JP2017059417A - Ion-conducting material for all-solid battery, all-solid battery arranged by use thereof, and manufacturing methods thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an all-solid battery having a low internal resistance, and adequate rate characteristic.SOLUTION: An ion-conducting material for an all-solid battery comprises a lithium vanadium oxide, part of which is substituted with a trivalent or quadrivalent cation; the substitution quantity of the cation is less than 30 atom% to the quantity of vanadium; and e.g. the lithium vanadium oxide has deliquescence. The all-solid battery comprises: a positive electrode layer including a positive electrode active material and a positive electrode solid electrolyte; a negative electrode layer including a negative electrode active material and a negative electrode solid electrolyte; and a solid electrolyte layer disposed between the positive and negative electrode layers. In the all-solid battery, the positive electrode solid electrolyte or the negative electrode solid electrolyte includes the ion-conducting material for an all-solid battery.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an all-solid-state battery ion-conductive material, an all-solid-state battery using an all-solid-state battery ion-conductive material, and a method for producing the same.

  A lithium ion secondary battery, which is a type of secondary battery, is a battery having a higher energy density than other secondary batteries such as nickel-hydrogen storage batteries. However, since the lithium ion secondary battery uses a flammable organic solvent in the liquid electrolyte, a safety device is used to prevent ignition or rupture that may occur due to overcurrent caused by a short circuit. May be required. In addition, in order to prevent such a phenomenon, restrictions may be imposed on the selection of battery materials and the design of battery structures.

  Therefore, development of an all-solid battery that uses a solid electrolyte instead of the liquid 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.

  However, in all solid state batteries, it is known that the contact resistance between the active material particles responsible for the battery reaction or between the active material particles and the solid electrolyte particles greatly affects the internal resistance of the battery. Yes. In particular, due to the volume change of the active material with repeated charge and discharge, the contact between the active material and the solid electrolyte, conductive agent, etc. tends to decrease, and the internal resistance tends to increase or the capacity tends to decrease. is there. Therefore, a technique for reducing the internal resistance is required.

  For example, Patent Document 1 discloses a lithium secondary battery in which at least one of a positive electrode and a negative electrode has active material particles coated with a coating layer containing a conductive agent and a lithium ion conductive inorganic solid electrolyte. .

  Further, in Patent Document 2, in order to suppress the reaction between the positive electrode active material and a solid electrolyte material such as a sulfide solid electrolyte material and reduce the interface resistance between them, the surface of the positive electrode active material has a polyanion structure. It is disclosed that a positive electrode active material having a coating layer made of a compound having a solid-state battery is used.

JP 2013-222530 A JP 2012-89406 A

  In all solid state batteries, it is difficult to fundamentally solve the interfacial delamination between the active material and the active material and between the active material and the solid electrolyte in the expansion and contraction of the active material particles during the charge / discharge cycle. In Patent Document 1, charge / discharge cycle characteristics are improved by reducing interfacial delamination between particles that occurs during charge / discharge. However, in the all solid state battery, further improvement of charge / discharge cycle characteristics is necessary. In Patent Document 2, the internal resistance can be reduced and the charge / discharge capacity can be improved. However, since the surface of the active material is covered with an ion conductive inorganic oxide, there is a gap between the active materials and between the active material and the solid electrolyte. Occurs. Therefore, an all-solid-state battery is expected in which resistance is reduced and rate characteristics are improved by further increasing the conduction of lithium ions in the electrode.

  Therefore, an object of the present invention is to provide an all solid state battery in which the internal resistance of the battery is reduced and the rate characteristics are improved.

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

  An ion conductive material for an all solid state battery including lithium vanadium oxide, wherein a part of the lithium vanadium oxide is substituted with a trivalent or tetravalent cation, and the amount of cation substitution is 30 atomic% with respect to vanadium. An ion conductive material for all solid state batteries that is less than

  According to the present invention, it is possible to provide an all solid state battery having low internal resistance and improved rate characteristics. 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 a figure which shows the relationship between the overvoltage and current value of the all-solid-state battery which concerns on an Example and a comparative example. It is a figure which shows the relationship between the overvoltage of the all-solid-state battery which concerns on an Example and a comparative example, and the element substitution amount of an ion conductive material.

  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.

  The positive electrode layer 2A includes a positive electrode active material 10A and a positive electrode solid electrolyte 20A. The negative electrode layer 2B includes a negative electrode active material 10B and a negative electrode solid electrolyte 20B. Hereinafter, the positive electrode active material 10A and the negative electrode active material 10B are also referred to as electrode active materials.

At least one of the positive electrode layer 2A and the negative electrode layer 2B includes an ion conductive material in which a part of lithium vanadium oxide (LiVO ₃ ) is substituted with a trivalent or tetravalent cation as a solid electrolyte. Hereinafter, the ion conductive material as a solid electrolyte contained in the positive electrode layer 2A is referred to as a positive electrode solid electrolyte 20A, and the solid electrolyte contained in the negative electrode layer 2B is referred to as a negative electrode solid electrolyte 20B.

<Ion conductive material>
An ion conductive material according to an embodiment of the present invention is obtained by replacing a part of lithium vanadium oxide with a trivalent or tetravalent cation. Lithium vanadium oxide is a solid electrolyte having deliquescence. By filling a solid electrolyte having deliquescence between the active materials, the active material particles can be brought into close contact with each other and held in the electrode layer, thereby improving the contact between the active materials. By replacing a part of this lithium vanadium oxide with a trivalent or tetravalent cation, the ionic conductivity in the lithium vanadium oxide can be improved. As a result, the rate characteristics of the battery can be improved. The trivalent or tetravalent cation has a lower valence than the pentavalent vanadium in the lithium vanadium oxide. Therefore, by substituting with an element having a low valence, the density of Li ions to be conducted is improved from the relationship of charge assurance of the lithium vanadium oxide, whereby the ionic conductivity is improved.

  Similarly to the lithium vanadium oxide, an ion conductive material obtained by substituting a part of the lithium vanadium oxide with a trivalent or tetravalent cation has deliquescence. By filling a solid electrolyte having deliquescence between the active materials, the active material particles can be brought into close contact with each other and held in the electrode layer, thereby improving the contact between the active materials. In addition, even if the interface between active material particles and active material particles or active material particles and solid electrolyte particles is peeled off due to charge / discharge cycles and the capacity is reduced, the electrode layer is placed in a humid atmosphere and deliquescent again. By removing proper 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.

  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 solid electrolyte having deliquescence for the production of an electrode layer in an all-solid battery, a matrix structure in which the solid electrolyte is filled with high density is formed in the gaps between the active material particles constituting the electrode layer. Is possible. Then, by filling the gaps between the active material particles constituting the electrodes with a high density of the solid electrolyte, the active material particles are in contact with each other through not only a point contact but a wider area solid electrolyte. It is like that.

An ion conductive material in which a part of the lithium vanadium oxide is substituted with a trivalent or tetravalent cation is, for example, a composition formula Li _{(1+ (5-a) x)} M _x V _(1-x) O _{(3 - bx) (2 ≦ a ≦} 4, 0 ≦ b ≦ 2, x = 0.01 ≦ x ≦ 0.3, M is Al, Ti, Zr, Ge, Ga, Sn, Si, at least one of Zn) It is represented by The composition formula is an example, and the present invention is not limited to this composition formula. In the composition formula, a represents the valence of the substitution element M, b represents the value obtained by dividing the valence of vanadium by the valence of the substitution element, and x represents the substitution amount of the substitution element M. X which is the substitution amount of M is preferably 0.01 or more and 0.3 or less, and more preferably 0.01 or more and 0.15 or less. If the substitution amount is less than 0.01, the effect of the substitution element cannot be obtained. If the substitution amount exceeds 0.3, the substitution element does not stay in the structure, but forms a different structure, thereby inhibiting ionic conduction and increasing the internal resistance.

<Positive electrode layer and negative electrode layer>
At least one of the positive electrode layer 2A and the negative electrode layer 2B includes, as the positive electrode solid electrolyte 20A or the negative electrode solid electrolyte 20B, an ion conductive material in which a part of the lithium vanadium oxide is substituted with a trivalent or tetravalent cation.

  In the electrode layer, the content of the ion conductive material according to one embodiment of the present invention varies depending on the particle diameter and type of the active material. It is considered that the larger the particle size of the active material, the more voids between the active materials. Therefore, the content of the ion conductive material is preferably increased. Note that this is not the case when an active material having a plurality of particle sizes is used in the electrode layer.

The ion 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 ionic conductivity is 1 × 10 ⁻⁸ S / cm or more, the ionic conductivity between the active material particles or between the active material and the solid electrolyte is determined by the ion conductive material filled between the active material particles. Therefore, the internal resistance of the battery can be satisfactorily reduced and a higher discharge capacity can be ensured.

Moreover, the ion conductive 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 conduction between the active material particles or between the active material and the solid electrolyte is caused by the ion conductive material filled between the active material particles. 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. Therefore, the ion conductive material in the all solid state battery is not in a deliquescent state, but is deposited in the gaps between the particles of the active material as crystals or non-crystals, and the electron conductivity and ion conductivity between the particles of the active material. Is well secured.

  In addition, the positive electrode layer 2A and the negative electrode layer 2B include a solid electrolyte having deliquescence and a solid electrolyte used in a general all-solid battery in addition to the ion conductive material according to the embodiment of the present invention as a solid electrolyte. May be included. Examples of solid electrolytes having deliquescence include lithium vanadium oxide and sulfide solid electrolytes. However, since a sulfide-based solid electrolyte may generate harmful substances such as hydrogen sulfide, it is preferable to use vanadium oxide.

  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 ion conductive material in the electrode layer is 5 parts by weight with respect to the total dry weight of the electrode active material and all solid electrolytes in the electrode layer (including solid electrolytes having deliquescence and other solid electrolytes). The amount is preferably 50 parts by weight or less. By setting the dry weight of the solid electrolyte having deliquescence to 5 parts by weight or more and 50 parts by weight or less, an all-solid battery having a low internal resistance, a good volume energy density, and a high discharge capacity can be manufactured.

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, by using the ionic conductive material according to the present invention in combination with another solid electrolyte, the interparticle between the ionic conductive material according to the present invention is used. It is possible to provide the electrode layer with high ionic conductivity due to the solid electrolyte while obtaining the effect of improving the contact property.

  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.

As the positive electrode active material 10A used for the positive electrode layer 2A, when the carrier is a lithium ion, for example, lithium manganese phosphate (LiMnPO ₄ ), lithium iron phosphate (LiFePO ₄ ), lithium cobalt phosphate (LiCoPO _4). Olivine type such as lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), manganese (III) lithium (LiMnO ₂ ), and LiNi _x Co _y Mn _z O ₂ (wherein 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 ) Or a lithium transition metal compound such as a polyanion type such as lithium vanadium phosphate (Li ₃ V ₂ (PO ₄ ) ₃ ). You can. 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.

As the negative electrode active material 10B to be contained in the negative electrode layer 2B, when the carrier is lithium ions, 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 particles of the active material preferably have a true sphere or an oval shape, and are preferably monodisperse. The average particle diameter of the active material is preferably 0.1 μm or more from the viewpoint of handling, and preferably 50 μm or less from the viewpoint of tap density. By improving the tap density, the contact between the particles of the active material in the electrode layer can be improved. The average particle size of the active material is obtained by observing a collection of particles of the active material with a scanning electron microscope or a transmission electron microscope, and calculating the arithmetic average of the particle sizes of 100 randomly extracted particles. Can do. The particle diameter is measured as an average of the major axis diameter and minor axis diameter of the particles in the electron microscope image.

  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 include stainless steel, aluminum, iron, nickel, titanium, carbon and other substrates, foils, and the like. Examples of the current collector used for the negative electrode layer include substrates such as stainless steel, copper, nickel, and carbon, foils, and the like.

<Solid electrolyte layer>
The solid electrolyte layer 2 </ b> C includes a solid electrolyte 30. As the solid electrolyte 30, 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 can be used. 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 30 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 solid electrolyte preparation step for preparing a solid electrolyte in an electrode layer, an electrode mixture preparation step for preparing an electrode mixture, a heat treatment of the electrode mixture, and molding. An electrode manufacturing process for manufacturing the electrode layer, 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 solid electrolyte preparation step, a metal precursor as a solid electrolyte raw material is mixed, and then this mixture is reacted in a solid phase at a high temperature to prepare a solid electrolyte for an electrode. 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 solid electrolyte is deliquesced and liquefied, and then the liquefied deliquescent solid electrolyte and the active material are mixed to obtain an electrode mixture (positive electrode mixture, negative electrode mixture). Prepare. The deliquescence of the solid electrolyte having deliquescence may be caused to react with water at normal temperature in the atmosphere. By reacting the deliquescent solid electrolyte with water in this manner, the deliquescent solid electrolyte can be dissolved substantially completely and mixed with the active material particles. By deliquescent the solid electrolyte having deliquescence, fluidity suitable for forming an electrode layer having high adhesion of active material particles can be obtained. In addition, after dissolving a deliquescent solid electrolyte in water, an appropriate organic solvent is added to appropriately improve the adhesion between the active material and the deliquescent solid electrolyte to form an electrode layer with good adhesion. Can do. Organic solvents include water, N-methylpyrrolidone, N, N-dimethylformamide, N, N-dimethylacetamide, methanol, ethanol, propanol, ethylene glycol, glycerin, dimethyl, depending on the type of solid electrolyte and binder. Sulfoxide, tetrahydrofuran and the like can be used.

  After deliquescence of the deliquescent solid electrolyte, an active material is added to the dissolved deliquescent solid electrolyte, and these are mixed and homogenized to prepare an electrode mixture. At this time, you may add the other solid electrolyte contained in an electrode layer, and a electrically conductive agent. The dry weight of the deliquescent solid electrolyte to be mixed is not less than 5 parts by weight with respect to the total dry weight of all solid electrolytes (including solid electrolytes having deliquescence and other solid electrolytes) in the electrode layer and the active material. It is preferable that the amount is not more than parts by weight. 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 solid electrolyte 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 heat treated and then molded 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. Heat treatment of the electrode mixture evaporates the water or organic solvent that dissolves the deliquescent solid electrolyte and deposits the deliquescent solid electrolyte around the active material particles. A matrix-like structure filled with a high density solid electrolyte can be formed. Therefore, the contact property between the particles of the active material through the solid electrolyte, that is, ionic conductivity is improved.

  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 a solid electrolyte having deliquescence is used, if the heating temperature is 15 ° C. or higher, moisture contained in the solid electrolyte having deliquescence can be evaporated and dried off in the air. In addition, if the heating temperature is 650 ° C. or lower, it is possible to avoid a solid phase reaction between the electrode active material and the solid electrolyte, thereby preventing the generation of a different phase with low ionic conductivity and suppressing an increase in internal resistance. can do. In particular, when the heating temperature is 100 ° C. or higher and 300 ° C. or lower, an electrode layer showing a high capacity can be formed by sufficiently eliminating the water contained in the deliquescent solid electrolyte while avoiding an increase in internal resistance. it can.

  The heat-treated 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 in a pair so that the solid electrolyte layer is disposed between the electrode layers. That is, when the positive electrode layer 2A containing the deliquescent solid electrolyte is manufactured, the positive electrode layer 2A is arranged 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 containing the solid electrolyte is manufactured, the negative electrode layer 2B is arranged such that the solid electrolyte layer 2C is interposed between the negative electrode layer 2B and the positive electrode layer 2A, Bond by pressure bonding. Alternatively, when both the positive electrode layer 2A and the negative electrode layer 2B include a deliquescent solid electrolyte, 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 disposed on the positive electrode layer 2A. Then, 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 battery produced in this way can be either an all-solid primary battery that irreversibly discharges or can be reversibly charged / discharged by appropriately selecting the configuration of the electrode and active material. All-solid-state secondary battery. 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 solid electrolyte layer can be determined by X-ray photoelectron spectroscopy, inductively coupled plasma emission spectroscopy, X-ray fluorescence analysis, X-ray diffraction, etc. It can be confirmed by analysis.

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

For Li in LiVO ₃ , Al is 5 at. An all-solid battery 1 using an ion conductive material with% substitution as a deliquescent solid electrolyte was produced.

Add 2.03 g lithium carbonate (Li ₂ CO ₃ ), 0.25 g aluminum oxide (Al ₂ O ₃ ) and 4.32 g divanadium pentoxide (V ₂ O ₅ ) into the mortar until uniform Mixed. 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 make LiVO ₃ 5 at. An ion conductive material substituted with% Al was obtained.

2.0 g of the obtained ion conductive material was dissolved in 2.0 g of pure water, and 3.0 g of N-methylpyrrolidone was added to prepare a deliquescent solid electrolyte solution. An electrode mixture paste was prepared by mixing 0.8 g of the adjusted deliquescent solid electrolyte solution and 0.6 g of LiCoO ₂ particles as the positive electrode active material until uniform in a mortar. The obtained electrode mixture is coated on an aluminum foil current collector, subjected to heat treatment at 100 ° C. for 2 hours to remove the solvent, and then punched into a disk shape having a cross-sectional area of 1 cm ² to form a positive electrode layer 2A was obtained.

Lithium foil and copper foil were pressure-bonded and punched out into a disk shape having a cross-sectional area of 1 cm ² to produce a negative electrode layer 2B. 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.

Implemented except that 0.2 g of titanium oxide (TiO ₂ ) was used instead of aluminum oxide (Al ₂ O ₃ ) and the amount of lithium carbonate (Li ₂ CO ₃ ) added was changed to 1.94 g. Prepared by the same procedure as in Example 1.

The amount of aluminum oxide (Al ₂ O ₃ ) was changed to 0.51 g, and the amount of lithium carbonate (Li ₂ CO ₃ ) added was changed to 2.22 g, divanadium pentoxide (V ₂ O ₅ ) Was prepared in the same procedure as in Example 1 except that the amount of was changed to 4.09 g.

The amount of aluminum oxide (Al ₂ O ₃ ) was changed to 1.0 g, and the addition amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.6 g, divanadium pentoxide (V ₂ O ₅ ) The same procedure as in Example 1 was conducted except that the amount of addition of was changed to 3.6 g.

The amount of aluminum oxide (Al ₂ O ₃ ) was changed to 1.52 g, the amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.96 g, divanadium pentoxide (V ₂ O ₅ ) Was prepared in the same procedure as in Example 1 except that the amount of was changed to 3.18 g.

The amount of aluminum oxide (Al ₂ O ₃ ) was changed to 1.78 g, and the addition amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 3.14 g, divanadium pentoxide (V ₂ O ₅ ) Was prepared in the same manner as in Example 1 except that the amount added was changed to 2.96 g.

The amount of titanium oxide (TiO ₂ ) was changed to 0.4 g, the addition amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.03 g, the addition of divanadium pentoxide (V ₂ O ₅ ) The product was prepared in the same procedure as in Example 2 except that the amount was changed to 4.09 g.

The amount of titanium oxide (TiO ₂ ) was changed to 0.8 g, the addition amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.22 g, the addition of divanadium pentoxide (V ₂ O ₅ ) The product was prepared in the same manner as in Example 2 except that the amount was changed to 3.64 g.

The amount of titanium oxide (TiO ₂ ) was changed to 1.2 g, the amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.4 g, and the addition of divanadium pentoxide (V ₂ O ₅ ) The product was prepared in the same procedure as in Example 2 except that the amount was changed to 3.18 g.

The amount of titanium oxide (TiO ₂ ) was changed to 1.4 g, the amount of lithium carbonate (Li ₂ CO ₃ ) was changed to 2.5 g, and the addition of divanadium pentoxide (V ₂ O ₅ ) The product was prepared in the same procedure as in Example 2 except that the amount was changed to 2.96 g.
<Comparative Example 1>

As Comparative Example 1, an all-solid battery was manufactured using LiVO ₃ having no element substitution as a deliquescent solid electrolyte. LiVO ₃ was produced by the following procedure.

1.85 g of lithium carbonate (Li ₂ CO ₃ ) and 4.55 g of vanadium pentoxide (V ₂ O ₅ ) were weighed and 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. As heat treatment conditions, the temperature was raised to 650 ° C. at a rate of 10 ° C./min in an air atmosphere, and then held at 650 ° C. for 10 hours. After heat treatment, the mixture was cooled to 100 ° C., to obtain a LiVO _3. Thereafter, the same procedure as in Example 1 was performed.

<Measurement of overvoltage>
About the all-solid-state battery which concerns on Examples 1-10 and the comparative example 1, the overvoltage resulting from the internal resistance at the time of discharge was evaluated. The overvoltages of the batteries according to Examples 1 to 10 and Comparative Example 1 manufactured were constant at 30 ° C. from the open circuit voltage when first charged to a final voltage of 4.25 V with a constant current and held for 1 hour in the open circuit state. The value obtained by subtracting the battery voltage when discharged for 10 seconds with current was used.

  FIG. 2 shows the relationship between the overvoltage and the current value of the all solid state batteries according to the example and the comparative example, specifically, the batteries of Example 1, Example 2, and Comparative Example 1 are 1.0, 1.5. The evaluation result of the overvoltage at the time of charging / discharging with each electric current value of 2.0, and 2.5 microamperes is shown. In FIG. 2, the vertical axis represents the relative value when the overvoltage when the charge / discharge current value of the all-solid-state battery according to Comparative Example 1 is 1.0 μA is 10, and the horizontal axis represents the charge / discharge current value.

  As shown in FIG. 2, in the all-solid-state batteries according to Examples 1 and 2, the charge / discharge current was compared with Comparative Example 1 using lithium vanadium oxide in which trivalent or tetravalent cations were not substituted. It was confirmed that there was little increase in overvoltage when increasing. From this result, it was shown that resistance can be reduced and rate characteristics can be improved by replacing lithium vanadium oxide with a trivalent or tetravalent cation.

  Table 1 and FIG. 3 show the relationship between the overvoltage of the all solid state battery according to the example and the comparative example and the element substitution amount of the ion conductive material, specifically, all the solid state batteries of Examples 1 to 10. The result of having evaluated the overvoltage at the time of charging / discharging with the charging / discharging electric current value of 0 microampere is shown. In FIG. 3, the vertical axis represents the relative value when the overvoltage when the all solid state battery according to Comparative Example 1 is charged and discharged at 1.0 μA is 10, and the horizontal axis is the atomic ratio of the substituted cation to Li.

  As shown in FIG. 3, it was confirmed that the cation to be substituted was lower than the overvoltage of Comparative Example 1 up to a region lower than 30 atomic% with respect to vanadium. On the other hand, it was found that when the cation to be substituted was 30 atomic% or more with respect to vanadium, the overvoltage was equal to or larger than that of Comparative Example 1. This is considered to be caused by the fact that when the atomic ratio of the element to be replaced is 30 atomic% or more, the element cannot be replaced and a different structure having a large resistance is formed. Further, it has been clarified after extensive investigation that even if it is slightly substituted with a trivalent or tetravalent cation, it is clear that the substitution amount is 0.01 atomic% relative to Li. Realistic. Therefore, it was confirmed that the substitution amount of the trivalent or tetravalent cation was in the range of 0.01 atomic% or more and lower than 30 atomic%. Further, the reduction of overvoltage due to substitution with trivalent Al or tetravalent Ti can be obtained with, for example, Sc, Y, La, Zr, Ge, Ga, Sn, Si, Zn, or the like.

From the above results, Li _{(1+ (5-a) x)} M _x V _(1-x) O _{(3- bx)} is used as a basic skeleton, and a part thereof is substituted with a trivalent or tetravalent cation. It was found that ion conductivity was improved, overvoltage was reduced, and rate characteristics were improved.

DESCRIPTION OF SYMBOLS 1 ... All-solid-state battery, 2A ... Positive electrode layer, 2B ... Negative electrode layer, 2C ... Solid electrolyte layer, 10A ... Positive electrode active material, 20A ... Positive electrode solid electrolyte, 10B ... Negative electrode active material, 20B ... Negative electrode solid electrolyte, 30 ... Solid electrolyte

Claims (8)

An ion conductive material for an all-solid battery containing lithium vanadium oxide,
A part of the lithium vanadium oxide is substituted with a trivalent or tetravalent cation,
An ion conductive material for an all-solid battery, wherein the cation substitution amount is less than 30 atomic% with respect to vanadium. An ion conductive material for an all solid state battery according to claim 1,
The lithium vanadium oxide is an ionic conductive material for all solid state batteries having deliquescence. An ion conductive material for an all solid state battery according to claim 1,
Composition formula _{Li (1+ (5-a)} x) M x V (1-x) O (3- bx) ((2 ≦ a ≦ 4, 0 ≦ b ≦ 2, x = 0.01 ≦ x ≦ 0 .3, and M is an ion conductive material for an all solid state battery represented by Al, Ti, Zr, Ge, Ga, Sn, Si, or Zn).   The electrode for all-solid-state batteries containing the ion conductive material for all-solid-state batteries in any one of Claims 1 thru | or 3, and a positive electrode active material or a negative electrode active material. A positive electrode layer comprising a positive electrode active material and a positive electrode solid electrolyte;
A negative electrode layer comprising a negative electrode active material and a negative electrode solid electrolyte;
A solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and an all-solid battery,
The said positive electrode solid electrolyte or the said negative electrode solid electrolyte is an all-solid-state battery containing the ion conductive material for all-solid-state batteries in any one of Claims 1 thru | or 3. The all-solid-state battery according to claim 5,
When the positive electrode solid electrolyte includes the all-solid-state battery ion-conductive material, the content of the all-solid-state battery ion-conductive material in the positive electrode layer is the total dry weight of the positive electrode active material and the positive electrode solid electrolyte. An all-solid battery that is 5 parts by weight or more and 50 parts by weight or less. The all-solid-state battery according to any one of claims 5 to 6,
When the all-solid-state battery ion-conducting material is included in the negative-electrode solid electrolyte, the content of the all-solid-state battery ion-conducting material in the negative-electrode layer is the total dry weight of the negative-electrode active material and the negative-electrode solid electrolyte. An all-solid battery that is 5 parts by weight or more and 50 parts by weight or less. A positive electrode layer comprising a positive electrode active material and a positive electrode solid electrolyte;
A negative electrode layer comprising a negative electrode active material and a negative electrode solid electrolyte;
A solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising:
The positive electrode solid electrolyte or the negative electrode solid electrolyte includes an ion conductive material for an all-solid battery,
The ion conductive material for an all-solid battery includes lithium vanadium oxide,
A part of the lithium vanadium oxide is substituted with a trivalent or tetravalent cation,
The cation substitution amount is less than 30 atomic% with respect to vanadium;
The lithium vanadium oxide has deliquescence,
An electrode mixture adjusting step of adjusting the positive electrode mixture or the negative electrode mixture by confusing with the positive electrode solid electrolyte or the negative electrode solid electrolyte after decontaminating the ion conductive material for the all-solid-state battery;
An electrode manufacturing step of manufacturing the positive electrode layer or the negative electrode layer by heat-treating the positive electrode mixture or the negative electrode mixture at 100 ° C. or more and 300 ° C. or less.

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