JP2017111891A - Electrode for all solid state battery, all solid state battery, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all-solid-state battery having good charge/discharge cycle characteristics. An electrode for an all-solid-state battery including a deliquescent material, wherein the deliquescent material has a plate-like structure, and the density ratio of the electrode for the all-solid-state battery to the true density of the deliquescent material is more than 0.1. It is largely 1.0 or less, for example, the deliquescent material is lithium vanadium oxide, and the lithium vanadium oxide contains lithium metavanadate, and is an all-solid battery electrode, an all-solid battery electrode, and an all-solid electrolyte layer. After deliquescing a battery or a deliquescent material, an electrode mixture preparation step of adjusting the electrode mixture, and heat treatment of the electrode mixture at 100° C. or higher and 300° C. or lower to manufacture an electrode for an all-solid battery A method of manufacturing an electrode for an all-solid-state battery, including the steps of: [Selection diagram] Figure 1

Description

  The present invention relates to an electrode for an all-solid battery, an all-solid battery, and a method for producing the same.

  Development of an all-solid battery using a solid electrolyte is underway. The all-solid-state battery does not contain a flammable organic solvent, and therefore has the advantage that the safety device can be simplified, and is recognized as a battery excellent in manufacturing cost and productivity. Moreover, since it is easy to laminate in series a junction structure composed of a pair of electrodes composed of a positive electrode and a negative electrode and a solid electrolyte layer sandwiched between these electrodes, a battery with high capacity and high output can be obtained while being stable. It is expected as a technology that can be manufactured.

For example, in Patent Document 1, in an all-solid battery in which a positive electrode layer and a negative electrode layer are arranged on both sides of a solid electrolyte layer, either the positive electrode layer or the negative electrode layer contains a lithium-containing compound, and the lithium-containing compound is An all solid state battery including lithium vanadium oxide having a valence of V of 3 ≦ x ≦ 5 and LiVO ₃ having deliquescence is disclosed.

WO15 / 159331

  Depending on the shape of the deliquescent material and the ratio of the electrode density to the true density of the deliquescent material, the cycle characteristics of the all-solid-state battery may be improved. Patent Document 1 does not describe the shape of the deliquescence material or the ratio of the electrode density to the true density of the deliquescence material.

  An object of this invention is to provide the electrode for all-solid-state batteries used for the all-solid-state battery which improved cycling characteristics.

  The features of the present invention for solving the above problems are as follows, for example.

  An electrode for an all solid state battery comprising a deliquescence material, wherein the deliquescence material has a plate-like structure, and the density ratio of the all solid state battery electrode to the true density of the deliquescence material is greater than 0.1 and greater than 1.0. An electrode for an all-solid battery, which is:

  ADVANTAGE OF THE INVENTION According to this invention, the electrode for all-solid-state batteries used for the all-solid-state battery which improved cycling characteristics can be provided. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is sectional drawing which shows typically an example of a structure of the all-solid-state battery which concerns on this embodiment. It is sectional drawing which shows an example of the electrode for all-solid-state batteries which concerns on this embodiment. It is a figure which shows the relationship between the capacity | capacitance maintenance factor and the electrode density in the charging / discharging cycle test of the all-solid-state battery which concerns on an Example and a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description shows specific examples of the contents of the present invention, and the present invention is not limited to these descriptions. Various modifications by those skilled in the art are within the scope of the technical idea disclosed in this specification. Changes and modifications are possible. In all the drawings for explaining the present invention, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

  FIG. 1 is a cross-sectional view schematically showing an example of the configuration of the all solid state battery according to the present embodiment. The all solid state battery 1 according to the present embodiment is a battery in which a solid electrolyte mediates conduction of ion carriers between electrodes. Moreover, it is preferable that the electrode is a bulk type all solid state battery formed mainly by a collection of active materials.

  In FIG. 1, the all solid state battery 1 includes a positive electrode layer 2A, a negative electrode layer 2B, and a solid electrolyte layer 2C disposed between the positive electrode layer 2A and the negative electrode layer 2B. Hereinafter, the positive electrode layer 2A and the negative electrode layer 2B are also referred to as an electrode layer and an electrode for an all solid state battery.

<Deliquescent material>
The deliquescent material which concerns on one Embodiment of this invention is a lithium vanadium oxide. Lithium vanadium oxide is a solid electrolyte and is a positive and negative electrode active material. By filling lithium vanadium oxide having deliquescence into the positive electrode or the negative electrode layer in a plate shape, the active material density in the electrode layer and the contact state between the active materials can be improved. As a result, the followability to Li expansion and contraction associated with the charge / discharge cycle is improved, and the charge / discharge cycle characteristics can be improved.

  In addition, even if the interface between the active material particles and the active material particles or the active material particles and the solid electrolyte layer 2C is peeled off due to the charge / discharge cycle and the capacity is reduced, the electrode layer is placed in a humid atmosphere and deliquescent again. By removing excess moisture, the peeled interface can be reconstructed. By reconstructing the peeled interface, the internal resistance is reduced and the capacity can be recovered. As a result, the charge / discharge cycle characteristics can be improved.

  The lithium vanadium oxide according to an embodiment of the present invention is accompanied by a change in the valence of vanadium corresponding to the effective capacity when the charge / discharge cycle is performed, and the vanadium valence at that time is 3 ≦ V ≦ 5. It changes arbitrarily in the range. By changing the valence of vanadium, more lithium ions can be inserted and desorbed, and a large capacity can be obtained.

  In one embodiment of the present invention, having deliquescence means having a property of deliquescence in a normal temperature range (0 ° C. or more and 100 ° C. or less) in the atmosphere. By using a deliquescent material as an active material for manufacturing an electrode layer in an all-solid-state battery, the gap between particles of the active material constituting the electrode layer can be reduced, and a plate-like structure filled with high density can be formed. It becomes possible. And by making the active material which comprises an electrode into a plate-shaped structure, between active materials is not a mere point contact, but contacts on a wider surface. In addition, it is thought that the same effect is acquired also with water-soluble lithium transition metal oxide, for example, lithium molybdenum oxide, lithium silicon oxide, etc. are mentioned. These materials may be used alone or in combination.

  In one embodiment of the present invention, having a plate-like structure means a structure in which plate-like substances are stacked in layers, and the plate-like substances are integrated to form a thin film. Is also included. By having such a plate-like structure, the gap between the particles of the active material constituting the electrode layer can be reduced, and an electrode layer filled with high density can be formed. As a result, the charge / discharge cycle can be improved.

<Electrode layer>
At least one of the positive electrode layer 2A and the negative electrode layer 2B contains deliquescent lithium vanadium oxide having a plate-like structure.

  In the electrode layer, the content of the deliquescent material according to one embodiment of the present invention varies depending on the particle diameter and type of the electrode material included. The larger the particle diameter of the electrode material, the more voids between the particles. Therefore, the content of the deliquescent material is preferably increased. This is not the case when an electrode material having a plurality of particle diameters is used for the electrode layer.

The ionic conductivity at 20 ° C. of the deliquescent material according to one embodiment of the present invention is preferably 1 × 10 ⁻⁸ S / cm or more, and more preferably 1 × 10 ⁻⁶ S / cm or more. . If the ionic conductivity is 1 × 10 ⁻⁸ S / cm or more, the ionic conductivity between the deliquescent materials and between the solid electrolyte layers 2C can be improved, so that the internal resistance of the battery is improved. It is possible to reduce and secure a higher discharge capacity.

Moreover, the deliquescent material concerning one Embodiment of this invention has the conductivity of the electron which generate | occur | produced by the battery reaction. The electron conductivity at 20 ° C. of the ion conductive material according to one embodiment of the present invention is preferably 1 × 10 ⁻⁸ S / cm or more, and more preferably 1 × 10 ⁻⁶ S / cm or more. preferable. When the electron conductivity is 1 × 10 ⁻⁸ S / cm or more, the electron conductivity of the electrode layer can be improved significantly. As a result, it is possible to satisfactorily reduce the internal resistance in the all solid state battery and ensure a higher discharge capacity.

  The electrode layer of the manufactured all-solid-state battery is usually in an environment isolated from moisture. For this reason, the deliquescent material in the all-solid-state battery is not in a deliquescent state, but is deposited as a plate-like crystal or non-crystal to ensure good electron conductivity and ion conductivity.

  The electrode layer of the manufactured all-solid-state battery can improve charge / discharge cycle characteristics by being densely filled with a deliquescent material having a plate-like structure. The electrode layer density at that time is preferably greater than 0.1 and 1.0 or less, and more preferably 0.4 or more and 1.0 or less, with respect to the true density of the deliquescent material. When the electrode layer density is 0.1 or less with respect to the true density, the ratio of the deliquescent material having a plate-like structure in the electrode layer is small, and a good contact state cannot be obtained in the electrode layer. Characteristics are degraded. When the electrode layer density is larger than 1.0 with respect to the true density, the stress in the electrode layer becomes excessive, so that the internal resistance increases due to cracking or peeling of the electrode material, and the cycle characteristics deteriorate.

  The positive electrode layer 2A and the negative electrode layer 2B are made of a solid electrolyte used in a general all-solid battery, carbon or the like to ensure electronic conductivity, in addition to the deliquescent material according to one embodiment of the present invention. A conductive agent may be included.

  Specific examples of solid electrolytes used in general all solid state batteries include oxide solid electrolytes such as perovskite oxides, NASICON oxides, LISICON oxides, and garnet oxides, Examples thereof include sulfide-based solid electrolytes and β alumina.

Examples of the perovskite oxide include Li—La—Ti perovskite oxide expressed as LiaLa _1-a TiO _{3, and} Li— expressed as Li _b La _1-b TaO _3. la-Ta-based perovskite-type _{oxide, Li c La 1-c NbO} 3 Li-La-Nb -based perovskite oxide represented as such, and the like (wherein, 0 <a <1,0 <B <1, 0 <c <1.) The NASICON-type oxide, for _example, in _{Li m X n Y o P p} O q ( Formula to ShuAkira crystals represented by _{Li 1 + l Al l Ti 2} -l (PO 4) 3 or the like, X is , B, Al, Ga, In, C, Si, Ge, Sn, Sb and Se, and Y is Ti, Zr, Ge, In, Ga, Sn and And at least one element selected from the group consisting of Al, and 0 ≦ l ≦ 1, m, n, o, p, and q are arbitrary positive numbers. It is done. As the LISICON type oxide, for example, Li ₄ XO ₄ -Li ₃ YO ₄ (wherein X is at least one element selected from Si, Ge, and Ti, and Y is P, As And at least one element selected from V.) and the like. Examples of the garnet oxide include Li—La—Zr-based oxides represented by Li ₇ La ₃ Zr ₂ O _{12 and the} like.

Examples of the sulfide-based solid electrolyte include Li ₂ S—P ₂ S ₅ , Li ₂ S—SiS ₂ , Li _3.25 P _0.25 Ge _0.76 S ₄ , and Li _4-r Ge _1-r P. _Examples include _r S ₄ (where 0 ≦ r ≦ 1), Li ₇ P ₃ S ₁₁ , Li ₂ S—SiS ₂ —Li ₃ PO _{4, and the} like. The sulfide-based solid electrolyte may be either a crystalline sulfide or an amorphous sulfide. In addition, as long as the crystal structure is equivalent, these solid electrolytes may be those in which some of the elements are replaced with other elements, or may have different element composition ratios. Moreover, these solid electrolytes may be used individually by 1 type, and may use multiple types.

  The content of the deliquescent material in the electrode layer is preferably 10 parts by weight or more and 100 parts by weight or less with respect to the total dry weight of all the (solid electrolyte, conductive additive) in the electrode layer. By setting the dry weight of the deliquescent material to 10 parts by weight or more and 100 parts by weight or less, an all-solid battery having high charge / discharge cycle characteristics, good volume energy density, and high discharge capacity can be produced.

The ionic conductivity at 20 ° C. of the solid electrolyte is preferably 1 × 10 ⁻⁶ S / cm or more, and more preferably 1 × 10 ⁻⁴ S / cm or more. If the ionic conductivity of the solid electrolyte is 1 × 10 ⁻⁶ S / cm or more, the ion conductive material according to one embodiment of the present invention and another solid electrolyte are used in combination to achieve one embodiment of the present invention. It becomes possible to give the electrode layer high ion conductivity due to the solid electrolyte while obtaining the effect of improving the contact property between particles by the ion conductive material.

  As an active material used for an all solid state battery according to an embodiment of the present invention, an active material used for a general all solid state battery can be used for each of the positive electrode and the negative electrode. For example, when the all-solid battery is a primary battery, an active material that occludes lithium ions is used for the electrode layer, and when the all-solid battery is a secondary battery, electricity that reversibly inserts and removes lithium ions. An active material having chemical activity is used for the electrode layer.

In the positive electrode layer 2A, a deliquescent material is usually used as an active material, but other active materials can also be included. As the positive electrode active material, when the carrier is a lithium ion, for example, an olivine type such as lithium manganese phosphate (LiMnPO ₄ ), lithium iron phosphate (LiFePO ₄ ), lithium cobalt phosphate (LiCoPO ₄ ), Lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), manganese dioxide (III) lithium (LiMnO ₂ ), and LiNi _x Co _y Mn _z O ₂ (where 0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1, x + y + z = 1.) Layered type such as ternary oxide, spinel type such as lithium manganate (LiMn ₂ O ₄ ), lithium vanadium phosphate ( A lithium transition metal compound such as a polyanion type such as Li ₃ V ₂ (PO ₄ ) ₃ ) can be used. When the carrier is a sodium ion, for example, sodium iron oxide (NaFeO ₂ ), sodium cobaltate (NaCoO ₂ ), sodium nickelate (NaNiO ₂ ), sodium manganese (III) dioxide (NaMnO ₂ ), phosphorus Sodium vanadium acid (Na ₃ V ₂ (PO ₄ ) ₃ ), sodium fluorinated sodium vanadium phosphate (Na ₃ V ₂ (PO ₄ ) ₂ F ₃ ), or the like can be used. In addition, copper chevrel phase compounds (Cu ₂ Mo ₆ S ₈ ), iron sulfide (FeS, FeS ₂ ), cobalt sulfide (CoS), nickel sulfide (NiS, Ni ₃ S ₂ ), titanium sulfide (TiS ₂ ), A chalcogen compound such as molybdenum sulfide (MoS ₂ ), a metal oxide such as TiO ₂ , vanadium ₂ O ₅ , CuO, or MnO ₂ , C ₆ Cu ₂ FeN _6, or the like can be used.

Similarly to the positive electrode layer, the negative electrode layer 2B can contain an active material other than the deliquescent material. As the negative electrode active material, when the carrier is a lithium ion, for example, a lithium transition metal oxide such as lithium titanate (Li ₄ Ti ₅ O ₁₂ ) can be used. In addition, alloys such as TiSi, La ₃ Ni ₂ Sn ₇ , carbon materials such as hard carbon, soft carbon, and graphite, simple substances such as lithium, indium, aluminum, tin, and silicon, or alloys containing these are used. be able to.

  The electrode layer may contain a conductive agent or a binder. Examples of the conductive agent include natural graphite particles, carbon black such as acetylene black, ketjen black, furnace black, thermal black, and channel black, carbon fibers, and metal particles such as nickel, copper, silver, gold, and platinum. Or these alloy particles etc. are mentioned. In addition, these electrically conductive agents may be used individually by 1 type, and may use multiple types. Examples of the binder include polyvinylidene fluoride (P vanadium DF), polytetrafluoroethylene (PTFE), polyhexafluoropropylene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, ethylene-propylene copolymer, and styrene-ethylene. -A butadiene copolymer etc. are mentioned. A thickener such as carboxymethyl cellulose and xanthan gum may be used in combination with the binder. In addition, these binders and thickeners may be used individually by 1 type, and may use multiple types.

  The positive electrode layer 2A and the negative electrode layer 2B may be laminated on a base material such as a current collector to constitute an electrode. Although the thickness of the electrode layer laminated | stacked can be suitably adjusted according to the structure of the electrode layer with which the all-solid-state battery 1 is provided, it is preferable to set it as 0.1 micrometer or more and 1000 micrometers or less, for example. Examples of the current collector used for the positive electrode layer 2A include substrates such as stainless steel, aluminum, iron, nickel, titanium, and carbon, foils, and the like. Moreover, as a collector used for the negative electrode layer 2B, a board | substrate, foil, etc., such as stainless steel, copper, nickel, and carbon, are mentioned, for example.

<Solid electrolyte layer>
The solid electrolyte layer 2C includes a solid electrolyte. As the solid electrolyte, it is possible to use a solid electrolyte having lithium ion conductivity which is a carrier responsible for a battery reaction and used in a general all solid state battery. For example, a solid electrolyte similar to the solid electrolyte used for the positive electrode layer 2A and the negative electrode layer 2B can be used. The solid electrolyte used for the solid electrolyte layer 2C may be the same as or different from the solid electrolyte used for the electrode layer.

<All-solid battery manufacturing method>
The method for producing an all-solid battery according to the present embodiment mainly includes a deliquescent material preparation step for preparing a deliquescent material in an electrode layer, an electrode mixture preparation step for preparing an electrode mixture, and forming an electrode mixture. It includes an electrode manufacturing process for manufacturing an electrode layer by heat treatment, a bonding process for bonding the electrode layer and the solid electrolyte layer, and an assembling process for incorporating the manufactured electrode into the battery casing.

  In the deliquescent material preparation step, the metal precursor as a raw material is mixed, and then this mixture is reacted in a solid phase at a high temperature to prepare a deliquescent material for electrodes. Examples of the metal precursor include carbonate, nitrate, acetate, chloride, oxide, nitride, and carbide. These precursors can be properly used depending on properties such as their melting points.

  In the electrode mixture preparation step, the deliquescent material is deliquesced and liquefied, and then the liquefied deliquescence material and other electrode materials are mixed to prepare an electrode mixture (positive electrode mixture, negative electrode mixture). . The deliquescence of the deliquescent material may be reacted with water in the atmosphere at room temperature. By reacting the deliquescent material and water in this manner, the deliquescent solid electrolyte can be substantially completely dissolved and mixed with the electrode material. By deliquescent the deliquescent material, fluidity suitable for forming a plate-like structure can be obtained. Further, by dissolving the deliquescence material in water and then adding an appropriate organic solvent, the adhesion between the deliquescence material and the other electrode material can be improved as appropriate, and an electrode layer with good adhesion can be formed. . Examples of the organic solvent include water, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, propanol, ethylene glycol, depending on the type of electrode material such as a solid electrolyte and a conductive agent. Glycerin, dimethyl sulfoxide, tetrahydrofuran and the like can be used.

  After the deliquescence material is deliquesced, another active material, a solid electrolyte, or a conductive agent is added to the dissolved deliquescence material, and these are mixed and homogenized to prepare an electrode mixture. The dry weight of the deliquescent material to be mixed is preferably 10 parts by weight or more and 100 parts by weight or less with respect to the total dry weight in the electrode layer. Moreover, a binder can be added with a solvent. Solvents include water, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, propanol, ethylene glycol, glycerin, dimethyl sulfoxide, depending on the type of conductive agent and binder. , Tetrahydrofuran and the like can be used. For mixing for preparing the electrode mixture, for example, high viscosity mixing means such as a homomixer, a disper mixer, a planetary mixer, a rotation / revolution mixer, and the like can be used.

  In the electrode manufacturing process, the prepared electrode mixture is molded and heat-treated to manufacture an electrode layer. The heat treatment may be performed in either an active gas atmosphere such as air or an inert gas atmosphere such as nitrogen gas or argon gas. Moreover, the gas type to be used may be one type alone or a combination of two or more types. By heat-treating the electrode mixture, moisture or an organic solvent dissolving the deliquescence material is evaporated, and a dense structure in which the deliquescence material is deposited in a plate shape can be formed. Therefore, the contact property between deliquescence materials becomes good.

  The heating temperature in the heat treatment can be an appropriate temperature depending on the composition of the electrode mixture, but is preferably 15 ° C. or higher and 650 ° C. or lower, more preferably 100 ° C. or higher and 300 ° C. or lower. When the deliquescent material is used, if the heating temperature is 15 ° C. or higher, moisture contained in the deliquescent material can be evaporated and dried off in the air. Further, if the heating temperature is 650 ° C. or less, it is possible to avoid a solid-phase reaction between the deliquescent material and other electrode materials, so that the generation of a different phase with low ion conductivity and the collapse of the plate-like structure are caused. Thus, an increase in internal resistance and a decrease in charge / discharge cycle characteristics can be suppressed. In particular, when the heating temperature is 100 ° C. or more and 300 ° C. or less, an electrode layer exhibiting high charge / discharge cycle characteristics is formed by sufficiently eliminating the water contained in the deliquescent solid electrolyte while avoiding an increase in internal resistance. can do.

  The electrode mixture is formed into an electrode layer. As a shape to shape | mold, it can be set as a suitable shape according to the form of an all-solid-state battery, For example, it can be set as a rectangular plate shape or disk shape. In molding, for example, pressure molding of about 5 MPa or more and 200 MPa or less can be performed, but it is preferable that the electrode mixture is not crushed because a grain boundary is generated. In addition, you may produce the electrode for all-solid-state batteries by making it join with a collector. In the case of joining with a current collector, an electrode mixture is applied on the current collector and then subjected to heat treatment, or an electrode for an all-solid-state battery is manufactured by fusing the hot electrode and the current collector. Can do. For application of the electrode mixture, for example, wet coating means such as a roll coater, a bar coater, a doctor blade, etc. can be used.

  In the bonding step, the manufactured electrode layer is bonded to the other electrode layer to be paired so that the solid electrolyte layer 2C is disposed between the electrode layers. That is, when the positive electrode layer 2A containing the deliquescent material is manufactured, the positive electrode layer 2A is disposed in such a manner that the solid electrolyte layer 2C is interposed between the positive electrode layer 2A and the negative electrode layer 2B. When the negative electrode layer 2B including the negative electrode layer 2B is disposed such that the solid electrolyte layer 2C is interposed between the negative electrode layer 2B and the positive electrode layer 2A, Wear and join. Alternatively, when both the positive electrode layer 2A and the negative electrode layer 2B contain a deliquescent material, the solid electrolyte layer 2C is disposed between the positive electrode layer 2A and the negative electrode layer 2B, and one surface of the solid electrolyte layer is bonded to the positive electrode layer 2A. The other surface is bonded to the negative electrode layer 2B by pressure. An output terminal for taking out electric power from the all solid state battery is connected to the electrode assembly in which the electrode layer and the solid electrolyte layer 2C are joined as necessary. The output terminal may be made of, for example, aluminum having voltage resistance and welded to a current collector or the like.

  In the assembling process, an insulating material is interposed in the manufactured electrode assembly and sealed in an exterior body to obtain an all-solid battery.

  The all solid state battery 1 thus manufactured can be an all solid state primary battery that performs irreversible discharge or reversibly charge / discharge by appropriately selecting the configuration of the electrode and the active material. A possible all-solid secondary battery can be obtained. In particular, all-solid-state secondary batteries are useful as household or industrial electric equipment, portable information communication equipment, power storage systems, power supplies for ships, railways, aircraft, hybrid cars, electric cars, and the like. In addition, the structure of the all-solid-state battery can be confirmed visually by disassembly, and the composition and structure of the electrode and the solid electrolyte layer can be determined by electron microscope, X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy, fluorescent X-ray analysis, Can be confirmed by X-ray diffraction analysis.

  Next, examples of the present invention will be described in detail, but the technical scope of the present invention is not limited thereto.

An all-solid-state battery 1 using lithium metavanadate LiVO ₃ as a deliquescent material was produced.

1.84 g of lithium carbonate (Li ₂ CO ₃ ) and 4.55 g of vanadium pentoxide (V ₂ O ₅ ) were put into a mortar and mixed until uniform. The obtained mixture was replaced with a platinum crucible and heat-treated in a box type electric furnace. The heat treatment was performed under the condition that the temperature was increased to 650 ° C. at a temperature increase rate of 10 ° C./min in an air atmosphere and then held at 650 ° C. for 10 hours. After the heat treatment, the mixture was cooled to 100 ° C. to obtain a deliquescent material lithium metavanadate LiVO ₃ .

  2.0 g of the obtained deliquescent material was dissolved in 2.0 g of pure water, and 3.0 g of N-methylpyrrolidone was added to prepare a deliquescent material solution. An electrode mixture paste was prepared by mixing 0.8 g of the adjusted deliquescent material solution and 0.01 g of the ketjen black carbon material, which is a conductive agent, until uniform in a mortar. The obtained electrode mixture was coated on an aluminum foil current collector, subjected to a heat treatment at 100 ° C. for 2 hours to remove the solvent, and then punched into a 10 mmφ disc shape to obtain a positive electrode layer 2A. It was.

  The negative electrode layer 2B was produced by punching out lithium foil into a disk shape of 10 mmφ. A PEO solid polymer film was used for the solid electrolyte layer 2C. A positive electrode layer 2A, a solid electrolyte layer 2C, and a negative electrode layer 2B were laminated in this order to produce an electrode assembly. The all-solid-state battery according to Example 1 is obtained by sandwiching both ends of the positive electrode side and the negative electrode side of the electrode assembly with a separator made of an insulating material and sandwiching it with a SUS exterior body from the outside, and caulking with a torque of 15 N · m. Manufactured.

  The same procedure as in Example 1 was performed except that the ketjen black carbon material used for the electrode mixture paste was not added.

  A ketjen black carbon material used for the electrode mixture paste was produced in the same procedure as in Example 1 except that the amount was changed to 0.005 g.

  A ketjen black carbon material used for the electrode mixture paste was produced in the same procedure as in Example 1 except that the amount of ketjen black carbon material was changed to 0.0075 g.

  A ketjen black carbon material used for the electrode mixture paste was produced in the same procedure as in Example 1 except that the amount was changed to 0.015 g.

  The same procedure as in Example 1 was performed except that the amount of the ketjen black carbon material used for the electrode mixture paste was changed to 0.02 g.

Comparative Example 1

As Comparative Example 1, an all solid state battery using LiCoO 2 as active material particles and LiVO ₃ as a deliquescent material between the particles was manufactured.

  Specifically, it was manufactured in the same procedure as in Example 1 except that 0.6 g of LiCoO 2 was added to the electrode mixture paste.

Comparative Example 2

  The same procedure as in Example 1 was performed except that the amount of the ketjen black carbon material used for the electrode mixture paste was changed to 0.03 g.

<Charging / discharging cycle test method>
About the all-solid-state battery which concerns on Examples 1-6 and Comparative Examples 1 and 2, the capacity maintenance rate in a charging / discharging cycle test was evaluated. The capacity retention rates of the batteries according to Examples 1 to 6 and Comparative Example 2 manufactured were 25 ° C., first discharged at a constant current to 150 mAhg ⁻¹ or a final voltage of 0 V, and held in an open circuit state for 1 hour, The charge / discharge cycle of charging to 150 mAhg ⁻¹ or a final voltage of 4.25 V at a constant current was repeated, and the ratio of the charge capacity at the 50th cycle to the initial charge capacity was defined as the capacity maintenance rate. Capacity maintenance rate of the battery according to Comparative Example 1 is initially charged at a constant current until 150 mAhg ^-1 or final voltage 4.25 V, after maintaining for one hour in an open circuit condition, 150 mAhg ^-1 or final voltage at a constant current The charge / discharge cycle for discharging to 3.0 V was repeated, and the ratio of the discharge capacity at the 50th cycle to the initial discharge capacity was defined as the capacity maintenance ratio.

In FIG. 2, sectional drawing of the electrode layer of the all-solid-state battery which concerns on an Example and a comparative example is shown. FIG. 2 a shows a typical cross-sectional view of Examples 1 to 6, and FIG. 2 b shows a cross-sectional view of Comparative Example 2. In FIG. 2a, it was observed that the electrode layer was densely formed with a deliquescent material having a plate-like structure. In FIG. 2b, it was observed that the deliquescent material was filled in the gaps between the LiCoO ₂ particles. Therefore, in Examples 1 to 6, the proportion of the deliquescent material in the electrode layer is higher than that in Comparative Example 2, and the electrode layer is densely formed of the deliquescent material having a plate-like structure. all right.

  Table 1 shows the capacity retention rate after 50 cycles of the mixture layer density and charge / discharge test of the all-solid-state battery electrode according to the examples and comparative examples, and FIG. 3 shows the capacity maintenance rate and deliquescence after 50 cycles. The relationship of the ratio of the mixture layer density to the true density of the material is shown. As shown in FIG. 3, the capacity retention ratios of Examples 1 to 6 maintained the initial capacity of 0.9 to 1.0, while the mixture layer density / true density ratio was 0.00. It was found that Comparative Example 1 which is 1 was 0.6, and Comparative Example 2 where LiCoO2 particles were added was 0.65, which was extremely low. From this result, it is possible to improve charge / discharge cycle characteristics by using a deliquescent material having a plate-like structure for the electrode layer and having a mixture layer density / true density ratio of greater than 0.1 and 1.0 or less. Indicated.

DESCRIPTION OF SYMBOLS 1 ... All-solid-state battery, 2A ... Positive electrode layer, 2B ... Negative electrode layer, 2C ... Solid electrolyte layer

Claims (6)

An electrode for an all solid state battery comprising a deliquescent material,
The deliquescent material has a plate-like structure,
The all-solid-state battery electrode, wherein the ratio of the density of the all-solid-state battery electrode to the true density of the deliquescent material is greater than 0.1 and 1.0 or less. The all-solid-state battery electrode according to claim 1,
The all-solid-state battery electrode, wherein the deliquescent material is lithium vanadium oxide. The all-solid-state battery electrode according to claim 2,
The lithium vanadium oxide is an electrode for an all solid state battery containing lithium metavanadate. The all-solid-state battery electrode according to claim 1,
The all-solid-state battery electrode, wherein the ratio of the density of the all-solid-state battery electrode to the true density of the deliquescent material is 0.4 or more and 1.0 or less.   An all solid state battery comprising the all solid state battery electrode according to claim 1 and a solid electrolyte layer. A method for producing an electrode for an all-solid battery comprising a deliquescent material,
The deliquescent material is a plate-like structure,
The density ratio of the all-solid-state battery electrode to the true density of the deliquescent material is greater than 0.1 and 1.0 or less;
An electrode mixture adjusting step of adjusting the electrode mixture after deliquescent the deliquescent material;
An electrode manufacturing step of manufacturing the electrode for an all solid state battery by heat-treating the electrode mixture at a temperature of 100 ° C. or more and 300 ° C. or less.

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