JP4674434B2 - Bipolar battery - Google Patents

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]
BACKGROUND OF THE INVENTION
The present invention relates to a bipolar battery in which a positive electrode layer and a negative electrode layer are disposed on both sides of a current collector.
[0002]
[Prior art]
In recent years, lithium ion secondary batteries that can achieve high energy density and high output density have been developed as large-capacity power supplies for electric vehicles and the like. The basic configuration of the lithium ion secondary battery is that a positive electrode in which a positive electrode active material such as lithium cobaltate and a conductive additive such as acetylene black are applied to an aluminum current collector using a binder, and carbon fine particles are bonded to a copper current collector. A negative electrode coated with a resin is placed through a polyolefin-based porous membrane separator, and LiPF ₆ It is what filled the non-aqueous electrolyte containing etc. When applied to an electric vehicle or the like, unit cells (cells) having this configuration are connected in series, and a battery module unit and modules are connected in series to form a battery pack.
[0003]
From the viewpoint of the energy density and output density of the battery, it is desired to improve connection resistance, space, and weight of connection between cells and connection between modules. Recently, a battery that employs a bipolar electrode unit that can reduce the resistance of connection between cells and can be expected to be compact has been proposed (see, for example, Patent Document 1). In this proposal, so-called clad material is used to roll two types of metal foil for the current collector, and gel electrolyte is used for the electrolyte. Therefore, a hermetic seal for each cell unit is indispensable. Tangles can occur. If a polymer solid 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 polymer battery configured using a polymer electrolyte as such an electrolyte, has the advantage of extremely high reliability because it does not contain an electrolyte solution and thus does not leak or generate gas. Yes. (For example, refer to Patent Documents 2 and 3.)
[0004]
[Patent Document 1]
JP-A-11-204136
[Patent Document 2]
Japanese Patent Laid-Open No. 2000-1000047
[Patent Document 3]
JP 2002-75455 A
[0005]
[Problems to be solved by the invention]
However, the conventional bipolar battery uses a metal foil or a laminate thereof for the current collector layer, so that there is a limit to the current collectors that can be used due to the problem of corrosion resistance on the positive electrode side or alloying with lithium on the negative electrode. It was done. In addition, a current collector foil having a thickness of about several tens of μm has a structure in which a positive electrode layer is disposed on one surface and a negative electrode layer is disposed on the other surface, which are 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, the object of the present invention is a novel current collector that has excellent corrosion resistance on the positive electrode side and does not cause alloying with lithium on the negative electrode, and has a thickness that is greater than that of the electrode layer and the electrolyte layer. It is an object of the present invention to provide a bipolar battery using a current collector having an appropriate length.
[0007]
[Means for Solving the Problems]
The present invention provides a bipolar structure having a structure in which an electrode laminate having a positive electrode layer on one surface of a single polymer electrolyte membrane and a negative electrode layer on the other surface is laminated via an electron conductive layer. Type lithium ion secondary In a battery, the electron conductive layer mainly contains an insulating polymer and an electron conductive filler. The thickness of the electron conductive layer is 0.1 to 10 μm, and the average particle size of the electron conductive filler particles is less than 0.5 μm. Bipolar characterized by Type lithium ion secondary It is a battery.
[0008]
【The invention's effect】
In the bipolar battery of the present invention, a non-metal foil (such as an insulating polymer and carbon black) can be used for the electron conductive layer as a current collector, which has excellent corrosion resistance on the positive electrode side, and lithium on the negative electrode. In addition, the electron conductive layer can be made thinner than the case of using a metal foil of several tens of μm (usually about 35 μm) by an ordinary method, and the thickness of the electron conductive layer can be reduced to the electrode layer and the electrolyte. An appropriate range (about 1 to 20 μm) for the layer (film) can be obtained, and the energy density and output density of the battery can be increased. Therefore, it becomes a useful power source in various industries.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0010]
In a first embodiment of a bipolar battery according to the present invention, an electrode laminate having a positive electrode layer on one surface of a single polymer electrolyte membrane and a negative electrode layer on the other surface is provided with an electronic conductivity. In the bipolar battery having a structure laminated through the layers,
The electron conductive layer mainly includes an insulating polymer and an electron conductive filler.
[0011]
The electron conductive layer is usually referred to as a current collector (cell spacing wall / electron conductor in a bipolar battery), and uses a metal foil having high electronic conductivity. Since it flows in the vertical direction, not so high electron conductivity is necessarily required. Conventionally, as an electrode manufacturing method, an electrode material slurry is applied to a metal foil and dried and solidified (in some cases, polymerized). For this reason, the metal foil to be used needs to have a certain degree of strength, and from these reasons, the thickness of the metal foil inevitably needs to be about 15 to 20 μm depending on the material. Therefore, in the first embodiment of the present invention, taking advantage of the characteristics of a bipolar battery, 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. It is.
[0012]
In the first embodiment of the bipolar battery according to the present invention, from the knowledge that a thin film obtained by filling an insulating polymer as an electron conductive layer with an electron conductive filler does not necessarily require a high electron conductivity. This is advantageous in that it can be easily made into a slurry and can select a raw material that can be easily thinned to about several μm. That is, a material other than metal can be used for the electron conductive layer as a current collector. In particular, an electron conductive layer using carbon as an electron conductive filler is the electron conductive layer (thin layer). In addition to this, the electron conductive layer can be formed by directly applying the raw material slurry for the electron conductive layer, and a bipolar battery having high energy density and high output density can be configured. Further, it is advantageous in that a material that does not have a problem of corrosion resistance on the positive electrode side or a problem of alloying with lithium on the negative electrode can be selected as compared with the metal foil. In addition, since a material that can be easily made into a slurry of the raw material can be selected, the electrode is not formed by applying the electrode raw material slurry on both surfaces of the current collector having a certain strength, for example, The electrode material slurry is applied to both surfaces of the polymer electrolyte layer having a certain strength to form an electrode, and the electron conductive layer material slurry is applied to the electrode 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. That is, since it is only necessary to form an electron conductive layer on the electrode as opposed to the conventional case, the electron conductive layer does not require any strength as required in the conventional manufacturing process and can be easily thinned. This is also extremely advantageous.
[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 5 μm from the viewpoint of reducing the thickness and increasing the energy density and output density of the battery. A range of 10 μm is desirable. When the thickness of the electron conductive layer is less than 1 μm, there is a possibility of ionic short-circuiting, and when it exceeds 20 μm, the merit 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 does not have a large electron conduction resistance with respect to the plane direction in a state where the electron conductive filler is dispersed in the insulating polymer. The ion conduction resistance only needs to be very large.
[0015]
Among these, the electron conductive filler is not particularly limited and can be appropriately selected from conventionally known ones, and carbon black, metal fine particles, conductive ceramics, and the like can be used. . Among these, carbon black is preferable in that it can be variously modified due to 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 (high energy density, high power 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. When it exceeds 0.5 μm, it is difficult to form a thin film. The size here is the average value of the particle size (size) of the (basic) particles of the electron conductive filler.
[0017]
Further, the insulating polymer is not particularly limited, and can be appropriately selected from conventionally known ones as shown below, for example.
[0018]
(1) A thermoplastic insulating polymer can be used. As such thermoplastic insulating polymer, for example, polyethylene, polypropylene, polystyrene and the like can be suitably used.
[0019]
Examples of a method for producing an electron conductive layer using the thermoplastic insulating polymer include, for example, electrons obtained by kneading and dispersing an electron conductive filler in a molten insulating polymer and forming a thin film by extrusion molding. Although the method of forming a conductive layer, etc. are mentioned, it should not be limited to these at all.
[0020]
(2) The insulating polymer and the electron conductive filler can be dispersed in a solvent. The solvent-dispersible insulating polymer does not affect the battery performance and may be dispersed in a solvent. As such a solvent-dispersible insulating polymer, for example, neoprene / toluene or various fluoroelastomer / methyl ethyl ketone can be used.
[0021]
As a method for 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 is used. Prepare a thin film of the electron conductive layer by, for example, applying the raw material slurry for the electron conductive layer directly on the electrodes respectively formed on both surfaces of the electrolyte layer having a certain strength by spray coating or doctor blade. Film can be formed.
[0022]
Also, by applying the raw material slurry for the electron conductive layer to a glass plate or PET film, drying the solvent to produce a thin film, attaching the thin film to the electrode, and then peeling the glass plate or PET film A thin film of an electron conductive layer can also be formed.
[0023]
Here, in any of the above 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 blending amount of the electron conductive filler in the raw material so as to be in the range of 10-30% 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 is 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 embodiments.
[0025]
FIG. 1 is a partial cross-sectional schematic view schematically showing a first embodiment of a bipolar battery according to the present invention. As shown in FIG. 1, a bipolar battery 1 of the present invention has a positive electrode layer 5 on one surface of a single polymer electrolyte membrane (polymer electrolyte layer 3) and a negative electrode layer 7 on the other surface. A structure in which a plurality of electrode laminates 9 having a plurality of layers are stacked via an electron conductive layer 11, wherein the electron conductive layer 11 mainly includes an insulating polymer and an electron conductive filler. To do. In other words, a bipolar electrode 9 ′ having a structure in which the positive electrode layer 5 is disposed on one surface of the electron conductive layer 11 as a current collector and the negative electrode layer 7 is disposed on the other surface is replaced with a polymer electrolyte membrane (polymer It can also be said that a plurality of layers are stacked via the electrolyte layer 3). That is, the positive electrode layer 5, the electron conductive layer (current collector) 11, and the negative electrode layer 7 are stacked in this order.
[0026]
In the first embodiment of the bipolar battery according to the present invention, n electrode stacks 9 and n + 1 electron conductive layers 11 are alternately stacked, and the electron conductive layer 11 is disposed as the outermost layer. Good.
[0027]
The number of electrode stacks is adjusted according to the desired voltage. If a sufficient output can be ensured even if the battery is made as thin as possible, the number of stacked bipolar electrodes may be reduced.
[0028]
Next, in a second embodiment of the bipolar battery according to the present invention, an electrode laminate having a positive electrode layer on one surface of a single polymer electrolyte membrane and a negative electrode layer on the other surface, A bipolar battery having a structure laminated through an electron conductive layer, wherein the electron conductive layer has a layer mainly containing an insulating polymer and an electron conductive filler on at least one side of the 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, metal foil) is used as a part of the electron conductive layer, the same effect as described in the first embodiment can be obtained. In addition to the above, in order to avoid the problem of corrosion resistance on the positive electrode side, 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. As a result, a copper foil that cannot normally be used is also 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. Therefore, a battery having a high energy density and a high output density can be formed 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 an electron conductive layer. It is something that can be done.
[0030]
In the second embodiment of the bipolar battery according to the present invention, a layer mainly including an insulating polymer and an electron conductive filler provided on at least one surface of the metal layer (hereinafter, also simply referred to as a main layer) Since the structure is the same as that of the electron conductive layer described in the first embodiment of the present invention, the description thereof is omitted here.
[0031]
Also in the second embodiment of the bipolar battery according to the present invention, the thickness of the electron conductive layer is the electron in the first aspect of the present invention 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, although the thickness of the main layer depends on the thickness of the metal layer, it is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm. When the thickness of the main layer is less than 0.1 μm, the merit is reduced in terms of energy density. The thickness of the main layer here means the thickness when it is provided on one side of the metal layer, and the total thickness of both sides when it is provided on both sides of the metal layer. .
[0032]
The main layer, which is one of the constituent elements of the electron conductive layer, has a large ion conduction resistance in the plane direction in a state where the electron conductive filler is dispersed in the insulating polymer, and the ion conduction resistance is very high. It only needs to be large.
[0033]
Among these, the electron conductive filler can be appropriately selected from conventionally known ones, and is preferably carbon black. This is because carbon black is preferable in terms of dispersibility of the main layer in the insulating polymer and various surface modifications. By using carbon black as the electron conductive filler of the main layer, the purpose (high energy density, high output density) can be achieved more easily and at low cost.
[0034]
Further, the insulating polymer is not particularly limited, and can be appropriately selected from conventionally known ones as shown below, for example.
[0035]
(1) A thermoplastic insulating polymer can be used. As such thermoplastic insulating polymer, for example, polyethylene, polypropylene, polystyrene and the like can be suitably used.
[0036]
As a method for producing a main layer and further 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 then extruded. 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, the main layer thin film is laminated to an electrode (specifically, an electrode formed on an electrolyte layer) and then laminated, and then a metal layer is laminated on the main layer thin film to form an electron conductive layer, Furthermore, although an electrode laminated body can also be formed, it should not be limited to these methods.
[0037]
(2) The insulating polymer and the electron conductive filler can be dispersed in a solvent. The solvent-dispersible insulating polymer does not affect the battery performance and may be dispersed in a solvent. As such a solvent-dispersible insulating polymer, for example, neoprene / toluene or various fluoroelastomer / methyl ethyl ketone can be used.
[0038]
As a method for producing the main layer, and further the electron conductive layer, using the solvent-dispersible insulating polymer, for example, for the main layer formed by dispersing the insulating polymer and the electron conductive filler in a solvent A raw material slurry was prepared, and the main layer raw material slurry was laminated on the electrodes (specifically, electrodes formed on the electrolyte layer) formed on both surfaces of the electrolyte layer having a certain strength, for example. The thin film of the main layer can be formed by spray coating directly on the metal layer or coating with a doctor blade. In addition, when the main layer thin film is formed on the electrode by direct spray coating, coating with a doctor blade, etc., after coating the main layer raw material slurry and laminating the metal layer, it is dried to form the main layer. A thin film may be formed. Thereby, an electron conductive layer and also an electrode laminated body can be formed together.
[0039]
Moreover, the electron conductive layer can be formed by applying the raw material slurry for the main layer to one or both sides of the metal layer and drying the solvent to form a main layer thin film. In this case, by laminating the surface of the electron conductive layer on the main layer (or metal layer) side with an electrode (specifically, an electrode formed on the electrolyte layer) and laminating it, an electrode laminate described later is formed. It can also be formed.
[0040]
Furthermore, after applying the raw material slurry for the main layer to a glass plate or a PET film and drying the solvent to produce a thin film, the thin film is attached to an electrode (specifically, an electrode formed on the electrolyte layer), Thereafter, the glass plate and the PET film are peeled off, so that the thin film of the main layer can be formed simultaneously with the formation of the electron conductive layer (and electrode laminate).
[0041]
Here, in any of the above production methods (1) and (2), the content of the electron conductive filler such as carbon black in the main layer to be obtained is preferably 5 to 50% by mass, more preferably 10%. It is desirable to adjust the blending amount of the electron conductive filler in the raw material so as to be in the range of ˜30 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 is difficult to form a uniform thin film.
[0042]
Further, 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 conventionally known ones can be used, for example, aluminum foil, stainless steel foil, nickel An aluminum clad material, a copper clad aluminum clad material, or a plating material of a combination of these metals can be preferably used. Moreover, what coated aluminum on the metal surface may be used. In some cases, a laminate of two or more metal foils may be used. From the viewpoint of corrosion resistance, ease of production, economy, etc., it is preferable to use an aluminum foil as the metal layer.
[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, it is a manufacturing problem, and when it exceeds 20 μm, the merit of the battery becomes small.
[0045]
The ratio of the thickness of the main layer to the metal layer is not particularly limited, but may be about 10: 1 to 1:20.
[0046]
Hereinafter, typical examples of the second aspect 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 partial cross-sectional schematic view schematically showing a second representative embodiment of the bipolar battery according to the present invention. As shown in FIG. 2, the 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 on the other surface. An electrode laminate 29 having a negative electrode layer 27 is laminated via an electron conductive layer 31, and the electron conductive layer 31 is at least one side of the metal layer 31a, and in the figure, the positive electrode layer 25 and The contact surface has a layer 31b (layer having electron conductivity) mainly including an insulating polymer and an electron conductive filler (layer having electron conductivity). In other words, the positive electrode layer 25 is disposed on one surface of the electron conductive layer 31 as a current collector (on the side of the layer 31b having electron conductivity in FIG. 2), and the other surface (in FIG. 2, the metal layer 31a). It can be said that a bipolar electrode 29 'having a structure in which the negative electrode layer 27 is disposed on the side) is laminated by way of a polymer electrolyte membrane (polymer electrolyte layer 23). That is, the positive electrode layer 25, the electron conductive layer (current collector) 31 (the electron conductive layer 31b, the metal layer 31a), and the negative electrode layer 27 are stacked in this order.
[0048]
In the second embodiment of the bipolar battery according to the present invention, n electrode stacks 29 and n + 1 electron conductive layers 31 are alternately stacked, and the electron conductive layer 31 is disposed as the outermost layer. Good.
[0049]
The number of electrode stacks is adjusted according to the desired voltage. If a sufficient output can be ensured even if the battery is made as thin as possible, the number of stacked 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) laminated in a sheet shape is used as a battery exterior material or battery case (see FIG. (Not shown). Conventionally, such as a metal-polymer composite laminate film in which the inner surfaces (both sides) of aluminum, stainless steel, nickel, copper, etc. are laminated with an insulator such as a polypropylene film, among battery exterior materials or battery cases that seal the bipolar battery body What was coat | covered with the well-known battery exterior material etc. are suitable.
[0051]
The bipolar battery according to the present invention is used for a lithium ion secondary battery in which charging / discharging is mediated by movement of lithium ions. However, as long as effects such as improvement of battery characteristics can be obtained, application to other types of batteries is not prevented.
[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 constituent feature that characterizes the present invention, 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, and the electron conductive filler is an insulating material. It is only necessary that the electron conduction resistance is not so large with respect to the plane direction and the ionic conduction resistance is very large when dispersed in the polymer.
[0055]
Carbon black or the like can be suitably used as the electron conductive filler, but is not limited thereto. The amount of the 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, or polystyrene can be used as the insulating polymer.
[0057]
(2) An insulating polymer and an electron conductive filler that can be dispersed in a solvent can be used. Here, as the insulating polymer dispersible in the solvent, it does not affect the battery performance as long as it can be dispersed in the solvent. For example, neoprene / toluene or various fluoroelastomers / methyl ethyl ketone can be used.
[0058]
[Positive electrode layer (also referred to as positive electrode active material layer)]
The positive electrode layer includes a positive electrode active material. In addition, the polymer electrolyte may include a polar polymer and a lithium salt, a conductive aid, a binder, and the like to increase electronic conductivity.
[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. This is because, by filling the space between the positive electrode active materials in the positive electrode layer with the polymer solid electrolyte, the ion 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 positive electrode layer may not contain a polymer electrolyte, and may contain a conventionally known binder that binds the positive electrode active material fine particles to each other. .
[0061]
As the positive electrode active material, a composite oxide of transition metal and lithium, which is also used in a solution-type lithium ion battery, can be used. Specifically, LiCoO ₂ Li / Co complex oxides such as LiNiO ₂ Li / Ni composite oxides such as spinel LiMn ₂ O _Four Li · Mn based complex oxide such as LiFeO ₂ And Li / Fe-based composite oxides. In addition, LiFePO _Four Transition metal and lithium phosphate compounds and sulfuric acid compounds; V ₂ O _Five , MnO ₂ TiS ₂ , MoS ₂ , MoO _Three Transition metal oxides and sulfides such as PbO ₂ , AgO, NiOOH and the like.
[0062]
In order to reduce the electrode resistance of the bipolar battery, the positive electrode active material may have a particle size smaller than that generally used in a solution type lithium ion battery in which the electrolyte is not solid. Specifically, the average particle diameter of the positive electrode active material is preferably 0.1 to 5 μm.
[0063]
The polymer for the polymer solid electrolyte is not particularly limited, and examples thereof include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. Such polyalkylene oxide polymer is LiBF. _Four , LiPF ₆ , LiN (SO ₂ CF _Three ) ₂ , LiN (SO ₂ C ₂ F _Five ) ₂ Lithium salt such as can be dissolved well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure. 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 to be included in both.
[0064]
As the lithium salt, LiBF _Four , LiPF ₆ , LiN (SO ₂ CF _Three ) ₂ , LiN (SO ₂ C ₂ F _Five ) ₂ Or a mixture thereof. However, it is not necessarily limited to these.
[0065]
Examples of the conductive aid include acetylene black, carbon black, and graphite. However, it is not necessarily limited to these.
[0066]
As the binder, polyvinylidene fluoride (PVDF), SBR, polyimide, or the like can be used. However, it is not necessarily limited to these.
[0067]
The amount of 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 priority, energy priority, etc.) and ion conductivity. It is.
[0068]
For example, in the case of using a solid polymer electrolyte, taking the case where the blending amount is determined as an example, if the blending amount of the solid polymer electrolyte in the positive electrode layer is too small, the ion conduction resistance and ion The diffusion resistance increases and the battery performance decreases. On the other hand, if the amount of the solid polymer electrolyte in the positive electrode layer is too large, the energy density of the battery will be reduced. Therefore, in consideration of these factors, a polymer solid electrolytic mass that matches the purpose may be determined. In addition, what is necessary is just to determine suitably similarly about the compounding quantity of another structural component.
[0069]
Here, solid polymer electrolyte of the present level (ionic conductivity: 10 ^-Five -10 ^-Four Let us specifically consider the case of manufacturing a bipolar battery that prioritizes battery reactivity using (S / cm). In order to obtain a bipolar battery having such characteristics, the conductive conductivity is increased or the bulk density of the active material is decreased to keep the electron conduction resistance between the active material particles low. At the same time, the gap is increased and the polymer solid electrolyte is filled in the gap. The ratio of the solid polymer electrolyte may be increased 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 (emphasis on output, emphasis on energy, etc.) and ion conductivity as described for the blending amount. A typical positive electrode active material layer has a thickness of about 10 to 500 μm.
[0071]
[Negative electrode layer]
The negative electrode layer includes a negative electrode active material. In addition to this, a polymer electrolyte, a lithium salt for increasing ionic conductivity, a conductive additive, a binder, etc. for increasing electronic conductivity 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. This is because, by filling the gap between the negative electrode active materials in the negative electrode layer with the polymer solid 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 negative electrode layer may not contain a polymer electrolyte, and may contain a conventionally known binder that binds negative electrode active material fine particles to each other. . Except for the type of the negative electrode active material, the contents are basically the same as those described in the section “Positive electrode layer”, and thus the description thereof is omitted here.
[0074]
As the negative electrode active material, a negative electrode active material that is also used in a solution-type lithium ion battery can be used. Specifically, carbon, metal oxide, lithium-metal composite oxide, and the like can be used, and carbon or lithium-transition metal composite oxide is preferable. This is because a battery excellent in capacity and output characteristics (for example, the battery voltage can be increased) can be configured by using these. As the lithium-transition metal composite oxide, for example, a lithium-titanium composite oxide can be used. Moreover, as carbon, graphite, hard carbon, soft carbon etc. can be used, for example.
[0075]
[Polymer electrolyte layer]
The polymer electrolyte layer should not be limited to a solid polymer electrolyte, and even a polymer gel electrolyte prevents liquid junction by forming an insulating layer around the cell layer. These can be used as long as they can be used, and these can be used in combination. In addition, the electrolyte layer can have a multilayer structure, and a layer in which the type of electrolyte and the composition ratio of the electrolyte are changed can be formed on the positive electrode side and the negative electrode side. When a polymer gel electrolyte is used, the ratio (mass ratio) between the polymer constituting the polymer gel electrolyte and the electrolytic solution is not particularly limited, but is 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 exhibits ion conductivity. Examples of the polymer having ion conductivity include known polymers such as polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof. As the lithium salt, LiBF _Four , LiPF ₆ , LiN (SO ₂ CF _Three ) ₂ , LiN (SO ₂ C ₂ F _Five ) ₂ Or a mixture thereof. However, it is not necessarily limited to these. Polyalkylene oxide polymers such as PEO and PPO are LiBF _Four , LiPF ₆ , LiN (SO ₂ CF _Three ) ₂ , LiN (SO ₂ C ₂ F _Five ) ₂ Lithium salt such as can be dissolved well. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.
[0077]
Further, the polymer gel electrolyte is one in which an electrolyte solution usually used in a lithium ion battery is contained 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 depending on the positive electrode layer and the negative electrode layer, the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.
[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 it as thin as possible as long as the function as an electrolyte can be secured. A typical polymer electrolyte layer has a thickness of about 10 to 100 μm.
[0080]
[Positive electrode and negative electrode terminal plate]
The positive electrode and the negative electrode terminal plate may be used as necessary. When used, it has a function as a terminal, and it is better to be as thin as possible from the viewpoint of thinning. However, the laminated electrode, electrolyte and current collector all have weak mechanical strength. It is desirable to have sufficient strength to pinch and support from above. Furthermore, it can be said that the thickness of the positive electrode and the negative electrode terminal plate is usually preferably about 0.1 to 2 mm from the viewpoint of suppressing the internal resistance at the terminal portion.
[0081]
As the material of the positive electrode and the negative electrode terminal plate, materials usually used in lithium ion batteries can be used. For example, aluminum, copper, titanium, nickel, stainless steel (SUS), and alloys thereof can be used. Aluminum is preferably used from the viewpoints of corrosion resistance, ease of production, economy, and the like.
[0082]
The material of the positive electrode terminal plate and the negative electrode terminal plate may be the same material or different materials. Furthermore, the positive electrode and the negative electrode terminal plate may be a laminate of different materials.
[0083]
[Positive electrode and negative electrode lead]
As for the positive electrode and the negative electrode lead, known leads usually used in lithium ion batteries can be used. In addition, since the part taken out from 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 (particularly electronic equipment) by contacting with them and causing electric leakage. In addition, it is preferable to coat with a heat-resistant insulating heat-shrinkable tube or the like.
[0084]
[Battery exterior material (battery case)]
In order to prevent external impact and environmental degradation when using a bipolar battery, in order to prevent external impact and environmental degradation during use, the entire battery stack, which is the body of the bipolar battery, is used as a battery exterior material or battery case. It is good to accommodate in. From the viewpoint of weight reduction, 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, or copper is coated with an insulator such as a polypropylene film is used. The battery stack is preferably housed and sealed by joining part or all of the peripheral part thereof by thermal fusion. In this case, the positive electrode and the negative electrode lead may be structured to be sandwiched between the heat-sealed portions and exposed to the outside of the battery exterior material. In addition, it is preferable to use a polymer-metal composite laminate film having excellent thermal conductivity because heat can be efficiently transferred from the heat source of the automobile and the inside of the battery can be quickly heated to the battery operating temperature.
[0085]
Next, in the present invention, an assembled battery in which a plurality of the above bipolar batteries are connected can be obtained. In other words, by using an assembled battery in which at least two or more bipolar batteries of the present invention are connected in series and / or in parallel, the battery capacity and output requirements for each purpose of use can be handled relatively inexpensively. It becomes possible to do.
[0086]
Specifically, for example, N bipolar batteries are connected in parallel, and N parallel bipolar batteries are further connected in series in a metal or resin battery case to form a battery pack. . At this time, the number of series / parallel connections of the bipolar battery is determined according to the purpose of use. For example, a large-capacity power source such as an electric vehicle (EV) or a hybrid electric vehicle (HEV) may be combined so as to be applicable to a driving power source for a vehicle that requires high energy density and high output density. Moreover, what is necessary is just to electrically connect the positive electrode terminal and negative electrode terminal for assembled batteries, and the electrode lead of each bipolar battery using a lead wire. Further, when the bipolar batteries are connected in series / parallel, they may be electrically connected using an appropriate connecting member such as a spacer or a bus bar. However, the assembled battery of the present invention should not be limited to those described here, and conventionally known ones can be appropriately employed. In addition, the assembled battery may be provided with various measuring devices and control devices according to usage, for example, a voltage measuring connector may be provided to monitor the battery voltage, etc. There is no particular limitation.
[0087]
In 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 the 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 a vehicle, for example, an electric vehicle or a hybrid electric vehicle, which has particularly strict requirements regarding energy density and output density. For example, it is convenient to install an assembled battery as a driving power source under the seat in the center of the body of an electric vehicle or hybrid electric vehicle because it allows a large in-house space and trunk room. However, the present invention should not be limited to these, and may be mounted in the lower part of the rear trunk room, or if the engine is not mounted like an electric vehicle, the engine in front of the vehicle body is mounted. It can also be mounted on parts that have been damaged. In the present invention, not only the assembled battery but also a bipolar battery may be mounted depending on the intended use, or a combination of these assembled battery and bipolar battery may be mounted. 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 and hybrid electric vehicle are preferable, but are not limited thereto.
[0088]
The method for producing the bipolar battery of the present invention is not particularly limited, and various conventionally known methods can be appropriately used. This will be briefly described below.
[0089]
(1) Formation of electron conductive layer
The electron conductive layer mainly containing the insulating polymer and the electron conductive filler is obtained as follows.
[0090]
(1) When using a thermoplastic polymer such as polyethylene, polypropylene, or polystyrene as the insulating polymer, knead and disperse the electronically conductive filler in the molten insulating polymer and make it into a thin film by extrusion molding. Is obtained.
[0091]
(2) In the case where an insulating polymer and an electron conductive filler that can be dispersed in a solvent are used, a slurry obtained 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, the slurry is obtained by applying the slurry on a support material such as a glass plate or a PET film and drying the solvent to produce a thin film. In the case of (2), an electrode to be formed in (2) and thereafter is previously formed on an appropriate support material (such as a glass plate or PET film) or an electrolyte layer, and an electron conductive layer is formed on the electrode. What is necessary is just to form in the procedure of 2 ▼. That is, the procedure described below is the procedure in the case of (1) above, and in the case of (2), the order of formation, application and lamination object or application and lamination object is exchanged. It is. However, as shown in FIGS. 1 and 2 already described, when the battery is configured, the electrode is formed on the existing current collector, but an electron conductive layer is formed on the electrode instead of the current collector. Except for, a battery can be formed in the same manner as (1). Therefore, since the battery manufacturing procedure using the manufacturing method (2) is performed in the embodiment, the description thereof is omitted here.
[0092]
(2) Application of positive electrode composition
The positive electrode composition is usually obtained as a slurry (positive electrode slurry) and applied onto a film such as PET. In addition, the electron conductive layer prepared in the above (1) may be prepared and applied to one surface thereof.
[0093]
The positive electrode slurry includes a positive electrode active material, and optionally includes a conductive additive, a binder, a polymerization initiator, a polymer raw material for a polymer electrolyte, a lithium salt, a solvent, and the like as other components. In the case of using a polymer gel electrolyte for the polymer electrolyte layer, it is sufficient that a conventionally known binder that binds the positive electrode active material fine particles, a conductive aid for enhancing electronic conductivity, a solvent, and the like be included. The host polymer, the electrolyte solution, the lithium salt, and the like, which are raw materials for the gel electrolyte, may not be included.
[0094]
Examples of the polymer raw material for the polymer electrolyte include PEO, PPO, and copolymers thereof, and preferably have 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]
Regarding the positive electrode active material, the conductive additive, the binder, and the lithium salt, the above-described compounds can be used.
[0096]
The polymerization initiator needs to be selected according to the compound to be polymerized. For example, benzyl dimethyl ketal is used as the photopolymerization initiator, and azobisisobutyronitrile is used as the thermal polymerization initiator.
[0097]
A 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, lithium salt, conductive additive, binder, polymer electrolyte polymer raw material and the like may be adjusted according to the purpose of the bipolar battery, and may be an amount usually used. The addition amount of the polymerization initiator is determined according to the amount of the polymer raw material of the polymer electrolyte. Usually, it is about 0.01-1 mass% with respect to a polymeric 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 positive electrode slurry, the cross-linking reaction may be advanced to increase the mechanical strength of the polymer solid electrolyte. For drying, a vacuum dryer or the like can be used. The drying conditions are determined according to the applied positive electrode slurry and cannot be uniquely defined, but are usually 1 to 6 hours at 80 to 120 ° C.
[0100]
(4) Application of negative electrode composition
The negative electrode composition is usually obtained as a slurry (positive electrode slurry) and applied onto a film such as PET. In addition, you may apply | coat the composition for negative electrodes (slurry for negative electrodes) containing a negative electrode active material to the surface of the electron conductive layer on the opposite side to the surface where the positive electrode layer was apply | coated.
[0101]
The negative electrode slurry contains a negative electrode active material, and optionally includes a conductive additive, a binder, a polymerization initiator, a polymer raw material for a polymer electrolyte, a lithium salt, a solvent, and the like as other components. Since the raw materials used and the amounts added are the same as those described in the section “(1) Application of positive electrode composition”, the description thereof is omitted here.
[0102]
(5) Formation of negative electrode layer
The electron conductive layer coated with the negative electrode slurry is dried to remove the contained solvent. At the same time, depending on the slurry for the negative electrode, the cross-linking reaction may be advanced to increase the mechanical strength of the polymer electrolyte. This work completes the bipolar electrode. For drying, a vacuum dryer or the like can be used. The drying conditions are determined according to the applied slurry for negative electrode and cannot be uniquely defined, but are usually 1 to 6 hours at 80 to 120 ° C.
[0103]
(6) Lamination of bipolar electrode and polymer electrolyte layer
Separately, a polymer electrolyte layer laminated between the electrodes is prepared.
[0104]
When the polymer solid electrolyte layer is used, for example, the polymer solid electrolyte is manufactured by curing a solution prepared by dissolving a polymer solid electrolyte raw material polymer, lithium salt, and the like in a solvent such as NMP. In the case of using a polymer gel electrolyte layer, for example, as a raw material for the polymer gel electrolyte, a pregel solution composed of a host polymer and an electrolytic solution, a lithium salt, a polymerization initiator and the like is simultaneously heated and dried in an inert atmosphere. It is produced by polymerizing (accelerating the crosslinking reaction).
[0105]
The thickness of these polymer electrolyte layers can be controlled using a spacer. In the case of using a photopolymerization initiator, the film may be formed by pouring into a light-transmitting gap and irradiating with ultraviolet rays to advance the crosslinking reaction. However, it is needless to say that the method is not limited to this. Depending on the type of polymerization initiator, radiation polymerization, electron beam polymerization, thermal polymerization, etc. are used properly. Since the raw material polymer, electrolytic solution, lithium salt, polymerization initiator, blending amount, etc. of the polymer electrolyte to be used are as described above, description thereof is omitted here.
[0106]
The positive and negative electrodes and polymer solid electrolyte layer produced as described above are sufficiently heated and dried under high vacuum, and then a plurality of positive and negative electrodes and polymer electrolyte layers are cut into appropriate sizes. A predetermined number of the cut bipolar electrodes and polymer electrolyte layers are bonded together to produce a laminated battery. The number of stacked layers is determined in consideration of battery characteristics required for the bipolar battery. An electrode is disposed on each outermost polymer electrolyte layer. In the outermost layer on the positive electrode side, an electrode in which only the positive electrode layer is formed on the electron conductive layer is disposed. 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 disposed. The step of obtaining the bipolar battery body (battery laminate) by laminating the positive and negative electrodes and the polymer electrolyte layer is preferably performed in an inert atmosphere from the viewpoint of preventing moisture and the like from being mixed into the battery. For example, the bipolar battery may be manufactured in an argon atmosphere or a nitrogen atmosphere.
[0107]
(7) Packing (Battery completion)
Finally, a positive electrode terminal plate and a negative electrode terminal plate are installed on both outermost electron conductive layers of the bipolar battery main body (battery laminate), and further, a positive electrode lead and a negative electrode lead are added to 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 having a low bonding temperature can be suitably used. A known bonding method can be used as appropriate.
[0108]
In order to prevent external impact and environmental degradation, the entire battery stack is sealed with a battery exterior material or battery case to complete a bipolar battery. The material of the battery exterior material (battery case) is preferably a metal (aluminum, stainless steel, nickel, copper, etc.) 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]
Examples of the present invention and comparative examples will be described below.
[0111]
As the polymer electrolyte, a polyether-type network polymer raw material synthesized according to literature methods is used (J. Electrochem. Soc., 145 (1998) 1521.), and lithium salt is LiN (SO ₂ C ₂ F _Five ) ₂ (Hereinafter, this is abbreviated as BETI).
[0112]
(1) Preparation of polymer electrolyte membrane
First, the polymer electrolyte membrane was produced as follows. A solution was prepared using 53% by mass of the above polymer material, 26% by mass of BETI as a lithium salt, 0.1% by mass of benzyldimethyl ketal as a photopolymerization initiator, and dry acetonitrile as a solvent. Acetonitrile was then removed by vacuum distillation. The thickness was defined using a Teflon (registered trademark) spacer, and the glass substrate was filled with this highly viscous solution, and irradiated with ultraviolet rays for 20 minutes for photopolymerization (crosslinking). The film was taken out and placed in a vacuum vessel and heat-dried at 90 ° C. for 12 hours under high vacuum to remove residual moisture and solvent. The thickness of the produced polymer electrolyte membrane was 20 μm.
[0113]
(2) Production of negative electrode layer
The negative electrode layer was produced as follows. Li as negative electrode active material _Four Ti _Five 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 raw material, 8% by mass of BETI, 0.1% by mass of azobisisobutyronitrile as the thermal polymerization initiator And 44% by mass of NMP as a solvent was added and sufficiently stirred to prepare a slurry. The slurry was coated on a PET fill with a coater and dried by heating at 90 ° C. for 2 hours or more in a vacuum dryer. Was made. The thickness of the produced negative electrode active material layer was 22 μm.
[0114]
(3) Preparation of positive electrode layer
The positive electrode layer was produced as follows. LiMn as positive electrode active material ₂ O _Four A positive electrode layer was used. Specifically, 29% by mass of LiMn with an average particle diameter of 2 μm ₂ O _Four 8.7% by mass of acetylene black, 17% by mass of the above polymer raw material, 7.3% by mass of BETI, and 0.1% by mass of azobisisobutyronitrile as a thermal polymerization initiator, A slurry was prepared by adding 41% by mass of NMP as a solvent and stirring sufficiently, and coated on a PET film with a coater, and heated and dried at 90 ° C. for 2 hours or more in a vacuum dryer to produce a positive electrode. . The thickness of the prepared positive electrode active material layer was 20 μm.
[0115]
In the following examples and comparative examples, production and experiments were all performed under the following conditions.
[0116]
(1) Size of electrode part: 30 mm × 30 mm,
(2) Number of electrode laminated cells (single battery layers): 10,
(3) Charging / discharging conditions: 0.2 C constant current, 27 V constant voltage charging was performed for a total of 10 hours, and the discharge was 10 V cut off at 0.1 C.
[0117]
Example 1
(1) Carbon black (about 30% by mass with respect to 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. A negative electrode layer / polymer electrolyte layer / positive electrode layer is formed on a copper foil, and the electron conductive layer (1) is disposed on the positive electrode layer, and further, the negative electrode layer / polymer electrolyte layer / positive electrode is further formed thereon. Layers were placed. This was repeated 10 times to place an aluminum foil on the last positive electrode layer.
[0119]
A nickel tab (terminal lead) was attached to the copper foil and the aluminum foil, and the electrode part was vacuum sealed in an aluminum laminate film pack to obtain a battery.
[0120]
As shown in this embodiment, in the present invention, a conventional current collector may be employed instead of the electron conductive layer for the electron conductive layer of the outermost electrode of the battery. In particular, the first embodiment that does not use a metal layer is useful in that the terminal leads can be easily connected.
[0121]
Example 2
(1) Disperse neoprene and carbon black in toluene (solid content of about 20% by mass, of which 40% by mass is carbon black), spray coat on PET film and dry with hot air to give a 5μm thick electron A conductive film was produced and used in place of the electron conductive film of Example 1 to construct a bipolar battery similar to that of Example 1.
[0122]
Example 3
The electron conductive film of Example 2 is formed on a copper foil having a thickness of 4 μm, and this electron-transmitting film is disposed with the negative electrode side surface of Example 1 made of copper foil. A battery was constructed.
[0123]
Comparative Example 1
Instead of the electron conductive film of Example 1, as shown in FIG. 3, 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 film on the negative electrode layer side. A bipolar battery similar to that of Example 1 was configured by laminating using the foil (second current collecting foil 51b).
[0124]
Using the fabricated bipolar battery as charging / discharging conditions, 0.2C constant current and 27V constant voltage charging were performed for a total of 10 hours, and discharging was performed at 10V cutoff at 0.1C. The results are shown in Table 1 with the ratio of the battery value of Comparative Example 1 taken. As can be seen from the results 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 an electron conductive layer that separates cells (unit cell layers) of a bipolar battery. The energy density of the bipolar battery can be improved as compared with the case of using a metal foil as the electric body.
[0125]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a partial sectional schematic view schematically showing a first embodiment of a bipolar battery according to the present invention.
FIG. 2 is a partial sectional schematic view schematically showing a second representative embodiment of a bipolar battery according to the present invention.
FIG. 3 is a partial cross-sectional schematic view schematically showing a bipolar battery using a conventional current collector and produced 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 ... single cell layer,
9 ', 29', 49 '... bipolar electrode,
11, 31 ... electron conductive layer,
31a ... metal layer,
31b ... layer having electron conductivity,
51 ... current collector foil,
51a ... First current collector foil,
51b ... Second current collector foil.

Claims (5)

Bipolar lithium ion secondary battery having a structure in which an electrode laminate having a positive electrode layer on one side of a polymer electrolyte membrane and a negative electrode layer on the other side is laminated via an electron conductive layer. In the next battery,
Electron conductivity layer is mainly seen contains an insulating polymer and an electron-conductive filler, has a thickness of 0.1~10μm electronically conductive layer, the average value of the particle size of the electronically conductive filler particles A bipolar lithium ion secondary battery having a thickness of less than 0.5 μm . Bipolar lithium ion secondary battery having a structure in which an electrode laminate having a positive electrode layer on one side of a polymer electrolyte membrane and a negative electrode layer on the other side is laminated via an electron conductive layer. In the next battery,
Electron conductivity layer have a layer mainly comprising at least one surface an insulating polymer and an electron conductive filler metal layer, the thickness of the electron-conducting layer is 0.1 to 10 [mu] m, an electron-conductive filler A bipolar lithium ion secondary battery having an average particle size of less than 0.5 μm . 3. The bipolar lithium ion secondary battery according to claim 2, wherein a negative electrode is formed on the metal layer side of the electron conductive layer, and a positive electrode is formed on the layer side mainly containing the insulating polymer and the electron conductive filler. . Electronic conductive filler, bipolar type lithium ion secondary battery according to any one of claims 1 to 3, wherein the carbon black. An assembled battery comprising a plurality of bipolar lithium ion secondary batteries according to any one of claims 1 to 4 .

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