. Further, since the resin current collector does not have a higher conductivity than the metal current collector, the container 20 side is required to efficiently take out the power supply voltage from the laminated battery module 21 to the outside of the lithium ion battery L. It is preferable that the current extraction portions 22a and 22b, which are the power supply voltage extraction portions provided in the above, have a large area, preferably substantially 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 to control the current at the time of internal short circuit, the configuration is simplified as compared with the configuration in which the electrode tab is separately 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 a second embodiment of the present invention.

The difference between the lithium-ion battery of the present 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 made of a laminated film, and the current provided in the container 20 is provided. The lead-out portions 22a and 22b (only the current lead-out portion 22a is shown in FIG. 6) are a metal foil attached to the inner surface of the container 20 which is the laminated film, or a conductivity formed on the inner surface of the container 20 by sputtering or the like. It was composed of parts.

Similar to the first embodiment described above, the current extraction portions 22a and 22b in the present embodiment also have the positive electrode current collector 7 and the negative electrode current collector of the cell 1 located at the uppermost and lowermost portions of the laminated battery module 21. It is formed in substantially the same shape as No. 8.

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 having an open upper surface, and the upper container body 20e and the lower container body 20e are formed. In FIG. 6 of the lower container main body 20f, a pair of upper container edge portions 20 g and lower container edge portions 20h projecting laterally from the left and right ends are provided.

The laminated 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 in a state where the internal space is depressurized, the upper container edge portion 20g and The lithium ion battery L of the present embodiment is configured by sealing the lower container edge portion 20h with a sealing member (not shown).

A part of the upper container edge portion 20g and the lower container edge portion 20h is further extended laterally, and the current drawing portions 22a and 22b are also extended to the upper container edge portion 20g and the lower container edge portion 20h. Electrode terminals 23, 24 for taking out electricity from the lithium ion battery L are formed by extending along the line.

Therefore, the same effect as that of the above-described first embodiment can be obtained by this embodiment as well.

(Modification example)
In each of the above-described embodiments, the current drawing portions 22a and 22b are formed in the upper container 20a and the lower container 20b constituting the container 20, respectively, but the current drawing portions are formed in at least one of the upper container 20a and the lower container 20b, respectively. 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 extraction 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 cut off at the time of an internal short circuit. There is no limit to the size as long as it can be made.

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 unit

Claims (4)

A lithium secondary cell having a current collector of the first pole on the first surface and a current collector of the second pole on the second surface, and the first surface of the pair of adjacent lithium secondary cells. A laminated lithium-ion battery in which a laminated battery module in which the second surfaces are laminated in series so as to be adjacent to each other is housed in a container.
The first-pole current collector and / or the second-pole current collector and the container on the outside of the laminated battery module have contact surfaces that come into contact with each other.
At least a part of the contact surface of the container is a current drawing portion to the outside of the laminated lithium ion battery.
The current drawing portion has conductivity and flexibility, and has
The container is provided with an opening, and the current drawing portion is attached to the outside of the container.
When the pressure inside the container rises, the current extraction portion is deformed by the pressure, so that the current collector of the first pole and / or the current collector of the second pole of the laminated battery module and the current. A lithium-ion battery characterized by being spatially separated from the drawer. The lithium ion battery according to claim 1, wherein the current extraction portion is made of a film-like base material made of a metal or a conductive polymer. In the lithium ion battery according to claim 1 or 2.
The lithium ion battery is characterized in that the lithium secondary cell is formed in a flat plate shape as a whole. In the lithium ion battery according to any one of claims 1 to 3.
The current extraction unit is a lithium ion battery in which the container is equal to the contact surface in contact with the current collector of the first pole and / or the current collector of the second pole.

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