JP2004164897A - Bipolar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bipolar battery made by using a novel collector excellent in corrosion resistance at a positive electrode side and not alloying with lithium at a negative electrode side, with its thickness appropriate in comparison with an electrode layer and an electrolyte layer. <P>SOLUTION: Of the bipolar battery 1 having a structure of laminating electrode lamination bodies formed by laminating a positive electrode layer 5 on one face of a sheet of polymer electrolyte film 3 and a negative electrode layer 7 on the other face through an electron conductive layer, the electron conductive layer 11 contains mainly an insulating polymer and an electron conductive filler. <P>COPYRIGHT: (C)2004,JPO

Description

【図面の簡単な説明】
【図１】本発明に係るバイポーラ電池の第一の実施形態を模式的に表わした部分断面概略図を示す。
【図２】本発明に係るバイポーラ電池の第二の代表的な一実施形態を模式的に表わした部分断面概略図を示す。
【図３】従来の集電体を用いたバイポーラ電池であって、比較例１で作製したバイポーラ電池を模式的に表わした部分断面概略図を示す。
【符号の説明】
１、２１、４１…バイポーラ電池、
３、２３、４３…高分子電解質膜（高分子電解質層）、
５、２５、４５…正極層、
７、２７、４７…負極層、
９、２９、４９…単電池層、
９’、２９’、４９’…バイポーラ電極、
１１、３１…電子伝導性層、
３１ａ…金属層、
３１ｂ…電子伝導性を有する層、
５１…集電箔、
５１ａ…第一集電箔、
５１ｂ…第二集電箔。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bipolar battery in which a positive electrode layer and a negative electrode layer are arranged on both sides of a current collector.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries capable of achieving high energy density and high output density have been developed as large-capacity power supplies for electric vehicles and the like. The basic structure of a lithium ion secondary battery is a positive electrode in which a positive electrode active material such as lithium cobalt oxide and a conductive additive such as acetylene black are applied to an aluminum current collector using a binder, and carbon fine particles are used as a binder for the copper current collector. The negative electrode applied by using is placed via a polyolefin-based porous membrane separator, and LiPF ₆ And the like. When applied to an electric vehicle or the like, unit cells (cells) having this configuration are connected in series, a battery module unit, and modules are connected in series to form an assembled battery.
[0003]
From the viewpoint of the energy density and the output density of the battery, it is desired to improve the connection resistance, space, and weight of the connection between cells and between modules. Recently, there has been proposed a battery employing a bipolar electrode unit that can reduce the resistance of the connection between cells and can be expected to be compact (for example, see Patent Document 1). In this proposal, the collector is made of two kinds of metal foils, ie, a clad material is used, so to speak, a gel electrolyte is used as the electrolyte. Therefore, a hermetic seal in each cell unit is indispensable. Entanglement may occur. If a solid polymer electrolyte is used instead of the gel electrolyte, a hermetic seal is not required, and a realistic bipolar battery can be constructed (for example, see Patent Documents 2 and 3). A bipolar battery, which is an all-solid-state polymer battery formed using a polymer electrolyte as such an electrolyte, has the advantage that there is no liquid leakage or gas generation because it does not contain an electrolytic solution, and the reliability is extremely high. I have. (For example, see Patent Documents 2 and 3.)
[0004]
[Patent Document 1]
JP-A-11-204136
[Patent Document 2]
JP 2000-100471 A
[Patent Document 3]
JP-A-2002-75455
[0005]
[Problems to be solved by the invention]
However, conventional bipolar batteries use a metal foil or a laminate thereof for the current collector layer. Had been. In addition, a positive electrode layer is disposed on one side of a current collector foil having a thickness of about several tens of μm, and a negative electrode layer is disposed on the other side, and this is a structure in which this is laminated via a polymer electrolyte layer. In comparison, the thickness of the current collector foil is increased, and the energy density and output density of the battery are reduced.
[0006]
Therefore, an object of the present invention is to provide a novel current collector having excellent corrosion resistance on the positive electrode side and not causing alloying with lithium at the negative electrode, and having a greater thickness than the electrode layer and the electrolyte layer. It is an object of the present invention to provide a bipolar battery using a current collector that is appropriate.
[0007]
[Means for Solving the Problems]
The present invention has a structure in which an electrode laminate having a positive electrode layer on one surface of one polymer electrolyte membrane and a negative electrode layer on the other surface is laminated via an electron conductive layer. In the bipolar battery, the electron conductive layer mainly includes an insulating polymer and an electron conductive filler.
[0008]
【The invention's effect】
In the bipolar battery of the present invention, a non-metallic foil (such as an insulating polymer and carbon black) can be used for the electron conductive layer as the current collector, and it has excellent corrosion resistance on the positive electrode side and lithium on the negative electrode. Alloying does not occur, and the electron conductive layer can be made thinner than in the case of using a metal foil of several tens of μm (usually about 35 μm) by an ordinary method. The thickness can be set to an appropriate range (about 1 to 20 μm) for the layer (film), and the energy density and the output density of the battery can be increased. Therefore, it is a useful power source in various industries.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0010]
The first embodiment of the bipolar battery according to the present invention has an electrode laminate having a positive electrode layer on one surface of one polymer electrolyte membrane and a negative electrode layer on the other surface, and an electron conductive layer. In a bipolar battery having a structure laminated through layers of
The electron conductive layer mainly comprises an insulating polymer and an electron conductive filler.
[0011]
The electron conductive layer is usually referred to as a current collector (a cell spacing wall and an electron conductor in a bipolar battery), and a metal foil having high electronic conductivity is used. Since it flows vertically, not so high electron conductivity is necessarily required. Conventionally, as a method for manufacturing an electrode, a slurry of an electrode material is applied to a metal foil and dried and solidified (in some cases, polymerized). Therefore, the metal foil to be used needs to have a certain level of strength. For these reasons, a thickness of about 15 to 20 μm is necessary depending on the material. Therefore, in the first embodiment of the present invention, a structure using a thin film in which an insulating polymer is newly filled with an electron conductive filler is used as the electron conductive layer, taking advantage of the feature of a bipolar battery. It is.
[0012]
In the first embodiment of the bipolar battery according to the present invention, a thin film in which an insulating polymer is filled with an electron conductive filler as an electron conductive layer is based on the finding that not so high electron conductivity is necessarily required. This is advantageous in that it can be easily formed into a slurry and a raw material that can be easily formed into a thin film of about several μm can be selected. That is, a material other than metal can be used for the electron conductive layer as the current collector. In particular, the electron conductive layer using carbon as the electron conductive filler can be used as the electron conductive layer (thin layer). In addition to the above, the electron conductive layer can be formed by directly applying the raw material slurry for the electron conductive layer, whereby a bipolar battery having a high energy density and a high output density can be formed. Further, as compared with metal foil, it is advantageous in that a material having no problem of corrosion resistance on the positive electrode side and no problem of alloying with lithium on the negative electrode can be selected. In addition, since it is possible to select a material from which the raw material can be easily slurried, structurally, instead of applying an electrode raw material slurry to both surfaces of a current collector having a certain strength to form an electrode, for example, An electrode material slurry is applied to both surfaces of a polymer electrolyte layer having a certain strength to form electrodes, and a material slurry for an electron conductive layer is applied to the electrodes formed on both surfaces of the polymer electrolyte layer and dried. This is advantageous in that the electron conductive layer can be formed by solidification or the like. That is, since it is sufficient to form the electron conductive layer on the electrode, contrary to the conventional method, the electron conductive layer does not require any strength required in the conventional manufacturing process, and can be easily thinned. This is also very advantageous in point.
[0013]
In the first embodiment of the bipolar battery according to the present invention, the thickness of the electron conductive layer is preferably 1 to 20 μm, more preferably 5 to 20 μm, from the viewpoint of reducing the thickness and increasing the energy density and output density of the battery. It is desirable that the thickness be in the range of 10 μm. If the thickness of the electron conductive layer is less than 1 μm, there is a possibility of an ionic short circuit, and if it exceeds 20 μm, the merit in terms of energy density is small.
[0014]
The electron conductive layer that can be used in the first embodiment of the bipolar battery according to the present invention, the electron conductive resistance is not large in the plane direction in a state where the electron conductive filler is dispersed in the insulating polymer. If the ion conduction resistance is very large, it is sufficient.
[0015]
Among them, the electron conductive filler is not particularly limited and may be appropriately selected from conventionally known ones, and may be carbon black, metal fine particles, conductive ceramics, or the like. . Among them, carbon black is preferable in that various surface modifications can be made from the dispersibility of the electron conductive layer in the insulating polymer. By using carbon black as the electron conductive filler of the electron conductive layer, the object (higher energy density and higher output density) can be achieved more easily and at low cost.
[0016]
The size of the electron conductive filler is preferably less than 0.5 μm from the viewpoint of dispersibility and the like. If it exceeds 0.5 μm, it becomes difficult to form a thin film. The size referred to here is the average value of the particle size (size) of the (basic) particles of the electron conductive filler.
[0017]
The insulating polymer is not particularly limited, and may be, for example, a polymer which can be appropriately selected from conventionally known polymers shown below.
[0018]
(1) A thermoplastic insulating polymer can be used. As such a thermoplastic insulating polymer, for example, polyethylene, polypropylene, polystyrene and the like can be suitably used.
[0019]
As a method for producing an electron conductive layer using the thermoplastic insulating polymer, for example, an electron conductive filler is kneaded and dispersed in a molten insulating polymer, and the thin film is formed by extrusion molding. Examples include a method of forming a conductive layer, but the method is not limited thereto.
[0020]
(2) Those in which the insulating polymer and the electron conductive filler can be dispersed in a solvent can also be used. The solvent-dispersible insulating polymer does not affect the battery performance and may be any one as long as it can be dispersed in a solvent. As the solvent-dispersible insulating polymer, for example, neoprene / toluene and various fluoroelastomers / methylethylketone can be used.
[0021]
As a method of producing an electron conductive layer using the solvent-dispersible insulating polymer, for example, a raw material slurry for an electron conductive layer obtained by dispersing the insulating polymer and an electron conductive filler in a solvent The raw material slurry for the electron conductive layer is prepared, for example, by direct spray coating on the electrodes formed on both sides of the electrolyte layer having a certain strength, for example, by coating with a doctor blade to form a thin film of the electron conductive layer. Film can be formed.
[0022]
Further, the raw material slurry for an electron conductive layer is applied to a glass plate or a PET film, a solvent is dried to form a thin film, the thin film is attached to an electrode, and then the glass plate or the PET film is peeled off. Alternatively, a thin film of an electron conductive layer can be formed.
[0023]
Here, in any of the production methods (1) and (2), the content of the electron conductive filler such as carbon black in the obtained electron conductive layer is preferably 5 to 50% by mass, more preferably. It is desirable to adjust the compounding amount of the electron conductive filler in the raw material so as to be in the range of 10 to 30% by mass. When the content of the electron conductive filler is less than 5% by mass, the resistance increases, and when it exceeds 50% by mass, it becomes difficult to form a uniform thin film.
[0024]
Hereinafter, a first representative embodiment of a bipolar battery according to the present invention will be briefly described with reference to the drawings. However, it goes without saying that the present invention should not be limited to such an embodiment.
[0025]
FIG. 1 is a schematic partial cross-sectional view schematically showing a first embodiment of a bipolar battery according to the present invention. As shown in FIG. 1, the bipolar battery 1 of the present invention has a positive electrode layer 5 on one surface of one polymer electrolyte membrane (polymer electrolyte layer 3) and a negative electrode layer 7 on the other surface. , Having a structure in which a plurality of electrode laminates 9 having the following structure are laminated via an electron conductive layer 11, wherein the electron conductive layer 11 mainly contains an insulating polymer and an electron conductive filler. Is what you do. In other words, the bipolar electrode 9 'having a structure in which the positive electrode layer 5 is disposed on one surface of the electron conductive layer 11 serving as a current collector and the negative electrode layer 7 is disposed on the other surface is connected to a polymer electrolyte membrane (polymer). It can be said that it has a structure in which a plurality of layers are interposed via the electrolyte layer 3). That is, it has a structure in which the positive electrode layer 5, the electron conductive layer (current collector) 11, and the negative electrode layer 7 are laminated in this order.
[0026]
In the first embodiment of the bipolar battery according to the present invention, n electrode laminates 9 and (n + 1) electron conductive layers 11 are alternately laminated, and the electron conductive layer 11 is arranged as the outermost layer. Good.
[0027]
The number of laminations of the electrode laminate is adjusted according to a desired voltage. If a sufficient output can be ensured even if the thickness of the battery is made as thin as possible, the number of times of stacking the bipolar electrodes may be reduced.
[0028]
Next, the second embodiment of the bipolar battery according to the present invention has a positive electrode layer on one surface of one polymer electrolyte membrane, an electrode laminate having a negative electrode layer on the other surface, A bipolar battery having a structure in which an electron conductive layer is interposed therebetween, wherein the electron conductive layer has a layer mainly containing an insulating polymer and an electron conductive filler on at least one side of a metal layer. It is.
[0029]
In the second embodiment of the bipolar battery according to the present invention, even when a metal layer (for example, a metal foil) is used as a part of the electron conductive layer, the same operation and effect as described in the first embodiment can be obtained. In addition to the above, a laminate of a metal layer and a layer in which an insulating polymer is filled with an electron conductive filler can be used as the electron conductive layer to avoid the problem of corrosion resistance on the positive electrode side. As a result, even a copper foil that cannot be used normally can be a kind of metal layer by laminating (arranging) a layer in which an insulating polymer is filled with an electron conductive filler such as carbon black on the positive electrode layer side. It can be used effectively as Therefore, even when a laminate of such a metal layer and a layer in which an insulating polymer is filled with an electron conductive filler is used as the electron conductive layer, a battery having a high energy density and a high power density must be formed. Can be done.
[0030]
In the second embodiment of the bipolar battery according to the present invention, a layer mainly provided with an insulating polymer and an electron conductive filler provided on at least one surface of the metal layer (hereinafter, also referred to simply as a main layer) is Since the configuration is the same as that of the electron conductive layer described in the first embodiment of the present invention described above, description thereof will be omitted.
[0031]
Also in the second embodiment of the bipolar battery according to the present invention, the thickness of the electron conductive layer is set so that the electron density in the first aspect of the present invention is increased from the viewpoint of increasing the energy density and output density of the battery by thinning. Desirably, it is about the same as the thickness of the conductive layer. Therefore, the thickness of the main layer depends on the thickness of the metal layer, but is preferably in the range of 0.1 to 20 μm, more preferably 0.5 to 10 μm. When the thickness of the main layer is less than 0.1 μm, the merit in energy density is reduced. In addition, the thickness of the main layer referred to here means the thickness when provided on one side of the metal layer, and refers to the total thickness of both sides when provided on both sides of the metal layer. .
[0032]
The main layer, which is one of the constituent requirements of the electron conductive layer, has a structure in which the electron conductive filler is dispersed in the insulating polymer, the electron conduction resistance is not large in the plane direction, and the ion conduction resistance is very low. It should be big.
[0033]
Among them, the electron conductive filler can be appropriately selected from conventionally known ones, and is preferably carbon black. It can be said that carbon black is preferable in that various surface modifications can be made from the dispersibility of the main layer in the insulating polymer. By using carbon black as the electron conductive filler of the main layer, the objectives (higher energy density and higher output density) can be achieved more easily at lower cost.
[0034]
Further, the insulating polymer is not particularly limited, and may be, for example, appropriately selected from conventionally known polymers shown below and used.
[0035]
(1) A thermoplastic insulating polymer can be used. As such a thermoplastic insulating polymer, for example, polyethylene, polypropylene, polystyrene and the like can be suitably used.
[0036]
The main layer using the thermoplastic insulating polymer, furthermore, as a method of manufacturing an electron conductive layer, for example, by kneading and dispersing an electron conductive filler in a molten insulating polymer, extrusion molding process. A thinned main layer can be formed. The thin film of the main layer can form an electron conductive layer by being laminated on one side or both sides of a metal layer. Alternatively, by laminating a thin film of the main layer on an electrode (specifically, an electrode formed on the electrolyte layer) or the like, and then laminating a metal layer on the thin film of the main layer, an electron conductive layer, Further, an electrode laminate can be formed, but the method is not limited to these methods.
[0037]
(2) Those in which the insulating polymer and the electron conductive filler can be dispersed in a solvent can also be used. The solvent-dispersible insulating polymer does not affect the battery performance and may be any one as long as it can be dispersed in a solvent. As the solvent-dispersible insulating polymer, for example, neoprene / toluene and various fluoroelastomers / methylethylketone can be used.
[0038]
As a method for producing the main layer using the solvent-dispersible insulating polymer, and further, an electron conductive layer, for example, for the main layer obtained by dispersing the insulating polymer and the electron conductive filler in a solvent A raw material slurry was prepared, and the raw material slurry for the main layer was formed on, for example, an electrode (specifically, an electrode formed on the electrolyte layer) formed on both sides of an electrolyte layer having a certain strength or laminated on the electrode. A thin film of the main layer can be formed by spray coating directly on the metal layer or coating with a doctor blade. In the case where a thin film of the main layer is formed by spray coating directly on the electrode, coating with a doctor blade, etc., a metal layer is laminated after applying the raw material slurry for the main layer, and then dried and dried. What is necessary is just to form a thin film. Thereby, the electron conductive layer and further the electrode laminate can be formed together.
[0039]
The electron conductive layer can be formed by applying the raw material slurry for the main layer to one or both surfaces of the metal layer and drying the solvent to prepare a thin film of the main layer. In this case, the surface of the electron conductive layer on the main layer (or metal layer) side is attached to an electrode (specifically, an electrode formed on an electrolyte layer) or the like to be laminated, whereby an electrode laminate described later is formed. It can also be formed.
[0040]
Further, the raw material slurry for the main layer is applied to a glass plate or a PET film, and a solvent is dried to form a thin film. Then, the thin film is attached to an electrode (specifically, an electrode formed on an electrolyte layer). Thereafter, by peeling off the glass plate or the PET film, the thin film of the main layer can be formed, and at the same time, the electron conductive layer (and further the electrode laminate) can be formed.
[0041]
Here, in any of the production methods (1) and (2), the content of the electron conductive filler such as carbon black in the obtained main layer is preferably 5 to 50% by mass, more preferably 10% by mass. It is desirable to adjust the compounding amount of the electron conductive filler in the raw material so as to be in the range of ３０30% by mass. When the content of the electron conductive filler is less than 5% by mass, the resistance increases, and when it exceeds 50% by mass, it becomes difficult to form a uniform thin film.
[0042]
The size of the electron conductive filler may be the same as the size of the electron conductive filler in the first embodiment described above.
[0043]
The metal layer (material), which is one of the constituent requirements of the electron conductive layer, is not particularly limited, and a conventionally known material can be used. For example, an aluminum foil, a stainless steel foil, nickel A clad material of aluminum and aluminum, a clad material of copper and aluminum, or a plated material of a combination of these metals is preferably used. Further, the metal surface may be coated with aluminum. In some cases, a laminate of two or more metal foils may be used. It is preferable to use an aluminum foil as the metal layer from the viewpoints of corrosion resistance, ease of production, economy, and the like.
[0044]
The thickness of the metal layer is also in the range of 1 to 20 μm, more preferably 3 to 10 μm, from the viewpoint of reducing the thickness of the electron conductive layer as a current collector in the bipolar battery and increasing the energy density and output density of the battery. It can be said that it is desirable. When the thickness of the metal layer is less than 1 μm, there is a problem in production, and when it exceeds 20 μm, the merit is reduced in terms of the energy density of the battery.
[0045]
The thickness ratio between the main layer and the metal layer is not particularly limited, but may be about 10: 1 to 1:20.
[0046]
Hereinafter, a typical example of the second embodiment of the present invention will be briefly described with reference to the drawings. However, it goes without saying that the present invention should not be limited to these embodiments.
[0047]
FIG. 2 is a schematic partial cross-sectional view schematically showing a second typical embodiment of the bipolar battery according to the present invention. As shown in FIG. 2, a second bipolar battery 21 of the present invention has a positive electrode layer 25 on one surface of one polymer electrolyte membrane (polymer electrolyte layer 23) and a positive electrode layer 25 on the other surface. It has a structure in which an electrode laminate 29 having a negative electrode layer 27 is laminated with an electron conductive layer 31 interposed therebetween, wherein the electron conductive layer 31 is formed on at least one side of a metal layer 31a, It is characterized in that a layer (layer having electron conductivity) 31b mainly containing an insulating polymer and an electron conductive filler is provided on the contacting surface. In other words, the positive electrode layer 25 is disposed on one surface of the electron conductive layer 31 as a current collector (in FIG. 2, on the side of the layer 31 b having electron conductivity), and the other surface (in FIG. 2, the metal layer 31 a It can be said that the bipolar electrode 29 'having a structure in which the negative electrode layer 27 is disposed on the (side) side has a structure in which a plurality of bipolar electrodes 29' are stacked via a polymer electrolyte membrane (polymer electrolyte layer 23). That is, it has a structure in which the positive electrode layer 25, the electron conductive layer (current collector) 31 (the layer 31b having electron conductivity, the metal layer 31a), and the negative electrode layer 27 are laminated in this order.
[0048]
In the second embodiment of the bipolar battery according to the present invention, n electrode laminates 29 and (n + 1) electron conductive layers 31 are alternately laminated, and the electron conductive layer 31 is disposed as the outermost layer. Good.
[0049]
The number of laminations of the electrode laminate is adjusted according to a desired voltage. If a sufficient output can be ensured even if the thickness of the battery is made as thin as possible, the number of times of stacking the bipolar electrodes may be reduced.
[0050]
In the bipolar battery according to the present invention, in order to prevent external impact and environmental degradation, the bipolar battery main body (see FIGS. 1 and 2) stacked in a sheet shape is connected to a battery exterior material or a battery case (see FIG. 1). (Not shown). Conventionally, such as a metal-polymer composite laminate film in which the inner surface (both surfaces) of aluminum, stainless steel, nickel, copper, etc. is laminated with an insulator such as a polypropylene film in the battery exterior material or battery case that seals the bipolar battery body Those covered with a known battery exterior material are suitable.
[0051]
The bipolar battery according to the present invention is used for a lithium ion secondary battery in which charge and discharge are mediated by movement of lithium ions. However, this does not prevent application to other types of batteries as long as effects such as improvement in battery characteristics can be obtained.
[0052]
Next, the components of the bipolar battery of the present invention will be described individually.
[0053]
[Electron conductive layer]
The electron conductive layer is a characteristic feature of the present invention, and is as described in the first and second embodiments.
[0054]
That is, the electron conductive layer that can be used in the present invention is characterized in that the electron conductive layer mainly contains an insulating polymer and an electron conductive filler. In the state of being dispersed in the polymer, it is sufficient that the electron conduction resistance is not large in the plane direction and the ionic conduction resistance is very large.
[0055]
As the electron conductive filler, carbon black or the like can be preferably used, but is not limited thereto. The amount of such an electron conductive filler, particularly carbon black, is preferably 5 to 50% by mass, more preferably 10 to 30% by mass.
[0056]
(1) A thermoplastic polymer such as polyethylene, polypropylene, and polystyrene can be used as the insulating polymer.
[0057]
{Circle around (2)} Insulating polymers and electron conductive fillers that can be dispersed in a solvent can be used. Here, the insulating polymer dispersible in the solvent may be any one that does not affect the battery performance and can be dispersed in the solvent, and examples thereof include neoprene / toluene and various fluoroelastomers / methylethylketone.
[0058]
[Positive electrode layer (also referred to as positive electrode active material layer)]
The positive electrode layer contains a positive electrode active material. In addition, a polymer having polarity as a polymer electrolyte, a lithium salt, a conductive auxiliary material for improving electron conductivity, a binder, and the like may be included.
[0059]
When a polymer solid electrolyte is used for the polymer electrolyte layer, it is desirable that the positive electrode layer also contains the polymer solid electrolyte. By filling the gap between the positive electrode active materials in the positive electrode layer with the solid polymer electrolyte, the ionic conduction in the positive electrode layer becomes smooth, and the output of the entire bipolar battery can be improved.
[0060]
On the other hand, when a polymer gel electrolyte is used for the polymer electrolyte layer, the polymer electrolyte may not be contained in the positive electrode layer, and it is sufficient if a conventionally known binder for binding the cathode active material fine particles is contained. .
[0061]
As the positive electrode active material, a composite oxide of a transition metal and lithium, which is also used in a solution-based lithium ion battery, can be used. Specifically, LiCoO ₂ Li-Co based composite oxides such as LiNiO ₂ Li-Ni based composite oxide such as spinel LiMn ₂ O ₄ Li-Mn based composite oxides such as LiFeO ₂ Li.Fe-based composite oxides such as In addition, LiFePO ₄ Phosphoric acid compounds and sulfuric acid compounds of transition metals and lithium; ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , MoO ₃ Transition metal oxides and sulfides such as PbO ₂ , AgO, NiOOH and the like.
[0062]
In order to reduce the electrode resistance of a bipolar battery, it is preferable that the particle size of the positive electrode active material be smaller than that generally used in a solution type lithium ion battery in which the electrolyte is not solid. Specifically, the average particle size of the positive electrode active material is preferably 0.1 to 5 μm.
[0063]
The polymer for a polymer solid electrolyte is not particularly limited, and examples thereof include polyethylene oxide (PEO), polypropylene oxide (PPO), and a copolymer thereof. Such a polyalkylene oxide-based polymer is LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ And other lithium salts. Further, by forming a crosslinked structure, excellent mechanical strength is exhibited. In the present invention, the polymer solid electrolyte is contained in at least one of the positive electrode active material layer and the negative electrode active material layer. However, in order to further improve the battery characteristics of the bipolar battery, it is preferable that both are included.
[0064]
As the lithium salt, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ Or a mixture thereof. However, it is not limited to these.
[0065]
Examples of the conductive additive include acetylene black, carbon black, and graphite. However, it is not limited to these.
[0066]
As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide or the like can be used. However, it is not limited to these.
[0067]
The amount of the positive electrode active material, solid polymer electrolyte, lithium salt, conductive additive, binder, etc. in the positive electrode layer should be determined in consideration of the intended use of the battery (output-oriented, energy-oriented, etc.) and ionic conductivity. It is.
[0068]
For example, in the case of using a solid polymer electrolyte, taking the case of determining the blending amount as an example, if the blending amount of the solid polymer electrolyte in the positive electrode layer is too small, the ionic conduction resistance or ion Diffusion resistance increases and battery performance decreases. On the other hand, if the blending amount of the solid polymer electrolyte in the positive electrode layer is too large, the energy density of the battery decreases. Therefore, the mass of the solid polymer electrolyte that meets the purpose may be determined in consideration of these factors. It should be noted that the amounts of the other components may be appropriately determined in the same manner.
[0069]
Here, the current level of polymer solid electrolyte (ion conductivity: 10 ^-5 -10 ^-4 (S / cm) to manufacture a bipolar battery giving priority to battery reactivity will be specifically considered. In order to obtain a bipolar battery having such features, the amount of the conductive auxiliary material is increased and the bulk density of the active material is reduced to keep the electron conduction resistance between the active material particles low. At the same time, the number of voids is increased, and the voids are filled with the solid polymer electrolyte. It is preferable to increase the proportion of the solid polymer electrolyte by such treatment.
[0070]
The thickness of the positive electrode layer is not particularly limited, and should be determined in consideration of the intended use of the battery (e.g., emphasis on output, energy, etc.) and ionic conductivity, as described for the blending amount. The thickness of a general positive electrode active material layer is about 10 to 500 μm.
[0071]
[Negative electrode layer]
The negative electrode layer contains a negative electrode active material. In addition, a polymer electrolyte, a lithium salt for improving ionic conductivity, a conductive auxiliary for improving electron conductivity, a binder, and the like may be included.
[0072]
When a polymer solid electrolyte is used for the polymer electrolyte layer, it is desirable that the negative electrode layer also contains the polymer solid electrolyte. By filling the gap between the negative electrode active materials in the negative electrode layer with the solid polymer electrolyte, the ionic conduction in the negative electrode layer becomes smooth, and the output of the entire bipolar battery can be improved.
[0073]
On the other hand, when a polymer gel electrolyte is used for the polymer electrolyte layer, the polymer electrolyte may not be contained in the negative electrode layer, and it is sufficient that a conventionally known binder that binds the negative electrode active material fine particles is included. . Except for the type of the negative electrode active material, the content is basically the same as that described in the section of “Positive electrode layer”, and thus the description is omitted here.
[0074]
As the negative electrode active material, a negative electrode active material used in a solution-type lithium ion battery can be used. Specifically, carbon, a metal oxide, a lithium-metal composite oxide, or the like can be used, but carbon or a lithium-transition metal composite oxide is preferable. By using these, a battery excellent in capacity and output characteristics (for example, battery voltage can be increased) can be configured. As the lithium-transition metal composite oxide, for example, a lithium-titanium composite oxide or the like can be used. As the carbon, for example, graphite, hard carbon, soft carbon, or the like can be used.
[0075]
[Polymer electrolyte layer]
The polymer electrolyte layer is not limited to a solid polymer electrolyte, and even if it is a polymer gel electrolyte, a liquid junction is prevented by forming an insulating layer around the unit cell layer. Anything that can be used can be used, and these can be used in combination. Further, the electrolyte layer may have a multilayer structure, and a layer in which the type of electrolyte and the composition ratio of the electrolyte are changed between the positive electrode side and the negative electrode side may be formed. When the polymer gel electrolyte is used, the ratio (mass ratio) of the polymer and the electrolyte constituting the polymer gel electrolyte is not particularly limited, but may be in the range of 20:80 to 95: 5. Use is common.
[0076]
The solid polymer electrolyte layer is a layer composed of a polymer having ion conductivity and a lithium salt, and the material is not limited as long as it has ion conductivity. Examples of the polymer having ion conductivity include known polymers such as polyethylene oxide (PEO), polypropylene oxide (PPO), and a copolymer thereof. As the lithium salt, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ Or a mixture thereof. However, it is not limited to these. Polyalkylene oxide polymers such as PEO and PPO are made of LiBF. ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ And other lithium salts. Further, by forming a crosslinked structure, excellent mechanical strength is exhibited.
[0077]
Further, the polymer gel electrolyte contains an electrolyte solution usually used in a lithium ion battery in a polymer matrix, as defined above.
[0078]
These solid polymer electrolytes or polymer gel electrolytes can be included in the positive electrode layer and / or the negative electrode layer as described above, in addition to the polymer electrolyte layer constituting the battery, but the polymer electrolyte layer constituting the battery, Different polymer electrolytes may be used for the positive electrode layer and the negative electrode layer, the same polymer electrolyte may be used, or different polymer electrolytes may be used for different layers.
[0079]
The thickness of the polymer electrolyte layer constituting the battery is not particularly limited. However, in order to obtain a compact bipolar battery, it is preferable to make the battery as thin as possible as long as the function as an electrolyte can be secured. The thickness of a general polymer electrolyte layer is about 10 to 100 μm.
[0080]
[Positive and negative terminal plates]
The positive and negative electrode terminal plates may be used as needed. When used, it is better to have as thin as possible from the viewpoint of thinning in addition to having the function as a terminal, but since the laminated electrodes, electrolyte and current collector all have low mechanical strength, It is desirable to have enough strength to sandwich and support from above. Further, from the viewpoint of suppressing the internal resistance at the terminal portion, it can be said that the thickness of the positive electrode and negative electrode terminal plates is usually preferably about 0.1 to 2 mm.
[0081]
As the material of the positive electrode terminal and the negative electrode terminal plate, a material usually used in a lithium ion battery can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), alloys thereof, and the like can be used. It is preferable to use aluminum from the viewpoints of corrosion resistance, ease of production, economy, and the like.
[0082]
The materials of the positive electrode terminal plate and the negative electrode terminal plate may be the same or different. Further, these positive and negative electrode terminal plates may be formed by laminating different materials from each other in multiple layers.
[0083]
[Positive and negative electrode leads]
As the positive and negative electrode leads, known leads that are usually used in lithium ion batteries can be used. In addition, since the part taken out of the battery exterior material (battery case) does not have a distance from the heat source of the automobile, it does not affect the automobile parts (especially electronic devices) by contacting them and causing a short circuit. It is preferable to coat with a heat-shrinkable heat-shrinkable tube or the like.
[0084]
[Battery exterior material (battery case)]
In order to prevent external shock and environmental degradation, the bipolar battery body must be entirely covered with a battery exterior material or battery case in order to prevent external impact and environmental degradation during use. It is good to house in. From the viewpoint of weight reduction, using a conventionally known battery exterior material such as a polymer-metal composite laminate film in which a metal (including an alloy) such as aluminum, stainless steel, nickel, and copper is coated with an insulator such as a polypropylene film. It is preferable that the battery stack is housed and hermetically sealed by joining a part or all of its peripheral portion by heat fusion. In this case, the positive electrode and the negative electrode lead may have a structure sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. It is preferable to use a polymer-metal composite laminate film or the like having excellent thermal conductivity in that heat can be efficiently transmitted from a heat source of an automobile and the inside of the battery can be quickly heated to a battery operating temperature.
[0085]
Next, in the present invention, an assembled battery formed by connecting a plurality of the above bipolar batteries can be provided. That is, by using at least two or more bipolar batteries of the present invention and connecting them in series and / or in parallel to form an assembled battery, it is possible to respond to the demand for battery capacity and output for each purpose of use relatively inexpensively. It becomes possible to do.
[0086]
Specifically, for example, the above-mentioned N bipolar batteries are connected in parallel, and N parallel bipolar batteries are further connected in series to be stored in a metal or resin battery pack case to form a battery pack. . At this time, the number of series / parallel connected bipolar batteries is determined according to the purpose of use. For example, a large-capacity power supply such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) may be combined so as to be applicable to a driving power supply of a vehicle requiring a high energy density and a high output density. Further, the positive electrode terminal and the negative electrode terminal for the assembled battery and the electrode lead of each bipolar battery may be electrically connected using a lead wire or the like. When the bipolar batteries are connected in series / parallel, they may be electrically connected using a suitable connecting member such as a spacer or a bus bar. However, the battery pack of the present invention should not be limited to the battery described here, and a conventionally known battery can be appropriately used. In addition, the assembled battery may be provided with various measuring devices and control devices according to the intended use, for example, a voltage measuring connector or the like may be provided to monitor the battery voltage. There is no particular limitation.
[0087]
According to the present invention, a vehicle equipped with the bipolar battery and / or the assembled battery as a driving power source can be provided. The bipolar battery and / or assembled battery of the present invention has various characteristics as described above, and is particularly a compact battery. For this reason, it is suitable as a power source for driving vehicles that have particularly strict requirements regarding energy density and output density, for example, electric vehicles and hybrid electric vehicles. For example, it is convenient to mount a battery pack as a driving power source under a seat in the center of the body of an electric vehicle or a hybrid electric vehicle, because it is possible to widen a company space and a trunk room. However, the present invention is not limited to these, and may be mounted at the lower part of the rear trunk room, or if the engine is not mounted like an electric vehicle, the engine at the front of the vehicle body is mounted. It can also be mounted on parts that were used. In the present invention, not only the assembled battery but also a bipolar battery may be mounted depending on the intended use, or the assembled battery and the bipolar battery may be mounted in combination. Further, as the vehicle on which the bipolar battery and / or the assembled battery of the present invention can be mounted as a driving power source, the above-described electric vehicle or hybrid electric vehicle is preferable, but is not limited thereto.
[0088]
The method for manufacturing the bipolar battery of the present invention is not particularly limited, and various conventionally known methods can be appropriately used. The following is a brief description.
[0089]
(1) Formation of electron conductive layer
An electron conductive layer mainly containing an insulating polymer and an electron conductive filler is obtained as follows.
[0090]
(1) When a thermoplastic polymer such as polyethylene, polypropylene, or polystyrene is used as the insulating polymer, the electron conductive filler is kneaded and dispersed in the melted insulating polymer, and is thinned by extrusion molding. Is obtained by
[0091]
(2) When the insulating polymer and the electron conductive filler are dispersible in a solvent, a slurry formed by dissolving the insulating polymer and the electron conductive filler in the solvent is directly spray-coated on the electrode, It is obtained by forming a film by coating with a blade. Alternatively, it can be obtained by applying the above slurry on a support material such as a glass plate or a PET film and drying the solvent to form a thin film. In the case of (2), the electrodes to be formed in (2) and thereafter are formed in advance on a suitable support material (glass plate, PET film, etc.) or an electrolyte layer, and the electron conductive layer is formed on such an electrode. What is necessary is just to form by the procedure of 2 ▼. In other words, the procedure described below is the procedure in the case of the above (1), and in the case of (2), the order of formation, application and lamination of the object or application and application of the lamination is exchanged. It is. However, when the battery is configured as shown in FIGS. 1 and 2 already described, an electrode is formed on the existing current collector, but an electron conductive layer instead of the current collector is formed on the electrode. A battery can be formed in the same manner as in (1) except for (1). Therefore, the procedure for manufacturing the battery using the manufacturing method of (2) is performed in the embodiment, and the description is omitted here.
[0092]
(2) Application of positive electrode composition
The composition for the positive electrode is usually obtained as a slurry (slurry for the positive electrode), and is applied on a film such as PET. Alternatively, the electron conductive layer prepared in the above (1) may be prepared and applied to one surface thereof.
[0093]
The positive electrode slurry contains a positive electrode active material, and optionally contains, as other components, a conductive additive, a binder, a polymerization initiator, a raw material of a polymer for a polymer electrolyte, a lithium salt, a solvent, and the like. When a polymer gel electrolyte is used for the polymer electrolyte layer, it is sufficient that a conventionally known binder for binding the positive electrode active material particles to each other, a conductive auxiliary material for increasing electron conductivity, a solvent, and the like are included. The host polymer, the electrolyte, the lithium salt, and the like as the raw material of the gel electrolyte may not be contained.
[0094]
Examples of the polymer material for the polymer electrolyte include PEO, PPO, and copolymers thereof, and the polymer material preferably has a crosslinkable functional group (such as a carbon-carbon double bond) in the molecule. By cross-linking the polymer gel electrolyte using this cross-linkable functional group, the mechanical strength is improved.
[0095]
As for the positive electrode active material, the conductive additive, the binder, and the lithium salt, the compounds described above can be used.
[0096]
The polymerization initiator needs to be selected according to the compound to be polymerized. For example, benzyldimethyl ketal is used as a photopolymerization initiator, and azobisisobutyronitrile is used as a thermal polymerization initiator.
[0097]
The solvent such as NMP is selected according to the type of the positive electrode slurry.
[0098]
The addition amount of the positive electrode active material, the lithium salt, the conductive additive, the binder, the polymer raw material of the polymer electrolyte, and the like may be adjusted according to the purpose of the bipolar battery, and may be the usual amount. The amount of the polymerization initiator to be added is determined according to the amount of the polymer raw material of the polymer electrolyte. Usually, it is about 0.01 to 1% by mass with respect to the polymer raw material.
[0099]
(3) Formation of positive electrode layer
The electron conductive layer coated with the positive electrode slurry is dried to remove the contained solvent. At the same time, depending on the slurry for the positive electrode, a cross-linking reaction may be advanced to increase the mechanical strength of the solid polymer electrolyte. For drying, a vacuum dryer or the like can be used. The drying conditions are determined according to the applied slurry for the positive electrode and cannot be uniquely defined, but are usually at 80 to 120 ° C. for 1 to 6 hours.
[0100]
(4) Application of composition for negative electrode
The composition for a negative electrode is usually obtained as a slurry (a slurry for a positive electrode), and is applied on a film such as PET. In addition, a negative electrode composition (negative electrode slurry) containing a negative electrode active material may be applied to the surface of the electron conductive layer opposite to the surface on which the positive electrode layer is applied.
[0101]
The negative electrode slurry contains a negative electrode active material, and optionally contains, as other components, a conductive additive, a binder, a polymerization initiator, a raw material of a polymer for a polymer electrolyte, a lithium salt, a solvent, and the like. The raw materials used and the amounts added are the same as those described in the section of “(1) Application of positive electrode composition”, and thus description thereof is omitted here.
[0102]
(5) Formation of negative electrode layer
The electron conductive layer to which the negative electrode slurry has been applied is dried to remove the contained solvent. At the same time, depending on the slurry for the negative electrode, the cross-linking reaction may proceed to increase the mechanical strength of the polymer electrolyte. By this operation, a bipolar electrode is completed. For drying, a vacuum dryer or the like can be used. The drying conditions are determined according to the applied slurry for the negative electrode and cannot be uniquely defined, but are usually at 80 to 120 ° C. for 1 to 6 hours.
[0103]
(6) Lamination of bipolar electrode and polymer electrolyte layer
Separately, a polymer electrolyte layer to be laminated between the electrodes is prepared.
[0104]
When the polymer solid electrolyte layer is used, the polymer solid electrolyte layer is produced by, for example, curing a solution prepared by dissolving a raw material polymer of the polymer solid electrolyte, a lithium salt, or the like in a solvent such as NMP. When a polymer gel electrolyte layer is used, for example, as a raw material of the polymer gel electrolyte, a pre-gel solution comprising a host polymer and an electrolyte solution, a lithium salt, a polymerization initiator, and the like are simultaneously heated and dried under an inert atmosphere. It is produced by polymerizing (promoting a crosslinking reaction).
[0105]
The thickness of these polymer electrolyte layers can be controlled using a spacer. In the case of using a photopolymerization initiator, it is preferable to pour the mixture into a light transmissive gap and irradiate ultraviolet rays to advance a crosslinking reaction to form a film. However, it is a matter of course that the present invention is not limited to this method. Depending on the type of the polymerization initiator, radiation polymerization, electron beam polymerization, thermal polymerization, and the like are properly used. The raw material polymer, electrolytic solution, lithium salt, polymerization initiator, blending amount, and the like of the polymer electrolyte to be used are as described above, and thus description thereof is omitted here.
[0106]
After the positive and negative electrodes and the polymer solid electrolyte layer prepared as described above are sufficiently heated and dried under a high vacuum, a plurality of the positive and negative electrodes and the polymer electrolyte layer are cut into appropriate sizes. A predetermined number of the cut-out bipolar electrodes and polymer electrolyte layers are attached to each other to produce a laminated battery. The number of layers is determined in consideration of battery characteristics required for a bipolar battery. Electrodes are arranged on the outermost polymer electrolyte layers. The outermost layer on the positive electrode side is provided with an electrode in which only the positive electrode layer is formed on the electron conductive layer. In the outermost layer on the negative electrode side, an electrode in which only the negative electrode layer is formed on the electron conductive layer is arranged. The step of laminating the positive and negative electrodes and the polymer electrolyte layer to obtain a bipolar battery main body (battery laminate) is preferably performed in an inert atmosphere from the viewpoint of preventing water and the like from entering the inside of the battery. For example, a bipolar battery is preferably manufactured in an argon atmosphere or a nitrogen atmosphere.
[0107]
(7) Packing (completion of battery)
Finally, a positive electrode terminal plate and a negative electrode terminal plate are respectively disposed on both outermost electron conductive layers of the bipolar battery body (battery laminate), and a positive electrode lead and a negative electrode lead are further provided on the positive electrode terminal plate and the negative electrode terminal plate. Are joined (electrically connected) and taken out. The method for joining the positive electrode lead and the negative electrode lead is not particularly limited, but ultrasonic welding or the like having a low joining temperature can be suitably used, but is not limited to this. A known joining method can be appropriately used.
[0108]
The entire battery stack is sealed with a battery exterior material or a battery case in order to prevent external impact and environmental degradation, thereby completing a bipolar battery. The material of the battery exterior material (battery case) is preferably a metal (aluminum, stainless steel, nickel, copper, or the like) whose inner surface is covered with an insulator such as a polypropylene film.
[0109]
【Example】
The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.
[0110]
Hereinafter, examples of the present invention and comparative examples will be described.
[0111]
As the polymer electrolyte, a raw material of a polyether-type network polymer synthesized according to the method of literature is used (J. Electrochem. Soc., 145 (1998) 1521.), and as the lithium salt, LiN (SO ₂ C ₂ F ₅ ) ₂ (Hereinafter referred to as BETI).
[0112]
(1) Preparation of polymer electrolyte membrane
First, the production of the polymer electrolyte membrane was performed as follows. A solution was prepared by adding 53% by mass of the above polymer material, 26% by mass of BETI as a lithium salt, and 0.1% by mass of benzyl dimethyl ketal as a photopolymerization initiator, and using dry acetonitrile as a solvent. Then acetonitrile was removed by vacuum distillation. The thickness was regulated using a Teflon (registered trademark) spacer, the space between the glass substrates was filled with this highly viscous solution, and ultraviolet light was irradiated for 20 minutes to perform photopolymerization (crosslinking). The film was taken out, placed in a vacuum vessel, and dried by heating under high vacuum at 90 ° C. for 12 hours to remove residual water and solvent. The thickness of the produced polymer electrolyte membrane was 20 μm.
[0113]
(2) Preparation of negative electrode layer
The production of the negative electrode layer was performed as follows. Li as negative electrode active material ₄ Ti ₅ O ₁₂ Was used. 28% by mass of this electrode active material, 3% by mass of acetylene black, 17% by mass of the above polymer material, 8% by mass of BETI, and 0.1% by mass of azobisisobutyronitrile as a thermal polymerization initiator were used. NMP as a solvent was added thereto, and 44% by mass of NMP was added thereto, and the mixture was sufficiently stirred to prepare a slurry. The slurry was applied on a PET fill with a coater, and dried by heating at 90 ° C. for 2 hours or more in a vacuum drier. Was prepared. The thickness of the manufactured negative electrode active material layer was 22 μm.
[0114]
(3) Preparation of positive electrode layer
The production of the positive electrode layer was performed as follows. LiMn as positive electrode active material ₂ O ₄ A positive electrode layer was used. Specifically, LiMn with an average particle size of 2 μm of 29% by mass ₂ O ₄ 8.7% by mass of acetylene black, 17% by mass of the above polymer material, 7.3% by mass of BETI, and azobisisobutyronitrile as a thermal polymerization initiator 0.1% by mass of the polymer material, A slurry was prepared by adding 41% by mass of NMP as a solvent to the mixture and sufficiently stirring to prepare a slurry. The slurry was applied on a PET fill with a coater, and dried by heating in a vacuum dryer at 90 ° C. for 2 hours or more to produce a positive electrode. . The thickness of the produced positive electrode active material layer was 20 μm.
[0115]
In the following examples and comparative examples, fabrication and experiments were performed under the following conditions.
[0116]
(1) Size of the electrode part: 30 mm × 30 mm,
(2) Number of electrode laminated cells (unit cell layers): 10,
{Circle around (3)} Charging / discharging conditions: 0.2 C constant current, 27 V constant voltage charging was performed for a total of 10 hours, and discharging was performed at 0.1 C and 10 V cut off.
[0117]
Example 1
{Circle around (1)} Carbon black (about 30% by mass based on the total amount of polyethylene and carbon black) is added to polyethylene, melt-kneaded, and stretched well using a hot press roll to form an electron conductive film having a thickness of 10 μm. used.
[0118]
By the above method, an electrolyte membrane, a positive electrode layer, and a negative electrode layer were produced, respectively. A negative electrode layer / a polymer electrolyte layer / a positive electrode layer is formed on a copper foil, and an electron conductive layer (1) is arranged on the positive electrode layer, and a negative electrode layer / a polymer electrolyte layer / a positive electrode is further formed thereon. The layers were arranged. This was repeated 10 times, and an aluminum foil was disposed on the last positive electrode layer.
[0119]
Nickel tabs (terminal leads) were attached to copper foil and aluminum foil, and the electrodes were vacuum-sealed in aluminum laminate film packs to obtain batteries.
[0120]
As shown in the present embodiment, in the present invention, a conventional current collector may be used as the electron conductive layer of the outermost electrode of the battery instead of the electron conductive layer. Particularly, in the first embodiment that does not use a metal layer, it is useful in that the terminal leads can be easily connected.
[0121]
Example 2
{Circle around (1)} Neoprene and carbon black are dispersed in toluene (solid content: about 20% by mass, of which 40% by mass is carbon black), spray-coated on a PET film, dried with hot air, and dried to a thickness of 5 μm. A conductive film was prepared, and a bipolar battery similar to that of Example 1 was formed using the electron conductive film of Example 1 instead of the electron conductive film.
[0122]
Example 3
The electron conductive film of Example 2 was formed on a copper foil having a thickness of 4 μm, and the electron transmitting film was disposed on the negative electrode side surface of Example 1 with copper foil. A battery was configured.
[0123]
Comparative Example 1
As shown in FIG. 3, instead of the electron conductive film of Example 1, a 20 μm thick aluminum foil (first current collector foil 51a) was used on the positive electrode layer side, and a 15 μm thick copper A bipolar battery similar to that of Example 1 was formed by laminating the foils (second current collector foil 51b).
[0124]
Using the prepared bipolar battery as a charge and discharge condition, charge and discharge at a constant current of 0.2 C and a constant voltage of 27 V for a total of 10 hours, and discharge at a cutoff of 10 V at 0.1 C to calculate the energy density of each battery. The results are shown in Table 1 in comparison with the value of the battery of Comparative Example 1. As can be seen from the results shown in Table 1, the use of a layer in which an electron conductive filler is dispersed and filled in an insulating polymer is used as the electron conductive layer separating the cells of a bipolar battery (layer between cells). The energy density of the bipolar battery can be improved as compared with the case where a metal foil is used as the electric body.
[0125]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a schematic partial cross-sectional view schematically illustrating a first embodiment of a bipolar battery according to the present invention.
FIG. 2 is a schematic partial sectional view schematically showing a second representative embodiment of a bipolar battery according to the present invention.
FIG. 3 is a schematic partial cross-sectional view of a bipolar battery using a conventional current collector, schematically showing the bipolar battery manufactured in Comparative Example 1.
[Explanation of symbols]
1, 21, 41 ... bipolar battery,
3, 23, 43: polymer electrolyte membrane (polymer electrolyte layer),
5, 25, 45 ... positive electrode layer,
7, 27, 47 ... negative electrode layer,
9, 29, 49 ... cell layer,
9 ', 29', 49 '... bipolar electrodes,
11, 31 ... electron conductive layer,
31a: metal layer,
31b ... a layer having electron conductivity,
51 ... current collector foil,
51a: first current collector foil,
51b ... second collector foil.

Claims (5)

In a bipolar battery having a structure in which an electrode laminate having a positive electrode layer on one surface of one polymer electrolyte membrane and a negative electrode layer on the other surface is laminated via an electron conductive layer,
A bipolar battery, wherein the electron conductive layer mainly contains an insulating polymer and an electron conductive filler. In a bipolar battery having a structure in which an electrode laminate having a positive electrode layer on one surface of one polymer electrolyte membrane and a negative electrode layer on the other surface is laminated via an electron conductive layer,
A bipolar battery, wherein the electron conductive layer has a layer mainly containing an insulating polymer and an electron conductive filler on at least one surface of the metal layer. 3. The bipolar battery according to claim 1, wherein the electron conductive filler is carbon black. An assembled battery comprising a plurality of the bipolar batteries according to claim 1 connected to each other. A vehicle comprising the bipolar battery according to any one of claims 1 to 3 and / or the battery pack according to claim 4.

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