JP2008171732A - Thin battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin battery from which a terminal for current collection can be easily taken out while surely sealing a power generating area performing battery reaction. <P>SOLUTION: The thin battery is equipped with a substrate 1, a positive electrode layer and a negative electrode layer formed on the substrate 1, an electrolyte layer performing ion conduction between both electrode layers, a positive current collector 3 electrically connected to the positive electrode layer, and a negative current collector 2 electrically connected to the negative electrode layer. A power generation area G performing battery reaction between both electrode layers through the electrolyte layer, a positive electrode current collection area P comprising a portion where is a part of the positive current collector 3 and does not overlap with the electrode layer, and a negative electrode current collection area N comprising a portion where is a part of the negative current collector 2 and does not overlap with the electrode layer are formed on the substrate 1 of the battery. The battery has a sealing film 7 which covers the power generation area G but does not cover the current collection areas P, N. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thin battery. In particular, the present invention relates to a thin film Li secondary battery in which a current collecting terminal can be easily pulled out.

  As an example of a thin film battery, a battery described in Patent Document 1 is known. This battery is a thin film lithium battery having a structure in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are sequentially laminated on a substrate.

  Here, lithium metal may be used for the negative electrode layer, but this lithium metal reacts with water and nitrogen when exposed to the outside air, and immediately forms hydroxides and nitrides. Therefore, in order to increase the life and reliability of the lithium battery, it is necessary to seal the power generation area where the battery reaction occurs between the positive and negative electrode layers.

  For example, in the battery of Patent Document 1, all battery constituent members of the base material, the positive electrode current collector, the positive electrode layer, the solid electrolyte layer, the negative electrode layer, and the negative electrode current collector are sealed with an epoxy resin. In addition, the battery component is entirely sandwiched between a pair of sealing films having a larger area than the base material, and the battery is sealed by sealing the peripheral edge of the sheet.

  When the sealing is performed, the lead portion is connected to the battery so that electricity can be taken out from each current collector. The lead part is attached by wire bonding a lead wire (for example, a gold wire) to the current collector or by bonding a lead piece (for example, a copper plate) to the current collector. In any case, the lead portion is arranged so that a part thereof is exposed from the sealing resin or the sealing film.

JP 59-226472 A

  However, the above thin film battery has a problem that it is difficult to draw out a current collecting terminal without increasing the thickness of the battery.

  As described above, if the entire battery is sealed with resin sealing or a sealing film, the moisture-proof property of the power generation area can be ensured to some extent. However, in the structure using a lead wire or lead piece as the lead part, the lead resin is covered with the sealing resin or the lead part is sandwiched between the sealing films, so that the thickness of the battery increases only in that part. . At present, when thin film batteries are expected to be applied to IC cards and the like, there is a strong demand for thinner batteries.

  The present invention has been made in view of the above circumstances, and one of its purposes is to provide a thin battery that can easily form a current collecting terminal in the battery while the power generation area can be reliably sealed. is there.

  The thin battery of the present invention includes a substrate, a positive electrode layer and a negative electrode layer formed above the substrate, an electrolyte layer that conducts ions between the two electrode layers, and a positive electrode electrically connected to the positive electrode layer. A thin battery comprising a current collector and a negative electrode current collector electrically connected to the negative electrode layer. On the battery substrate, a power generation area where a battery reaction is performed between both electrode layers via an electrolyte layer, a positive electrode current collection area consisting of a portion of the positive electrode current collector that does not overlap with the electrode layer, Three areas are formed, which are a part of the negative electrode current collector and a negative electrode current collection area formed of a portion that does not overlap with the electrode layer. And the battery of this invention is provided with the sealing film which covers a power generation area, but does not cover at least one part of both current collection areas.

  According to the battery with this structure, the power generation area is covered with the sealing film, so that the power generation area can be surely made into a moisture-proof structure. On the other hand, since at least a part of each current collecting area is not covered with the sealing film, the exposed current collecting area itself can be used as a lead portion. At that time, since the surface of the current collection area to be the lead part is not covered with the sealing film, the lead part such as a metal piece is connected to the current collector, and the connection part is covered with the sealing film Compared with, the connecting portion does not become thick.

  As one form of this invention battery, it is preferable that a sealing film is a magnitude | size which covers only a power generation area substantially.

  If the size of the sealing film is made smaller than that of the base material and only the power generation area is covered, at least a part of each current collection area is necessarily exposed without being covered by the sealing film. Therefore, this exposed current collection area can be used as a lead part.

  As one form of the battery of the present invention, the sealing film has an opening formed in a part thereof, each current collection area is exposed from this opening, and the power generation area is covered with a surface other than the opening. preferable.

  Even if the contour size of the sealing film is a sheet wider than the power generation area, if an opening is provided in a part of the film and at least a part of each current collection area is exposed from the opening, The exposed current collection area can be used as a lead portion.

  As one form of the battery of the present invention, the sealing film preferably has a laminated structure including a bonding layer fused to the object to be sealed and a base material layer that is not substantially melted by heat at the time of fusion. .

  If the sealing film provided with a joining layer is used, a sealing object and a sealing film can be heat-sealed easily, and a battery can be sealed reliably.

  As one form of the battery of the present invention, the bonding layer may be any one of polypropylene, polyethylene, polyamide and polyester modified with an acidic group.

  Polypropylene, polyethylene, polyamide, and polyester modified with acidic groups are all melted at a relatively low temperature, and sufficient adhesive properties can be obtained. Therefore, these materials can be suitably used as the bonding layer of the sealing film.

  As one form of this invention battery, the sealing film consists of three or more layers, and it is preferable that any layer except one surface layer and the other surface layer is metal foil.

  If metal foil is used for the sealing film, higher moisture resistance can be obtained compared to the resin film, and a more reliable battery can be constructed. Moreover, the insulation of a battery structural member and a sealing film is securable by making one surface layer and the other surface layer into insulating materials, such as resin.

  As one form of the battery of the present invention, it is preferable that there is no overlapping portion between the positive electrode layer and the negative electrode layer when the battery is viewed in plan.

  Usually, in the case of an arrangement in which the positive electrode layer and the negative electrode layer overlap, an electrolyte layer is interposed between the two electrodes. In that case, if a pinhole occurs in the thickness direction of the electrolyte layer, a short circuit occurs between the two electrodes. On the other hand, if there is no overlap between the positive electrode layer and the negative electrode layer, the problem of short circuit between both electrodes can be reduced.

  According to the thin battery of the present invention, by providing the sealing film that covers the power generation area and does not cover at least a part of the positive electrode current collection area and the negative electrode current collection area, the power generation area can have a moisture-proof structure, and the collection of each electrode. Since at least a part of the electricity area is exposed, the current collecting terminal can be easily pulled out.

[Basic battery configuration]
The battery of the present invention can be suitably used as a lithium ion battery, and has a basic configuration including a positive electrode layer, a negative electrode layer, an electrolyte layer, a positive electrode current collector, and a negative electrode current collector. Usually, all the layers are formed in a thin film. Among these, the positive electrode layer and the negative electrode layer may have a laminated structure with overlapping portions when the battery is viewed in plan, or may have a structure without overlapping portions. In the former case, it is easy to reduce the area of the battery, and in the latter case, even if pinholes are generated in the thickness direction of the electrolyte layer, it is easy to suppress a short circuit between both electrode layers. When the battery is viewed in plan, the electrode configuration in which there is no overlapping portion between both electrode layers includes forming the positive electrode layer and the negative electrode layer in a comb-like shape and arranging them in parallel so as to be fitted to each other. .

  The battery of the present invention having such a structure includes three areas: a power generation area, a positive current collection area, and a negative current collection area. And the electric power generation area is covered with the sealing film, and both current collection areas are exposed without being covered with the sealing film.

(Power generation area)
The power generation area is an area where a battery reaction is performed between the positive electrode layer and the negative electrode layer via the electrolyte layer. In a battery having a laminated structure in which an electrolyte layer is interposed between a positive electrode layer and a negative electrode layer, when the battery is viewed in plan, a portion where these two electrode layers overlap is a power generation area. On the other hand, when both electrode layers are arranged in parallel without overlapping, the outline of the portion where these two electrode layers are arranged is the power generation area. An electrolyte layer that conducts ions between the positive and negative electrode layers is also accommodated in the power generation area.

(Collector area)
When the battery is viewed in plan, the current collection area consists of a positive electrode current collection area consisting of a part of the positive electrode current collector that does not overlap with the electrode layer, and a part of the negative electrode current collector that does not overlap with the electrode layer. It consists of a negative electrode current collection area. Of each current collector, the portion overlapping with the electrode layer is covered with the sealing film as a power generation area, but at least part of the portion not overlapping with the electrode layer is exposed from the sealing film, but the battery characteristics It does not have a big influence on. Rather, it is preferable that the current collector is partially exposed from the sealing film because the exposed portion can be a lead portion. Usually, since the positive electrode layer, the negative electrode layer, the electrolyte layer, the positive electrode current collector and the negative electrode current collector are formed above the base material, the current collector area is formed by laminating the base material and one of the current collectors. It becomes the place that was done.

  In some cases, at least one of the electrode layers also functions as a current collector. For example, when the negative electrode layer is formed of an alloy, a part of the negative electrode layer can be used as a current collector, and the current collector can be used as a current collection area. In this case, each current collection area is a part of one electrode layer that does not overlap with the other electrode layer, or a part of each electrode layer that does not overlap with the electrolyte layer.

(Sealing film)
<Material>
The sealing film is made of a material that has low water permeability and can ensure insulation against the constituent members of the battery. Specifically, resin and metal foil can be suitably used as the material for the sealing film. Specific examples of the resin include polypropylene (PP), polyethylene (PE), polystyrene (PS), polyamide (PA), polyethylene terephthalate (PET), and the like. Specific examples of the metal include aluminum and an aluminum alloy.

<Size>
The sealing film has a size that covers at least the power generation area. However, it is preferable that the film has a size that covers an area slightly wider than the outline of the overlapping part of the two electrode layers or the part where the two electrode layers are arranged in parallel with a margin. By using a sealing film of such a size, structural members that contribute to the battery reaction, such as both electrodes and the electrolyte layer, can be reliably covered with the sealing film to form a moisture-proof structure. The outer size of the sealing film may be smaller than the base material or larger than the base material. In the case of a sealing film smaller than the base material, a sealing film having a size that substantially covers only the power generation area may be used. If a sealing film of such a size is used, a battery that covers the power generation area with the film and does not cover each current collection area can be easily formed. On the other hand, in the case of a sealing film larger than the base material, the sealing film may have an opening at a position corresponding to each current collection area. Even if the sealing film is larger than the base material, if the opening is partially formed, only the current collecting area is covered with the sealing film by making the opening correspond to the current collecting area. No battery can be formed easily. The size of the opening may be appropriately determined in consideration of the size of the current collection area. Furthermore, the shape of the opening is not particularly limited, and various shapes such as a circle and a polygon can be selected. In addition, the opening part here includes not only the case where the outer edge of the opening part is closed and the hole formed in the outline of the sealing film, but also the case where the outer edge of the opening part is a notch extending to the outline of the sealing film. It is.

<Structure>
The sealing film preferably has a laminated structure including a base material layer and a bonding layer. Since the sealing film needs to seal the power generation area by being in close contact with the object to be sealed, it is desirable that the sealing film be adhered to the object to be sealed so as not to easily peel off. Therefore, a favorable sealing structure can be formed by providing the bonding layer that is fused to the object to be sealed by heat fusion and the base material layer that is not melted even by the heat at the time of heat fusion.

  The sealing target with which the bonding layer of the sealing film comes into contact may be one of the constituent members of the battery, or may be another sealing film that faces the battery. In particular, in the case of a sealing film having an opening, it is preferable that the peripheral edge of the opening is in close contact with a battery component, for example, a current collector.

  As the material of the bonding layer, any of polypropylene, polyethylene, polyamide, and polyester modified with an acidic group can be suitably used. Examples of the acidic group include a hydroxyl group, a sulfone group, a carboxyl group, a mercapto group, a sulfate group, and a phosphate group.

  As the material for the base material layer, any of polypropylene, polyethylene, polyamide, polyester, and polyethylene terephthalate can be suitably used.

  It is also preferable that the sealing film has a laminated structure of a resin film and a metal foil. Since the metal foil is superior in water permeability compared to the resin film, a battery with a high moisture-proof structure can be formed. For example, a sealing film having a three-layer structure in which a base material layer is formed on one surface side of the metal foil and a bonding layer is formed on the other surface side can be suitably used. If the sealing film of this structure, both sides of the metal foil is covered with a resin film, so that high moisture resistance can be ensured with the metal foil, and the front and back of the sealing film are kept insulative, Insulation between the battery constituent member and the sealing film can be ensured.

<Sealing method>
The sealing method of a sealing film will not be specifically limited if it is a method which can be closely_contact | adhered to sealing object. Typically, the resin film may be thermocompression bonded to the battery constituent member or the opposing resin film by heat sealing or roll press. In particular, it is preferable that the outer edge portion of the sealing film is sufficiently adhered so that no gap is formed between the outer peripheral portion and the object to be sealed.

(Positive electrode layer)
<Material>
The positive electrode layer is composed of a layer containing an active material that absorbs and releases ions. In the case of a lithium ion battery, the positive electrode layer is an oxide such as lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and olivine type lithium iron phosphate (LiFePO ₄ ). One selected from the group consisting of these or a mixture thereof can be suitably used. The positive electrode layer may be a sulfide, for example, one selected from the group consisting of sulfur (S), lithium sulfide (Li ₂ S), and titanium sulfide (TiS ₂ ), or a mixture thereof. In addition, examples of the material for the positive electrode layer include copper-lithium oxide (Li ₂ CuO ₂ ) and vanadium oxides such as LiV ₃ O ₃ , V ₂ O, and Cu ₂ V ₂ O ₇ . All of the oxides described above have heat resistance against the heating temperature (about 200 to 250 ° C.) during solder reflow. The thickness of the positive electrode layer is preferably about 10 to 300 μm. A more preferable thickness of the positive electrode layer is 100 μm or less, and a more preferable thickness of the positive electrode layer is 30 μm or less.

<Method for forming positive electrode layer>
As a method for forming the positive electrode layer, a wet method or a dry method can be used. Examples of the wet method include a sol-gel method, a colloid method, and a casting method. Examples of the dry method include a vapor deposition method that is a vapor deposition method, an ion plating method, a sputtering method, a laser ablation method, and the like.

(Negative electrode layer)
<Material>
The negative electrode layer is also composed of a layer containing an active material that occludes and releases ions. In the case of a lithium ion battery, as the negative electrode layer, one selected from the group consisting of Li metal and a metal capable of forming an alloy with Li metal, or a mixture or alloy thereof can be preferably used. The metal capable of forming an alloy with Li is at least one selected from the group consisting of aluminum (Al), silicon (Si), tin (Sn), bismuth (Bi), zinc (Zn), and indium (In). (Hereinafter referred to as alloying material) is good. In addition, carbon materials such as graphite, lithium titanium oxides having a spinel structure such as Li ₄ Ti ₅ O ₁₂ , Li ₄ Fe _0.5 Ti ₅ O ₁₂ , Li ₄ Zn _0.5 Ti ₅ O ₁₂ , sulfides such as TiS ₂ , Nitrogen compounds such as LiCo _2.6 O _0.4 N and mixtures thereof can be cited as the material for the negative electrode layer. Among these, carbon materials and oxides have heat resistance against the heating temperature (about 200 to 250 ° C.) during solder reflow. The thickness of the negative electrode layer is preferably about 0.5 to 80 μm. A more preferable thickness of the negative electrode layer is 1 to 40 μm.

  The negative electrode layer made of the above-described alloy is preferable because the negative electrode layer itself can have a function as a current collector and has a high ability to occlude and release lithium ions. In particular, silicon (Si) has a greater ability to occlude and release lithium than graphite, and can increase the energy density.

  In addition, by using an alloy phase with Li metal as the anode layer material, the effect of reducing the migration resistance of Li ions at the interface between the alloyed material alloyed with Li metal and the Li ion conductive solid electrolyte layer Therefore, the increase in resistance of the alloying material at the initial stage of charge in the first cycle is alleviated.

  Furthermore, when the single metal of the alloying material is used as the negative electrode layer, there is a problem that the discharge capacity becomes significantly smaller than the charge capacity in the first charge / discharge cycle. By using the negative electrode layer material obtained by alloying the material, this irreversible capacity is almost eliminated. This eliminates the need to fill the positive electrode active material amount by an irreversible capacity, thereby improving the capacity density of the thin film battery.

<Method for forming negative electrode layer>
The method for forming the negative electrode layer is preferably a vapor deposition method. Examples of the vapor deposition method include a PVD (physical vapor phase synthesis) method and a CVD (chemical vapor phase synthesis) method. Specifically, examples of the PVD method include a vacuum deposition method, a sputtering method, an ion plating method, and a laser ablation method, and examples of the CVD method include a thermal CVD method and a plasma CVD method.

(Electrolyte layer)
<Material>
The electrolyte layer is made of a material that has ionic conductivity and is so small that electron conductivity can be ignored. In the case of an electrolyte layer for a lithium ion battery, it is a Li ion conductor, the Li ion conductivity (20 ° C) of the electrolyte layer is 10 ^-5 S / cm or more, and the Li ion transport number is 0.999 or more. A layer is preferred. In particular, it is sufficient that the Li ion conductivity is 10 ⁻⁴ S / cm or more and the Li ion transport number is 0.9999 or more. The material of the solid electrolyte layer is preferably a sulfide system, preferably a solid electrolyte layer composed of Li, P, and S, and may further contain oxygen. For example, Li ₃ PO ₄ , LiPON mixed with nitrogen in Li ₃ PO ₄ , Li ₂ S-SiS ₂ , Li ₂ S-P ₂ S ₅ , Li ₂ S-B ₂ S _3, etc. As a material for the solid electrolyte layer, a solid glassy solid electrolyte, a lithium ion conductive solid electrolyte obtained by doping a lithium halide such as LiI or a lithium oxyacid salt such as Li ₃ PO ₄ into these glasses can be suitably used. The solid electrolyte layer made of these composite oxides has heat resistance against the heating temperature (about 200 to 250 ° C.) during solder reflow. The thickness of the solid electrolyte layer is preferably about 3 to 80 μm. A more preferable thickness of the solid electrolyte layer is 5 to 20 μm.

<Method for forming electrolyte layer>
The method for forming the electrolyte layer is preferably a vapor deposition method. Examples of the vapor deposition method include a PVD (physical vapor phase synthesis) method and a CVD (chemical vapor phase synthesis) method. Specifically, examples of the PVD method include a vacuum deposition method, a sputtering method, an ion plating method, and a laser ablation method, and examples of the CVD method include a thermal CVD method and a plasma CVD method.

[Other components]
(Base material)
Usually, a positive electrode layer, a negative electrode layer, an electrolyte layer and an insulating layer are formed above a conductive substrate, or a current collector layer is formed above an insulating substrate and then the positive electrode layer, the negative electrode layer, the electrolyte layer and An insulating layer is formed. Base materials include insulating substrates such as alumina, glass and polyphenylene sulfide (PPS) and polyimide (PI) films, semiconductor substrates such as silicon, and conductive materials such as platinum, gold, iron, nickel, aluminum, copper, and stainless steel. A conductive substrate can be used. All of these materials have heat resistance against the heating temperature (about 200 to 250 ° C.) during solder reflow. The thickness of the substrate is preferably about 3 to 80 μm. A more preferable thickness of the substrate is 5 to 25 μm. When a resin base material is used, the resulting battery is likely to have flexibility. Furthermore, the base material itself may have a laminated structure of a resin film and a metal foil. Such a base material can ensure high moisture resistance with a metal foil, and can ensure the insulation with a battery structural member with a resin film, or can be easily adhered to a sealing film covering the battery. In particular, a base material in which the metal foil is covered with a resin film is preferably used.

(Current collector)
A current collector is usually bonded to each of the positive electrode layer and the negative electrode layer. A metal foil or the like is suitable for the current collector. Examples of the negative electrode current collector material include one selected from copper (Cu), nickel (Ni), iron (Fe), chromium (Cr), and alloys thereof. Since these metals do not form an intermetallic compound with lithium (Li), defects due to the intermetallic compound with lithium, specifically, expansion and contraction due to charge and discharge, cause structural breakdown of the negative electrode layer and collect current Can be prevented, or the bondability of the negative electrode layer can be reduced and the negative electrode layer can easily fall off the current collector. Specific examples of the positive electrode current collector include one selected from aluminum (Al), nickel (Ni), alloys thereof, and stainless steel.

  These current collectors can be formed by a PVD method or a CVD method. In particular, when the current collector is formed in a predetermined pattern, the current collector having a predetermined pattern can be easily formed by using an appropriate mask.

(Ion conductive material)
Furthermore, it is preferable to impregnate at least the positive electrode layer with an ion conductive material. By impregnating the positive electrode layer with the ion conductive material, the resistance of the positive electrode layer can be reduced, and the capacity reduction of the battery can be improved. The ion conductive material is preferably fluid. Specifically, an ionic liquid or an ion conductive polymer material prepared in a slurry form with a solvent can be used.

<Ionic liquid>
An ionic liquid is generally a liquid composed only of ions composed of a combination of an organic cation and an anion.

  Examples of the organic cation include imidazolium ions such as dialkylimidazolium cation and trialkylimidazolium cation, tetraalkylammonium ion, alkylpyridinium ion, dialkylpyrrolidinium ion, and dialkylpiperidinium ion.

  In particular, among dialkyl imidazolium ions, 1-ethyl-3-methylimidazolium ion (EMI +) is preferable. Of the trialkylimidazolium ions, 1,2-dimethyl-3-propylimidazolium ion (DMPI +) is preferable. As the tetraalkylammonium ion, dimethylethylmethoxyammonium ion (DMEMA +) is desirable. The alkylpyridinium ion is preferably 1-butylpyridinium ion (BP +), the dialkylpyrrolidinium ion is methylpropylpyrrolidinium ion (Py13 +), and the dialkylpiperidinium ion is preferably methylpropylpiperidinium ion (PP13 +).

Examples of the anion as a counter of the organic _{cation, PF 6 -, PF 3 (} C 2 F 5) 3 -, PF 3 (CF 3) 3 -, BF 4 -, BF 2 (CF 3) 2 -, BF ₃ (CF ₃ )-, BOB-, Tf-, Nf-, TFSI-, BETI-, DCA-, and the like can be used.

Examples of ionic liquids include dialkylimidazolium tetrafluoroborate (DI · BF ₄ ), dialkylimidazolium tristrifluoromethanesulfonylmethide (DI · C (CF ₃ SO ₂ ) ₃ ), and dialkyl hexafluorophosphate. Examples thereof include organic salts having organic cations such as imidazolium (DI · PF ₆ ) and trialkylimidazolium tris trifluoromethanesulfonyl methide (TI · C (CF ₃ SO ₂ ) ₃ ).

In particular, DI · BF ₄ , DI · C (CF ₃ SO ₂ ) ₃ and TI · C (CF ₃ SO ₂ ) ₃ are preferable because they are excellent in ion conductivity, chemical stability and electrochemical stability. Other practical applications include 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI • BF ₄ ) and 1-ethyl-3-methylimidazolium tristrifluoromethanesulfonylmethide (EMI • C (CF ₃ SO ₂ ) ₃ ) and 1,2-dimethyl-3-propylimidazolium tris trifluoromethanesulfonyl methide (DMPI · C (CF ₃ SO ₂ ) ₃ ) are also suitable ionic liquids.

  These ionic liquids may be used alone or as a mixture of plural kinds.

Further, as the supporting salt dissolved as an electrolyte in the ionic liquid, a lithium salt in which a cation forms lithium ions is used. As the lithium salt, such as chloride anions (Cl-, ClO ₄ -), a bromide anion (Br @ -), iodide anion (I-), fluoride anions _{{BF 4 -, PF 6 -} , CF 3 SO _3- , N (CF ₃ CF ₂ SO ₂ ) _2- , or tristrifluoromethanesulfonylmethide ion (C (CF ₃ SO ₂ ) _3- )}, bisoxalatoborate anion (BOB-), dicyanoamine anion ( DCA-) or the like, or a salt composed of one or more types.

<Ion conductive polymer material>
As the ion conductive polymer material, a material that is water-insoluble, has substantially negligible electronic conductivity, and has ion conductivity is preferable. Examples thereof include polyester, polyamine, polysulfide, polyether copolymer, polyether crosslinked product, and ion conductive polymer obtained by dissolving a lithium salt in a comb polymer having a polyether side chain. In addition, ionic conductive materials such as polyanion-type polymer ionic conductors having a lithium salt in the polymer side chain, or silylamide polymer materials obtained by mixing a compound having a carbon-carbon double bond and a lithium silylamide compound, are used. Used as a conductive polymer material.

Lithium salts dissolved in comb polymers having polyester, polyamine, polysulfide, polyether copolymer, polyether cross-linked, and polyether side chains include lithium bistrifluoromethanesulfonate ((CF ₃ SO ₂ ) ₂ NLi), lithium bispentafluoroethanesulfonate imide ((C ₂ F ₅ SO ₂ ) ₂ NLi), bis (1,2-benzenediolate (2-)-O, O ′) lithium borate, bis (2, 3-Naphthalenediolate (2-)-O, O ') lithium borate, bis (2,2-biphenyldiolate (2-)-O, O') lithium borate, bis (5-fluoro-2-oleate- l-benzenesulfonyl Le acid -O, O ') lithium borate, hexafluoro lithium phosphate (LiPF _6), lithium hexafluoroantimonate (LiSbF _6), hexafluoro shed lithium acid (LiAsF _6), tetrafluoroboric Sanli Um (LiBF _4), lithium perchlorate (LiClO _4), lithium chloride (LiCl), lithium bromide (LiBr), lithium hydroxide (LiOH), lithium nitrate (LiNO _3), lithium sulfate (Li ₂ SO ₄₎ Can be used.

  The compounds having a carbon-carbon double bond include methacrylonitrile, acrylonitrile, acrylic acid, methacrylic acid, maleic acid, itaconic acid, vinylpropionic acid, methyl acrylate, ethyl acrylate, normal propyl acrylate, acrylic Examples include isopropyl acid, normal butyl acrylate, methyl methacrylate, ethyl methacrylate, hydroxyl ethyl methacrylate, vinyl formate, vinyl acetate, butadiene, vinylene carbonate, vinyl ethylene carbonate, divinyl ethylene carbonate, and the like. Furthermore, examples of the lithium silylamide compound include lithium bis (trimethylsilyl) amide and lithium bis (triethylsilyl) amide.

<Solvent>
Solvents for ion conductive polymer materials dissolve ion conductive polymer materials such as alcohols such as ethanol, ketones such as acetone, or nonpolar solvents such as hexane. Any material that does not react with the layer can be used. The blend of the ion conductive polymer material and the solvent is preferably about 1 g / L to 300 g / L.

  The battery of the present invention will be described with reference to FIGS. 1 is a plan view of the main part of the battery, and FIG. 2 is a partial longitudinal sectional view of the main part of the battery. Moreover, FIG. 3 is explanatory drawing which shows the formation procedure of the sealing structure (sealing structure 1) of this invention battery. First, the structure of the battery will be described, and then the procedure for forming the sealing structure will be described.

  As shown in FIGS. 1 and 2, this battery has a negative electrode current collector 2 and a positive electrode current collector 3 formed on a part of a substrate 1, and a negative electrode current collector 3 is formed on the current collectors 2 and 3. A negative electrode layer 4 is formed so as to cover the electric current body 2, and a positive electrode layer 5 is formed so as to cover the positive electrode current collector 3. The negative electrode layer 4 is formed at a position that does not overlap the positive electrode layer 5 when the battery is viewed in plan.

  Each of the current collectors 2 and 3 has linear terminal portions 21 and 31 and a plurality of branch portions 22 and 32 that branch from the terminal portions 21 and 31 in a comb-tooth shape. The negative electrode current collector 2 and the positive electrode current collector 3 are arranged such that the branching portion 32 of the positive electrode current collector 3 is disposed between the branching portions 22 of the negative electrode current collector 2 so that the comb-tooth portions are engaged with each other. The terminal portion 21 and the terminal portion 31 on the positive electrode side are formed in parallel.

  On the other hand, the negative electrode layer 4 is formed on the branch portion 22 of the negative electrode current collector 2, and the positive electrode layer 5 is formed on the branch portion 32 of the positive electrode current collector 3. Each of the negative electrode layer 4 and the positive electrode layer 5 has a configuration in which strip-like comb teeth portions 41 and 51 are alternately arranged in parallel. With such an arrangement of the negative electrode layer 4 and the positive electrode layer 5, both the electrode layers 4 and 5 are disposed on substantially the same plane.

  In the region sandwiched between the terminal portion 31 on the positive electrode side and the terminal portion 21 on the negative electrode side, the entire region where the comb teeth portions 41 and 51 of the negative electrode layer 4 and the positive electrode layer 5 are arranged in parallel is the electrolyte layer. 6 covered. A region covered with the electrolyte layer 6 is a power generation area G. Further, the terminal portions 21 and 31 that are located on both sides of the power generation area G and are not covered with the electrolyte layer 6 become the negative electrode current collection area N and the positive electrode current collection area P.

  When the power generation area G is formed, an ionic liquid is applied to the area G. The ionic liquid may be impregnated in the positive electrode layer 5, but here, the ionic liquid is applied to most of the power generation area G including the negative electrode layer 4. For example, the coating is performed not on the entire power generation area G but on the inner side except the peripheral edge of the area G. At this time, the ionic liquid is prevented from adhering to the positive and negative current collecting areas P and N.

  In such a battery, the power generation area G is sealed with a sealing film 7 as shown in FIG. The sealing film 7 has a smaller area than the base material 1 and is slightly larger than the power generation area G. The sealing film 7 has a three-layer structure in which a base material layer is formed on one surface side of the metal foil and a bonding layer is formed on the other surface side. The bonding layer is melted by heating the sealing film 7 and fused to the object to be sealed.

  Such a film 7 is disposed so as to cover the power generation area G. Subsequently, the sealing object on which the sealing film 7 is arranged is roll-pressed. Then, the peripheral edge of the sealing film 7 is heat-sealed by heat sealing.

  By this roll press and heat sealing, the sealing film 7 is adhered to the object to be sealed while covering the power generation area G. However, since the size of the sealing film 7 substantially corresponds to the size of the power generation area G, the current collection areas N and P are exposed without being covered by the sealing film 7. Therefore, the current collection areas N and P that are not covered with the sealing film 7 can be used as lead portions for taking out electricity while ensuring the moisture resistance of the power generation area G. Further, since it is not necessary to form a lead portion by connecting a metal piece or the like to the current collector as in a conventional battery, the thickness of the joint portion of the lead portion can be reduced.

  Further, in this battery, since the bipolar layers 4 and 5 do not overlap in the thickness direction, the bipolar layers 4 and 5 are not short-circuited even if there is a pinhole in the electrolyte layer 6.

  Next, a battery having a sealing structure (sealing structure 2) different from that of Example 1 will be described with reference to FIG. The power generation area of this battery, that is, the laminated structure of the positive electrode layer 5, the negative electrode layer 4, the positive electrode current collector 3, the negative electrode current collector 2, and the electrolyte layer 6 with respect to the substrate 1 is the same as in Example 1, and the sealing film is The three-layer structure is the same as in the first embodiment. However, the shape and size of the sealing film are the main differences from Example 1. Hereinafter, this difference will be mainly described.

  The sealing film 7 in this example has an area in the contour larger than that of the substrate 1. However, openings 71 are formed at positions corresponding to the respective current collection areas N and P. More specifically, a pair of square openings 71 are formed on both sides of the rectangular sealing film 7.

  Furthermore, in this example, the back surface of the base material 1, that is, the surface where the power generation area G is not formed is also covered with the sealing film. In the sealing film 7 covering the back surface of the base material, the opening 71 is not formed.

  In order to seal the battery, first, the sealing film 7 in which the opening is formed is disposed on the surface side (power generation area G side) to be sealed. At that time, the current collecting areas N and P are exposed from the opening. Next, the sealing film 7 having no opening is disposed on the back side to be sealed. That is, the sealing target is sandwiched between both sealing films 7. And the sealing object pinched | interposed with the sealing film 7 is roll-pressed, and the peripheral part of the film 7 is heat-sealed and it fuse | melts.

  Also in the sealing structure of this example, the power generation area is covered with the sealing film, but the current collection areas N and P are not covered with the sealing film 7. Therefore, the current collection areas N and P that are not covered with the sealing film can be used as lead portions for taking out electricity while ensuring the moisture resistance of the power generation area.

  Next, a battery having a structure different from those of the first and second embodiments will be described with reference to FIG. This battery is different only in the laminated structure of the positive electrode layer 5, the negative electrode layer 4, the positive electrode current collector 3, the negative electrode current collector 2, and the electrolyte layer 6 formed on the substrate 1, and the sealing structure of the power generation area is What is necessary is just to be the same as that of Example 1 or Example 2.

  In this battery, first, the positive electrode current collector 3 and the negative electrode current collector 2 are formed at positions distant from the base material 1.

  Next, the positive electrode layer 5 is formed so as to overlap a part of the positive electrode current collector 3. The side of the positive electrode layer 5 that does not overlap the positive electrode current collector 3 is positioned between the positive electrode current collector 3 and the negative electrode current collector 2. That is, in the positive electrode layer 5, a portion that overlaps the positive electrode current collector 3 is a thin portion 52, and a portion that does not overlap the positive electrode current collector 3 is a thick portion 53.

  Next, the electrolyte layer 6 is formed on the positive electrode layer 5. The electrolyte layer 6 is a stepped layer composed of an upper step portion 61 and a lower step portion 62, the upper step portion 61 covers a part of the positive electrode layer 5, and the lower step portion 62 is formed on the substrate 1. The lower step portion 62 is disposed between the positive electrode layer 5 and the negative electrode current collector 2. The thickness of the lower step portion 62 of the electrolyte layer is substantially the same as the thickness of the negative electrode current collector 2.

  Further, the negative electrode layer 4 is formed on the electrolyte layer 6. The negative electrode layer 4 is also a stepped layer including an upper step portion 42 and a lower step portion 43. The upper step part 42 of the negative electrode layer covers the upper step part 61 of the electrolyte layer, the lower step part 43 of the negative electrode layer covers a part of the lower step part 62 of the electrolyte layer, and the remaining part covers a part of the negative electrode current collector 2. ing.

  In the battery having this configuration, a power generation area G in which the positive electrode layer 5, the electrolyte layer 6, and the negative electrode layer 4 are laminated is formed between the current collectors 2 and 3. Further, the positive electrode current collection area P where the positive electrode current collector 3 is exposed is formed on one side of the power generation area G, and the negative electrode current collection area N where the negative electrode current collector 2 is exposed is formed on the other side of the power generation area G. The

  In such a battery, the number of layers where the layers overlap most (the place where the positive electrode layer 5, the electrolyte layer 6, and the negative electrode layer 4 are laminated) is the number of all layers 2, 3, 4, 5 , 6 less than the number of layers when overlapping. In this example, with respect to five layers 2 to 6, the number of laminated layers at the thickest portion of the battery is three layers of the positive electrode layer 5, the electrolyte layer 6, and the negative electrode layer 4. Further, since the positive electrode layer 5, the electrolyte layer 6, and the negative electrode layer 4 have a laminated structure, the battery area can be reduced as compared with the case where the electrode layers 4 and 5 are arranged in parallel without overlapping. And even in the battery of such a configuration, if the power generation area G is covered with a sealing film and both current collector areas N and P are exposed from the sealing film, the thickness of the battery is made as thin as possible, The current collectors 2 and 3 can be used as lead portions.

  In this example, the positive electrode layer 5 is in contact with the base material 1, but the positive electrode layer 5 and the negative electrode layer 4 in FIG. 5 may be replaced, and the negative electrode layer 4 may be in contact with the base material 1.

  Next, a battery having a structure different from those of Examples 1 to 3 will be described with reference to FIG. This battery is different only in the laminated structure of the positive electrode layer 5, the negative electrode layer 4, the positive electrode current collector 3, the negative electrode current collector 2, and the electrolyte layer 6 formed on the substrate 1, and the sealing structure of the power generation area is What is necessary is just to be the same as that of Example 1 or Example 2.

  The battery of this example is similar to Example 1, and is the same as Example 1 in that the positive electrode current collector 3, the positive electrode layer 5, and the negative electrode layer 4 are each in a comb-teeth shape. However, the arrangement location of the negative electrode layer 4 is different from that in Example 1, and the negative electrode layer 4 also functions as a negative electrode current collector.

  Also in this battery, the positive electrode current collector 3 is formed on a part of the substrate 1, and the positive electrode layer 5 is formed on the current collector 3. Next, in this battery, almost the entire surface of the substrate 1 including the positive electrode layer 5 is covered with the electrolyte layer 6. On the electrolyte layer 6, the negative electrode layer 4 is formed at a position that does not overlap with the positive electrode layer 5 when the battery is viewed in plan. That is, the positive electrode layer 5 and the negative electrode layer 4 do not exist on the same plane.

  In the case of this example, the negative electrode layer 4 is made of an alloy material or the like, so that the negative electrode layer 4 itself has a function as a negative electrode current collector. In this case, the negative electrode layer 4 itself is composed of a plurality of comb teeth and a current collector that connects one end side of the comb teeth, and the positive electrode layer 5 and the negative electrode layer 4 are arranged in parallel. As the power generation area, the terminal portion of the positive electrode current collector 3 as the positive electrode current collection area, and the current collector portion of the negative electrode layer 4 as the negative electrode current collection area. In particular, it is preferable that the current collector that is a part of the negative electrode layer 4 is not overlapped with the electrolyte layer 6.

  In the battery having such a configuration, since one electrode layer 4 or 5 is covered with the electrolyte layer 6 and the other electrode layer 5 or 4 is present on the electrolyte layer 6, there is something between the bipolar layers 4 and 5. Even if there is a conductive foreign matter, a short circuit between the bipolar layers 4 and 5 due to interfacial conduction through the foreign matter can be effectively suppressed.

  And if the sealing structure similar to Example 1 or Example 2 is applied to said battery, an electric power generation area will be sealed with the sealing film, and each current collection area will comprise the state exposed from the sealing film. it can.

  In this example, the positive electrode layer 5 is in contact with the base material 1, but the positive electrode layer 5 and the negative electrode layer 4 in FIG. 6 may be replaced, and the negative electrode layer 4 may be in contact with the base material 1. In addition, a negative electrode current collector may be separately formed on the negative electrode layer 4.

(Prototype example)
1 and 2 were used to form the sealing structures of the inventive example and the comparative example, and the initial capacity of the battery, the capacity after standing for 3 months, and the thickness of the battery after sealing were examined. . Specific common specifications of each invention example and comparative example are as follows.

Base material → Material: Polyphenylene sulfide (PPS), Thickness: 50μm
Current collector → Material: Ni film for both positive and negative electrodes, Thickness: 0.2 μm
Positive electrode layer → MnO ₂ grains, carbon black, polyvinylidene fluoride mixed in N-methyl-2-pyrrolidone at a weight ratio of 8: 2: 1, screen-printed and vacuum-dried at 150 ° C, Thickness 100μm
Negative electrode layer → Material: Li metal film, Thickness: 25 μm
Electrolyte layer → Material: Li-PS composition, thickness: 10 μm, deposition method: Excimer laser using a mixed target of Li ₂ S and P ₂ S ₅ adjusted so that the molar ratio of Li / P is 2.0 Film formed by ablation method.
Positive electrode impregnated ionic liquid → EMI-FSI dissolved with 0.3 mol / kg of LiTFSI as a supporting salt.
Power generation area → area: 3cm ²

  In addition, Table 1 shows the individual specifications and evaluation results of the inventive examples and comparative examples. In Table 1, “positive / negative electrode line width” is the width of each comb tooth portion of the positive / negative electrode layer, and “gap” is an adjacent interval between the comb tooth portion of the positive electrode layer and the comb tooth portion of the negative electrode layer. It is.

  As is clear from these results, in all of the inventive examples, no decrease in capacity is observed regardless of the passage of time after the production of the battery. On the other hand, in Comparative Example 1, although the battery was thin, it was sealed by dipping only with resin, so it was considered that sufficient sealing could not be performed, and the capacity after being left for 3 months was greatly reduced. Moreover, although the capacity | capacitance fall was not seen in the comparative example 2, since Ni tab was used as a lead part, it turns out that the thickness of the battery after sealing is large. The “battery thickness after sealing” in the table is slightly thinner than the sum of the constituent layers by the roll press described in Examples 1 and 2.

  The battery of the present invention can be suitably used as a lithium secondary battery. For example, this battery is expected to be used as a power source for various electric / electronic devices such as a mobile type and a portable type.

1 is a plan view showing a main part of a battery of the present invention of Example 1. FIG. 1 is a longitudinal sectional view showing a main part of a battery of the present invention of Example 1. FIG. It is explanatory drawing which shows the sealing structure of Example 1, (A) shows the battery before sealing, (B) shows the battery after sealing. It is explanatory drawing which shows the sealing structure of Example 2, (A) shows the battery before sealing, (B) shows the battery after sealing. FIG. 6 is a longitudinal sectional view showing the main part of the battery of the present invention in Example 3. It is a longitudinal cross-sectional view which shows the principal part of this invention battery of Example 4. FIG.

Explanation of symbols

1 Base material 2 Negative electrode current collector 3 Positive electrode current collector 4 Negative electrode layer 5 Positive electrode layer
6 Solid electrolyte layer 7 Sealing film
21, 31 Terminal section 22, 32 Branch section 41, 51 Comb section 71 Opening section
42 Upper part 43 Lower part 52 Thin part 53 Thick part 61 Upper part 62 Lower part
G Power generation area N Negative current collection area P Positive current collection area

Claims (7)

A substrate, positive electrode layers and negative electrode layers formed above the substrate, an electrolyte layer that conducts ions between both electrode layers, and a positive electrode current collector electrically connected to the positive electrode layer And a negative electrode current collector electrically connected to the negative electrode layer,
On the battery substrate, a power generation area where a battery reaction is performed between both electrode layers via an electrolyte layer, a positive electrode current collection area consisting of a portion of the positive electrode current collector that does not overlap with the electrode layer, Three areas of a negative electrode current collector area consisting of a part of the negative electrode current collector that does not overlap with the electrode layer are formed,
A thin battery comprising a sealing film that covers the power generation area but does not cover at least a part of both current collection areas.   The thin battery according to claim 1, wherein the sealing film has a size that substantially covers only the power generation area.   2. The sealing film according to claim 1, wherein an opening is formed in a part of the sealing film, each current collection area is exposed from the opening, and the power generation area is covered with a surface other than the opening. Thin battery.   4. The sealing film according to claim 1, wherein the sealing film has a laminated structure including a bonding layer fused to a sealing target and a base material layer that is not substantially melted by heat at the time of fusion. The thin battery as described in Crab.   The thin battery according to claim 4, wherein the bonding layer is any one of polypropylene, polyethylene, polyamide, and polyester modified with an acidic group.   The thin film according to any one of claims 1 to 5, wherein the sealing film is composed of three or more layers, and one of the layers excluding one surface layer and the other surface layer is a metal foil. .   The thin battery according to claim 1, wherein when the battery is viewed in plan, there is no overlapping portion between the positive electrode layer and the negative electrode layer.

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