JP5381292B2 - Bipolar electrode and bipolar secondary battery using the same - Google Patents

Description

  The present invention relates to a bipolar electrode and a bipolar secondary battery using the same. In particular, the present invention relates to a bipolar electrode and a bipolar electrode using the same, which can effectively suppress an increase in electrical resistance.

  In recent years, hybrid vehicles (HEV), electric vehicles (EV), and fuel cell vehicles have been manufactured and sold from the viewpoint of environment and fuel consumption, and new developments are continuing. In these so-called electric vehicles, it is indispensable to use a power supply device capable of discharging and charging. As the power supply device, a secondary battery such as a lithium ion battery or a nickel metal hydride battery, an electric double layer capacitor, or the like is used. In particular, lithium ion secondary batteries are considered suitable for electric vehicles because of their high energy density and high durability against repeated charging and discharging, and various developments have been intensively advanced. However, in order to apply to the power sources for driving motors of various automobiles as described above, it is necessary to use a plurality of secondary batteries connected in series in order to ensure a large output.

  However, when a battery is connected via the connection portion, the output is reduced due to the electrical resistance of the connection portion. Further, the battery having the connection portion has a disadvantage in terms of space. That is, the connection portion causes a reduction in the output density and energy density of the battery.

  In order to solve this problem, bipolar secondary batteries such as bipolar lithium ion secondary batteries have been developed. A bipolar secondary battery has a structure in which a plurality of bipolar electrodes, each having a positive electrode active material layer formed on one side of a current collector and a negative electrode active material layer formed on the other side, are stacked via an electrolyte layer or a separator. Have

  The current collector used in such a bipolar secondary battery is preferably made of a material that is lighter and more conductive in order to ensure a higher output density. Therefore, in recent years, a current collector composed of a polymer material to which a conductive filler is added in place of the conventional metal foil has been proposed. For example, Patent Document 1 discloses a current collector including a conductive resin in which metal particles or carbon particles are mixed as a conductive filler in a polymer material.

JP 2006-190649 A

  However, when a current collector containing a conductive resin as in Patent Document 1 is used, the active material layer formed on the surface of the current collector is peeled off from the current collector. There was a problem that electrical resistance would increase.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a bipolar electrode that can effectively prevent an increase in electrical resistance.

  The present inventors have intensively studied to solve the above problems. In the process, the inventors have found that the following decomposition of the supporting salt in the electrolyte is involved as one of the causes of the active material layer peeling from the current collector. The supporting salt containing fluorine (F) generates hydrogen fluoride (HF) by being thermally decomposed by heat generated by the charge / discharge reaction of the battery or by being hydrolyzed by a small amount of water remaining in the electrolyte. Since the surface of the current collector that is in contact with the active material layer is exposed to an electric potential, the presence of hydrogen fluoride oxidizes the resin contained in the current collector, thereby degrading the current collector. In particular, the surface of the current collector that is in contact with the positive electrode active material layer is susceptible to electric potential, so that the resin is easily oxidized. Thereby, the active material layer peels from the current collector, and as a result, the electric resistance of the bipolar electrode increases. The present inventors have further researched on this problem, and by providing a protective layer that adsorbs hydrogen fluoride between a current collector including a resin layer having conductivity and an active material layer, The present invention was completed by obtaining the knowledge that the deterioration of the electric body can be prevented.

  That is, the bipolar electrode of the present invention is formed on a current collector including a conductive resin layer, a positive electrode active material layer formed on one surface of the current collector, and the other surface of the current collector. And a negative electrode active material layer. A protective layer containing a hydrogen fluoride adsorbing material is interposed between the current collector and the positive electrode active material layer or between the current collector and the negative electrode active material layer.

  According to the present invention, hydrogen fluoride generated by the decomposition of the supporting salt containing fluorine is absorbed by the protective layer present between the current collector and the active material layer, so that the collector including the conductive resin layer is contained. Electrical deterioration is suppressed. Therefore, peeling of the active material layer from the current collector is prevented, and an increase in electrical resistance of the bipolar electrode can be effectively prevented.

1 is a schematic cross-sectional view schematically showing a bipolar electrode according to an embodiment of the present invention. It is the cross-sectional schematic which represented typically the bipolar electrode which concerns on other one Embodiment of this invention. It is the figure which represented typically the example of the application form of the protective layer which concerns on this invention. 1 is a schematic cross-sectional view schematically showing a bipolar secondary battery according to an embodiment of the present invention. FIG. 5A is an external view schematically showing an assembled battery according to an embodiment of the present invention, FIG. 5A is a plan view of the assembled battery, FIG. 5B is a front view of the assembled battery, and FIG. It is a side view. It is a conceptual diagram of the vehicle carrying the bipolar secondary battery or assembled battery of this invention.

  Hereinafter, preferred embodiments of the present invention will be described. In this embodiment, a current collector including a conductive resin layer, a positive electrode active material layer formed on one surface of the current collector, a negative electrode active material layer formed on the other surface of the current collector, And a bipolar electrode. In the bipolar electrode, a protective layer containing a hydrogen fluoride adsorbent is interposed between the current collector and the positive electrode active material layer or between the current collector and the negative electrode active material layer. Yes.

  Hereinafter, the present embodiment will be described with reference to the drawings. However, the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

<Bipolar electrode>
FIG. 1 is a cross-sectional view schematically showing the entire structure of a bipolar electrode according to an embodiment of the present invention. In the bipolar electrode 23 of the present embodiment shown in FIG. 1, a protective layer 33 is formed on one surface of the current collector 11, and the positive electrode active material layer 13 is formed on the surface of the protective layer 33. A negative electrode active material layer 15 is formed on the other surface of the current collector 11. The current collector 11 is made of a conductive resin layer in which ketjen black (not shown) is dispersed as a conductive filler in a base material made of polyethylene. In the current collector 11, irregularities are formed on the surface on the side where the protective layer 33 is formed, whereby the adhesion between the current collector 11 and the protective layer 33 is enhanced. Aluminum oxide (Al ₂ O ₃ ) particles (not shown) are dispersed as a hydrogen fluoride adsorbent in the protective layer. Since aluminum oxide is porous, hydrogen fluoride generated by the decomposition of the supporting salt in the electrolyte is adsorbed on the pores of the aluminum oxide. Such an adsorption action of aluminum oxide suppresses the current collector 11 from being deteriorated by hydrogen fluoride. Therefore, peeling of the positive electrode active material layer 13 from the current collector 11 is prevented, and an increase in electric resistance of the bipolar electrode 23 is effectively suppressed. Hereinafter, main components of the bipolar electrode of this embodiment will be described.

[Current collector]
The current collector has a function of mediating the movement of electrons from one surface on which the positive electrode active material layer is formed to the other surface on which the negative electrode active material layer is formed. The current collector according to this embodiment essentially includes a resin layer having conductivity, and may further include other layers as necessary.

  The conductive resin layer is an essential component for the current collector of this embodiment, and can contribute to weight reduction of the current collector as well as functioning as an electron transfer medium. The resin layer may include a base material made of a polymer material, a conductive filler, and other members as necessary.

  There is no restriction | limiting in particular in resin used for a base material, A conventionally well-known nonelectroconductive polymer material or a conductive polymer material can be used without a restriction | limiting. Preferred non-conductive polymer materials include, for example, polyethylene (PE; high density polyethylene (HDPE), low density polyethylene (LDPE)), polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), poly Ether nitrile (PEN), polyimide (PI), polyamideimide (PAI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA) , Polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), and polystyrene (PS). Among these, it is preferable to use polyethylene, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, and polyimide from the viewpoint of potential resistance. Moreover, it is preferable to use polyethylene, a polypropylene, and a polyimide from a viewpoint of durable medium.

  Preferable conductive polymer materials include, for example, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Since such a conductive polymer material has sufficient conductivity without adding a conductive filler, it is advantageous in terms of facilitating the manufacturing process or reducing the weight of the current collector. These non-conductive polymer materials or conductive polymer materials may be used alone or in a combination of two or more.

  A conductive filler may be added to the conductive polymer material or the non-conductive polymer material as necessary. In particular, when the resin used as the base material of the current collector is made of only a non-conductive polymer, a conductive filler is inevitably necessary to impart conductivity to the resin. The conductive filler can be used without particular limitation as long as it is a substance having conductivity. For example, metals, conductive carbon, etc. are mentioned as a material excellent in electroconductivity, electric potential resistance, or lithium ion barrier | blocking property.

  The metal is not particularly limited, but at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, Sb, and K, or these metals It is preferable to contain an alloy or metal oxide containing. These metals are resistant to the potential of the positive electrode or negative electrode formed on the current collector surface. Among these, an alloy containing at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, and Cr is more preferable.

  Specific examples of the alloy include stainless steel (SUS), Inconel (registered trademark), Hastelloy (registered trademark), and other Fe—Cr alloys, Ni—Cr alloys, and the like. By using these alloys, higher potential resistance can be obtained.

  The conductive carbon is not particularly limited, but is at least selected from the group consisting of acetylene black, vulcan, black pearl, carbon nanofiber, ketjen black, carbon nanotube, carbon nanohorn, carbon nanoballoon, and fullerene. It is preferable that 1 type is included. These conductive carbons have a very wide potential window, are stable in a wide range with respect to both the positive electrode potential and the negative electrode potential, and have excellent conductivity. Among these, it is more preferable to include at least one selected from the group consisting of carbon nanotubes, carbon nanohorns, ketjen black, carbon nanoballoons, and fullerenes. Since these conductive carbons have a hollow structure, the surface area per mass is large, and the current collector can be further reduced in weight. In addition, electroconductive fillers, such as these metals and electroconductive carbon, can be used individually by 1 type or in combination of 2 or more types.

  The size of the conductive filler is not particularly limited, and fillers of various sizes can be used depending on the size and thickness of the resin layer or the shape of the conductive filler. As an example, the average particle diameter when the conductive filler is granular is preferably about 0.1 to 10 μm from the viewpoint of facilitating molding of the resin layer. In the present specification, “particle diameter” means the maximum distance L among the distances between any two points on the contour line of the conductive filler. As the value of “average particle diameter”, the average particle diameter of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The calculated value shall be adopted. The particle diameter and average particle diameter of an active material and a hydrogen fluoride adsorbent described later can be defined similarly.

  The content of the conductive filler contained in the resin layer is not particularly limited. In particular, when the resin includes a conductive polymer material and sufficient conductivity can be secured, it is not always necessary to add a conductive filler. However, when the resin is made of only a nonconductive polymer material, it is essential to add a conductive filler in order to impart conductivity. In this case, the content of the conductive filler is preferably 5 to 35% by mass, more preferably 5 to 25% by mass, and further preferably 5 to 5% by mass with respect to the total mass of the non-conductive polymer material. 15% by mass. By adding such an amount of conductive filler to the resin, sufficient conductivity can be imparted to the non-conductive polymer material while suppressing an increase in the mass of the resin layer.

  The form of the current collector is not particularly limited as long as it includes a resin layer having conductivity, and can take various forms. For example, the shape of the current collector may be a laminate including other layers as needed in addition to the resin layer. Examples of other layers other than the resin layer include a metal layer and an adhesive layer, but are not limited thereto. For example, a single resin layer having conductivity may form a current collector alone, or two or more resin layers having conductivity may be stacked. By laminating a plurality of resin layers in this manner, even if minute pinholes (cracks) are generated in each resin layer, the positions of the cracks do not coincide with each other, so that a liquid junction can be prevented. Thus, when laminating | stacking a some resin layer, these resin layers can be adhere | attached by heat sealing | fusion. In addition to the resin layer, a metal layer containing a metal such as aluminum, nickel, or copper, or an alloy thereof may be provided between the resin layers. By including such a metal layer, liquid junction between the positive electrode active material layer and the negative electrode active material layer in the bipolar electrode due to ion permeation in the resin layer can be prevented, and long-term reliability with improved lifetime characteristics Bipolar secondary batteries with excellent performance can be constructed. Examples of the method of laminating the resin layer and the metal layer include a method of depositing metal (plating or sputtering) on the resin layer, a method of fusing resin on the metal foil, and the like. In addition, when the current collector is formed by laminating two or more resin layers or metal layers, the two layers are from the viewpoint of reducing the contact resistance at the interface between the layers or preventing the adhesion surface from peeling off. It may be bonded via an adhesive layer. Examples of the material used for such an adhesive layer include metal oxide-based conductive pastes including zinc oxide, indium oxide, and titanium oxide; and carbon-based conductive pastes including carbon black, carbon nanotubes, and graphite. Preferably used.

  The thickness of the current collector is preferably thinner in order to increase the output density of the battery by reducing the weight. In a bipolar secondary battery, the current collector existing between the positive electrode active material layer and the negative electrode active material layer of the bipolar electrode may have a high electric resistance in the horizontal direction in the stacking direction. It is possible to reduce the thickness. Specifically, the thickness of the current collector is preferably 1 to 200 μm, more preferably 5 to 150 μm, and still more preferably 10 to 100 μm. By having such a thickness, it is possible to construct a battery having excellent output characteristics and excellent long-term reliability.

  Further, in the current collector, it is preferable that the surface on the surface side on which a protective layer described later has fine irregularities. In addition, “the unevenness of the current collector” in this specification can be measured by the surface roughness Ra defined in JIS B0601 (1994). The surface roughness Ra is preferably 1 to 3000 nm, and more preferably 5 to 1000 nm. Thus, the adhesion between the current collector and the protective layer can be improved by providing fine irregularities on the surface of the current collector.

  There is no restriction | limiting in particular as a method of giving an unevenness | corrugation to a collector. As an example, there is a method in which fine particles such as alumina having an appropriate particle diameter are applied to the surface of the current collector, and a heat press treatment is performed on the particles. As another example, there is a method in which a concavo-convex sheet made of polyethylene terephthalate or the like having appropriate concavo-convex is superimposed on the surface of the current collector, and a heat press treatment is performed on the concavo-convex sheet. In addition, a method such as a wet blast method or a drive last method may be used.

[Positive electrode active material layer]
The positive electrode active material layer includes a positive electrode active material. The positive electrode active material has a composition that occludes ions during discharging and releases ions during charging. A preferable example is a lithium-transition metal composite oxide that is a composite oxide of a transition metal and lithium. Specifically, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Fe-based composite oxides and those obtained by replacing some of these transition metals with other elements can be used. These lithium-transition metal composite oxides are excellent in reactivity and cycle characteristics, and are low-cost materials. Therefore, it is possible to form a battery having excellent output characteristics by using these materials for electrodes. In addition, the positive electrode active material includes transition metal oxides such as LiFePO ₄ and lithium phosphate compounds and sulfuric acid compounds; transition metal oxides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ , and sulfides. Materials; PbO ₂ , AgO, NiOOH, etc. can also be used. The positive electrode active material may be used alone or in the form of a mixture of two or more.

  The average particle diameter of the positive electrode active material is not particularly limited, but is preferably 1 to 100 μm, more preferably 1 to 20 μm, from the viewpoint of increasing the capacity, reactivity, and cycle durability of the positive electrode active material. Within such a range, the secondary battery can suppress an increase in the internal resistance of the battery during charging and discharging under high output conditions, and can extract a sufficient current. When the positive electrode active material is secondary particles, it can be said that the average particle diameter of the primary particles constituting the secondary particles is preferably in the range of 10 nm to 1 μm. It is not limited to. However, it goes without saying that, depending on the manufacturing method, the positive electrode active material may not be a secondary particle formed by aggregation, agglomeration, or the like. As the particle diameter of the positive electrode active material and the particle diameter of the primary particles, a median diameter obtained using a laser diffraction method can be used. The shape of the positive electrode active material varies depending on the type and manufacturing method, and examples thereof include a spherical shape (powdered shape), a plate shape, a needle shape, a column shape, and a square shape, but are not limited thereto. Any shape can be used without any problems. Preferably, an optimal shape that can improve battery characteristics such as charge / discharge characteristics is appropriately selected.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode active material. The negative electrode active material has a composition capable of releasing ions during discharge and storing ions during charging. The negative electrode active material is not particularly limited as long as it can reversibly occlude and release lithium. Examples of the negative electrode active material include metals such as Si and Sn, TiO, Ti ₂ O ₃ , TiO ₂ , or Metal oxides such as SiO ₂ , SiO, SnO ₂ , complex oxides of lithium and transition metals such as Li _4/3 Ti _5/3 O ₄ or Li ₇ MnN, Li—Pb alloys, Li—Al alloys , Li, or carbon materials such as natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, or hard carbon. Moreover, it is preferable that a negative electrode active material contains the element alloyed with lithium. By using an element that forms an alloy with lithium, it is possible to obtain a battery having a high capacity and an excellent output characteristic having a higher energy density than that of a conventional carbon-based material. The negative electrode active material may be used alone or in the form of a mixture of two or more.

  The element alloying with lithium is not limited to the following, but specifically, Si, Ge, Sn, Pb, Al, In, Zn, H, Ca, Sr, Ba, Ru, Rh, Ir, Pd, Pt, Ag, Au, Cd, Hg, Ga, Tl, C, N, Sb, Bi, O, S, Se, Te, Cl, and the like. Among these, from the viewpoint of configuring a battery having excellent capacity and energy density, at least one selected from the group consisting of carbon materials and / or Si, Ge, Sn, Pb, Al, In, and Zn. It is preferable to include an element, and it is particularly preferable to include an element of a carbon material, Si, or Sn. These may be used alone or in combination of two or more.

  Note that the particle diameter and shape of the negative electrode active material are not particularly limited, and can take the same form as the above-described positive electrode active material, and thus detailed description thereof is omitted here.

  The active material layer may contain other materials if necessary. For example, a conductive aid, a binder, and the like can be included. When an ion conductive polymer is included, a polymerization initiator for polymerizing the polymer may be included.

  A conductive support agent means the additive mix | blended in order to improve the electroconductivity of an active material layer. Examples of the conductive aid include carbon powders such as acetylene black, carbon black, ketjen black, and graphite, various carbon fibers such as vapor grown carbon fiber (VGCF; registered trademark), expanded graphite, and the like. However, it goes without saying that the conductive aid is not limited to these.

  Examples of the binder include polyvinylidene fluoride (PVdF), polyimide, PTFE, SBR, and a synthetic rubber binder. However, it goes without saying that the binder is not limited to these. When the binder and the matrix polymer used as the gel electrolyte are the same, it is not necessary to use a binder.

  The compounding ratio of the components contained in the active material layer is not particularly limited. The blending ratio can be adjusted by appropriately referring to known knowledge about the lithium ion secondary battery. The thickness of the active material layer is not particularly limited, and conventionally known knowledge about the lithium ion secondary battery can be appropriately referred to. As an example, the thickness of the active material layer is preferably about 10 to 100 μm, and more preferably 20 to 50 μm. If the active material layer is about 10 μm or more, the battery capacity can be sufficiently secured. On the other hand, if the active material layer is about 100 μm or less, it is possible to suppress the occurrence of the problem of an increase in internal resistance due to the difficulty in diffusing lithium ions in the electrode deep part (current collector side).

  The method for forming the positive electrode active material layer (or the negative electrode active material layer) on the surface of the protective layer or current collector is not particularly limited, and known methods can be used in the same manner. For example, as described above, a positive electrode active material (or a negative electrode active material) and, if necessary, an electrolyte salt for increasing ion conductivity, a conductive auxiliary agent for increasing electron conductivity, and a binder are appropriately used. A positive electrode active material slurry (or a negative electrode active material slurry) is prepared by dispersing and dissolving in a solvent. This is applied onto a current collector, dried to remove the solvent, and then pressed to form a positive electrode active material layer (or negative electrode active material layer) on the current collector. In this case, the solvent is not particularly limited, and N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide, cyclohexane, hexane, water and the like can be used. When adopting polyvinylidene fluoride (PVdF) as a binder, NMP is preferably used as a solvent.

  In the above method, the positive electrode active material slurry (or the negative electrode active material slurry) is applied and dried on the protective layer or the current collector, and then pressed. At this time, the porosity of the positive electrode active material layer (or the negative electrode active material layer) can be controlled by adjusting the pressing conditions.

  Specific means and press conditions for the press treatment are not particularly limited, and can be appropriately adjusted so that the porosity of the positive electrode active material layer (or the negative electrode active material layer) after the press treatment becomes a desired value. Specific examples of the press process include a hot press machine and a calendar roll press machine. Also, the pressing conditions (temperature, pressure, etc.) are not particularly limited, and conventionally known knowledge can be referred to as appropriate.

[Protective layer]
The protective layer is formed between the current collector and the active material layer so as to be in contact with the current collector and the active material layer. The protective layer contains a hydrogen fluoride adsorbent, and further contains additives such as a conductive additive and a binder as necessary.

The hydrogen fluoride adsorbent has a function of adsorbing hydrogen fluoride generated by the decomposition of the supporting salt. The hydrogen fluoride adsorbing material is not particularly limited as long as it is a material having a function of adsorbing hydrogen fluoride, but is preferably a metal oxide porous body having excellent hydrogen fluoride adsorbing ability. Specific materials include aluminum oxide (Al ₂ O ₃ ), boron oxide (B ₂ O ₃ ), gallium oxide (Ga ₂ O ₃ ), indium oxide (In ₂ O ₃ ), and magnesium oxide (MgO). Is mentioned. Of these, aluminum oxide is most preferable. Further, BET specific surface area of the hydrogen fluoride adsorbent, from the viewpoint of adsorption ability of the hydrogen fluoride, it is preferably 0.9 m ² / g or more, more preferably 1,3m ² / g or more.

  The average particle diameter of the hydrogen fluoride adsorbent is preferably 0.01 to 100 μm, and more preferably 0.1 to 20 μm. When the average particle diameter or content of the hydrogen fluoride adsorbent is in such a range, the contact resistance between the current collector or active material layer and the protective layer can be suppressed, and the adsorption ability of hydrogen fluoride can be reduced. It can be improved.

  The content of the hydrogen fluoride adsorbent contained in the protective layer is preferably 20 to 95% by mass and more preferably 50 to 90% by mass with respect to the total mass of the components contained in the protective layer. .

The form of the protective layer is that a protective layer containing a hydrogen fluoride adsorbent is interposed between the current collector and the positive electrode active material layer, or between the current collector and the negative electrode active material layer. If it is a form, there will be no restriction | limiting in particular, The following various forms can be taken. The protective layer is preferably formed in a wider area, as can be seen from the function of preventing the active material layer from peeling off from the current collector. Specifically, it is preferably 10 to 150 area%, more preferably 50 to 120 area%, and 70 to 110 area% with respect to the area of one surface in the surface direction of the active material layer. More preferably, it is most preferably 100 area%.

  Examples of the coating form of the protective layer are shown in FIGS. According to FIG. 2, a protective layer 33 is formed on the peripheral edge of the positive electrode active material layer 13 between the current collector 11 and the positive electrode active material layer 13. That is, the peripheral edge portion of the positive electrode active material layer 13 is bonded to the current collector 11 via the protective layer 33. The central portion of the positive electrode active material layer 13 is directly bonded to the current collector 11. When the current collector 11 and the positive electrode active material layer 13 are bonded to each other, the peripheral portion of the positive electrode active material layer 13 is particularly easily peeled off. Therefore, the protective layer 33 is formed only on the peripheral portion of the positive electrode active material layer 13. Is also effective. FIG. 3 shows an example of a pattern in which a protective layer is formed in a portion where the current collector and the active material layer can be bonded. FIG. 3A shows a form in which a protective layer is formed on the entire surface where the current collector and the active material layer can be bonded as shown in FIG. FIG. 3B is a form in which a protective layer is formed on the peripheral edge of the surface where the current collector and the active material layer can be bonded as shown in FIG. In addition, it may be formed by patterning as shown in FIG. 3C or 3D.

  The thickness of the protective layer is preferably 0.1 to 50 μm, and more preferably 1 to 30 μm. When it is 0.1 μm or more, the hydrogen fluoride adsorption ability can be improved. On the other hand, when it is 50 μm or less, the resistance of the protective layer can be kept low.

  In the bipolar electrode of this embodiment, the protective layer may be formed only on the surface where the positive electrode active material layer of the current collector is formed, or may be formed only on the surface where the negative electrode active material layer is formed. Of course, it may be formed on both surfaces. In particular, the surface of the current collector that is in contact with the positive electrode active material layer is susceptible to electric potential, so that oxidation by hydrogen fluoride occurs easily. Therefore, the deterioration of the current collector can be effectively prevented by forming the protective layer on the surface on which the positive electrode active material layer is formed. In addition, since fluorine and silicon have a high affinity, the silicon-based negative electrode material easily reacts with hydrogen fluoride and degrades the negative electrode active material layer. Moreover, since the volume of the silicon-based negative electrode material changes to about 6 times due to occlusion / release of lithium ions, the silicon-based negative electrode material has a feature of being easily peeled off from the current collector. Therefore, when the negative electrode active material includes a silicon-based negative electrode material containing silicon, it is also preferable to form a protective layer on the surface on the side where the negative electrode active material layer is formed.

  In addition to the hydrogen fluoride adsorbent, the protective layer may contain other additives such as a conductive additive or a binder as necessary. As the conductive auxiliary agent or binder, the same ones as those added to the above active material layer can be used. The conductivity of the protective layer can be increased by adding a conductive aid. Further, by including a binder, the binding property between the current collector and the protective layer and between the protective layer and the active material layer can be improved. It is preferable that content of the conductive support agent contained in a protective layer is 3-40 mass% with respect to the total mass of the component contained in a protective layer. Sufficient conductivity can be secured when the content of the conductive auxiliary is 3% by mass or more. On the other hand, when the content of the conductive assistant is 40% by mass or less, an increase in irreversible reaction with lithium ions can be prevented. Moreover, it is preferable that content of the binder contained in a protective layer is 2-50 mass%. When the binder content is 2% by mass or more, a sufficient binding force can be secured. On the other hand, when the binder content is 50% by mass or less, an increase in internal resistance can be prevented.

  In the bipolar electrode of this embodiment, the method for forming the protective layer is not particularly limited, and a conventionally known technique can be appropriately employed. For example, first, a slurry containing a hydrogen fluoride adsorbent and, if necessary, a conductive additive or a binder is prepared. As the solvent used in this case, a solvent used when forming the above-described active material layer can be used without limitation. Then, the slurry is applied to the surface of the current collector. The coating method is not particularly limited, and a screen printing method, an inkjet method, or the like can be appropriately employed. Thereafter, the protective layer is formed by drying the solvent contained in the applied slurry. Further, an active material layer is formed on the protective layer, and the method for forming the active material layer is as described above.

<Bipolar type secondary battery>
FIG. 4 is a cross-sectional view schematically showing the overall structure of a bipolar secondary battery which is an embodiment of the present invention. The bipolar secondary battery 10 of this embodiment shown in FIG. 4 has a structure in which a substantially rectangular power generation element 21 in which a charge / discharge reaction actually proceeds is sealed inside a laminate film 29 that is a battery exterior material. .

  As shown in FIG. 4, the power generation element 21 of the bipolar secondary battery 10 according to the present embodiment includes a positive electrode active material layer 13 that is electrically coupled to one surface of the current collector 11. And a plurality of bipolar electrodes 23 having a negative electrode active material layer 15 electrically coupled to the opposite surface. Each bipolar electrode 23 is laminated via the electrolyte layer 17 to form the power generation element 21. The electrolyte layer 17 has a configuration in which an electrolyte is held at the center in the surface direction of a separator as a base material. At this time, the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23 face each other through the electrolyte layer 17. The bipolar electrodes 23 and the electrolyte layers 17 are alternately stacked. That is, the electrolyte layer 17 is interposed between the positive electrode active material layer 13 of one bipolar electrode 23 and the negative electrode active material layer 15 of another bipolar electrode 23 adjacent to the one bipolar electrode 23. ing.

  The adjacent positive electrode active material layer 13, electrolyte layer 17, and negative electrode active material layer 15 constitute one unit cell layer 19. Therefore, it can be said that the bipolar secondary battery 10 has a configuration in which the single battery layers 19 are stacked. Further, for the purpose of preventing liquid junction due to leakage of the electrolytic solution from the electrolyte layer 17, a seal portion (insulating layer) 31 is disposed on the outer peripheral portion of the unit cell layer 19. A positive electrode active material layer 13 is formed only on one side of the positive electrode outermost layer current collector 11 a located in the outermost layer of the power generation element 21. The negative electrode active material layer 15 is formed only on one surface of the outermost current collector 11b on the negative electrode side located in the outermost layer of the power generation element 21. However, the positive electrode active material layer 13 may be formed on both surfaces of the outermost layer current collector 11a on the positive electrode side. Similarly, the negative electrode active material layer 15 may be formed on both surfaces of the outermost layer current collector 11b on the negative electrode side.

  Furthermore, in the bipolar secondary battery 10 shown in FIG. 4, the positive electrode current collector plate 25 is disposed so as to be adjacent to the outermost layer current collector 11a on the positive electrode side, and this is extended from the laminate film 29 that is a battery outer packaging material. Derived. On the other hand, the negative electrode current collector plate 27 is disposed so as to be adjacent to the outermost layer current collector 11b on the negative electrode side, and similarly, this is extended and led out from the laminate film 29 which is an exterior of the battery.

  In the bipolar secondary battery 10 shown in FIG. 4, a seal portion 31 is usually provided around each single cell layer 19. The purpose of the seal portion 31 is to prevent the adjacent current collectors 11 in the battery from coming into contact with each other and a short circuit caused by a slight irregularity at the end of the unit cell layer 19 in the power generation element 21. Is provided. By installing such a seal portion 31, long-term reliability and safety are ensured, and a high-quality bipolar secondary battery 10 can be provided.

  Note that the number of stacks of the unit cell layers 19 is adjusted according to a desired voltage. Further, in the bipolar secondary battery 10, the number of stacking of the single battery layers 19 may be reduced if a sufficient output can be secured even if the thickness of the battery is made as thin as possible. Even in the bipolar secondary battery 10, in order to prevent external impact and environmental degradation during use, the power generation element 21 is sealed under reduced pressure in a laminate film 29 that is a battery exterior material, and the positive electrode current collector plate 25 and the negative electrode current collector 25. A structure in which the electric plate 27 is taken out of the laminate film 29 is preferable. Hereinafter, main components of the bipolar secondary battery of this embodiment will be described.

[Electrolyte layer]
There is no restriction | limiting in particular in the electrolyte which comprises an electrolyte layer, Polymer electrolytes, such as a liquid electrolyte and a polymer gel electrolyte and a polymer solid electrolyte, can be used suitably.

  The liquid electrolyte is obtained by dissolving a lithium salt as a supporting salt in a solvent. Examples of the solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propionate (MP), methyl acetate (MA), and methyl formate (MF). 4-methyldioxolane (4MeDOL), dioxolane (DOL), 2-methyltetrahydrofuran (2MeTHF), tetrahydrofuran (THF), dimethoxyethane (DME), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) , And γ-butyrolactone (GBL). These solvents may be used alone or as a mixture of two or more.

As the supporting salt (lithium salt) is not particularly _{limited, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiSbF 6, LiAlCl 4, Li 2 B 10 Cl 10, LiI, LiBr, LiCl Inorganic acid anion salts such as LiAlCl, LiHF ₂ , LiSCN, LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, LiBOB (lithium bisoxide borate), LiBETI (lithium bis (perfluoroethylenesulfonylimide); And organic acid anion salts such as Li (C ₂ F ₅ SO ₂ ) ₂ N). Among them, a fluorine-containing supporting _{salt, LiPF 6, LiBF 4, LiAsF} 6, LiTaF 6, LiSbF 6, and preferably contains LiHF _2, and most preferably LiPF _6. These electrolyte salts may be used alone or in the form of a mixture of two or more.

  On the other hand, the polymer electrolyte is classified into a gel electrolyte containing an electrolytic solution and a polymer solid electrolyte containing no electrolytic solution. The gel electrolyte has a configuration in which the above liquid electrolyte is injected into a matrix polymer having lithium ion conductivity. Examples of the matrix polymer having lithium ion conductivity include a polymer having polyethylene oxide in the main chain or side chain (PEO), a polymer having polypropylene oxide in the main chain or side chain (PPO), polyethylene glycol (PEG), poly Acrylonitrile (PAN), polymethacrylic acid ester, polyvinylidene fluoride (PVdF), copolymer of polyvinylidene fluoride and hexafluoropropylene (PVdF-HFP), polyacrylonitrile (PAN), poly (methyl acrylate) (PMA), poly (Methyl methacrylate) (PMMA) etc. are mentioned. In addition, mixtures of the above-described polymers, modified products, derivatives, random copolymers, alternating copolymers, graft copolymers, block copolymers, and the like can also be used. Among these, it is desirable to use PEO, PPO and their copolymers, PVdF, PVdF-HFP. In such a matrix polymer, an electrolyte salt such as a lithium salt can be well dissolved.

  In addition, when an electrolyte layer is comprised from a liquid electrolyte or a gel electrolyte, you may use a separator for an electrolyte layer. Specific examples of the separator include a microporous film made of a polyolefin such as polyethylene or polypropylene, a hydrocarbon such as polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP), glass fiber, or the like.

  The polymer solid electrolyte has a structure in which a supporting salt (lithium salt) is dissolved in the matrix polymer, and does not include an organic solvent that is a plasticizer. Therefore, when the electrolyte layer is composed of a polymer solid electrolyte, there is no fear of liquid leakage from the battery, and the battery reliability can be improved.

  A matrix polymer of a polymer gel electrolyte or a polymer solid electrolyte can exhibit excellent mechanical strength by forming a crosslinked structure. In order to form a crosslinked structure, thermal polymerization, ultraviolet polymerization, radiation polymerization, electron beam polymerization, etc. are performed on a polymerizable polymer (for example, PEO or PPO) for forming a polymer electrolyte, using an appropriate polymerization initiator. A polymerization treatment may be performed. In addition, the said electrolyte may be contained in the active material layer of an electrode.

[Seal part]
The seal portion (insulating layer) has a function of preventing contact between current collectors and a short circuit at the end of the single cell layer. As a material constituting the seal portion, any material having insulating properties, sealability against falling off of solid electrolyte, sealability against moisture permeation from the outside (sealing property), heat resistance under battery operating temperature, etc. Good. For example, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin, rubber and the like can be used. Of these, polyethylene resin and polypropylene resin are preferably used as the constituent material of the insulating layer from the viewpoints of corrosion resistance, chemical resistance, ease of production (film forming property), economy, and the like.

[Battery exterior materials]
As the battery exterior material, a conventionally known metal can case can be used, and a bag-like case using a laminate film containing aluminum that can cover the power generation element can be used. For example, a laminate film having a three-layer structure in which polypropylene, aluminum, and nylon are laminated in this order can be used as the laminate film, but the laminate film is not limited thereto. In this embodiment, a laminate film that is excellent in high output and cooling performance and can be suitably used for a battery for large equipment such as for EV and HEV is desirable.

<Battery assembly>
An assembled battery can be obtained by electrically connecting a plurality of bipolar secondary batteries of this embodiment in series or in parallel. Thus, it becomes possible to adjust a capacity | capacitance and a voltage freely by parallelizing a some battery in series or in parallel.

  FIG. 5 is an external view of a typical embodiment of the assembled battery according to the present invention, FIG. 5A is a plan view of the assembled battery, FIG. 5B is a front view of the assembled battery, and FIG. 6C is an assembled battery. FIG.

  As shown in FIG. 5, the assembled battery 300 according to this embodiment forms a small assembled battery 250 that can be attached and detached by connecting a plurality of bipolar secondary batteries of this embodiment in series or in parallel. A large capacity and large output suitable for a vehicle driving power source and an auxiliary power source that require a high volume energy density and a high volume output density by connecting a plurality of these detachable small assembled batteries 250 in series or in parallel. It is also possible to form an assembled battery 300 having 5A is a plan view of the assembled battery, FIG. 5A is a front view, and FIG. 5C is a side view. The small assembled battery 250 that can be attached and detached is provided with an electrical connection means such as a bus bar. The assembled battery 250 is stacked in a plurality of stages using the connection jig 310. How many bipolar secondary batteries are connected to produce the assembled battery 250, and how many assembled batteries 250 are laminated to produce the assembled battery 300 depends on the vehicle (electric vehicle) to be mounted. It may be determined according to the battery capacity and output.

<Vehicle>
The vehicle according to the present embodiment is characterized by mounting the lithium ion battery according to the present embodiment or a combination battery formed by combining a plurality of these. In this embodiment, since a battery having a long life and excellent long-term reliability and output characteristics can be configured, it is possible to configure a plug-in hybrid electric vehicle having a long EV travel distance and an electric vehicle having a long charge travel distance when such a battery is mounted. . In other words, the lithium ion battery of this embodiment or an assembled battery formed by combining a plurality of these batteries can be used as a power source for driving the vehicle. The lithium ion battery of the present embodiment or a combination battery formed by combining a plurality of these is a vehicle, for example, a hybrid vehicle, a fuel cell vehicle, an electric vehicle (for automobiles, all four-wheel vehicles (passenger cars, trucks, buses and other commercial vehicles, This is because it can be used for motorcycles (including motorcycles) and tricycles (in addition to mini vehicles, etc.)) to provide a long-life and highly reliable vehicle. However, the application is not limited to automobiles. For example, it can be applied to various power sources for moving vehicles such as other vehicles, for example, trains, and power sources for mounting such as uninterruptible power supplies. It is also possible to use as.

  FIG. 6 is a conceptual diagram of a vehicle equipped with the assembled battery of this embodiment. As shown in FIG. 6, in order to mount the assembled battery 300 on a vehicle such as the electric vehicle 400, the battery pack 300 is mounted under the seat at the center of the vehicle body of the electric vehicle 400. This is because if it is installed under the seat, the interior space and the trunk room can be widened. The place where the assembled battery 300 is mounted is not limited to the position under the seat, but may be a lower part of the rear trunk room or an engine room in front of the vehicle. The electric vehicle 400 using the assembled battery 300 as described above has high durability and can provide sufficient output even when used for a long period of time. Furthermore, it is possible to provide electric vehicles and hybrid vehicles that are excellent in fuel efficiency and running performance. A vehicle equipped with the assembled battery of this embodiment can be widely applied to a hybrid vehicle, a fuel cell vehicle and the like in addition to an electric vehicle as shown in FIG.

  The effect of this invention is demonstrated using a following example and a comparative example. However, the technical scope of the present invention is not limited only to the following examples.

[Example 1]
<Production of bipolar secondary battery>
(Current collector)
A sheet having a thickness of 30 μm was prepared by adding 10 wt% of ketjen black (manufactured by Lion Corporation, EC600JD) as a conductive additive to polypropylene (PP).

(Surface roughening)
The surface of the current collector was roughened by pressing a polyethylene terephthalate (PET) film having irregularities of 3 μm against both surfaces of the current collector, performing a heated roll press, and cooling. Thereby, unevenness | corrugation of 500 nm (surface roughness RaJIS B0601 (1994)) was formed in the collector surface.

(Protective layer)
85% by mass of aluminum oxide (average particle size: 1.0 μm) as a hydrogen fluoride adsorbent, 5% by mass of acetylene black as a conductive additive, 10% by mass of polyvinylidene fluoride (PVDF) as a binder, N as a slurry viscosity adjusting solvent -Methyl-2-pyrrolidone (NMP) was mixed to prepare an absorption layer slurry. The slurry was applied to one surface of the current collector (surface on the side where the positive electrode active material layer is formed) and dried to form a protective layer having a thickness of 5 μm.

(Positive electrode active material layer)
A positive electrode active material slurry was prepared by mixing 85% by mass of LiMn ₂ O ₄ as a positive electrode active material, 5% by mass of acetylene black as a conductive additive, 10% by mass of PVDF as a binder, and an appropriate amount of NMP as a slurry viscosity modifier. . The slurry was applied to the surface of the current collector on which the protective layer was formed and dried to form a positive electrode active material layer having a thickness of 98 μm.

(Negative electrode active material layer)
The negative electrode active material slurry was prepared by mixing 85% by mass of artificial graphite as the negative electrode active material, 5% by mass of acetylene black as the conductive additive, 10% by mass of PVDF as the binder, and NMP as the slurry viscosity modifier. The slurry was applied to the other surface of the current collector where the positive electrode active material layer was not formed, and dried to form a negative electrode active material layer having a thickness of 46 μm.

  The obtained positive electrode active material layer / current collector / negative electrode active material layer laminate was subjected to a heat roll press treatment, and the heat press was performed to such an extent that the electrode did not break through the film.

  The obtained electrode is cut into 140 mm × 90 mm, and a peripheral part of the electrode 10 mm is prepared with a portion not previously coated with an electrode, whereby a 120 × 70 mm electrode part and a 10 mm seal on the peripheral part are prepared. A bipolar electrode having the following structure was prepared.

  A sealing sheet (PP) was disposed at the sealing margin of the obtained electrode. And from this, the separator was disposed so as to cover all the current collectors on the positive electrode side. Thereafter, a sealing sheet was disposed on a portion where the electrode was not applied (a portion corresponding to a portion where the sealing sheet was installed).

(Electrolyte layer)
An electrolytic solution was prepared by dissolving LiPF ₆ as a supporting salt at a concentration of 1M in a 1: 1 mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC). 10% by mass of PVDF-HFP containing 10% of hexafluoropropylene (HFP) copolymer as a host polymer was added to 90% by mass of the electrolytic solution and mixed. An appropriate amount of dimethyl carbonate (DMC) was mixed as a viscosity adjusting solvent to prepare an electrolyte.

  The electrolyte was applied to the positive electrode active material layer and the negative electrode active material layer, and DMC was dried, thereby completing a bipolar electrode infiltrated with the gel electrolyte.

  Three layers of the obtained bipolar electrode were laminated, and the outer peripheral portion of the single cell layer was sealed by hot pressing the seal portion from above and below. The obtained laminate was sandwiched between aluminum tabs for current extraction (130 mm × 80 mm, thickness 100 μm), and vacuum sealed using an aluminum laminate film as an exterior material.

[Example 2]
A bipolar electrode was produced in the same manner as in Example 1 except that the thickness of the protective layer was 10 μm.

[Example 3]
A bipolar electrode was produced in the same manner as in Example 1 except that the thickness of the protective layer was 20 μm.

[Example 4]
A bipolar electrode was produced in the same manner as in Example 1 except that the surface roughening treatment was not performed. In addition, the unevenness | corrugation of the collector surface which does not perform a surface roughening process was 10 nm.

[Example 5]
A bipolar electrode was produced in the same manner as in Example 4 except that the thickness of the protective layer was 10 μm. In addition, the unevenness | corrugation of the collector surface which does not perform a surface roughening process was 10 nm.

[Example 6]
A bipolar electrode was produced in the same manner as in Example 4 except that the thickness of the protective layer was 20 μm. In addition, the unevenness | corrugation of the collector surface which does not perform a surface roughening process was 10 nm.

[Example 7]
A bipolar secondary battery was produced in the same manner as in Example 1 except that the average particle diameter of aluminum oxide used for the protective layer was 3.0 μm.

[Example 8]
A bipolar secondary battery was fabricated in the same manner as in Example 7 except that the thickness of the protective layer was 10 μm.

[Example 9]
A bipolar secondary battery was fabricated in the same manner as in Example 7 except that the thickness of the protective layer was 20 μm.

[Comparative Example 1]
A bipolar secondary battery was fabricated in the same manner as in Example 1 except that the protective layer was not formed and the surface roughening treatment was not performed.

[Comparative Example 2]
A bipolar secondary battery was fabricated in the same manner as in Example 1 except that the protective layer was not formed.

<Calculation of initial resistance value>
Each bipolar secondary battery fabricated as described above was charged to 4.2 V at a current value of 1 CA for 2 hours in an atmosphere of 25 ° C., and then charged for 30 minutes at a current value of 1 CA, and the state of charge : SOC) was adjusted to 50%. Then, the battery was discharged at a current value of 3CA for 20 seconds, and the DC resistance value was calculated from the voltage drop amount ΔV. Table 1 shows the relative values of Examples and Comparative Examples when the DC resistance value of Comparative Example 1 is 1.00.

<Calculation of resistance value after storage at 55 ° C>
Each bipolar secondary battery was stored at 55 ° C. for 2 weeks, and then the direct current value was calculated in the same manner as described above. Table 1 shows the relative values of Examples and Comparative Examples when the DC resistance value of Comparative Example 1 after storage at 55 ° C. is 1.00. The results are shown in Table 1.

According to Table 1, in Examples 1 to 9, the rate of increase in resistance value after storage at 55 ° C. with respect to the initial current value was significantly lower than in Comparative Examples 1 and 2. This was considered to be due to the fact that the protective layer adsorbed hydrogen fluoride generated by the decomposition of LiPF ₆ to suppress the deterioration of the current collector on the surface in contact with the positive electrode active material layer.

  Further, as the average particle of aluminum oxide becomes smaller, the HF absorption ability is improved, that is, the increase in battery resistance is suppressed, and as the thickness of the protective layer becomes thinner, the initial resistance value and the rate of increase in resistance value tend to be suppressed. I understood that. In Examples 1 to 3, in which the surface of the current collector is uneven, the initial resistance value is reduced by increasing the adhesion between the current collector and the protective layer, and the protective layer and the positive electrode active material layer. It was.

10 Bipolar secondary battery,
11 Current collector,
11a The outermost layer current collector on the positive electrode side,
11b The outermost layer current collector on the negative electrode side,
13 positive electrode active material layer,
15 negative electrode active material layer,
17 electrolyte layer,
19 cell layer,
21 power generation elements,
23 Bipolar electrode,
25 positive current collector,
27 negative current collector,
29 Laminated film,
31 seal part,
33 protective layer,
250 small battery pack,
300 battery packs,
310 connection jig,
400 vehicles.

Claims (12)

A current collector comprising a conductive resin layer;
A positive electrode active material layer formed on one surface of the current collector;
A bipolar electrode including a negative electrode active material layer formed on the other surface of the current collector,
A bipolar electrode in which a protective layer containing a hydrogen fluoride adsorbent is interposed between the current collector and the positive electrode active material layer or between the current collector and the negative electrode active material layer.   The bipolar electrode according to claim 1, wherein the protective layer is formed between the current collector and the positive electrode active material layer. The protective layer is formed between the current collector and the negative electrode active material layer,
The bipolar electrode according to claim 1, wherein the negative electrode active material layer includes a silicon-based negative electrode material.   The bipolar electrode according to any one of claims 1 to 3, wherein a surface of the current collector on which the protective layer is formed has irregularities.   The bipolar electrode according to claim 1, wherein the hydrogen fluoride adsorbent contains aluminum oxide.   The bipolar electrode according to claim 1, wherein the protective layer is formed between the current collector and a peripheral portion of the positive electrode active material layer or the negative electrode active material layer. . The bipolar electrode according to any one of claims 1 to 6,
A bipolar secondary battery having a power generation element formed by laminating an electrolyte layer containing a supporting salt and a solvent.   The bipolar secondary battery according to claim 7, wherein the supporting salt is a fluorine-containing supporting salt. The bipolar secondary battery according to claim 8, wherein the supporting salt is LiPF ₆ .   An assembled battery comprising a plurality of the bipolar secondary batteries according to claim 7 electrically connected.   A vehicle on which the bipolar secondary battery according to claim 7 or the assembled battery according to claim 10 is mounted as a power source for driving a motor. Preparing a slurry containing a hydrogen fluoride adsorbent;
Applying the slurry to one surface of a current collector including a conductive resin layer, and forming a protective layer;
Forming either the positive electrode active material layer or the negative electrode active material layer on the surface of the protective layer;
Forming a remaining one of the positive electrode active material layer or the negative electrode active material layer on the other surface of the current collector.

Images