JP5204574B2 - Bipolar lithium ion secondary battery - Google Patents

Description

  The present invention relates to a bipolar lithium ion secondary battery.

  In recent years, in order to protect the environment, the development of next-generation energy has been promoted in place of fossil fuels such as gasoline. In the automobile industry, the introduction of electric cars and hybrid cars is the best, and the development of motor drive batteries is underway. In addition, for household electricity, development of large-capacity batteries as an emergency power source in the event of a disaster is underway. In addition, there is an increasing demand for high energy density batteries used in portable electronic devices such as mobile phones.

The basic configuration of the lithium ion secondary battery is as follows: a positive electrode in which a positive electrode active material layer made of an active material such as lithium cobaltate, a conductive additive such as acetylene black, a binder, and the like is formed on an aluminum foil current collector; And a negative electrode in which a negative electrode active material layer made of carbon particles, a binder and the like is formed on a copper foil current collector is disposed via a polyolefin-based porous separator, and nonaqueous electrolysis containing LiPF _{6 and the} like It has a structure filled with liquid. However, when a large number of lithium ion secondary batteries are used in combination in series connection or parallel connection, the resistance of inter-cell connection is added, so that the voltage characteristics of the entire assembled battery at the time of charging / discharging deteriorate. As a countermeasure, it has been proposed to use a bipolar electrode in which a positive electrode active material layer and a negative electrode active material layer are formed on both sides of one current collector (see, for example, Patent Documents 1 and 2). . Bipolar lithium ion secondary batteries have the advantage that, in the battery element, current flows in the direction in which bipolar electrodes are stacked, that is, in the thickness direction of the battery, so that the battery path is short and the current loss is small.

JP-A-8-7926 JP 9-23003 A

  The above-mentioned patent documents specifically describe a material in which an aluminum foil and a copper foil are clad as a current collector used for a bipolar electrode. Bipolar lithium-ion secondary batteries using a clad material of aluminum foil and copper foil as a current collector can reduce the overall resistance of the battery, but it is easy to clad a metal material in the first place. However, since it is more difficult to clad the metal foil, it is expensive to produce a large-area current collector on an industrial scale. Another problem is that pinholes (through holes) are likely to occur in the clad material during the process of clad the metal foil. On the other hand, the stainless steel foil exemplified as a current collector in Patent Document 2 has corrosion resistance to both the positive electrode and negative electrode environments, and thus does not need to be clad with a dissimilar material. The bipolar lithium ion secondary battery using the foil as a current collector was found to have significantly reduced battery characteristics as compared with the one using a clad material of aluminum foil and copper foil.

  Accordingly, the present invention has been made in view of the above problems, and improves the battery characteristics of a bipolar lithium ion secondary battery using a stainless steel foil, which is advantageous for industrial scale production, as a current collector. For the purpose.

The inventors of the present invention cannot obtain sufficient battery characteristics in a bipolar lithium ion secondary battery using a stainless steel foil as a current collector because the interface resistance between the stainless steel foil and the active material is large and the internal resistance of the battery The surface of the stainless steel foil current collector was roughened with SiC abrasive paper, but the battery characteristics were not significantly improved.
Therefore, the present inventors have conducted various studies on the roughened form of the surface of the stainless steel foil in order to reduce the interfacial resistance between the stainless steel foil and the positive electrode / negative electrode active material and improve the battery characteristics. It has been found that it is effective to roughen the stainless steel foil so as to have surface roughness, maximum height and surface area increase rate, and the present invention has been completed.
That is, the present invention has a surface roughness (SPa) of 0.1 μm or more and a maximum when a surface area having a side of 50 μm is measured with a scanning confocal laser microscope having a resolution of 0.01 μm by chemical etching. A positive electrode active material layer on one surface of a stainless steel foil current collector having a rough surface with a height (SRmax) of 10 μm or less and a surface area increase rate obtained by dividing the surface area by the projected area is 1.5 or more A bipolar lithium ion secondary battery is characterized in that a bipolar electrode having a negative electrode active material layer formed on the other surface is laminated via an electrolyte layer.

  According to the present invention, even when a stainless steel foil having corrosion resistance in a positive / negative electrode environment is used as a current collector for a bipolar electrode, the overall battery resistance can be reduced and battery characteristics such as output characteristics and cycle characteristics are improved. Bipolar lithium ion secondary battery can be realized. Moreover, the stainless steel foil used in the present invention does not need to be clad like an aluminum foil or a copper foil. It becomes possible to reduce the size and weight.

Hereinafter, the bipolar lithium ion secondary battery of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic cross-sectional view for explaining the configuration of a bipolar lithium ion secondary battery of the present invention. In FIG. 1, the bipolar lithium ion secondary battery of the present invention has a positive electrode active material layer 2 formed on one surface of a stainless steel foil 1 as a current collector and a negative electrode active material layer 3 formed on the other surface. In addition, an electrode laminate in which bipolar electrodes 4 and electrolyte layers 5 are alternately laminated is sandwiched between a positive electrode terminal plate 6 and a negative electrode terminal plate 7. Only the positive electrode active material layer 2 is formed on the positive electrode terminal plate 6 disposed in the outermost layer on the positive electrode side, and only the negative electrode active material layer 3 is formed on the negative electrode terminal plate 7 disposed on the outermost layer on the negative electrode side. Yes. Furthermore, the bipolar lithium ion secondary battery of the present invention prevents each current collector and the positive electrode active material layer 2 and the negative electrode active material layer 3 from being in direct contact, and at least the positive electrode active material of the electrode laminate. The sealing part 8 for interrupting | blocking the layer 2, the negative electrode active material layer 3, and the electrolyte layer 5 from external air is provided.

The surface of the stainless steel foil 1 as a current collector needs to have a specific roughened form in order to remarkably improve the interface resistance with the active material. When an active material layer is formed on a general stainless steel foil, the resistance is significantly higher than when an active material layer is formed using copper as a current collector. However, when chemical etching is performed by immersion in an etching solution such as an aqueous solution containing FeCl ₃ and HCl, pitting corrosion occurs and a surface having pores is obtained, and the oxide film on the surface becomes very thin. . By appropriately changing the etching conditions, the surface roughness (SPa) is 0.1 μm or more and the maximum height (SRmax) is 10 μm or less, and the surface area increase rate obtained by dividing the surface area by the projected area is 1.5 or more. A roughened surface can be formed. When a later-described positive electrode active material layer 2 and negative electrode active material layer 3 are formed on the surface of the stainless steel foil 1 having such a roughened surface, the contact resistance between the active material and the current collector collects copper. It was found to be equal to or less than that of the electric body.

  Although there are many unexplained parts about the mechanism, a dense oxide film is usually formed on the surface of the stainless steel foil. When an active material layer is formed through the oxide film, the active material layer is used as a conductive assistant. The contact point of acetylene black or the like added to is only the oxygen deficiency point of the oxide film, and it is considered that resistance becomes high because the movement of electrons becomes extremely difficult. On the other hand, when the negative electrode active material layer 3 is formed on the chemically etched stainless steel foil 1 having a roughened surface, acetylene black having a particle size of submicron or less enters the pores, and the contact point is Become very much. In addition, the resistance of the oxide film itself decreases as the thickness decreases. For these reasons, it is considered that the contact resistance between the active material and the current collector can be significantly reduced. Even when the positive electrode active material layer 2 is formed on the stainless steel foil 1 having a specific roughened surface, since the active material layer contains acetylene black or the like as a conductive auxiliary agent, the same effect as the negative electrode side is obtained. It seems that the contact resistance reduction effect was obtained.

Surface roughness When the surface area increase ratio divided by (SPa) is the projected area of 0.1μm smaller or when the surface area _{(S) (S 0) (} S / S 0) is less than 1.5, the such acetylene black The carbon material cannot enter the pores, and the effect of reducing contact resistance is reduced. On the other hand, when the maximum height (SRmax) is larger than 10 μm, graphite having a large particle diameter as an active material enters the pores, and there are few contact points with respect to a carbon material such as acetylene black having a small particle diameter. Therefore, the contact resistance reduction effect is reduced. The preferred surface roughness (SPa) in the present invention is 0.2 μm or more and 1.5 μm or less, and the preferred surface area increase rate (S / S ₀ ) is 2.0 or more and 8.0 or less.
Further, if the maximum height (SRmax) exceeds 1/2 of the thickness (t) of the stainless steel foil 1 as a current collector, a pinhole (through hole) may occur in the stainless steel foil 1. When the through hole is generated, the positive electrode active material layer 2 and the negative electrode active material layer 3 that should be separated from each other are short-circuited, resulting in a decrease in output. In order to suppress the generation of through holes, the maximum height (SRmax) is preferably 1/2 or less of the thickness (t) of the stainless steel foil 1 and more preferably 1/4 or less.

The chemical etching conditions are not particularly limited as long as the above-described roughened surface can be formed, but an aqueous solution containing 5% by mass to 30% by mass of FeCl ₃ and 2% by mass to 20% by mass of HCl, 10% by mass to 35% by mass. % of CuCl ₃ and in the etching solution such as an aqueous solution containing a 2% by mass to 20% HCl, it is desirable to dip 5 to 120 seconds at 35 ° C. to 70 ° C..

  Since the stainless steel foil 1 as the current collector needs to play a role as a current collector for the positive electrode on one side and a current collector on the other side as the other side, the positive electrode operating potential and the negative electrode operating potential are required. It is necessary to have corrosion resistance. If it is an austenitic system, C: 0.015 mass% or less, Si: 0.5 mass% or less, Mn: 2.0 mass% or less, Cr: 16 mass% to 32 mass%, Ni: 5 mass% to 30 % By mass, Mo: 3.0% by mass or less, Cu: 2.0% by mass or less, Nb: 0.80% by mass or less, Ti: 0.40% by mass or less, Al: 0.50% by mass or less, B: What contains 0.3 mass% or less and the remainder consists of Fe and an irreversible impurity is preferable. On the other hand, if it is a ferrite type, Cr: 16 mass%-32 mass%, C: 0.015 mass% or less, Si: 0.5 mass% or less, Mn: 2.0 mass% or less, Mo: 3.0 % By mass, Ni: 2.0% by mass or less, Cu: 2.0% by mass or less, Nb: 0.80% by mass or less, Ti: 0.40% by mass or less, Al: 0.50% by mass or less, B : 0.3 mass% or less is preferable, and the balance is composed of iron and inevitable impurities. Examples of JIS steel types include SUS304, SUS316L, and SUS310S for austenite, and SUS436, SUS444, and SUS447J1 for ferrite.

  Cr is the most important element for maintaining the corrosion resistance as stainless steel in the battery environment. In order to provide corrosion resistance, it is necessary to contain 16.0% by mass. However, when the Cr content is high, the toughness and workability are lowered, so the upper limit of the Cr content is 32% by mass.

  Ni is an element necessary for maintaining the formation and corrosion resistance of the austenitic stainless steel. If it is less than 5% by mass, the corrosion resistance in the battery environment cannot be maintained. Moreover, since the corrosion resistance in this environment is saturated at 30% by mass and the cost is increased, the upper limit is set to 30% by mass. On the other hand, in the case of ferrite, Ni is basically an unnecessary element, and if the content is large, the upper limit is set to 2.0% by mass because it causes hardening and high cost.

  C forms carbides, which serve as recrystallization nuclei for the randomization of recrystallized ferrite in the final annealing. However, C is an element that increases the strength after cold rolling annealing, and if it is too high, the ductility is lowered.

  Si is usually used for the purpose of deoxidation, but its solid solution strengthening ability is high, and if its content is too large, the material is hardened and the ductility is lowered, so the content was made 0.5% by mass or less.

  Mn is an austenite forming element, has a small solid solution strengthening ability and has little adverse effect on the material. However, if the content is large, Mn fume is generated during melting, and the manufacturability is lowered. Therefore, the component range is desirably 2.0% by mass or less.

  Mo is an element effective for improving the corrosion resistance. Excessive addition causes a decrease in hot workability and an increase in cost due to solid solution strengthening at a high temperature and delay of dynamic recrystallization.

  Nb is an element that fixes C and N and improves impact resistance and secondary workability. However, if it is added too much, the material hardens and adversely affects processability. Moreover, since it raises recrystallization temperature, it was set to 0.80 mass% or less, Preferably it was set to 0.10 mass%-0.80 mass%.

  Ti is an element that fixes C and N and improves workability and corrosion resistance. However, if too much is added, surface defects such as Ti-based inclusions that cause cracks in drawing work exist, so when added, the content should be 0.40% by mass or less, preferably 0.05% by mass to 0%. 40% by mass.

  Al is an element effective for deoxidation and oxidation resistance, but excessive addition causes surface defects. Therefore, when added, the content is 0.50% by mass or less, preferably 0.01% by mass. % To 0.50% by mass.

  B is an alloy component that has the effect of fixing N and improving the corrosion resistance and workability, and is added as necessary. In order to exert the above action, it is desirable to add 0.005% by mass or more. However, if excessively added, the hot workability and weldability are deteriorated, so the content was made 0.3% by mass or less.

  The stainless steel foil 1 may contain the following elements in addition to P and S which are inevitably contained.

V, Zr: V is a useful element from the viewpoint of improving workability due to the effect of precipitating solid solution C as carbides, and Zr is useful from the viewpoint of improving workability and toughness by capturing oxygen in steel as an oxide. However, since productivity will fall when it adds abundantly, the appropriate content of V and Zr is 0.01 mass%-0.30 mass%.
In addition to these, Ca, Mg, Co, REM, and the like may be contained in the scrap, which is a raw material, during melting, but there is no effect on the corrosion resistance and workability unless they are contained in large amounts.

  In a current lithium ion secondary battery, an aluminum foil of about 30 μm is generally used as a positive electrode current collector and a copper foil of about 20 μm is used as a negative electrode current collector. Therefore, a current collector of a bipolar electrode is 50 μm. By using a thinner stainless steel foil 1, it is possible to reduce the size. Since the stainless steel foil 1 having the specific roughened surface described above does not need to be clad, the manufacturing cost of the current collector is significantly reduced. In particular, it is possible to reduce the size and weight by using a stainless steel foil 1 thinner than 30 μm. However, in order to manufacture it at a low cost, it is a ferritic stainless steel that requires less work hardening by rolling and can be rolled without an intermediate annealing step. Desirably steel.

  The positive electrode active material layer 2 and the negative electrode active material layer 3 contain a known binder resin such as polyvinylidene fluoride (PVDF) in order to bind an active material, a conductive agent, etc., and to secure adhesion with a current collector. can do. Since the binder resin usually has insulating properties, it is desired that the binder resin be contained as little as possible in the active material layer. When the adhesion between the stainless steel foil 1 having a roughened surface, the positive electrode active material layer 2 and the negative electrode active material layer 3 is improved, the content of the binder resin is decreased, in other words, the content of the active material is increased. The battery performance can be improved as well as the overall resistance of the battery can be reduced. That is, it is possible to expect a synergistic effect of further reducing the battery internal resistance and improving the battery capacity density. The preferable content of the binder resin in the present invention is 5% by mass to 10% by mass.

Examples of the active material used for the positive electrode active material layer 2 include Li _x MO ₂ (where M represents one or more transition metals and 0.05 ≦ x ≦ 1.10), and more specifically. LiCoO ₂ , LiNiO ₂ , LiNi _y Co _(1-y) O ₂ (0.3 ≦ y ≦ 0.95), LiMn ₂ O ₄ , LiFePO _{4, and} other lithium composite oxides.
The active material used for the anode active material layer 3 may be any material that can insert and desorb lithium ions, such as pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, and glass. And carbon materials such as carbonaceous materials, organic polymer fired bodies (furan resin or the like carbonized by firing at a suitable temperature), carbon fibers, activated carbon and the like. Among these, a carbon material having a (002) plane spacing of 3.70 mm or more and a true density of less than 1.70 g / cc and having no exothermic peak at 700 ° C. or higher by differential thermal analysis in an air stream is preferable. Used.

As the electrolyte layer 5, an electrolytic solution in which a lithium salt is used as an electrolyte and this is dissolved in an organic solvent is preferably used. However, in this case, it is necessary to dispose a separator in the electrolyte layer 5. As a separator, a well-known thing which can be used for a lithium ion secondary battery can be used without a restriction | limiting. Examples of the electrolyte include lithium salts such as LiClO ₄ , LiBF ₄ , LiPF ₆ , LiAsF ₆ , LiCF ₃ SO ₃ , and these may be used alone or in combination of two or more. . Examples of the organic solvent include, but are not limited to, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, γ-butyrolactone, tetrohydrofuran, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, and the like. May be used alone or in combination of two or more. Further, a solid polymer electrolyte such as polyethylene oxide (PEO) may be used as the electrolyte layer 5 instead of such an electrolytic solution.

  As the positive electrode terminal plate 6 and the negative electrode terminal plate 7, known ones that can be used for lithium ion secondary batteries can be used without limitation.

  The sealing unit 8 serves to block the positive electrode active material layer 2, the negative electrode active material layer 3, and the electrolyte layer 5 from the outside air. The material constituting the sealing portion 8 may be any material that can prevent moisture from the outside air from entering the inside of the battery, but one or more selected from polybutylene terephthalate, polyphenylene sulfide, and aromatic polyamide resin. The sealing resin is preferably used. The reason is that when these sealing resins are in a molten state and injection molded, the sealing resin enters into the pores of the stainless steel foil 1 having the roughened surface described above, and the bond with the surface of the stainless steel foil 1 is strong. This is because a completely sealed state can be obtained. Moreover, the electrolytic solution does not enter the interface between the stainless steel foil 1 and the sealing resin, and the sealed state can be maintained for a long time. Therefore, a battery having excellent long-term stability and safety can be obtained.

  The bipolar lithium ion secondary battery configured as described above is preferably pressurized in the stacking direction. By applying pressure in the stacking direction, disturbance of the current distribution accompanying expansion / contraction of the active material layer accompanying charge / discharge can be prevented, and the battery performance can be maintained as good.

  Hereinafter, although an example and a comparative example explain the present invention still in detail, the present invention is not limited to these.

<Examples 1-6 and Comparative Examples 1-10>
A bipolar lithium ion secondary battery having the same configuration as that shown in FIG. 1 was produced as follows.
Prior to the formation of the negative electrode active material layer and the positive electrode active material layer, C: 0.006% by mass, Si: 0.24% by mass, Mn: 0.19% by mass, Ni: 0.14% by mass, Cr: 21.%. 9% by mass, P: 0.034% by mass, S: 0.001% by mass, Cu: 0.07% by mass, Mo: 1.12% by mass, balance Fe and stainless steel having a thickness of 20 μm consisting of irreversible impurities The surface (both surfaces) of the foil was roughened by various methods shown in the “Roughening treatment” column of Table 1 below (Examples 1 to 6 and Comparative Examples 1 to 8).
The chemical etching treatment includes 22 mass% FeCl ₃ +5 mass% HCl aqueous solution (containing 75.6 g / L of Fe ³⁺ : etching liquid A), aqua regia (etching liquid B), or 8 mass% HNO ₃ +3 mass% HF ( Various metal foils were immersed in the etching solution C) at a predetermined temperature for a predetermined time.
Each of the emery paper polishing, dull rolling, and shot blasting was subjected to hydrochloric acid immersion treatment as a post treatment. The hydrochloric acid immersion treatment was performed by immersing various metal foils in a 10% by mass hydrochloric acid aqueous solution (50 ° C.) for 30 seconds.
In Comparative Example 9 and Comparative Example 10, a metal foil that was not roughened was used.

The surface of various metal foils was observed at a magnification of 5,000 times with a scanning confocal laser microscope (OLS 1200 manufactured by Olympus Optical Co., Ltd., Ar ion laser) with a resolution of 0.01 μm, and a measurement area of 50 μm × 50 μm was observed. On the other hand, after image processing was performed once for isolated point removal and once for image luminance averaging, surface roughness (SPa) and maximum height (SRmax) were measured. Next, the surface area (S) with respect to the projected area (S ₀ ) of 50 μm □ was measured. And as the area increase rate by roughening was determined S / S _0. The results are shown in Table 1.

  The negative electrode active material layer was prepared by mixing 90% by mass of graphite powder, 5% by mass of acetylene black as a conductive additive and 5% by mass of polyvinylidene fluoride as a binder, and dispersing this in N-methyl-2-pyrrolidone. The slurry was applied to one side of various metal foils and dried. Next, the positive electrode active material layer was mixed with 90% by mass of lithium manganate powder, 5% by mass of acetylene black as a conductive additive and 5% by mass of polyvinylidene fluoride as a binder, and this was mixed with N-methyl-2. -Dispersed in pyrrolidone and formed into a slurry form was applied to the other side of various metal foils and dried. Thereafter, a metal foil having an active material layer formed on both surfaces was compression-molded with a roller press to produce a bipolar electrode. In addition, as an electrode for taking a lead, a stainless steel foil having a positive electrode active material layer formed on only one surface and a stainless steel foil having a negative electrode active material layer formed on only one surface were prepared.

These electrodes are cut to a predetermined size, and three bipolar electrodes, one positive terminal plate, one negative terminal plate, a separator made of a microporous polypropylene film having a thickness of 25 μm and a seal made of polybutylene terephthalate. An electrode group provided with a stop was produced. Thereafter, an electrolytic solution in which 1 mol of LiPF ₆ was dissolved in a mixed solvent of ethylene carbonate 50 vol% and dimethyl carbonate 50 vol% was injected to produce a series type bipolar lithium ion secondary battery.

(Battery characteristics evaluation)
Each of the bipolar lithium ion secondary batteries of Examples 1 to 6 and Comparative Examples 1 to 10 was fully charged at a constant charging rate of 0.5 CmA, and then each of 0.5 CmA, 1.0 CmA, or 3.0 CmA was constant. The discharge electricity quantity at the 10th cycle when discharged at a discharge rate of 2 is shown in Table 2 as a relative value. The charge rate (or discharge rate) XCmA is defined by the following equation.
X (CmA) = battery capacity (mAh) / charge time (or discharge time) (h)
As an index representing the difference in capacity of the target battery, here, the discharge electric quantity at the 10th cycle when the battery of Example 1 was discharged at a discharge rate of 0.5 CmA was set to 1.00.

  As is apparent from Tables 1 and 2, by using a stainless steel foil that has been roughened so as to have a predetermined roughened form by chemical etching, the amount of discharge electricity at the same discharge rate is increased, that is, output characteristics. Improvement was confirmed.

<Examples 7 to 10>
Except that the stainless steel foil was changed to the stainless steel foil shown in Table 3 below, the surface roughening treatment was carried out so as to have the same SPa, SRmax and S / S ₀ as in Example 1, and bipolar lithium was obtained in the same manner as in Example 1. Ion secondary batteries were fabricated and battery characteristics were evaluated. The results are shown in Table 3.

  As shown in Table 3, no matter which stainless steel foil was used, good battery characteristics were obtained by performing a roughening treatment so as to obtain a predetermined roughened form by chemical etching.

<Examples 1, 11 and 12>
A bipolar lithium ion secondary battery was produced in the same manner as in Example 1 except that the material of the sealing part was changed to the resin shown in Table 4 below. The battery characteristics were evaluated after the wet test of the batteries of Examples 1, 11 and 12 (humidity 98%, temperature 49 ° C. for 1000 hours). The results are shown in Table 4.

  As shown in Table 4, it was revealed that a good hermetic state could be obtained by using any of polybutylene terephthalate, polyphenylene sulfide, and aromatic polyamide resin as the sealing resin.

It is a schematic cross section for demonstrating the structure of the bipolar type lithium ion secondary battery of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Stainless steel foil, 2 Positive electrode active material layer, 3 Negative electrode active material layer, 4 Bipolar type electrode, 5 Electrolyte layer, 6 Positive electrode terminal board, 7 Negative electrode terminal board, 8 Sealing part.

Claims (2)

The surface roughness (SPa) is 0.1 μm or more and the maximum height (SRmax) when a surface region having a side of 50 μm is measured with a scanning confocal laser microscope having a resolution of 0.01 μm by chemical etching. and at 10μm or less, one of the stainless steel foil current collector having a surface area increase rate divided by the surface area (S) of the projection area _{(S 0) (S / S} 0) is roughened is 1.5 or more A bipolar lithium ion secondary battery, wherein a bipolar electrode having a positive electrode active material layer formed on one surface and a negative electrode active material layer formed on the other surface is laminated via an electrolyte layer.   Having a sealing portion formed of at least one selected from polybutylene terephthalate, polyphenylene sulfide, and aromatic polyamide resin for blocking the positive electrode active material layer, the negative electrode active material layer, and the electrolyte layer from outside air. The bipolar lithium ion secondary battery according to claim 1, characterized in that:

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