JP4720384B2 - Bipolar battery - Google Patents

Description

  The present invention relates to a bipolar battery.

  In recent years, reduction of carbon dioxide emissions has been strongly desired for environmental protection. In the automobile industry, there are high expectations for reducing carbon dioxide emissions by introducing electric vehicles (EVs) and hybrid electric vehicles (HEVs), and we are eager to develop secondary batteries for motor drives that hold the key to their practical application. Has been done. As a secondary battery, attention is focused on a stacked bipolar battery that can achieve high energy density and high output density (see Patent Document 1).

A typical bipolar battery includes a battery element in which a plurality of bipolar electrodes are connected in series with an electrolyte layer interposed therebetween. In the bipolar electrode, a positive electrode is formed by providing a positive electrode active material layer on one surface of a current collector, and a negative electrode is formed by providing a negative electrode active material layer on the other surface. A single battery layer is formed by sequentially stacking a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer, and the single battery layer is sandwiched between a pair of current collectors. Bipolar batteries have the advantage that a current path is short and current loss is small because current flows in the direction of stacking bipolar electrodes in the battery element, that is, the thickness direction of the battery (hereinafter referred to as “stacking direction”).
JP 2001-236946 A

  In the bipolar battery, when the electrolyte contained in the electrolyte layer oozes out, the layers are electrically connected to each other and do not function as a battery. This is called a liquid junction. When the electrolyte layer is composed of a liquid or semi-solid gel electrolyte, a seal member is provided between the current collectors around the unit cell layer in order to prevent a liquid junction from being caused by electrolyte leakage. It is provided so as to surround it.

  However, the current collector is a thin metal, and complicated work is required to seal between the current collectors.

  An object of the present invention is to provide a bipolar battery that improves the sealing performance when an electrolyte layer is formed from a liquid or semi-solid gel electrolyte.

In order to achieve the above object, the present invention provides a single battery layer in which a positive electrode active material layer, an electrolyte layer made of a liquid or semi-solid gel electrolyte, and a negative electrode active material layer are sequentially laminated between a pair of current collectors. A single cell element composed of sandwiched,
A sealing portion for sealing the single cell element, and a flexible exterior material provided with a conductive portion having conductivity that contacts each of the current collectors ,
The outer packaging material is a bipolar battery that has electrical insulation except for the conductive portion and is configured to extract current from the conductive portion .

Since a single cell element is sealed with an exterior material, even when the electrolyte layer is formed from a liquid or semi-solid gel electrolyte, a seal is provided between the current collectors. There is no need to provide a section. Therefore, it is possible to provide a bipolar battery that improves the sealing performance against electrolyte leakage by eliminating the complicated work for sealing between the current collectors. In addition, the seal portion in the exterior material can easily form a seal having a higher sealing property than the seal applied between the current collectors, and liquid leakage does not occur from the bipolar battery. Further, since the current is taken out from the conductive portion, there is no need to lead out the lead portion from which the current is taken out from the seal portion of the exterior material, and thus the single cell element can be reliably sealed with the exterior material.

  Embodiments of the present invention will be described below with reference to the drawings. For easy understanding, each component is exaggerated in the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a bipolar battery 11 according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 3A and 3B are cross-sectional views showing the conductive portion 41 of the exterior material 40 in an enlarged manner.

  Referring to FIGS. 1 and 2, bipolar battery 11 is generally formed by sequentially laminating positive electrode active material layer 21, electrolyte layer 22 made of a liquid or semi-solid gel electrolyte, and negative electrode active material layer 23. A unit cell element 30 configured by sandwiching the unit cell layer 20 between a pair of current collectors 31, 32, a seal portion 43 for sealing the unit cell element 30, and the current collectors 31, 32 And a flexible exterior member 40 provided with conductive portions 41 and 42 having electrical conductivity in contact with each other. The exterior material 40 is a general term for an upper exterior material 40a shown on the upper side in the drawing and a lower exterior material 40b shown on the lower side in the drawing.

  The positive electrode active material layer 21 is provided on one surface of the positive electrode current collector 31, and the negative electrode active material layer 23 is provided on one surface of the negative electrode current collector 32. The positive electrode active material layer 21 is opposed to one surface of the electrolyte layer 22, and the negative electrode active material layer 23 is opposed to the other surface of the electrolyte layer 22, so that the positive electrode current collector 31, the electrolyte layer 22, and the negative electrode current collector are By laminating 32, the cell element 30 is assembled.

  In a battery element in which a plurality of single battery layers are stacked via a current collector, the current collector is made of a material and structure that is stable with respect to both the positive electrode active material and the negative electrode active material. It is necessary to select. On the other hand, since the bipolar battery 11 of this embodiment includes only one single cell element 30 and the positive electrode and the negative electrode are independent, the most suitable material for the positive electrode current collector 31 and the negative electrode current collector 32 is used. Can be selected easily. For example, aluminum is used for the positive electrode current collector 31, and copper is used for the negative electrode current collector 32, for example. The thickness of the current collectors 31 and 32 is not particularly limited, but is about 1 μm to 100 μm.

  The exterior material 40 is formed from a flexible sheet-like material. The internal pressure of the internal space surrounded by the exterior material 40 is set to a pressure lower than the atmospheric pressure. The unit cell element 30 is pressurized from both sides along the thickness direction by the hydrostatic pressure using atmospheric pressure, and the conductive portions 41 and 42 of the exterior member 40 are in close contact with the current collectors 31 and 32, respectively. The packaging material 40 has electrical insulation except for the conductive portions 41 and 42. It is desirable that the packaging material 40 is chemically stable with respect to the electrolyte material and does not transmit electrolyte or gas. By sealing the single cell element 30 with the exterior material 40, the impact applied to the single cell element 30 from the outside can be alleviated, and environmental degradation due to liquid leakage or the like can be prevented.

  As shown in a partially enlarged view in FIG. 2, the packaging material 40 is preferably formed from a laminate film 50 including a metal foil layer 51 and electrically insulating resin layers 52 and 53. This is because the heat sealing property is good, the possibility that the electrolyte comes into contact with air can be reduced, and further, it is preferable for reducing the weight. The laminate film 50 covers a metal foil layer 51 made of a metal (including an alloy) such as aluminum, stainless steel, nickel, or copper with electrically insulating resin layers 52 and 53 made of a synthetic resin such as polyethylene, polypropylene, or polycarbonate. It has a three-layer structure. The laminate film 50 is also preferably excellent in thermal conductivity. This is because when mounted on an automobile, heat can be efficiently transmitted from the automobile heat source to the bipolar battery 11 and the single cell element 30 can be quickly heated to the battery operating temperature.

  The seal portion 43 of the exterior material 40 is formed from, for example, a heat sealing layer. The unit cell element 30 is sealed by joining the seal portion 43 by heat fusion. When the single battery element 30 is sealed by the two exterior members 40, the seal part 43 is provided over the entire periphery of the peripheral edge of the exterior member 40, and the bag-like exterior member 40 having a part opened. When the battery element 30 is sealed, a seal portion 43 is provided at the opening.

  Since the current flows in the thickness direction of the unit cell element 30, the conductive portions 41 and 42 of the exterior member 40 function as terminals for taking out the current. Since it is not necessary to lead out the lead portion for taking out the current from the seal portion 43 of the exterior member 40, the single cell element 30 can be reliably sealed by the exterior member 40.

  It is desirable that the conductive portions 41 and 42 are disposed on the inner side of the projection surfaces of the current collectors 31 and 32. This is because the laminate film 50 has flexibility, and if the conductive portions 41 and 42 are larger than the projection surface of the current collectors 31 and 32, the conductive portions 41 and 42 may be short-circuited.

  With reference to FIGS. 3A and 3B, the conductive portions 41 and 42 of the exterior material 40 include a conductive resin material 61. In this figure, only the conductive portion 41 is illustrated, but the conductive portion 42 is similarly configured. The conductive portion 41 shown in FIG. 3A is configured by replacing the part of the electrically insulating resin layers 52 and 53 with the conductive resin material 61 while leaving the metal foil layer 51 of the laminate film 50. . The conductive part 41 in this case has a three-layer structure of conductive resin material 61 -metal foil layer 51 -conductive resin material 61. The conductive portion 41 shown in FIG. 3B is configured by eliminating the metal foil layer 51 of the laminate film 50 and replacing a part of the electrically insulating resin layers 52 and 53 with the conductive resin material 61. . In this case, the conductive portion 41 is made of a single layer of conductive resin material 61. The conductive resin material 61 is manufactured, for example, by adding a conductive filler to an electrically insulating resin material such as polypropylene.

  Here, the conductive resin material 61 has electrical anisotropy with conductivity in the thickness direction of the unit cell element 30 and insulation with respect to the surface direction of the unit cell element 30. It is desirable that This is because the characteristic of the bipolar battery 11 that current flows in the thickness direction of the unit cell element 30 is not impaired.

  Since the bipolar battery 11 according to the first embodiment employs a form in which one single cell element 30 is sealed with an exterior material 40, the electrolyte layer 22 is composed of a liquid or semi-solid gel electrolyte. Even in this case, it is not necessary to provide the seal portion 43 between the current collectors 31 and 32. Therefore, it is possible to provide the bipolar battery 11 in which the sealing performance against electrolyte leakage is improved by fundamentally eliminating the troublesome work for sealing between the current collectors 31 and 32. . Further, the seal portion 43 in the exterior material 40 can easily form a seal having a higher sealing property than the seal applied between the current collectors 31 and 32, and no liquid leakage occurs from the bipolar battery 11. .

  The configuration of the bipolar battery 11 of the present invention is not particularly limited, and may be any known material used for a general lithium ion secondary battery, except for those specifically described. Hereinafter, a positive electrode active material layer, a negative electrode active material layer, an electrolyte, and the like that can be used for the bipolar battery 11 will be described for reference.

(Positive electrode active material layer)
The positive electrode includes a positive electrode active material. In addition to this, a conductive aid, a binder, and the like may be included. The gel electrolyte is sufficiently infiltrated into the positive electrode and the negative electrode by chemical crosslinking or physical crosslinking.

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, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, Li · Mn-based composite oxide such as spinel LiMn ₂ O _4, Li · such LiFeO ₂ Examples thereof include Fe-based composite oxides. In addition, transition metal and lithium phosphate compounds and sulfuric acid compounds such as LiFePO ₄ ; transition metal oxides and sulfides such as V ₂ O ₅ , MnO ₂ , TiS ₂ , MoS ₂ , and MoO ₃ ; PbO ₂ , AgO, NiOOH etc. are mentioned.

  The particle size of the positive electrode active material is not limited as long as it can be formed into a paste by spraying the positive electrode material and spray coating or the like, but in order to further reduce the electrode resistance of the bipolar battery, the electrolyte is not a solid solution type What is smaller than the generally used particle size used in the lithium ion battery of the present invention may be used. Specifically, the average particle diameter of the positive electrode active material is preferably 0.1 μm to 10 μm.

  The polymer gel electrolyte is a solid polymer electrolyte having ion conductivity containing an electrolyte solution usually used in a lithium ion battery. Further, in the polymer skeleton having no lithium ion conductivity, In addition, those holding the same electrolytic solution are also included.

Here, the electrolyte solution (electrolyte salt and plasticizer) contained in the polymer gel electrolyte may be any electrolyte solution that is normally used in lithium ion batteries. For example, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiTaF. ₆ , inorganic acid anion salts such as LiAlCl ₄ and Li ₂ B ₁₀ Cl ₁₀ , organic acid anions such as LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, and Li (C ₂ F ₅ SO ₂ ) ₂ N Including at least one lithium salt (electrolyte salt) selected from ionic salts, cyclic carbonates such as propylene carbonate and ethylene carbonate; chain carbonates such as dimethyl carbonate, methyl ethyl carbonate, and diethyl carbonate; tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane Ethers such as 1,2-dimethoxyethane and 1,2-dibutoxyethane; Lactones such as γ-butyrolactone; Nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; Methyl acetate Further, those using an organic solvent (plasticizer) such as an aprotic solvent in which at least one selected from methyl formate or a mixture of two or more thereof can be used. However, it is not necessarily limited to these.

  Examples of the polymer having ion conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

  For example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), etc. are used as the polymer having no lithium ion conductivity used for the polymer gel electrolyte. it can. However, it is not necessarily limited to these. Note that PAN, PMMA, etc. are in a class that has almost no ionic conductivity. Therefore, the PAN, PMMA, and the like can be used as a polymer having the ionic conductivity described above, but are used here as a polymer gel electrolyte. This is exemplified as a polymer having no lithium ion conductivity.

As the lithium salt, for _{example, LiPF 6, LiBF 4, LiClO} 4, LiAsF 6, LiTaF 6, LiAlCl 4, Li 2 B 10 Cl 10 and the like inorganic acid anion _{salts, Li (CF 3 SO 2)} 2 N, An organic acid anion salt such as Li (C ₂ F ₅ SO ₂ ) ₂ N or a mixture thereof can be used. However, it is not necessarily limited to these.

  Examples of the conductive assistant include acetylene black, carbon black, and graphite. However, it is not necessarily limited to these.

  In this embodiment, these electrolyte solution, lithium salt, and polymer (polymer) are mixed to prepare a pregel solution, and the positive electrode and the negative electrode are impregnated.

  The blending amount of the positive electrode active material, the conductive additive, and the binder in the positive electrode should be determined in consideration of the intended use of the battery (emphasis on output, energy, etc.) and ion conductivity. For example, if the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too small, the ionic conduction resistance and the ionic diffusion resistance in the active material layer will increase and the battery performance will deteriorate. On the other hand, when the amount of the electrolyte in the positive electrode, particularly the solid polymer electrolyte, is too large, the energy density of the battery decreases. Therefore, in consideration of these factors, the solid polymer electrolytic mass meeting the purpose is determined.

  The thickness of the positive electrode 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.

(Negative electrode active material layer)
The negative electrode includes a negative electrode active material. In addition to this, a conductive aid, a binder, and the like may be included. Since the contents other than the type of the negative electrode active material are basically the same as the contents described in the section “Positive electrode”, the description is omitted here.

  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. For example, metal oxide, lithium-metal composite oxide metal, carbon and the like are preferable. More preferred are carbon, transition metal oxide, and lithium-transition metal composite oxide. More preferred are titanium oxide, lithium-titanium composite oxide, and carbon. These may be used alone or in combination of two or more.

  In this embodiment, the positive electrode active material layer uses lithium-transition metal composite oxide as the positive electrode active material, and the negative electrode active material layer uses carbon or lithium-transition metal composite oxide as the negative electrode active material. Is used. This is because a battery having excellent capacity and output characteristics can be configured.

(Electrolyte layer)
The electrolyte layer is a layer composed of a polymer having ion conductivity, and the material is not limited as long as it exhibits ion conductivity.

  The electrolyte of this embodiment is a polymer gel electrolyte. As described above, after impregnating a pregel solution into a separator as a substrate, the electrolyte is used as a polymer gel electrolyte by chemical crosslinking or physical crosslinking.

  Such a polymer gel electrolyte is an all-solid polymer electrolyte having ion conductivity such as polyethylene oxide (PEO) containing an electrolytic solution usually used in a lithium ion battery. A polymer gel electrolyte that contains a similar electrolyte solution in a polymer skeleton having no lithium ion conductivity such as vinylidene (PVDF) is also included. Since these are the same as the polymer gel electrolyte described as a kind of electrolyte contained in the positive electrode, description thereof is omitted here. The ratio of the polymer and the electrolyte constituting the polymer gel electrolyte is wide. When 100% of the polymer is an all-solid polymer electrolyte and 100% of the electrolyte is a liquid electrolyte, all of the intermediates correspond to the polymer gel electrolyte. The term “polymer electrolyte” includes both a polymer gel electrolyte and an all solid polymer electrolyte.

  The polymer gel electrolyte can be contained in the positive electrode and / or the negative electrode as described above in addition to the polymer electrolyte constituting the battery, but uses a polymer electrolyte that differs depending on the polymer electrolyte constituting the battery, the positive electrode, and the negative electrode. Alternatively, the same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.

  The thickness of the electrolyte 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. The thickness of a general solid polymer electrolyte layer is about 10 to 100 μm. However, the shape of the electrolyte can be easily formed so as to cover the upper surface of the electrode (positive electrode or negative electrode) as well as the outer periphery of the side surface, taking advantage of the characteristics of the manufacturing method. It is not always necessary to have a substantially constant thickness.

(Second Embodiment)
FIG. 4 is a cross-sectional view showing a bipolar battery 12 according to the second embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which is common in the member shown in FIGS. 1-3, and the description is abbreviate | omitted in part.

  The second embodiment is different from the first embodiment in that it is a bipolar battery 11 having one single battery element 30 in that it is a stacked type bipolar battery 12 having a plurality of single battery elements 30. .

  In the stacked type bipolar battery 12, a plurality (two in the illustrated example) of the single cell elements 30 are each sealed by the exterior material 70 and the conductive portion 74 of the exterior material 70 is provided. Are electrically connected in series. The exterior material 70 is a general term for an upper exterior material 70a shown on the upper side in the figure, a lower exterior material 70b shown on the lower side in the figure, and a central exterior material 70c shown in the center in the figure. Reference numeral “73” denotes a seal portion for sealing the unit cell element 30.

  In the figure, the upper unit cell element 30 is sealed with exterior members 70a and 70c, and the lower unit cell element 30 is sealed with exterior members 70c and 70b. That is, the exterior material 70 c interposed between the unit cell elements 30 is shared to seal each of the two unit cell elements 30. The negative electrode current collector 32 of the upper unit cell element 30 and the positive electrode current collector 31 of the lower unit cell element 30 are electrically connected via the conductive portion 74 of the exterior member 70c. Thereby, the upper unit cell element 30 and the lower unit cell element 30 are electrically connected in series. The conductive portions 71, 72, and 74 are formed in the same manner as in the first embodiment.

  The bipolar battery 12 of the second embodiment includes a plurality of unit cell elements 30. However, if attention is paid to the individual unit cell elements 30, one unit cell as in the first embodiment. A form in which the element 30 is sealed with the exterior material 70 is employed. For this reason, even when the electrolyte layer 22 is composed of a liquid or semi-solid gel electrolyte, it is not necessary to provide the seal portion 43 between the current collectors 31 and 32. Therefore, it is possible to provide the bipolar battery 12 that improves the sealing performance against leakage of the electrolyte by fundamentally eliminating the troublesome work for sealing between the current collectors 31 and 32. . Further, the seal portion 73 in the exterior material 70 can easily form a seal having higher sealing performance than the seal applied between the current collectors 31 and 32, and no liquid leakage occurs from the bipolar battery 12. .

(Modified example of conductive parts 41, 42, 71, 72, 74)
Hereinafter, taking the conductive part 41 as an example, a modification of the conductive part 41 will be described with reference to FIGS.

  5A and 5B, the conductive portion 41 of the exterior material 40 may include a resin material 63 in which a metal piece 62 is embedded. The conductive portion 41 shown in FIG. 5A leaves the metal foil layer 51 of the laminate film 50 and replaces a part of the electrically insulating resin layers 52 and 53 with a resin material 63 in which a metal piece 62 is embedded. It is configured. The conductive portion 41 in this case has a three-layer structure of a resin material 63 in which a metal piece 62 is embedded, a metal foil layer 51, and a resin material 63 in which a metal piece 62 is embedded. The conductive portion 41 shown in FIG. 5B is obtained by eliminating the metal foil layer 51 of the laminate film 50 and replacing a part of the electrically insulating resin layers 52 and 53 with a resin material 63 in which a metal piece 62 is embedded. It is configured. In this case, the conductive portion 41 is made of a single layer of resin material 63 in which a metal piece 62 is embedded. The resin material 63 in which the metal piece 62 is embedded is manufactured by embedding a copper wire in an electrically insulating resin material such as polypropylene, for example.

  With reference to FIGS. 6A and 6B, the conductive portion 41 of the exterior material 40 may include a minute hole 64. The conductive portion 41 shown in FIG. 6A is configured by leaving the metal foil layer 51 of the laminate film 50 and forming a hole 64 reaching the metal foil layer 51 in a part of the electrically insulating resin layers 52 and 53. Has been. In this case, the conductive portion 41 presses the outer packaging material 40 against the unit cell element 30, and the current collector 31 and the metal foil layer 51 are in direct contact with each other due to the presence of the holes 64, thereby ensuring conductivity. The conductive portion 41 shown in FIG. 6B is configured by forming a hole 64 that penetrates the laminate film 50. The conductive portion 41 in this case ensures conductivity by pressing the outer packaging material 40 against the single cell element 30 and the current collector 31 directly faces the outside due to the presence of the holes 64. The through-hole 64 is set to a size that does not hinder the function of preventing electrolyte leakage. An adhesive or non-adhesive coating agent having excellent conductivity may be interposed in the hole 64. This is because the conductivity is more reliable, and in the case of the through hole 64, leakage of the electrolyte can be prevented.

  With reference to FIGS. 7A and 7B, the conductive portion 41 of the exterior material 40 may include a conductive polymer film 65. The conductive portion 41 shown in FIG. 7A is configured by replacing the part of the electrically insulating resin layers 52 and 53 with the conductive polymer film 65 while leaving the metal foil layer 51 of the laminate film 50. Yes. In this case, the conductive portion 41 has a three-layer structure of conductive polymer film 65 -metal foil layer 51 -conductive polymer film 65. The conductive portion 41 shown in FIG. 7B is configured by eliminating the metal foil layer 51 of the laminate film 50 and replacing a part of the electrically insulating resin layers 52 and 53 with the conductive polymer film 65. Yes. In this case, the conductive portion 41 includes a single conductive polymer film 65.

(Third and fourth embodiments)
FIG. 8 is a cross-sectional view showing an assembled battery 81 according to the third embodiment, and FIG. 9 is a cross-sectional view showing an assembled battery 82 according to the fourth embodiment.

  The assembled batteries 81 and 82 are configured by electrically connecting a plurality of the bipolar batteries 11 and 12 described above in parallel and / or in series. By paralleling and / or serializing, the capacity and voltage can be freely adjusted. When the bipolar batteries 11 and 12 are connected in parallel, the conductive parts 41 and 41, 42 and 42, 71 and 71, and 72 and 72 having the same polarity are connected via an appropriate connecting member such as a bus bar.

  The assembled battery 81 shown in FIG. 8 is obtained by connecting a plurality (four in the illustrated example) of the bipolar battery 11 of the first embodiment in series. In the assembled battery 81, a plurality of bipolar batteries 11 are stacked by superimposing conductive portions 41 and conductive portions 42 having different electrical polarities, and a plurality of single cell elements 30 are electrically connected via the conductive portions 41 and 42. Connected in series. The assembled battery 81 is attached with the positive electrode output terminal 83 in contact with the positive electrode side conductive part 41 of the uppermost bipolar battery 11 and the negative electrode output terminal 84 in contact with the negative electrode side conductive part 42 of the lowermost bipolar battery 11. It is attached. In order to ensure the contact between the conductive portions 41 and 42, the assembled battery 81 is pressurized from both sides along the lamination direction of the bipolar battery 11.

  The assembled battery 82 shown in FIG. 9 is obtained by connecting a plurality (two in the illustrated example) of the bipolar battery 12 of the second embodiment in series. In the assembled battery 82, a plurality of bipolar batteries 12 are stacked by superimposing conductive portions 71 and conductive portions 72 having different electrical polarities, and a plurality of single cell elements 30 are connected via the conductive portions 71, 72, and 74. They are electrically connected in series. The assembled battery 82 is also attached with positive and negative output terminals 83 and 84 in contact with the conductive portions 71 and 72, and is pressurized from both sides along the lamination direction of the bipolar battery 12.

  According to the third and fourth embodiments, the bipolar batteries 11 and 12 are connected in series to form the assembled batteries 81 and 82, whereby a high capacity and high output battery can be obtained. In addition, since the individual bipolar batteries 11 and 12 have a structure in which no liquid junction occurs, the reliability is high and the long-term reliability as the assembled batteries 81 and 82 can be improved. As a result, the assembled batteries 81 and 82 are optimal. Further, if any of the bipolar batteries 11 and 12 is defective, the bipolar batteries 11 and 12 can be easily replaced.

  Depending on the required capacity and voltage, it is possible to make an assembled battery in which all of the plurality of bipolar batteries 11 and 12 are connected in parallel, or an assembled battery in which series connection and parallel connection are combined.

1 is a perspective view showing a bipolar battery according to a first embodiment of the present invention. It is sectional drawing which follows the 2-2 line of FIG. 3A and 3B are cross-sectional views showing an enlarged conductive portion of the exterior material. It is sectional drawing which shows the bipolar battery which concerns on the 2nd Embodiment of this invention. FIGS. 5A and 5B are cross-sectional views showing a main part of a conductive part including a resin material in which a metal piece is embedded. FIGS. 6A and 6B are cross-sectional views of a main part showing a conductive part including minute holes. FIGS. 7A and 7B are cross-sectional views showing the main part of a conductive part including a conductive polymer film. It is sectional drawing which shows the assembled battery which concerns on 3rd Embodiment. It is sectional drawing which shows the assembled battery which concerns on 4th Embodiment.

Explanation of symbols

11, 12 Bipolar battery,
20 cell layers,
21 positive electrode active material layer,
22 electrolyte layer,
23 negative electrode active material layer,
30 cell element,
31, 32 current collector,
40 (40a, 40b) exterior material,
41, 42 conductive part,
43 Seal part,
50 Laminated film,
51 metal foil layer,
52, 53 electrically insulating resin layer,
61 conductive resin material,
62 metal pieces,
63 Resin material with embedded metal pieces,
64 holes,
65 conductive polymer film,
70 (70a, 70b, 70c) exterior material,
71, 72, 74 conductive parts,
73 seal part,
81, 82 battery pack.

Claims (9)

A single battery element configured by sandwiching a single battery layer in which a positive electrode active material layer, an electrolyte layer made of a liquid or semi-solid gel electrolyte, and a negative electrode active material layer are sequentially stacked between a pair of current collectors; ,
A sealing portion for sealing the single cell element, and a flexible exterior material provided with a conductive portion having conductivity that contacts each of the current collectors ,
The said exterior material is a bipolar battery which has electrical insulation except the said electroconductive part, and takes out an electric current in the said electroconductive part .   The plurality of unit cell elements are characterized in that each unit cell element is sealed by the exterior material and electrically connected in series via the conductive portion of the exterior material. The bipolar battery according to claim 1.   The bipolar battery according to claim 1, wherein the exterior material is formed of a laminate film including a metal foil layer and an electrically insulating resin layer.   The bipolar battery according to claim 1, wherein the conductive portion is disposed inside a projection surface of the current collector.   The bipolar battery according to claim 1, wherein the conductive portion includes a conductive resin material.   The conductive resin material has electrical anisotropy with conductivity in the thickness direction of the unit cell element and insulation with respect to the surface direction of the unit cell element. The bipolar battery according to claim 5.   The bipolar battery according to claim 1, wherein the conductive portion includes a resin material in which a metal piece is embedded. The conductive portion is seen containing a small hole,
The minute hole is formed in a part of the resin layer leaving the metal foil layer in the exterior material formed from a laminated film including a hole penetrating the exterior material or a metal foil layer and an electrically insulating resin layer. The bipolar battery according to claim 1, wherein the bipolar battery is formed of holes formed so as to reach the metal foil layer .   The bipolar battery according to claim 1, wherein the conductive part includes a conductive polymer film.

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