JP2008140552A - Electrode for bipolar battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for improving endurance reliability of a bipolar battery. <P>SOLUTION: The electrode for a bipolar battery includes a collector equipped with a cathode side metal layer, an anode side metal layer, and an interlayer arranged between the cathode side metal layer and the anode side metal layer with a Young's modulus of 1/100,000 to 1/2 of that of the cathode side metal layer as well as that of the anode side metal layer, a cathode electrically coupled with a side of the cathode side metal layer of the collector, an anode electrically coupled with a side of the anode side metal layer of the collector. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a bipolar battery electrode, and more particularly to a bipolar battery electrode that can improve the durability reliability of the bipolar battery by absorbing stress generated in the bipolar battery due to vibration or the like.

  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 lithium ion secondary battery that can achieve a high energy density and a high output density. However, in order to apply to an automobile, it is necessary to use a plurality of secondary batteries connected in series in order to ensure a large output.

  However, when a battery is connected via the connection portion, the output is reduced due to the electrical resistance of the connection portion. Further, the battery having the connection portion has a disadvantage in terms of space. In other words, the output volume and energy density of the battery are reduced due to the occupied volume of the connection portion.

  In order to solve the above problem, a bipolar battery in which a positive electrode and a negative electrode are arranged on both sides of a current collector has been developed. However, the current collector generally formed from a metal foil has poor long-term durability.

As a battery with improved durability, Patent Document 1 discloses a non-aqueous electrolyte secondary battery using stainless steel as a current collector.
JP 2001-236946 A

  However, since the battery described in Patent Document 1 does not include a member that can absorb the stress generated by vibration when vibration due to heat is applied, the battery is shocked and the durability reliability of the battery is remarkably increased. There was a problem of lowering.

  Then, an object of this invention is to provide the means which can improve the durable reliability of a bipolar battery.

  In view of the above problems, the present inventors have conducted intensive research. As a result, the current collector is disposed between the positive electrode side metal layer, the negative electrode side metal layer, and the positive electrode side metal layer and the negative electrode side metal layer. A bipolar battery electrode comprising a current collector comprising an intermediate layer having a Young's modulus of the positive electrode side metal layer and a Young's modulus of the negative electrode side metal layer of 1/100000 to 1/2. As a result, it was found that the intermediate layer can absorb stress generated by vibration and the like, and the durability reliability of the bipolar battery can be improved.

  That is, the present invention is arranged between the positive electrode side metal layer, the negative electrode side metal layer, and the positive electrode side metal layer and the negative electrode side metal layer, the Young's modulus of the positive electrode side metal layer and the negative electrode side metal layer A current collector comprising an intermediate layer having a Young's modulus of 1 / 100,000 to 1/2 of the Young's modulus; a positive electrode electrically coupled to the positive electrode side metal layer side of the current collector; and A bipolar battery electrode, comprising: a negative electrode electrically coupled to the negative electrode side metal layer side.

  Moreover, this invention is a bipolar battery containing the said electrode for bipolar batteries.

  Further, the present invention is an assembled battery in which a plurality of the bipolar batteries are connected.

  Further, the present invention is a vehicle on which the bipolar battery or the assembled battery is mounted as a motor driving power source.

  The bipolar battery electrode of the present invention can improve the durability reliability of the bipolar battery.

  The bipolar battery electrode of the present invention is disposed between a positive electrode side metal layer, a negative electrode side metal layer, and the positive electrode side metal layer and the negative electrode side metal layer, and the Young's modulus of the positive electrode side metal layer and the negative electrode A current collector comprising an intermediate layer having a Young's modulus of 1 / 100,000 to 1/2 of the Young's modulus of the side metal layer, a positive electrode electrically coupled to the positive electrode side metal layer side of the current collector, And a negative electrode electrically coupled to the negative electrode side metal layer side of the current collector. FIG. 1 is a conceptual diagram showing the structure of a bipolar battery. The bipolar battery has a structure in which the current collector 10, the positive electrode 20, the electrolyte layer 30, the negative electrode 40, and the current extraction tab 11 are stacked, and the current collector 10 existing between the batteries connected in series is a positive electrode. A battery that functions as both a current collector and a negative electrode current collector.

  Conventionally, a current collector of a bipolar battery is usually formed from a metal foil such as an aluminum foil, a copper foil, or a stainless steel foil, or a clad material. In the present invention, as shown in FIG. , The positive electrode side metal layer 12, the negative electrode side metal layer 13, and the intermediate layer 14 disposed between the positive electrode side metal layer 12 and the negative electrode side metal layer 13, wherein the Young's modulus of the intermediate layer 14 is It is characterized in that the Young's modulus of the positive electrode side metal layer 12 and the Young's modulus of the negative electrode side metal layer 13 are smaller.

  The current collector of a normal battery that is not a bipolar type transfers charge through a tab attached to the end of the current collector, and the current collector collects the charge generated on the negative electrode side into the tab or supplies it from the tab. A function of transmitting the generated electric charge to the positive electrode side. Therefore, the current collector needs to have a low electric resistance in the horizontal direction (surface direction) in which charges move, and a metal foil having a certain thickness is used to reduce the electric resistance in the horizontal direction.

  On the other hand, in the current collector 10 of a bipolar battery, unlike a normal battery, the charge generated on the negative electrode 40 side is directly supplied to the positive electrode 20 existing on the opposite side of the current collector 10. For this reason, the current flows in the stacking direction of the components of the bipolar battery, and does not need to flow in the horizontal direction. Therefore, it is not always necessary to use a conventional metal foil in order to reduce the electrical resistance in the horizontal direction. Regarding the tab from which the current is finally extracted, it is desirable to use a metal tab that is in surface contact with the current collector.

  In view of the circumstances peculiar to such a bipolar battery, the present inventors are arranged between a positive electrode side metal layer, a negative electrode side metal layer, and the positive electrode side metal layer and the negative electrode side metal layer, and the positive electrode side The current collector provided with an intermediate layer having a Young's modulus of the metal layer and a Young's modulus of the negative electrode side metal layer absorbs stress generated in the bipolar battery due to vibration or the like It was found that the durability reliability of the bipolar battery can be improved.

  Subsequently, the constituent materials of the bipolar battery of the present invention will be described in detail.

  The current collector contained in the bipolar battery electrode of the present invention includes a positive electrode side metal layer, a negative electrode side metal layer, and the positive electrode side metal layer disposed between the positive electrode side metal layer and the negative electrode side metal layer. And an intermediate layer having a Young's modulus of 1/10000 to 1/2, preferably 1/10000 to 1/10 of the Young's modulus of the negative electrode side metal layer. If it is an intermediate layer having a Young's modulus exceeding the Young's modulus of the positive electrode side metal layer and the Young's modulus of the negative electrode side metal layer, the effect of vibration resistance may not be exhibited. If the intermediate layer has a Young's modulus of less than 1 / 100,000 of the Young's modulus of the negative electrode side metal layer, the intermediate layer may not exhibit sufficient conductivity.

  The material constituting the intermediate layer is not particularly limited as long as the intermediate layer has a Young's modulus that is 1 / 100,000 to 1/2 or less of the Young's modulus of the positive electrode side metal layer and the Young's modulus of the negative electrode side metal layer. For example, a corrugated metal material or a conductive polymer material is preferably used. The material for forming the intermediate layer may be used alone or in combination of two or more.

  As the metal material having the corrugated shape, any metal material having a corrugated shape and having conductivity can be used. In the present invention, the “wave shape” includes a wave shape as shown in FIG. 3A, a comb shape as shown in FIG. 3B, and a zigzag shape as shown in FIG. 3C.

  Examples of the metal material preferably include stainless steel, aluminum, copper, nickel, titanium, and the like, and aluminum, copper, and stainless steel are more preferable from the viewpoints of weight reduction and low cost.

  An example of the polymer material is a conductive polymer. These conductive polymers are considered to be conductive because the conjugated polyene system forms an energy band. As a typical example, a polyene-based conductive polymer that has been put into practical use in an electrolytic capacitor or the like can be used. Specifically, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, polyoxadiazole, or a mixture thereof is preferable, from the viewpoint that it can be used stably in an electronic conductivity and battery. Polyaniline, polypyrrole, polythiophene, and polyacetylene are more preferable.

  In addition, the intermediate layer may include a polymer material that does not have conductivity, in which case conductive particles (also referred to as a conductive filler) are included. Specific examples of conductive particles include, but are not limited to, aluminum particles, SUS particles, carbon particles, silver particles, gold particles, copper particles, and titanium particles. Alloy particles may be used. The conductive particles are not limited to those described above, and carbon nanotubes or the like that are put into practical use as so-called filler-based conductive resin compositions can be used.

  The ratio of the polymer material having no conductivity and the conductive particles in the intermediate layer is not particularly limited, but preferably, with respect to the total mass of the polymer material having no conductivity and the conductive particles, There are 2-20% by weight of conductive particles. By allowing a sufficient amount of conductive particles to be present, the conductivity of the current collector can be sufficiently ensured.

  The distribution of the conductive particles in the intermediate layer may not be uniform, and the particle distribution may be changed inside the current collector. A plurality of conductive particles may be used, and the distribution of the conductive particles may change inside the current collector.

  In this embodiment, the intermediate layer includes a polymer material that binds the conductive particles in addition to the conductive particles. By using a polymer material as a constituent material of the current collector, the binding property of the conductive particles can be improved and the reliability of the battery can be improved.

  The distribution of the polymer material in the current collector may not be uniform, and the distribution of the polymer material may change within the current collector. A plurality of polymer materials may be used, and the distribution of the polymer materials may be changed inside the current collector.

  Examples of the polymer material are preferably polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE). ), Styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), silicone, and epoxy resin There may be mentioned at least one selected from the group. Among these, polypropylene, polyethylene, and epoxy resin are more preferable from the viewpoint of low Young's modulus, low cost, chemical stability, and the like.

  Examples of the metal material used for the positive electrode side metal layer are at least selected from the group consisting of aluminum, iron, chromium, nickel, titanium, vanadium, molybdenum, niobium, gold, silver, platinum, and alloys of these metals. One is preferred. Among these, aluminum is more preferable from the viewpoints of stability to the positive electrode potential, light weight, low cost, and the like.

  Examples of the metal material used for the negative electrode side metal layer include aluminum, copper, iron, chromium, nickel, titanium, vanadium, molybdenum, niobium, gold, silver, platinum, and an alloy of these metals. Preferred is at least one selected. Among these, copper and nickel are more preferable from the viewpoints of stability against the negative electrode potential, light weight, and low cost.

  Further, the metal material used for the positive electrode side metal layer and the metal material used for the negative electrode side metal layer may be the same or different, but in consideration of the corrosion resistance of the electrode, the positive electrode side The metal material used for the metal layer is preferably different from the metal material used for the negative electrode side metal layer.

  The current collector may contain other materials as necessary.

  The thicknesses of the intermediate layer, the positive electrode side metal layer, and the negative electrode side metal layer current collector are not particularly limited, but are preferably thin from the viewpoint of increasing the output density of the battery. As described above, in the bipolar battery, the current collector that exists between the positive electrode and the negative electrode may have a high electrical resistance in a direction parallel to the stacking direction. Is possible. Specifically, the thickness of the current collector is preferably 5 to 50 μm.

  The thickness of the intermediate layer included in the current collector is preferably 100 nm to 5 μm, more preferably 300 to 1000 nm, and particularly preferably 500 to 800 nm. If the thickness is less than 100 nm, the adhesiveness may decrease and may peel off. If the thickness exceeds 5 μm, the thickness increases, resulting in a decrease in output density.

  Moreover, it is preferable that the thickness of at least one of the positive electrode side metal layer and the negative electrode side metal layer provided in the current collector is preferably 0.05 to 1 μm, More preferably, it is 1 μm. If it is less than 0.05 μm, pinholes may be generated, and it may be difficult to sufficiently block ions. If it exceeds 1 μm, the output density of the bipolar battery may decrease as a result of a high-density metal material. .

  The resistance value in the current collector is not particularly limited, but preferably the current collector material so that the resistance value in the current collector portion is 1/100 or less of the resistance value of the entire battery. It is desirable to select

  The method for forming the current collector having the above configuration is not particularly limited. When a metal material having a corrugated shape is used for the intermediate layer, for example, a method in which a positive electrode side metal layer and a negative electrode side metal layer are bonded to both surfaces of the corrugated metal material using an adhesive, etc. It can be employed to form a current collector.

  When a polymer material is used for the intermediate layer, for example, (1) a step of applying a polymer material on the surface of a metal foil, a step of drying the polymer material, and a surface of the dried polymer material Bonding the metal foil onto the surface; (2) applying a polymer material on the surface of the metal foil; bonding the metal foil onto the surface of the polymer material; (3) a step of applying a polymer material on the surface of a metal foil, a step of drying the polymer material, and a surface of the dried polymer material. And (4) a method including a step of forming a metal layer on both surfaces of the polymer material by a vacuum film forming method; or (5) ) A method comprising a step of laminating a metal foil on both sides of a polymer material; Etc. is adopted, it is possible to form the current collector.

  Examples of the method used in the step of laminating the metal foil on the surface of the polymer material of (1) to (2) and the step of laminating the metal foil on both surfaces of the polymer material of (5) , A method of bonding a metal foil and a polymer material using an adhesive; a method of bonding a metal foil and a polymer material by thermocompression bonding using a laminator or a heating press machine; and a structure as shown in FIG. A dry laminating method in which the metal foil and the polymer material are bonded using the dry laminator 50 having the above; or an extrusion laminating method in which the polymer material is bonded to the extruded metal foil while being heated and melted by an extruder such as a T-die extruder. Among them, the dry lamination method is more preferable from the viewpoint of productivity.

  Moreover, as an example of the vacuum film-forming method of said (3) and (4), vacuum vapor deposition methods, such as physical vapor deposition method and chemical vapor deposition method, or sputtering method etc. are mentioned preferably.

An active material layer is formed on the current collector. The active material layer is a layer containing an active material that plays a central role in the charge / discharge reaction. The active material layer on the positive electrode side contains a positive electrode active material, and the active material layer on the negative electrode side contains a negative electrode active material. What is necessary is just to select a positive electrode active material and a negative electrode active material suitably according to the kind of battery. For example, if the battery is the lithium secondary battery, examples of the positive electrode active material, Li · Co-based composite oxide such as LiCoO _2, Li · Ni-based composite oxide such as LiNiO _2, spinel LiMn ₂ O _And lithium-transition metal composite oxides such as Li · Mn composite oxides such as _4, and Li · Fe composite oxides such as LiFeO ₂ . In addition, transition metal and lithium phosphate compounds and sulfate 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. These may be used alone or in combination of two or more.

  The average particle size of the positive electrode active material is preferably 5 μm or less, more preferably 3 μm or less, and even more preferably 1 μm or less. The lower limit of the average particle diameter of the positive electrode active material is not particularly limited, but from the viewpoint of sufficiently forming a conductive network in the electrode, the average particle diameter of the positive electrode active material is preferably 0.01 μm or more, and more Preferably it is 0.1 micrometer or more.

Examples of the negative electrode active material include carbon materials such as crystalline carbon materials and amorphous carbon materials, and metal materials such as lithium-transition metal composite oxides. Specific examples include natural graphite, artificial graphite, carbon black, activated carbon, carbon fiber, coke, soft carbon, hard carbon, Li ₄ Ti ₅ O _{12 and the} like. These may be used alone or in combination of two or more.

  The average particle size of the negative electrode active material is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. The lower limit of the average particle diameter of the negative electrode active material is not particularly limited, but from the viewpoint of sufficiently forming a conductive network in the electrode, the average particle diameter of the negative electrode active material is preferably 0.01 μm or more, and more Preferably it is 0.1 micrometer or more.

The bipolar battery electrode of the present invention may contain other components such as a conductive additive, an ion conductive polymer, and a supporting salt. Examples of the conductive assistant include acetylene black, carbon black, and graphite. By including a conductive additive, the conductivity of electrons generated at the electrode can be increased, and the battery performance can be improved. Examples of the ion conductive polymer include polyethylene oxide (PEO) and polypropylene oxide (PPO). The supporting salt may be selected according to the type of battery. When the battery is a lithium battery, LiBF ₄ , LiPF ₆ , Li (SO ₂ CF ₃ ) ₂ N, LiN (SO ₂ C ₂ F ₅ ) ₂ , and the like can be given.

  The amount of the electrode constituent material such as the active material, the lithium salt, and the conductive additive is preferably determined in consideration of the intended use of the battery (output importance, energy importance, etc.) and ion conductivity.

  The electrolyte layer may be a liquid, gel, or solid phase.

  The liquid electrolyte has a form in which a lithium salt as a supporting salt is dissolved in an organic solvent as a plasticizer. Examples of the organic solvent that can be used as the plasticizer include carbonates such as ethylene carbonate (EC) and propylene carbonate (PC).

  In consideration of safety when the battery is damaged and prevention of liquid junction, the electrolyte layer is preferably a gel polymer electrolyte layer or an all-solid electrolyte layer.

  By using a gel polymer electrolyte layer as an electrolyte, the fluidity of the electrolyte is lost, the outflow of the electrolyte to the current collector can be suppressed, and the ionic conductivity between the layers can be blocked. Examples of the gel electrolyte matrix polymer include PEO, PPO, PVdF, polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), PAN, PMA, and PMMA. Moreover, as a plasticizer, it is possible to use the electrolyte solution normally used for a lithium ion battery.

  Further, even when an all-solid electrolyte layer is used as the electrolyte, the fluidity of the electrolyte is lost, so that the electrolyte does not flow out to the current collector, and the ion conductivity between the layers can be blocked. When the all solid electrolyte layer is used, the current collector may have a high porosity because there is no fear of permeation of the electrolyte solution from the electrolyte layer.

  The gel polymer electrolyte is produced by adding an electrolyte solution usually used in a lithium ion battery to an all solid polymer electrolyte such as PEO or PPO. It may be produced by holding an electrolytic solution in a polymer skeleton having no lithium ion conductivity, such as PVdF, PAN, or PMMA. The ratio of the polymer constituting the gel polymer electrolyte to the electrolytic solution is not particularly limited. If 100% of the polymer is an all solid polymer electrolyte and 100% of the electrolytic solution is a liquid electrolyte, all of the intermediates are the concept of a gel polymer electrolyte. include. The all solid electrolyte includes all electrolytes having Li ion conductivity such as a polymer or an inorganic solid.

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

  In addition, when an electrolyte layer is comprised from a liquid electrolyte or a gel polymer electrolyte, you may use a separator for an electrolyte layer. Specific examples of the separator include a microporous film made of polyolefin such as polyethylene or polypropylene.

The electrolyte layer preferably contains a supporting salt in order to ensure ionic conductivity. When the battery is a lithium secondary battery, LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ C ₂ F ₅ ) ₂ , or a mixture thereof is used as the supporting salt. it can. However, it is not necessarily limited to these. As described above, polyalkylene oxide polymers such as PEO and PPO often dissolve lithium salts such as LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) _2. Yes. Moreover, excellent mechanical strength is exhibited by forming a crosslinked structure.

  A battery may be configured by combining a plurality of batteries in series, in parallel, or in series and parallel. Capacitance and voltage can be freely adjusted by paralleling in series.

  The number of batteries in the assembled battery and the manner of connection may be determined according to the output and capacity required of the battery. When the assembled battery is configured, the stability of the battery is increased as compared with the unit cell. By configuring the assembled battery, the influence on the entire battery due to the deterioration of one cell can be reduced.

  The battery or the assembled battery can be preferably used as a power source for driving the vehicle. When the battery or the assembled battery of the present invention is used in a hybrid vehicle or an electric vehicle, the life and reliability of the vehicle can be improved. However, the use is not limited to automobiles, and for example, it can be applied to trains.

  Then, the manufacturing method of the bipolar battery of this invention is demonstrated. A coating method can be used when forming a layer containing a polymer material in the current collector. For example, the method of preparing the slurry containing a polymeric material, apply | coating and hardening this is mentioned. Since the specific forms of the polymer material and the conductive particles used for the preparation of the slurry are as described above, the description thereof is omitted here.

  Examples of the other components contained in the slurry include conductive particles and a solvent. Since specific examples of the polymer material and the conductive particles are as described above, description thereof is omitted here.

  The bipolar battery electrode of the present invention is, for example, forming a current collector (current collector forming step), preparing an active material slurry by adding an active material to a solvent (active material slurry preparing step), The active material slurry is applied to the surface of the current collector and dried to form a coating film (coating film forming process), and the laminate produced through the coating film forming process is pressed in the laminating direction (pressing) Step). When an ion conductive polymer is added to the active material slurry and a polymerization initiator is further added for the purpose of crosslinking the ion conductive polymer, it is simultaneously with drying in the coating film forming process, or before or after the drying. A polymerization treatment may be performed (polymerization step).

  Since the method for forming the current collector is as described in the section of the configuration of the bipolar battery electrode of the present invention, detailed description thereof is omitted here.

  A desired active material, a conductive auxiliary agent, and other components (for example, a binder, an ion conductive polymer, a supporting salt (lithium salt), a polymerization initiator, etc.) are mixed in a solvent to obtain an active material. Prepare a slurry. Since the specific form of each component blended in the active material slurry is as described in the section of the configuration of the bipolar battery electrode of the present invention, detailed description is omitted here.

  Examples of the components contained in the positive electrode active material slurry include a positive electrode active material, a binder, a conductive additive, and a solvent. The positive electrode active material slurry may be one kind or plural. As binders, polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyether nitrile (PEN), polyimide (PI), polyamide (PA), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR) ), Polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyvinylidene fluoride (PVdF), or mixtures thereof. In order to prevent aggregation of the positive electrode active material and the conductive additive, a dispersant may be used. As the dispersant, a compound having a dispersing action such as polyoxystearylamine can be used.

  Examples of components contained in the negative electrode active material slurry include a negative electrode active material, a binder, a conductive additive, and a solvent. The negative electrode active material slurry may be one kind or plural. As the binder, the same binder as that used for the positive electrode active material slurry can be used.

  The solvent of each slurry is not particularly limited, but is not particularly limited, and conventionally known knowledge about electrode production can be appropriately referred to. As an example of the solvent, N-methyl-2-pyrrolidone (NMP), dimethylformamide, dimethylacetamide, methylformamide and the like can be used. When adopting polyvinylidene fluoride (PVdF) as a binder, NMP may be used as a solvent. It is possible to control the viscosity of the slurry by increasing or decreasing the amount of solvent.

  The compounding ratio of the components contained in each slurry is not particularly limited.

  After the electrodes are formed, the solvent is removed by drying. When the raw material of the solid electrolyte is polymerized by this stage and does not become a solid electrolyte, the polymerization reaction may be advanced. For example, when a photopolymerization initiator is contained in the ink, the polymerization reaction of the raw material may be advanced by irradiating predetermined light.

  FIG. 5 is an external view of a bipolar battery according to the present invention. As shown in FIG. 5, the bipolar battery 100 has a rectangular flat shape, and a positive electrode tab 11 </ b> A and a negative electrode tab 11 </ b> B for taking out electric power are drawn out from both sides thereof. The current extraction tab 11 is preferably formed from a highly conductive material such as aluminum, copper, or nickel. The current extraction tab 11 preferably covers the entire projection surface of the bipolar battery element 160 including the bipolar battery electrode and the electrolyte layer of the present invention, and the current extraction tab 11 and the bipolar battery element 160 are packaged. It is preferably covered with a material (for example, an aluminum laminate film) 180. The outer periphery of the exterior member 180 is sealed by vacuum sealing and pressing by atmospheric pressure, and the bipolar battery element 160 is sealed with the positive electrode tab 11A and the negative electrode tab 11B pulled out.

  FIG. 6 is an external view of the assembled battery 300 according to the present invention. A plurality of bipolar batteries may be connected in series or in parallel to form an assembled battery module 250, and a plurality of assembled battery modules 250 may be connected in series or in parallel to form an assembled battery 300. FIG. 6 shows a plan view (FIG. A), a front view (FIG. B), and a side view (FIG. C) of the assembled battery 300. The assembled battery module 250 is electrically connected like a bus bar. The assembled battery modules 250 are stacked in a plurality of stages using the connection jig 310. How many bipolar batteries are connected to create the assembled battery module 250, and how many assembled battery modules 250 are stacked to create the assembled battery 300 depends on the vehicle (electric vehicle) to be mounted. It may be determined according to the battery capacity and output.

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

(Example 1)
1. Current collector As shown in FIG. 3A, an aluminum foil (thickness: 10 μm), which is a metal layer on the positive electrode side, is bonded to one side of a stainless foil (thickness: 35 μm) having a corrugated shape, and alpha cyano, which is an adhesive. A copper foil (thickness) as a negative electrode side metal layer is bonded to the surface opposite to the surface to which the aluminum foil is bonded by using an acrylate monomer (trade name: Aron Alpha (registered trademark), manufactured by Toagosei Co., Ltd.). Was bonded using an alpha cyanoacrylate monomer (trade name: Aron Alpha (registered trademark), manufactured by Toagosei Co., Ltd.) as an adhesive to obtain a current collector.

2. Preparation of positive electrode active material slurry Spinel type lithium manganate (LiMn ₂ O ₄ ) (85% by mass) as a positive electrode active material, acetylene black (5% by mass) as a conductive auxiliary agent, and polyvinylidene fluoride (PVdF) as a binder A suitable amount of N-methyl-2-pyrrolidone (NMP), which is a slurry viscosity adjusting solvent, was added to a solid content of 10% by mass to prepare a positive electrode active material slurry.

3. Preparation of negative electrode active material slurry N-methyl, which is a slurry viscosity adjusting solvent, with respect to a solid content of hard carbon (90% by mass) as a negative electrode active material and polyvinylidene fluoride (PVdF) (10% by mass) as a binder An appropriate amount of -2-pyrrolidone (NMP) was added to prepare a negative electrode active material slurry.

4). 1. Production of bipolar battery electrode The positive electrode active material slurry prepared in 1. The laminated body was obtained by applying on one side of the current collector obtained in the above with a desktop coater and drying. Next, the obtained laminate was pressed using a press so that the thickness of the applied positive electrode active material slurry layer was 30 μm.

  Next, the above 3. The negative electrode active material slurry prepared in (1) was applied to the surface where the positive electrode active material slurry was not applied (the surface where the stainless steel foil was exposed) with a desktop coater and dried to obtain a laminate. Next, the obtained laminate was pressed using a press so that the thickness of the applied negative electrode active material slurry layer was 30 μm to obtain a bipolar electrode.

5. Preparation of terminal positive electrode and terminal negative electrode As a positive electrode disposed at the end of a bipolar battery, a positive electrode active material slurry was applied in a size of 120 mm in length and 70 mm in width on an aluminum foil having a length of 140 mm, a width of 90 mm, and a thickness of 20 μm. By drying and pressing, a terminal positive electrode was produced in which a positive electrode was formed on the aluminum foil and a 10 mm seal margin was formed in the peripheral part.

  Also, as a negative electrode disposed at the end of the bipolar battery, a negative electrode active material slurry is applied in a size of 120 mm long and 70 mm wide on a copper foil having a length of 140 mm, a width of 90 mm, and a thickness of 20 μm, dried, and pressed. As a result, a negative electrode was formed on the copper foil, and a terminal negative electrode in which a 10 mm seal margin was formed in the peripheral portion was produced.

6). Preparation of electrolyte material LiPF ₆ as a lithium salt dissolved in a 1M concentration in a mixed solution in which the ratio of propylene carbonate (PC) to ethylene carbonate (EC) is 1: 1 as an electrolyte solution ( 90 mass%) and a matrix polymer PVdF-HFP (10 mass%), an appropriate amount of DMC as a viscosity adjusting solvent was added to prepare an electrolyte material.

7). Formation of Gel Electrolyte Layer On both sides of a polypropylene porous film (thickness: 20 μm), the above 6. The gel electrolyte layer was obtained by apply | coating the electrolyte material produced by 1 and drying DMC.

8). Bipolar battery assembly 5. On the terminal positive electrode prepared in step 7, the above 7. The gel electrolyte layer prepared in step 1 was placed, and a polyethylene film having a width of 12 mm as a sealing material was placed around the gel electrolyte layer. Similarly, five bipolar electrodes and five gel electrolyte layers are sequentially laminated, and finally the above 5. The terminal negative electrode prepared in (1) was laminated with the negative electrode active material slurry layer facing downward. The seal part at the periphery of the laminate was subjected to a hot press under the conditions of 0.2 MPa, 160 ° C., and 5 seconds, and each layer was sealed to obtain a bipolar battery element.

  Separately, an aluminum plate having a length of 130 mm, a width of 80 mm, and a thickness of 100 μm, which can cover the entire projection surface of the bipolar battery element, a part of which extends to the outside of the projection surface of the bipolar battery element. A high voltage terminal was created. A bipolar battery was completed by sandwiching the bipolar battery element produced above with this terminal, vacuum-sealing it with an aluminum laminate film so as to cover it, and pressing both sides at atmospheric pressure.

(Example 2)
Above 1. Instead of the stainless steel foil having a corrugated shape, an aluminum foil which is a positive electrode side metal layer using a film-like polymer material having a thickness of 30 μm in which 20% by mass of carbon particles are dispersed with respect to 100% by mass of polypropylene. (Thickness: 8 μm) and the method of adhering the copper foil (thickness: 10 μm) which is the negative electrode side metal layer, except that the method (hot press method) for performing thermocompression bonding under the conditions shown in Table 1 below was used. A bipolar battery was produced in the same manner as in Example 1.

(Example 3)
A polymer material in which 20% by mass of carbon particles were dispersed in 100% by mass of epoxy resin on an aluminum foil (thickness: 15 μm) as a positive electrode side metal layer was applied using a desktop coater. Next, a copper foil (thickness: 10 μm) as the negative electrode side metal layer was bonded onto the surface of the epoxy resin, and the epoxy resin was thermally cured at a temperature of 130 ° C. to produce a current collector. The thickness of the epoxy resin layer as the intermediate layer was 10 μm.

  A bipolar battery was produced in the same manner as in Example 1 except that the current collector was produced as described above.

Example 4
Above 1. Instead of the stainless steel foil having the corrugated shape, polyaniline dissolved in a xylene solvent was applied onto an aluminum foil (thickness: 15 μm) using a desktop coater. Thereafter, the solvent was dried, and then a copper foil (thickness: 10 μm) as a negative electrode side metal layer was bonded onto the surface of the polyaniline, and further the solvent was dried to prepare a current collector (dry lamination method). . The thickness of the polyaniline layer as an intermediate layer was 5 μm.
A bipolar battery was produced in the same manner as in Example 1 except that the current collector was produced as described above.

(Example 5)
A polymer material in which 20% by mass of carbon particles are dispersed with respect to 100% by mass of polyethylene (PE) and a copper foil (thickness: 10 μm) as a negative electrode side metal layer are extruded and laminated under the conditions shown in Table 2 below. Bonded by performing the method. Next, aluminum was formed as a positive electrode side metal layer on the surface opposite to the surface to which the copper foil was bonded by vacuum deposition to obtain a current collector. The thickness of the polymer material layer as an intermediate layer was 20 μm, and the thickness of the aluminum layer was 600 nm.

  A bipolar battery was produced in the same manner as in Example 1 except that the current collector was produced as described above.

(Example 6)
On a copper foil (thickness: 10 μm), polyaniline dissolved in a xylene solvent was applied using a desktop coater. Thereafter, the solvent was dried to form polyaniline as a polymer material for the intermediate layer. Aluminum was formed as a positive electrode side metal layer on the surface opposite to the surface to which the copper foil was bonded by vacuum deposition to obtain a current collector. The thickness of the polyaniline layer was 10 μm, and the thickness of the aluminum layer was 600 nm.

  A bipolar battery was produced in the same manner as in Example 1 except that the current collector was produced as described above.

(Example 7)
On one side of a film-like polymer material having a thickness of 30 μm in which 20% by mass of carbon particles are dispersed with respect to 100% by mass of polyethylene terephthalate (PET), a negative electrode side metal copper is formed by sputtering. I let you. Subsequently, aluminum which is a positive electrode side metal was formed into a current collector by vacuum deposition on a surface opposite to the surface on which copper was formed. The thickness of the aluminum layer was 600 nm, and the thickness of the copper layer was 800 nm.

  A bipolar battery was produced in the same manner as in Example 1 except that the current collector was produced as described above.

(Comparative Example 1)
A bipolar battery was produced in the same manner as in Example 1 except that stainless steel foil (thickness: 30 μm) was used as the current collector.

(Comparative Example 2)
A bipolar battery was fabricated in the same manner as in Example 1 except that a clad material (thickness: 30 μm) in which the positive electrode side metal was aluminum and the negative electrode side metal was copper was used as the current collector.

  The Young's modulus of the material of the intermediate layer used in Examples 1 to 7 and Comparative Examples 1 and 2, and the Young's modulus of the aluminum foil used as the positive electrode side metal layer and the copper foil used as the positive electrode side metal layer are shown in the following table. 3 shows. The Young's modulus was measured by the measuring method of JIS Z2280, JIS R1602, and JIS R1605.

(Evaluation 1)
A charge / discharge test was performed on each of the batteries of Examples 1 to 7 and Comparative Examples 1 and 2. In the experiment, constant current charging (CC) was performed at a current of 0.5 mA up to 21.0 V, then charging (CV) was performed at a constant voltage, and charging was performed for 10 hours. Thereafter, the battery was fixed in an oven at 70 ° C., and a monotonous vibration of 50 Hz with an amplitude of 3 mm was applied for 200 hours in a direction perpendicular to the electrode surface of the battery. Subsequently, it discharged to 15V and measured the capacity | capacitance. Evaluation showed the capacity | capacitance after vibration when the capacity | capacitance before vibration was 100% as a ratio. The results are shown in Table 4 below.

  As can be seen from Table 4, it was found that the bipolar batteries of Examples 1 to 7 having the bipolar battery electrode of the present invention had a higher capacity retention rate than the bipolar battery of the comparative example. This is presumably because the bipolar batteries of Examples 1 to 7 are provided with a layer having a low Young's modulus on the current collector and have high durability against vibration. Further, from the results of the bipolar batteries of Examples 1 to 7 and the results of the bipolar battery of Comparative Example 1, the corrosion resistance of the bipolar battery electrode of the present invention included in the bipolar battery of the Example is a comparative example. It can be said that it is superior to the corrosion resistance of the electrode of the bipolar battery of No. 1.

(Evaluation 2)
An AC impedance of 10 kHz was measured for each of the batteries of Examples 1 to 7. Table 5 below shows the AC impedance of each battery when the value of Example 1 is 100%.

  It can be said that the value of AC impedance of 10 kHz in Table 5 represents a value obtained by combining the ion resistance between the layers of the bipolar battery electrode and the electronic resistance in the current collector. Since the battery of FIG. 5 has the same electrode and electrolyte configuration, the difference in the 10 kHz AC impedance value in Table 5 represents the difference in the electron transfer resistance in the current collector of the bipolar battery electrode. I can say that.

  As can be seen from Table 5, the batteries of Examples 4 and 6 using a conductive polymer as the intermediate layer of the current collector, and Example 5 in which the positive electrode side metal layer of the current collector was formed by the vacuum film formation method. The battery of Example 7 in which the positive electrode side metal layer of the current collector and the negative electrode side metal layer of the current collector were formed by a vacuum film formation method was 10 kHz in comparison with the batteries of Examples 1 to 3. It was found that the impedance value was high, that is, the battery resistance was low. Although the detailed mechanism of such a result is unknown, when a conductive polymer is used as the intermediate layer of the current collector, the adhesion between the positive electrode side metal layer of the current collector and the negative electrode side metal layer of the current collector It is considered that the resistance of the battery is lowered because of the improvement in performance. In addition, when at least one of the positive electrode side metal layer and the negative electrode side metal layer of the current collector is formed by a vacuum film formation method, adhesion with the polymer material that is an intermediate layer of the current collector is improved. It is thought that resistance became low.

  The bipolar electrode of the present invention is used for a battery such as a lithium secondary battery. A preferred application of the lithium secondary battery is a vehicle.

It is a conceptual diagram which shows the structure of a bipolar battery. It is a cross-sectional schematic diagram which shows the structure of the electrical power collector used for this invention. It is the cross-sectional schematic which shows one Embodiment of the electrical power collector used for this invention. It is the cross-sectional schematic which shows one Embodiment of the electrical power collector used for this invention. It is the cross-sectional schematic which shows one Embodiment of the electrical power collector used for this invention. It is the schematic of a dry laminator. It is an external view of the bipolar battery containing the electrode for bipolar batteries of this invention. It is an external view of the assembled battery containing the electrode for bipolar batteries of this invention. It is a conceptual diagram of the vehicle carrying the assembled battery containing the electrode for bipolar batteries of this invention.

Explanation of symbols

10 Current collector,
11 Current extraction tab,
11A positive electrode tab,
11B negative electrode tab,
12 positive electrode side metal layer,
13 negative electrode side metal layer,
14 Middle layer,
20 positive electrode,
30 electrolyte layer,
40 negative electrode,
50 Dry laminator,
51 base material feeding part,
52 Adhesive (gravure coat),
53 dryer,
54 Second base material feeding section,
55 Combiner roll,
56 Laminate winding part,
100 bipolar battery,
160 bipolar battery element,
180 exterior material,
250 battery module,
300 battery packs,
310 connecting jig,
400 Electric car.

Claims (23)

The positive electrode side metal layer, the negative electrode side metal layer, and the positive electrode side metal layer and the negative electrode side metal layer are arranged between the Young's modulus of the positive electrode side metal layer and the Young's modulus of the negative electrode side metal layer. A current collector comprising an intermediate layer having a Young's modulus of ~ 1/2;
A positive electrode electrically coupled to the positive electrode side metal layer side of the current collector;
A negative electrode electrically coupled to the negative electrode side metal layer side of the current collector;
An electrode for a bipolar battery, comprising:   The bipolar battery electrode according to claim 1, wherein the intermediate layer is formed of a metal material having a wavy shape.   The bipolar battery electrode according to claim 1, wherein the intermediate layer is formed of a conductive polymer material in which a conductive filler is dispersed in a polymer material having no conductivity.   The polymer material is polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, styrene butadiene rubber, polyacrylonitrile, polymethyl acrylate, polymethyl methacrylate, polyvinyl chloride, polyvinylidene fluoride, silicone And at least one selected from the group consisting of epoxy resins.   The bipolar battery electrode according to claim 1, wherein the intermediate layer is formed of a conductive polymer.   6. The bipolar electrode according to claim 5, wherein the conductive polymer is at least one selected from the group consisting of polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazole. Type battery electrode.   The positive electrode side metal layer is formed of at least one selected from the group consisting of aluminum, iron, chromium, nickel, titanium, vanadium, molybdenum, niobium, gold, silver, platinum, and alloys of these metals. Item 7. The bipolar battery electrode according to any one of Items 1 to 6.   The negative electrode side metal layer is formed of at least one selected from the group consisting of aluminum, copper, iron, chromium, nickel, titanium, vanadium, molybdenum, niobium, gold, silver, platinum, and alloys of these metals. The electrode for bipolar batteries according to any one of claims 1 to 7.   The bipolar battery electrode according to any one of claims 1 to 8, wherein a thickness of at least one of the positive electrode side metal layer and the negative electrode side metal layer is 0.05 to 1 µm.   The bipolar of any one of Claims 1-9 further provided with the positive electrode active material layer arrange | positioned at the surface of the said positive electrode side metal layer, and the negative electrode active material layer arrange | positioned at the surface of the said negative electrode side metal layer. Type battery electrode.   The bipolar battery electrode according to claim 10, wherein the positive electrode active material layer contains a lithium-transition metal composite oxide.   The bipolar battery electrode according to claim 10 or 11, wherein the negative electrode active material layer contains a carbon material or a lithium-transition metal composite oxide.   A bipolar battery comprising the bipolar battery electrode according to claim 1, an electrolyte layer, and a current extraction tab.   The bipolar battery according to claim 13, wherein the current extraction tab covers the entire projection surface of the bipolar battery element including the bipolar battery electrode and the electrolyte layer, and an exterior material covers the current extraction tab.   The bipolar battery according to claim 13 or 14, wherein the electrolyte layer is a gel polymer electrolyte layer.   The bipolar battery according to claim 13 or 14, wherein the electrolyte layer is an all-solid electrolyte layer.   An assembled battery in which a plurality of bipolar batteries according to any one of claims 10 to 16 are connected.   A vehicle on which the bipolar battery according to any one of claims 10 to 16 or the assembled battery according to claim 17 is mounted as a motor driving power source. Applying a polymer material on the surface of the metal foil;
Drying the polymeric material;
Bonding a metal foil on the surface of the dried polymer material;
The manufacturing method of the electrode for bipolar batteries of any one of Claims 3-12 containing this. Applying a polymer material on the surface of the metal foil;
Bonding a metal foil on the surface of the polymer material;
Thermally curing the polymeric material;
The manufacturing method of the electrode for bipolar batteries of any one of Claims 3-12 containing this. Applying a polymer material on the surface of the metal foil;
Drying the polymeric material;
Forming a metal layer on the surface of the dried polymer material by a vacuum film formation method;
The manufacturing method of the electrode for bipolar batteries of any one of Claims 3-12 containing this.   The manufacturing method of the electrode for bipolar batteries of any one of Claims 3-12 including the process of forming a metal layer on both surfaces of a polymeric material by the vacuum film-forming method.   The manufacturing method of the electrode for bipolar batteries of Claim 21 or 22 whose said vacuum film-forming method is a vacuum evaporation method or sputtering method.

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