JP2007173212A - Outer packaging material for electrochemical device and electrochemical device using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outer packaging material capable of enhancing durability of an electrochemical device. <P>SOLUTION: The outer packaging material 160 for the electrochemical device containing as a battery element at least an electrolyte layer interposed between a positive active material and a negtive active material, comprises a ceramic part 161 containing ceramic and a resin film 163 or metal foil 165. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exterior material for an electrochemical device, and more particularly to a material constituting the exterior material for an electrochemical device.

  Currently, electrochemical devices include manganese batteries, alkaline manganese batteries, nickel-based primary batteries, oxyride batteries, silver oxide batteries, mercury batteries, air zinc batteries, lithium batteries, seawater batteries, and other primary batteries, lead storage batteries, lithium ion secondary batteries Secondary batteries such as batteries, nickel-hydrogen batteries, nickel-cadmium batteries, or sodium-sulfur batteries, or phosphoric acid fuel cells, polymer electrolyte fuel cells, molten carbonate fuel cells, or solid oxide fuel cells Such fuel cells, electric double layer capacitors, dye-sensitized solar cells and the like are known.

The electrochemical device includes a single cell layer in which a positive electrode active material layer, an electrolyte layer, and a negative electrode active material layer are arranged in this order, and generates a current by a chemical reaction in the single cell layer. What added the collector further as needed on the structure of the said single cell layer or an electrochemical device is called a battery element. For the purpose of protecting battery elements, improving the handleability of electrochemical devices, and preventing liquid leakage when liquids are used as battery elements, battery elements enclosed in exterior materials are in circulation. Yes. For example, Patent Document 1 discloses an electrochemical device using an exterior material made of a laminate sheet made of a resin film and a metal foil.
JP 2001-52748 A

  As shown in Patent Document 1, conventionally, a laminate sheet made of a resin film and a metal foil has been used as an exterior of an electrochemical device. However, a short circuit may occur when the resin film that separates the metal foil from the battery components is damaged for some reason. Further, when the exterior material is formed only by the resin film without using the metal foil that causes a short circuit, the gas permeation amount or the water permeation amount is increased, which may deteriorate the battery element. For this reason, in order to improve the durability of an electrochemical device, improvement of the exterior material has been demanded. In particular, when a high voltage battery including a series battery is used for a power source, the necessity is high.

  Then, an object of this invention is to provide the exterior | packing material which can improve the durability of an electrochemical device.

  The present inventors have focused on the fact that ceramics that have not been noticed as exterior materials for electrochemical devices until now have excellent properties such as insulating properties, gas barrier properties, or water permeability, and ceramic and resin films or It has been found that the above problem can be solved by using a metal foil in combination.

  That is, the present invention is an exterior material for an electrochemical device that includes, as a battery element, at least an electrolyte layer sandwiched between a positive electrode active material layer and a negative electrode active material layer, and includes a ceramic part containing ceramic, a resin film, or a metal foil The above-mentioned problem is solved by an exterior material characterized by comprising:

  According to the present invention, an exterior material capable of improving the durability of an electrochemical device can be provided.

  A first aspect of the present invention is an exterior material for an electrochemical device including at least a battery element as an electrolyte layer sandwiched between a positive electrode active material layer and a negative electrode active material layer, the ceramic part containing ceramic, a resin film or An exterior material comprising a metal foil.

  Details of the components of the exterior material of the present invention, the arrangement of each component, and the manufacturing method will be described below.

[Ceramic part]
The ceramic portion referred to in the present invention refers to both ceramics and other materials, and ceramics. Ceramic is a material that has not been attracting attention as a packaging material for electrochemical devices until now, but because it is excellent in insulation, gas barrier properties, and water-impermeable properties, it is possible to include a ceramic in the packaging material of electrochemical devices. The durability of can be improved.

  The ceramic used in the ceramic part is not particularly limited, and either an oxide ceramic or a non-oxide ceramic can be preferably used, but an oxide ceramic is more preferable. An oxide ceramic is excellent in insulation, heat resistance, or corrosion resistance.

  The oxide ceramic is not particularly limited, but an oxide containing at least one selected from the group consisting of silicon, aluminum, zirconium, yttrium, magnesium, calcium, scandium, beryllium, thorium, uranium, and titanium is preferable. More preferably, it is an oxide ceramic containing one or more elements selected from the group consisting of silicon, aluminum, zirconium, yttrium, magnesium, calcium, and scandium.

  Silica-containing ceramics include silica gel or silica-alumina gel, aluminum-containing ceramics include alumina, zirconium-containing ceramics include zirconia, yttrium-containing ceramics include yttria, and magnesium. Examples of the ceramic containing magnesium include magnesia, the ceramic containing calcium includes calcia, the ceramic containing scandium includes scandia, the ceramic containing beryllium includes beryllia, and the ceramic containing thorium includes tria. Examples of the ceramic containing uranium include urania, and examples of the ceramic containing titanium include titania, barium titanate, or strontium titanate. That. Among these, silica gel or silica alumina gel is particularly preferable. Silica gel or silica alumina gel is hygroscopic and has the advantage that it is difficult to deliquesce or not.

  Although it does not specifically limit as a non-oxide ceramic, Silicon nitride, silicon carbide, or boron nitride is mentioned.

  As the ceramic part composed of ceramic and other substances, a ceramic part including a plurality of particulate ceramics and a binder for connecting the particulate ceramics, or a plurality of film-like ceramics, and the film And a ceramic part including a binder for bonding the ceramics together.

  When the particulate ceramic is used, the shape is not particularly limited, and examples thereof include a spherical shape, a plate shape, a needle shape, a column shape, and an indefinite shape.

  Although it does not specifically limit about the average particle diameter of a particulate ceramic, 0.1-100 micrometers is preferable, More preferably, it is 1-20 micrometers. When the average particle diameter is within the above range, the insulating properties and the dispersibility in the binder are excellent. When particles having a shape other than a spherical shape are used, the absolute maximum length of the particles is defined as the particle diameter of the particles. Here, the “absolute maximum length” refers to the maximum distance among the distances between any two points on the particle outline. The absolute maximum length can be confirmed by microscopic observation.

  By using a binder in combination with the particulate ceramic, it is possible to suppress the occurrence of cracks when vibration is applied to the exterior material or when a mechanical load is applied.

  The binder is preferably a resin, specifically, at least one selected from the group consisting of polyolefins such as polyethylene, polypropylene, polybutylene, polyvinyl chloride, and polyvinyl acetate; polyimide; and polyamideimide is more preferable. Polyethylene or polypropylene. These are preferable because they have insulating properties.

  When the particulate ceramic and the binder are used in combination, the ratio of the particulate ceramic to the total amount of the particulate ceramic and the binder is preferably 1 to 70% by volume, more preferably 2 to 60% by volume. . When the ratio of the ceramic is 1% by volume or more, the insulating property is excellent, and when the ratio is 70% by volume or less, the generation of voids in the ceramic part can be suppressed. By suppressing the generation of voids, for example, exposure of the metal foil, leakage when using a liquid electrolyte, intrusion of water, or intrusion of outside air can be suppressed.

  When using a film-like ceramic, the shape is not particularly limited. Also, a film made of ceramics of different materials may be used. As the binder for adhering the film-shaped ceramics, those mentioned in the above-mentioned particulate ceramic can be preferably used. You may use together a particulate ceramic and a film-form ceramic.

  As a ceramic part which consists of ceramics, what consists of a film-form ceramic is preferable. Further, two or more films made of ceramics of different materials may be used, or two or more films made of ceramics formed by different methods may be used. When two or more films made of ceramics having different formation methods are used, the effect of suppressing dielectric breakdown is improved.

  The thickness of the ceramic portion is not particularly limited, but when the dielectric breakdown voltage of the ceramic portion is B [V / μm] and the battery voltage of the electrochemical device is E [V], the thickness t of the ceramic portion t [μm It is preferable that the following formula 1 is satisfied.

  If the ceramic part is sandwiched between two electrodes and the voltage is gradually increased, the current will suddenly increase when a certain voltage is reached, a part of the ceramic part will melt and a hole will open, or the binder will carbonize. And come to energize. The voltage at this time is referred to as “dielectric breakdown voltage (B)”. The measuring method of the dielectric breakdown voltage conforms to JIS K 6911. The battery voltage (E) of the electrochemical device can be measured with a voltmeter.

[Resin film]
The packaging material of the present invention can include a resin film. By including the resin film, the flexibility of the exterior material can be improved. When an exterior material that is excellent in flexibility is used, there are advantages that the appearance of the electrochemical device can be easily formed into a target shape, and that it is difficult to break.

  The constituent material of the resin film is not particularly limited and can be appropriately selected depending on the characteristics of the battery element. For example, polyvinyl chloride, polyethylene, nylon (registered trademark), polyethylene naphthalate, polypropylene, polyethylene terephthalate, polyamide, Examples thereof include at least one selected from the group consisting of polyimide and polyimideamide.

  The thickness of the resin film is not particularly limited and can be appropriately selected according to the target mass or the like of the electrochemical device. In the present invention, since a ceramic layer containing ceramic is used in combination, it is used for a conventional laminate sheet. It is also possible to form it thinner than the thickness of the resin film to be formed.

[Metal foil]
The exterior material of this invention can contain metal foil. By including a metal foil, gas barrier properties or water impermeability can be improved.

  In a conventional electrochemical device, a conductive metal foil is connected to a positive electrode active material layer or a positive electrode active material layer and a negative electrode active material layer or a negative electrode active material layer. A short circuit occurred due to contact with the electric body. However, in one embodiment of the present invention, since the ceramic portion is interposed between the positive electrode active material layer and the metal foil, a short circuit can be suppressed.

  Although it does not specifically limit as a constituent material of metal foil, For example, at least 1 sort (s) selected from the group which consists of aluminum, stainless steel, gold | metal | money, silver, platinum, or an alloy containing these is mentioned.

  It does not specifically limit as thickness of metal foil, According to the target mass etc. of an electrochemical device, it can select suitably.

[Arrangement of each component]
Although the arrangement | positioning form of each component of the exterior material 160 is illustrated to AF of FIG. 1, this invention is not limited to these arrangement | positioning forms. Further, the number of components is not limited to that shown in FIG. 1, and more components can be used. Further, in FIG. 1, the shape of each component is shown in a simplified manner for the sake of explanation, but the shape of the exterior material of the present invention is not limited to FIG. 1, and is appropriately determined according to the type of each electrochemical device. Selected.

  The exterior material 160 of the present invention may be composed of, for example, a ceramic part 161 and a resin film 163 as shown in FIG. 1A, or a ceramic part 161 and a metal as shown in FIG. It may be made of the foil 165, or may be made of the ceramic portion 161, the resin film 163, and the metal foil 165 as shown in FIG. However, when the metal foil 165 is included as illustrated in B to D of FIG. 1, the ceramic portion 161 is disposed so as to electrically separate the metal foil 165 and the battery element (not shown). Is preferred. When the electrochemical device includes an electrode terminal connected to the battery element in addition to the battery element, the ceramic portion is disposed so as to electrically separate the metal foil and the electrode terminal. The term “electrically separated” in the present invention refers to preventing current flowing through the battery element or electrode terminal from flowing out to the metal foil included in the exterior material.

  As described above, when the resin film that separates the metal foil from the battery component is damaged for some reason, the conventional laminate sheet is exposed to the battery element or the electrode terminal. In some cases, a circuit is generated in the exterior, that is, a short circuit occurs. However, in the present invention, since the ceramic portion containing ceramic is used, the exposure of the metal foil is suppressed, so that the above problem can be solved.

  In addition, as described above, when the exterior material is formed only by the resin film without using the metal foil, the gas permeation amount or the water permeation amount is increased. Although depending on the type of electrochemical device, some battery elements are easily oxidized, so when an exterior material is formed only with a resin film, the battery element may deteriorate, but ceramic is insulated. Since not only the property but also the gas barrier property is excellent, the durability of the electrochemical device can be improved by using a ceramic together as in the present invention. Also, depending on the type of electrochemical device, some electrolytes contain strong oxidizing agents or strong reducing agents, and there is a possibility that invaded water may be electrolyzed inside the electrochemical device. When an exterior material is formed only with a film, there is a risk that the battery element will deteriorate, but since ceramic is excellent not only in insulation but also in water impermeability, it can be electrochemically combined with ceramic as in the present invention. The durability of the device can also be improved. Furthermore, depending on the type of electrochemical device, there is an electrochemical device that operates at a temperature of 100 ° C. or higher, and there is a possibility that the invaded water may vaporize inside the electrochemical device. However, the ceramic element is not only insulative but also water-impermeable, so the combined use of ceramic as in the present invention can improve the durability of the electrochemical device. It can also be improved.

  Moreover, the exterior material 160 of the present invention may include two or more layers of ceramic portions 161a and 161b, for example, as shown in FIG. Each of these ceramic parts may contain the same type of ceramic, or may contain different types of ceramic. In addition, as described above, these ceramic portions may be a ceramic portion including a particulate ceramic and a ceramic portion including a film-shaped ceramic. These ceramic parts may be ceramic parts formed by different methods. Details of the method of forming the ceramic portion will be described in the section of forming method described later. Further, a binder may be disposed between the ceramic part 161a and the ceramic part 161b, and these ceramic parts may be connected.

  Further, the ceramic portion 161 included in the exterior material 160 of the present invention may be provided on the entire surface, for example, as shown in FIGS. 1A to 1E, or as shown in FIGS. , May be provided partially.

[Formation method]
The method for forming the ceramic portion is not particularly limited, and a conventionally known method can be used. For example, when a particulate ceramic and a binder are used, the binder and the particulate ceramic are added to and mixed with the binder solvent, and then the solvent is removed, or the particles are mixed in the binder melted by heating. And a method of adding a ceramic in the form of a material.

  In the case of using a film-like ceramic, a conventionally known ceramic sintering method can be used, for example, a hot press method, a reaction sintering method, a room temperature sintering method, a hot static pressure sintering method. Further, a gas pressure sintering method, a two-step sintering method, an electrolytic oxidation method, an evaporation method, or the like can be used, and an evaporation method is more preferably used.

  Preferable examples of the vapor deposition method include at least one method selected from the group consisting of a vacuum vapor deposition method, a sputtering method, an ion plating method, and a CVD method.

  When an electrolytic oxide film or a vapor deposition method is used, the ceramic part may be formed on the surface of a component of the exterior material or on the surface of an electrode terminal or the like.

  The second of the present invention is an electrochemical device including the above-described exterior material.

  Electrochemical devices are used in a variety of applications, for example, digital cameras, mobile phones, notebook computers, portable game machines, hearing aids, or mobile power sources such as vehicles, or stationary power sources such as household power sources. Power supply.

  In addition to mobile power supplies, stationary power supplies are also transported from the production plant to the purchaser's permission. In the case of electrochemical devices using conventional exterior materials, the metal foil of the exterior material is exposed due to vibration. As a result, the electrochemical device may be short-circuited. Also, for example, when used for vehicles or households, high voltage is applied, pinholes or carbonization occurs in the resin part of the exterior material, the metal foil of the exterior material is exposed, and the electrochemical device is short-circuited There was a case. However, the electrochemical device using the exterior material of the present invention can solve these problems for the reasons described above, and can exhibit excellent durability.

  Currently, electrochemical devices include manganese batteries, alkaline manganese batteries, nickel-based primary batteries, oxyride batteries, silver oxide batteries, mercury batteries, air zinc batteries, lithium batteries, seawater batteries, and other primary batteries, lead storage batteries, lithium ion secondary batteries Secondary batteries such as batteries, nickel-hydrogen batteries, nickel-cadmium batteries, or sodium-sulfur batteries, or phosphoric acid fuel cells, polymer electrolyte fuel cells, molten carbonate fuel cells, or solid oxide fuel cells Such fuel cells are known. Among these, a non-aqueous electrolyte such as a lithium battery or a high voltage type electric double layer capacitor is preferably used. Since the exterior material of the present invention is excellent in non-water permeability, it is significant to apply the present invention to an electrochemical device using a non-aqueous electrolyte.

  As the lithium battery, a bipolar lithium ion secondary battery is preferable. Bipolar lithium ion secondary batteries are often used for power supplies that require high voltage, and high voltage is often applied to the exterior, so that the present invention is of great significance.

  Details of each component of the bipolar lithium ion secondary battery will be described below, but the present invention is not limited thereto.

[Negative electrode active material layer]
The negative electrode active material layer includes a negative electrode active material that releases ions during discharge and can store ions during charge. As the negative electrode active material, a metal oxide such as TiO, Ti ₂ O ₃ TiO ₂ or SnO ₂ , a composite oxide of lithium and a transition metal such as Li _4/3 Ti _5/3 O ₄ , or Li ₇ MnN, Li -Pb type alloy, Li-Al type alloy, Li, and at least 1 sort (s) selected from the group which consists of C etc. are mentioned.

  The particle diameter of the negative electrode active material is not particularly limited and can be appropriately determined according to the purpose.

  The negative electrode active material layer can contain a conductive additive, a binder, a polymerization initiator, an electrolyte, or the like depending on the purpose. Examples of the conductive assistant include acetylene black, carbon black, graphite, activated carbon, carbon fiber, coke, soft carbon, and hard carbon. Examples of the binder include polytetrafluoroethylene and polyvinylidene fluoride (hereinafter referred to as “PVDF”). Examples of the polymerization initiator include thermal polymerization initiators such as azobisisobutyronitrile (AIBN), and photopolymerization initiators such as benzyldimethyl ketal (BDK). Details of the electrolyte are described in the section of the electrolyte layer described later.

[Positive electrode active material layer]
The positive electrode active material layer includes a positive electrode active material that can occlude ions during discharge and release ions during charge. As the positive electrode active material, a composite oxide of lithium and a transition metal, a transition metal oxide, a transition metal sulfide, PbO ₂ , AgO, NiOOH, or the like can be used.

Examples of the composite oxide of lithium and a transition metal include Li-Mn composite oxides such as LiMnO ₂ and LiMn ₂ O ₄ , Li—Co composite oxides such as LiCoO _2, and Li—Ni systems such as LiNiO _2. Examples include composite oxides, Li—Fe-based composite oxides such as LiFeO ₂ , phosphate compounds of lithium and transition metals such as LiFePO ₄ , and sulfate compounds of lithium and transition metals. Examples of the transition metal oxide include V ₂ O ₅ , MnO ₂ , V ₂ MoO ₈ , and MoO ₃ . Examples of the transition metal sulfide include TiS _{2 and} MoS ₂ .

  The particle diameter of the positive electrode active material is not particularly limited, and can be appropriately determined according to the purpose.

  The positive electrode active material layer can contain the above-mentioned conductive assistant, the above-mentioned binder, the above-mentioned polymerization initiator, the electrolyte described later, or the like depending on the purpose.

[Electrolyte layer]
The electrolyte layer electrically insulates the positive electrode active material layer and the negative electrode active material layer, passes ions flowing from the negative electrode active material layer to the positive electrode active material layer during discharging, and charges from the positive electrode active material layer to the negative electrode active material during charging. Pass ions flowing through the layer.

  The electrolyte layer can be classified according to its form into one comprising an electrolytic solution, one comprising a gel electrolyte, or one comprising an intrinsic polymer electrolyte. These details are described below.

[Electrolyte]
The electrolytic solution is a liquid electrolyte, and an electrolytic solution in which a supporting salt is dissolved in a nonaqueous solvent can be used.

  The non-aqueous solvent is not particularly limited, but cyclic carbonates such as propylene carbonate (hereinafter also referred to as “PC”) or ethylene carbonate (hereinafter also referred to as “EC”); dimethyl carbonate, methyl ethyl carbonate, Or chain carbonates such as diethyl carbonate; ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane, or 1,3-dioxolane, diethyl ether Lactones such as γ-butyrolactone; nitriles such as acetonitrile; esters such as methyl propionate; amides such as dimethylformamide; esters such as methyl acetate and methyl formate; sulfolane; At least one can be mentioned is selected from the group consisting of and 3-methyl-1,3-oxazolidin-2-one; Sid.

No particular limitation is imposed on the supporting _{salt, LiBF 4, LiPF 6, LiClO} 4, Li (C 2 F 5 SO 2) 2 N, LiN (SO 2 CF 3) 2, and _{LiN (SO 2 C 2 F 5} ) 2 At least one selected from the group consisting of:

  In the case of using an electrolytic solution, it is preferable that a separator be disposed between the positive electrode active material layer and the negative electrode active material layer so that the electrolyte solution and the separator are combined to form an electrolyte layer.

  Although it does not specifically limit as a separator, A polypropylene, polyolefin, etc. are mentioned. These can be used in a shape allowing an electrolyte solution such as a nonwoven fabric or a microporous membrane to pass through. The thickness of a separator is not specifically limited, It determines suitably according to the objective.

[Gel electrolyte]
The gel electrolyte is a gel electrolyte in which an electrolytic solution is held in a polymer skeleton that forms a three-dimensional network structure by interaction between molecular chains such as chemical bonding, crystallization, or molecular entanglement.

  As the electrolytic solution, those described in the above-mentioned section of the electrolytic solution can be used.

  As the skeleton polymer, a polymer electrolyte may be used, or a polymer having no ion conductivity may be used. Examples of the polymer electrolyte include an intrinsic polymer electrolyte described later. Although it does not specifically limit as a polymer which does not have ion conductivity, PVDF, polyvinyl chloride, polyacrylonitrile, polymethylmethacrylate, these copolymers, or these alloys etc. are mentioned.

[Intrinsic polymer electrolyte]
The intrinsic polymer electrolyte is a solid electrolyte and is distinguished from a gel electrolyte containing an electrolytic solution. When an intrinsic polymer electrolyte is used as the electrolyte layer, since the intrinsic polymer electrolyte does not allow gas to pass through, the gas generated from the gas generating agent tends to remain at the interface between the electrolyte layer and the positive electrode active material layer or the negative electrode active material layer, and a small amount. The gas generating agent is preferable because the effects of the present invention can be exhibited, and the effects of the present invention can be exhibited in a shorter time.

  Although it does not specifically limit as a polymer which comprises an intrinsic polymer electrolyte, Polyethylene oxide, a polypropylene oxide, etc. are mentioned.

  In order to improve ionic conductivity, an electrolyte layer may be obtained by adding a supporting salt to an intrinsic polymer electrolyte, or an ionic dissociation group such as a carboxyl group, a phosphate group, a sulfonate group, or a siloxylamine group. What is introduced into the intrinsic polymer electrolyte may be used as the electrolyte layer. The supporting salt is as described above in the section of the electrolytic solution.

[Current collector]
The current collector of the bipolar lithium ion secondary battery has a negative electrode active material layer disposed on one surface and a positive electrode active material layer disposed on the other surface, excluding the end current collector disposed at the end.

  The material of the current collector is not particularly limited, but includes at least one selected from the group consisting of nickel, stainless steel, iron, titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and copper. More preferred is nickel or stainless steel, and further preferred is stainless steel.

  The current collector may be used in a single layer structure, may be used in a multilayer structure composed of different types of layers, or a clad material coated with these may be used.

[Other components]
The bipolar lithium ion secondary battery of the present invention may include other components depending on purposes. For example, an electrode terminal or a seal part can be included.

  The material constituting the electrode terminal is preferably the material constituting the current collector. However, the current collector and the electrode terminal are independent from each other, and they need not be the same material.

  The electrode terminal is connected to the current collector at the end, and allows a current generated from the unit cell to flow outside or a current supplied during charging to flow inside. For this reason, when an electrode terminal and metal foil of an exterior material contact, a short circuit may arise.

  The seal portion is disposed so as to keep the electrolyte solution between the positive electrode active material layer and the negative electrode active material layer when an electrolyte solution is used as the electrolyte layer, for example, between the current collector and the current collector. Is done.

  As a material constituting the seal portion, urethane resin, epoxy resin, polyethylene resin, polypropylene resin, polyimide resin or the like is preferable, and urethane resin or epoxy resin is more preferable. These are excellent in corrosion resistance, chemical resistance, moldability, or economy.

[Construction]
2 to 4 show schematic cross-sectional views of a hyperbolic lithium ion secondary battery provided with the exterior material of the present invention.

  As described above, in the present invention, the ceramic portion 261 may be formed on the entire exterior material 260 as shown in FIG. In FIG. 2, reference numeral 20 denotes a single cell layer, 210 denotes an electrolyte layer, 220 denotes a positive electrode active material layer, 230 denotes a negative electrode active material layer, 240 denotes a current collector, 242 denotes an electrode terminal, 250 denotes a seal portion, 263 denotes a resin film, Reference numeral 265 denotes a metal foil.

  Further, as described above, in the present invention, the ceramic portion 361 may be formed on a part of the exterior material 360 as shown in FIG. In FIG. 3, reference numeral 30 denotes a single cell layer, 310 denotes an electrolyte layer, 320 denotes a positive electrode active material layer, 330 denotes a negative electrode active material layer, 340 denotes a current collector, 342 denotes an electrode terminal, 350 denotes a seal portion, 363 denotes a resin film, Reference numeral 365 denotes a metal foil.

  2 and 3, it can be seen that the ceramic portions (261, 361) are disposed between the metal foils (265, 365) and the electrode terminals (242, 342).

  Depending on the structure of the bipolar lithium ion secondary battery, the end current collector 441 may be used instead of the electrode terminal without providing the electrode terminal as shown in FIG. It is preferable to dispose the ceramic part 461 between the body 441 and the metal foil 465. In FIG. 4, reference numeral 40 denotes a single cell layer, 410 denotes an electrolyte layer, 420 denotes a positive electrode active material layer, 430 denotes a negative electrode active material layer, 440 denotes a current collector, 442 denotes an electrode terminal, 450 denotes a seal portion, and 465 denotes a metal foil. Show.

  A third aspect of the present invention is an assembled battery formed by connecting a plurality of the above-described electrochemical devices in series, parallel, or series-parallel.

  By using the electrochemical device including the exterior material of the present invention, an assembled battery with improved durability can be provided.

  The connection method in particular when connecting the some electrochemical device which comprises an assembled battery is not restrict | limited, A conventionally well-known method can be employ | adopted suitably. For example, a technique using welding such as ultrasonic welding or spot welding, or a technique of fixing using rivets, caulking, or the like can be employed. Note that a plurality of electrochemical devices constituting the assembled battery may be connected in parallel, a plurality of electrochemical devices may be connected in series, or a series connection and a parallel connection may be combined.

  A fourth aspect of the present invention is a vehicle equipped with the above-described electrochemical device or the above-mentioned assembled battery as a driving power source.

  Vehicles that use an electrochemical device as a driving power source include, for example, vehicles that drive wheels by a motor, such as fully electric vehicles that do not use gasoline, hybrid vehicles such as series hybrid vehicles and parallel hybrid vehicles, and fuel cell vehicles. Can be mentioned. Since the electrochemical device or the assembled battery of the present invention is excellent in durability, the reliability of the vehicle and the output maintaining characteristics over a long period of time can be improved.

  The preferred embodiments have been described above, but the present invention is not limited to the above-described embodiments, and various modifications, omissions, and additions can be made by those skilled in the art.

The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples.

Example 1
<Production of bipolar electrode>
Lithium manganate (LiMn ₂ O ₄ ) (average particle size: 10 μm) (90 parts by mass) as a positive electrode active material, acetylene black (5 parts by mass) as a conductive additive, and polyvinylidene fluoride (PVdF) as a binder (5 parts by mass) was mixed, and then an appropriate amount of N-methyl-2-pyrrolidone (NMP) as a slurry viscosity adjusting solvent was added to prepare a positive electrode active material slurry.

  Further, hard carbon (average particle size: 9 μm) (90 parts by mass) as a negative electrode active material and polyvinylidene fluoride (PVdF) (10 parts by mass) as a binder are mixed, and then N— which is a slurry viscosity adjusting solvent. An appropriate amount of methyl-2-pyrrolidone (NMP) was added to prepare a negative electrode active material slurry.

  On the other hand, stainless steel foil (size: 250 × 250 × 0.02 mm) was prepared as a current collector. The positive electrode active material slurry prepared above was applied to the center of one surface of the prepared current collector by a doctor blade method to form a coating film. Next, this coating film was dried at 130 ° C. for 10 minutes, and then subjected to a press treatment at a linear pressure of 2 t / m using a roll press machine to form a positive electrode active material layer (size: 240 × 240 × 0.05 mm). Formed. Furthermore, the negative electrode active material slurry prepared above was applied to the other surface of the current collector by a doctor blade method to form a coating film. Next, this coating film was dried at 130 ° C. for 10 minutes, and then subjected to a press treatment at a linear pressure of 2 t / m using a roll press machine to form a negative electrode active material layer (size: 250 × 250 × 0.05 mm). Formed to complete a bipolar electrode.

  Nine of the above bipolar electrodes were prepared, and further, as the outermost layer electrode, a positive electrode active material layer (positive electrode side outermost layer current collector) or a negative electrode active material layer (negative electrode side) was formed on one surface of the current collector. One of each of the outermost layer current collectors) was prepared, and a total of 11 electrodes were prepared.

  On the exposed portion of the current collector on the side where the positive electrode active material layer (9 bipolar electrodes + 1 negative electrode side outermost layer) of the electrode prepared above was formed, a frame-shaped laminated sheet (modified) A three-layer laminated sheet of polypropylene (PP) -polyethylene terephthalate (PET) -modified PP, size: outer dimension = 270 × 270 mm, inner dimension = 240 × 240 mm, thickness = 40 μm) was bonded by thermal fusion.

<Production of battery element>
As separators, 10 sheets of PP microporous membrane (size: 250 × 250 × 0.02 mm) were prepared.

  Subsequently, the bipolar electrodes and separators produced above were alternately laminated to produce a laminate. In this case, the lamination was performed so that the positive electrode active material layer and the negative electrode active material layer of the adjacent bipolar electrode face each other, and the final electrode side of each outermost layer electrode was disposed in the outermost layer. Thereafter, adjacent seal layers (laminated sheets) were bonded together by heat fusion. At this time, the lamination sheet was adhered such that a part of the outer periphery of the lamination sheet was left as an injection port for injecting an electrolyte solution described later.

On the other hand, as an electrolytic solution, LiPF ₆ which is a lithium salt is dissolved at a concentration of 1M in a mixed solution (EC: PC = 1: 2 (volume ratio)) of ethylene carbonate (EC) and propylene carbonate (PC). Prepared. This electrolytic solution was injected from the above-mentioned injection port, and the injection port was sealed by heat sealing under vacuum conditions, to produce a battery element.

  Further, two aluminum plates (size: 300 × 250 × 0.1 mm) were prepared as electrode terminals for both electrodes. This aluminum plate was bonded with a carbon-based conductive adhesive so that the outermost layer current collector and the three sides were aligned. At this time, the terminals were bonded so that the directions of extracting the terminals were reversed.

<First charge / discharge and degassing>
A total of 10 battery elements similar to the above were prepared, and each battery element was charged with a constant current of 50 mA to a voltage of 42 V for 8 hours, and then discharged with a constant current of 50 mA to a voltage of 25 V. . Battery elements that do not operate at this time are considered to be short-circuited, and are excluded from the subsequent tests (the number of excluded battery elements is referred to as “first short-circuit number”).

  Subsequently, a part of the seal layer (laminated sheet) was cut out, the gas generated inside the battery element at the time of the first charge / discharge was removed, and the cut-out part was vacuum-sealed by thermal fusion again.

<Encapsulation in laminate sheet>
Two exterior materials (from outside, nylon (Nyl) (thickness: 30 μm) + aluminum (Al) (thickness: 40 μm) + polyethylene naphthalate (PEN) and alumina (Al ₂ O ₃ ) particles (spherical, average particles) A mixed layer (PEN: Al ₂ O ₃ = 95: 5 (volume ratio)) (thickness (t): 8 μm) + PP (thickness: 30 μm, size: 290 × 290 mm) was prepared. . In this embodiment, “mixed layer of PEN and Al ₂ O ₃ ” corresponds to “ceramic part”, PEN is a binder, and Al ₂ O ₃ is ceramic. In addition, the said aluminum laminate sheet was produced with the following method. That is, immediately after applying tolylene diisocyanate prepared to a solid content of 5% by mass with ethyl acetate as an anchor coat layer on one surface of an aluminum foil, Nyl having a thickness of 30 μm was laminated by an extrusion laminating method at a processing speed of 10 m / min. It was. On the other side of the aluminum foil, tolylene diisocyanate prepared with ethyl acetate to a solid content of 5% by weight was applied as an anchor coating layer, and at the same time, two-component curing was performed as an anchor coating layer on the mixed layer (8 μm). A type polyurethane adhesive was applied, and PP having a thickness of 30 μm was sandwich-laminated by extrusion laminating at a processing speed of 10 m / min to produce a laminate sheet. The mixed layer was obtained by melting PEN at 280 ° C., mixing and stirring Al ₂ O ₃ , and extrusion molding.

  With the two exterior materials, the battery element prepared above is sandwiched so that the positive electrode terminal and the negative electrode terminal are led out, and the four sides of the film are sealed by thermal fusion under vacuum conditions, A bipolar lithium ion secondary battery was completed. Prior to heat sealing, a modified PP sheet (thickness: 40 μm) was previously bonded to the exterior passage portion of the aluminum plate as the electrode terminal by heat sealing.

<Evaluation>
The bipolar lithium ion secondary battery produced above was charged and discharged at a voltage of 25 to 42 V, and then charged at a constant voltage of 42 V.

  Subsequently, the battery in a charged state was placed on a vibration test apparatus, and 5 to 50 Hz repeated sweep, acceleration of 1 G, and vibration for 24 hours were applied. Thereafter, the voltage of the battery subjected to vibration was measured. The voltage at this point is referred to as “post-vibration voltage”. In addition, a battery whose voltage does not reach 25 V at this time is regarded as a short circuit, and is excluded from the subsequent tests (the number of excluded batteries is referred to as “the number of short circuits after vibration”).

  Further, after the above test, the sample was left at 25 ° C., and the voltage was measured after being left for one week and left for one month. The voltage at each time point is referred to as “voltage after standing for one week” and “voltage after standing for one month”, respectively. In addition, regarding the battery whose voltage does not reach 25V at each time point, it is considered that a short circuit has occurred (the number of short circuits at each time point is the number of short circuits after being left for one week) and the number of short circuits after being left for one month. The battery whose voltage did not reach 25 V when left for one week was excluded from the subsequent tests.

  The results of the number of short circuits and the measured voltage for the above test are shown in Table 1 below.

(Example 2)
The same as Example 1 except that the mixing ratio of each component in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material was PEN: Al ₂ O ₃ = 50: 50 (volume ratio). A bipolar lithium ion secondary battery was fabricated and evaluated. The results are shown in Table 1 below.

(Example 3)
The same as Example 1 except that the mixing ratio of each component in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material was PEN: Al ₂ O ₃ = 30: 70 (volume ratio). A bipolar lithium ion secondary battery was fabricated and evaluated. The results are shown in Table 1 below.

Example 4
The same as Example 1 except that the mixing ratio of each component in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material was PEN: Al ₂ O ₃ = 20: 80 (volume ratio). A bipolar lithium ion secondary battery was fabricated and evaluated. The results are shown in Table 1 below.

(Example 5)
Bipolar lithium ion secondary by the same method as in Example 2 except that the Al ₂ O ₃ particles in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material are replaced with silica alumina gel particles. A battery was prepared and evaluated. The results are shown in Table 1 below.

(Example 6)
Except that the Al ₂ O ₃ particles in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material were replaced with silica gel particles, a nonaqueous electrolyte battery was produced by the same method as in Example 2 above, Evaluation was performed. The results are shown in Table 1 below.

(Example 7)
There is no “mixed layer of PEN and Al ₂ O ₃ particles”, and an Al ₂ O ₃ film (thickness (t): 5 μm) between the exterior passage portion of the electrode terminal (aluminum plate) and the modified PP. A bipolar lithium ion secondary battery was prepared and evaluated by the same method as in Example 1 except that the outer packaging material having a structure in which) was disposed was used. The results are shown in Table 1 below. The Al ₂ O ₃ film was formed by a sputtering method. In this example, “Al ₂ O ₃ film formed by sputtering” corresponds to “ceramic part”.

(Example 8)
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 7 except that a silica (SiO ₂ ) film was formed instead of the Al ₂ O ₃ film. The results are shown in Table 1 below.

Example 9
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 7 except that a magnesia (MgO) film was formed instead of the Al ₂ O ₃ film. The results are shown in Table 1 below.

(Example 10)
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 7 except that a zirconia (ZrO ₂ ) film was formed instead of the Al ₂ O ₃ film. The results are shown in Table 1 below.

(Example 11)
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 7 except that an yttria (Y ₂ O ₃ ) film was formed instead of the Al ₂ O ₃ film. The results are shown in Table 1 below.

(Example 12)
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 7 except that a calcia (CaO) film was formed instead of the Al ₂ O ₃ film. The results are shown in Table 1 below.

(Example 13) A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 8 except that an Al ₂ O ₃ film was formed by vacuum deposition instead of sputtering. It was. The results are shown in Table 1 below.

(Example 14)
A bipolar lithium ion secondary battery was prepared and evaluated by the same method as in Example 2 except that an Al ₂ O ₃ film was formed at the exterior passage site by the same method as in Example 8 above. It was. The results are shown in Table 1 below.

(Example 15)
Except that the thickness (t) of the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material was 2 μm, and the average particle diameter of the Al ₂ O ₃ particles was 1 μm, the above examples A bipolar lithium ion secondary battery was prepared by the same method as in No. 2 and evaluated. The results are shown in Table 1 below.

(Example 16)
A bipolar lithium ion secondary battery is produced in the same manner as in Example 2 except that PEN in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material is replaced with PET (polyethylene terephthalate). And evaluated. The results are shown in Table 1 below.

(Example 17)
A bipolar lithium ion secondary battery was fabricated and evaluated in the same manner as in Example 2 except that PEN in the “mixed layer of PEN and Al ₂ O ₃ particles” of the exterior material was replaced with PP. went. The results are shown in Table 1 below.

(Example 18)
Film-like ceramic (PEN: Al ₂ O ₃ = 50: 50 (volume ratio)) composed of polyethylene naphthalate (PEN) and alumina (Al ₂ O ₃ ) particles (spherical, average particle diameter: 1 μm) (thickness) A bipolar lithium ion secondary battery was prepared and evaluated in the same manner as in Example 2 except that a laminate obtained by stacking two (t): 4 μm) was used as the ceramic part. The results are shown in Table 1 below.

Example 19
Film-like ceramic (PEN: Al ₂ O ₃ = 50: 50 (volume ratio)) composed of polyethylene naphthalate (PEN) and alumina (Al ₂ O ₃ ) particles (spherical, average particle diameter: 1 μm) (thickness) (T): 4 μm) and a film-like ceramic (PEN: SiO ₂ = 50: 50 (volume ratio)) composed of PEN and SiO ₂ particles (spherical, average particle diameter: 1 μm) (thickness (t): A bipolar lithium ion secondary battery was prepared and evaluated in the same manner as in Example 2 except that the 4 μm laminate was used as the ceramic part. The results are shown in Table 1 below.

(Example 20)
A film-like ceramic (PEN: Al ₂ O ₃ = 50: 50 (volume ratio)) composed of PEN and Al ₂ O ₃ particles (spherical, average particle diameter: 1 μm) (thickness (t): 4 μm), and A laminated body of a film-like ceramic (PEN: MgO = 50: 50 (volume ratio)) (thickness (t): 4 μm) made of PEN and MgO particles (spherical, average particle diameter: 1 μm) is used as a ceramic part. A bipolar lithium ion secondary battery was produced and evaluated in the same manner as in Example 2 except that it was not. The results are shown in Table 1 below.

(Example 21)
The thickness of the mixed layer of PEN and Al ₂ O ₃ particles was set to 4 μm, and as the second ceramic layer, sputtering was performed between the exterior passage site of the electrode terminal (aluminum plate) and the modified PP. A bipolar lithium ion secondary battery was prepared and evaluated in the same manner as in Example 2 except that an Al ₂ O ₃ film (thickness (t): 2 μm) was provided. The results are shown in Table 1 below.

(Comparative example)
A bipolar lithium ion secondary battery was prepared and evaluated in the same manner as in Example 1 except that a material having no “mixed layer of PEN and Al ₂ O ₃ particles” was used as the exterior material. Went. The results are shown in Table 1 below.

  In addition, the battery element of the battery produced in each of the above examples and comparative examples has a structure in which ten unit cells are electrically connected in series. Since each unit cell has a voltage of 4.2V, the battery voltage (E) of each battery was 42V. The dielectric breakdown voltage (B) [V / μm] of the “insulating layer” provided in each example was 10 V / μm.

  From the comparison between each example and each comparative example, in the exterior passage portion of the electrode terminal of the bipolar lithium ion secondary battery sealed in the exterior made of the metal-resin laminate sheet, the electrode inside the exterior and the electrode An insulating layer containing ceramic is provided between the terminal and the metal foil (Examples 1 to 6, 15, and 16 to 20) or between the exterior and the electrode terminal (Examples 7 to 14 and 21). If provided, it is shown that effects such as improvement in yield and suppression of vibration and voltage drop during storage can be obtained.

  Further, from the comparison between Examples 1 to 14 and 16 to 21 and Example 15, when the thickness (t) of the provided insulating layer satisfies a predetermined condition (E / B <t), the above effect is obtained. It can be seen that it can be exhibited more remarkably.

  From the above, according to the present invention, in the bipolar lithium ion secondary battery in which the voltage between the terminals may be relatively large, the electrode terminal in the exterior passage portion of the electrode terminal and the metal foil constituting the laminate sheet; It is suggested that a short circuit between the two is effectively prevented, and as a result, a decrease in voltage during excitation and storage can be effectively suppressed.

It is the figure which illustrated the arrangement form of each component of the exterior material of the present invention. It is the cross-sectional schematic of the bipolar type lithium ion secondary battery to which the exterior material of this invention is applied. It is the cross-sectional schematic of the bipolar type lithium ion secondary battery to which the exterior material of this invention is applied. It is the cross-sectional schematic of the bipolar type lithium ion secondary battery to which the exterior material of this invention is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Single cell layer 25 Battery element 30 Single cell layer 35 Battery element 40 Single cell layer 45 Battery element 160 Exterior material 161 Ceramic part 163 Resin film 165 Metal foil 210 Electrolyte layer 220 Positive electrode active material layer 230 Negative electrode active material layer 240 Current collector 242 Electrode terminal 260 Exterior material 261 Ceramic part 263 Resin film 265 Metal foil 310 Electrolyte layer 320 Positive electrode active material layer 330 Negative electrode active material layer 340 Current collector 342 Electrode terminal 360 Exterior material 361 Ceramic part 363 Resin film 365 Metal foil 410 Electrolyte layer 420 positive electrode active material layer 430 negative electrode active material layer 440 current collector 442 electrode terminal 441 end current collector 461 ceramic portion 463 resin film 465 metal foil

Claims (16)

An outer packaging material for an electrochemical device including at least a battery element as an electrolyte layer sandwiched between a positive electrode active material layer and a negative electrode active material layer,
An exterior material comprising a ceramic part containing ceramic and a resin film or a metal foil. When the dielectric breakdown voltage of the ceramic part is B [V / μm] and the battery voltage of the electrochemical device is E [V], the thickness t [μm] of the ceramic part is expressed by the following formula 1:

The exterior material according to claim 1, wherein:   The exterior material according to claim 1 or 2, wherein the ceramic portion includes a plurality of particulate ceramics and a binder for connecting the particulate ceramics.   The exterior material according to claim 3, wherein the binder is at least one selected from the group consisting of polyolefin, polyimide, and polyamideimide.   The packaging material according to claim 3 or 4, wherein a ratio of the particulate ceramic to a total amount of the particulate ceramic and the binder is 1 to 70% by volume.   6. The ceramic according to claim 1, wherein the ceramic is an oxide ceramic containing one or more elements selected from the group consisting of silicon, aluminum, zirconium, yttrium, magnesium, calcium, and scandium. Exterior material.   The packaging material according to claim 6, wherein the oxide ceramic is at least one selected from the group consisting of silica gel and silica alumina gel.   The said ceramic part is an exterior material in any one of Claims 1-7 containing a film-form ceramic.   The packaging material according to claim 8, wherein the insulating layer is provided by a vapor deposition method.   The packaging material according to claim 8 or 9, comprising two or more layers of the ceramic.   The exterior material according to any one of claims 1 to 10, wherein the ceramic portion is provided on the entire surface.   The electrochemical device containing the exterior | packing material of any one of Claims 1-11. An electrode terminal connected to the battery element;
The exterior material includes the metal foil,
13. The electrochemical device according to 12, wherein the ceramic portion of the exterior material is disposed so as to electrically separate the metal foil and the electrode terminal.   The electrochemical device according to claim 12 or 13, which is a bipolar lithium ion secondary battery.   A battery pack comprising a plurality of electrochemical devices according to any one of claims 12 to 13 electrically connected in series, parallel, or series-parallel.   The vehicle which mounts the electrochemical device of any one of Claims 12-14, or the assembled battery of Claim 15 as a drive power supply.

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