WO2017128983A1 - Positive electrode composite material for all-solid-state lithium ion battery and preparation method and application therefor - Google Patents

Abstract

Provided in the present invention are a positive electrode composite material for an all-solid-state lithium ion battery, and a preparation method and an application therefor, the positive electrode positive material having a core-shell structure, the core comprising positive electrode active material, and the shell comprising a polymer electrolyte and a sulphide solid-state electrolyte. The positive electrode composite material for an all-solid-state lithium ion battery provided in the present invention has a simple preparation procedure, and can effectively improve the interface problem between the positive electrode and inorganic solid electrolyte of a lithium ion battery; an all-solid-state lithium ion battery prepared using said material has good recycling service life and better safety performance.

Description

All-solid lithium ion battery cathode composite material, preparation method and application thereof

Priority information

Priority is claimed on Japanese Patent Application No. 201610063735.8, filed on Jan. 29,,,,,,,,

Technical field

The invention belongs to the field of lithium ion batteries, and particularly relates to an all-solid lithium ion battery cathode composite material and a preparation method thereof, a cathode material, a cathode and an all-solid lithium ion battery.

Background technique

In the prior art, the preparation methods of the positive electrode of the all-solid lithium ion battery are generally classified into three types, namely, a powder tablet type, a vacuum coating type, and a coating type. The powder tableting type is a method in which a positive electrode active material, an inorganic solid electrolyte powder and a conductive agent are mixed in a certain ratio and then pressed under a certain pressure. During the preparation of the method, volume expansion or volume shrinkage of the positive electrode active material occurs. The effect causes the solid-solid contact interface effect between the positive active material and the inorganic solid electrolyte particles to deteriorate, and the solid-solid contact interface effect has a greater influence on the performance of the entire battery when the battery is subjected to external impact; vacuum coating type The positive electrode active material is directly coated on the current collector by means of sputter coating, evaporation coating, pulsed laser deposition film or ion plating film. This method requires specific equipment, is expensive, and has low efficiency, which restricts to some extent. Commercial application; the coated positive electrode sheet is obtained by uniformly mixing a positive electrode active material, an inorganic solid electrolyte, a conductive agent and a binder in a specific solvent in a specific solvent, and then coating the mixed slurry on the current collector. The method requires a binder to be added during coating, and the added binder component is non-lithium Conductor, will affect the conductivity of lithium ions inside the positive electrode, thus affecting the electrochemical performance of the battery. In order to solve the above technical problems, the prior art discloses that the surface of the positive electrode material is coated with LiNbO ₃ , SiO ₂ , Al ₂ O ₃ , Ni ₂ S ₃ , Li ₃ PS ₄ or the like. The methods of coating with oxides such as LiNbO ₃ , SiO ₂ , and Al ₂ O ₃ include fluidized bed method, pulsed laser deposition, etc. These methods are complicated in operation, expensive in equipment, and low in ion conductivity of the coating layer. Affecting the rate performance of the positive electrode material; while coating with a sulfide such as Ni ₂ S ₃ or Li ₃ PS ₄ , although the ionic conductivity can be improved to some extent, the positive electrode active material and the sulfide inorganic solid in the positive electrode cannot be solved. The problem of the solid-solid contact interface effect between electrolytes.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent. To this end, an object of the present invention is to provide an all-solid lithium ion battery positive electrode composite material and a preparation method thereof, a positive electrode material, a positive electrode, and an all solid state The lithium ion battery can effectively solve the problem of the solid-solid interface layer existing between the cathode material and the sulfide solid electrolyte in the prior art and the problem of low ion conductivity.

According to an aspect of the present invention, the present invention provides an all-solid lithium ion battery positive electrode composite material having a core-shell structure, the core including a positive electrode active material, and the shell including a polymer electrolyte and a sulfide Solid electrolyte.

The present invention can reduce the direct contact between the positive electrode active material and the inorganic solid electrolyte by coating the surface of the positive electrode active material with the shell layer containing the polymer electrolyte and the inorganic solid electrolyte, thereby improving the interface problem between the positive electrode and the inorganic solid electrolyte; In addition, the present invention uses a shell layer containing a polymer electrolyte and an inorganic solid electrolyte to coat a cathode active material to obtain a cathode composite material. On the one hand, the inventors have also found that the polymer electrolyte contained in the shell layer not only has good lithium ion conductivity. At the same time, it has good bonding performance, can reduce the use of non-ionic conductivity component binder in the coating process of the positive electrode material, and the polymer electrolyte component also has certain elastomeric properties, which can alleviate the positive electrode active material to a certain extent. The volume expansion effect during charging and discharging; on the other hand, the sulfide solid electrolyte contained in the shell layer can not only improve the ionic conductivity of the shell polymer electrolyte, but also increase the electrochemical window of the shell polymer electrolyte, so that Positive electrode composites can match high ion power The inorganic solid electrolyte and the negative electrode of the battery safety is higher, long cycle life.

According to a second aspect of the present invention, the present invention also provides a method for preparing a solid-state lithium ion battery positive electrode composite material. According to an embodiment of the present invention, the method includes:

(1) dissolving the polymer and the lithium salt in an organic solvent in a mass ratio of (20 to 85): (80 to 15) to obtain a polymer electrolyte;

(2) mixing the polymer electrolyte in the step (1) with a sulfide solid electrolyte to obtain an emulsion;

(3) adding a positive electrode active material to the emulsion of the step (2), wrapping the emulsion with the positive electrode composite material, and drying to obtain a positive electrode composite material having a core-shell structure, wherein the core includes a positive electrode active material A material comprising a polymer electrolyte and a sulfide solid electrolyte.

According to a third aspect of the present invention, the present invention further provides an all-solid-state lithium ion battery positive electrode material. According to an embodiment of the present invention, an all-solid lithium ion battery positive electrode material includes a positive electrode composite material and a positive electrode conductive agent, and the positive electrode composite The material is the all-solid lithium ion battery positive electrode composite material proposed by the invention.

According to a fourth aspect of the invention, the invention further provides an all-solid-state lithium ion battery positive electrode comprising a positive electrode material as set forth in the present application, in accordance with an embodiment of the present invention.

According to a fifth aspect of the present invention, the present invention also provides an all-solid-state lithium ion battery, which according to an embodiment of the present invention includes a battery case and a battery cell located in the battery case, the battery core The present invention includes a positive electrode, a negative electrode, and an inorganic solid electrolyte layer between the positive electrode and the negative electrode, wherein the positive electrode is the lithium ion proposed in the present application. Sub-cell positive.

DRAWINGS

FIG. 1 is a schematic structural view of a positive electrode composite material of an all-solid lithium ion battery according to the present application.

Specific implementation method

In order to make the technical problems, technical solutions and beneficial effects of the present invention more clear, the present invention will be further described in detail below with reference to the embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

According to a first aspect of the present invention, the present invention provides an all-solid lithium ion battery positive electrode composite material, according to an embodiment of the present invention, the positive electrode composite material has a core-shell structure, the core includes a positive electrode active material, The shell includes a polymer electrolyte and a sulfide solid electrolyte.

According to an embodiment of the present invention, in the solid-state lithium ion battery positive electrode composite material, the polymer electrolyte may be selected from the group consisting of a polyoxyethylene polymer electrolyte, a polyvinylidene fluoride polymer electrolyte, a polyacrylonitrile-based polymer electrolyte, and a poly At least one of a methyl methacrylate-based polymer electrolyte and a polyvinyl polymer electrolyte; further preferably, the polymer electrolyte is selected from the group consisting of a polyoxyethylene polymer electrolyte, a polyvinylidene fluoride polymer electrolyte, At least one of polyacrylonitrile-based polymer electrolytes. Thus, by using the above polymer electrolyte, the lithium ion conductivity of the shell layer can be further improved, and at the same time, the shell has good bonding properties, thereby reducing the use of the nonionic conductivity component binder during the coating process of the cathode material. Moreover, the polymer electrolyte component also has certain elastomeric properties, which can alleviate the volume expansion effect of the positive active material during charge and discharge to a certain extent.

The polymer electrolyte of the present invention is a polymer electrolyte in the conventional sense in the prior art, that is, a complex of a polymer and a lithium salt formed by a complex reaction of a polymer and a lithium salt under certain conditions.

The inventors have found in many experiments that a positive electrode composite material for a positive electrode of a lithium ion battery is prepared by using a shell-coated positive electrode active material containing the above polymer electrolyte and a sulfide solid electrolyte, and the prepared battery has high safety. Performance and cycle performance; after repeated tests, it was found that the polyelectrolyte not only has good bonding property, but also has good ionic conductivity. After being mixed with a sulfide solid electrolyte, it is coated on the surface of the positive electrode active material. The prepared positive electrode not only has a solid-solid interface effect with the inorganic solid electrolyte, but also has a good charge and discharge capacity of the positive electrode itself.

In the all-solid-state lithium ion battery positive electrode composite according to the above embodiment of the present invention, preferably, the sulfide solid electrolyte is selected from the group consisting of glassy Li ₂ SP ₂ S ₅ and crystalline Li _{x '} M _y' PS _z' Or at least one of Li ₂ SP ₂ S ₅ in a glass-ceramic state, wherein M is at least one of Si, Ge, and Sn, x'+4y'+5=2z', and 0≤y'≤1.

According to a particular embodiment of the invention, it is further preferred that the glassy state of Li ₂ SP ₂ S _{5 is} selected from the group consisting of 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ , 80Li ₂ S- At least one of 20P ₂ S ₅ ; the glass-ceramic state of Li ₂ SP ₂ S _{5 is} selected from the group consisting of 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ , 80Li ₂ S- in a glass-ceramic state At least one of 20P ₂ S ₅ ; the crystalline state of Li _{x '} M _y' PS _{z' is} selected from the group consisting of Li ₃ PS ₄ , Li ₄ SnS ₄ , Li ₄ GeS ₄ , Li ₁₀ SnP ₂ S ₁₂ , Li ₁₀ At least one of GeP ₂ S ₁₂ and Li ₁₀ SiP ₂ S ₁₂ .

According to the present invention, the solid-state lithium ion battery positive electrode composite material preferably has a mass ratio of the polymer electrolyte to the sulfide solid electrolyte of 1:99 to 99:1; further preferably, the polymer electrolyte The mass ratio to the sulfide solid electrolyte is 2:8 to 1:99; or the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 8:2 to 99:1; still more preferably, the polymerization The mass ratio between the electrolyte of the substance and the solid electrolyte of the sulfide is 1:9 to 1:99; or the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 9:1 to 99:1. Thus, by using the polymer electrolyte of the above ratio, the lithium ion conductivity of the shell layer can be further improved, and the adhesion property of the shell can be improved, and the use of the nonionic conductive component binder in the coating process of the cathode material can be reduced. In addition, the ionic conductivity of the shell polymer electrolyte can be further improved, and the electrochemical window of the shell polymer electrolyte can be increased, so that the obtained cathode composite material can match the inorganic solid electrolyte and the anode with high ionic conductivity. The battery is safer and has a long cycle life.

According to the present invention, the all-solid lithium ion battery positive electrode composite material preferably has a mass ratio of the polymer electrolyte and the sulfide solid state electrolyte to the positive electrode active material of (40 to 5): (60 to 95) ). The mass ratio of the total amount of the polymer electrolyte and the sulfide solid electrolyte to the positive electrode active material is (40 to 5): (60 to 95), which not only can well relieve the interface between the positive electrode and the inorganic solid electrolyte. The impact problem can also ensure the charge and discharge efficiency of the positive electrode.

According to the all-solid-state lithium ion battery positive electrode composite material proposed by the present invention, preferably, the positive electrode active material is selected from the group consisting of LiFe _x Mn _y M _z PO ₄ (0≤x≤1, 0≤y≤1, 0≤z≤1 , x + y + z = 1, where M is at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo), Li ₃ V ₂ (PO ₄ ) ₃ , Li ₃ V ₃ (PO ₄ ) ₃ , LiNi _0.5-x Mn _1.5-y M _x+y O ₄ (-0.1≤x≤0.5, 0≤y≤1.5, M is Li, Co, Fe, Al, Mg, Ca, Ti, Mo, At least one of Cr, Cu, and Zn, LiVPO ₄ F, Li _1+x L _1-y-z M _y N _z O ₂ (L, M, N are Li, Co, Mn, Ni, Fe, At least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1 ≤ x ≤ 0.2, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, 0 ≤ At least one of y+z≤1.0), Li ₂ CuO ₂ , and Li ₅ FeO ₄ ; preferably, the positive active material is selected from the group consisting of LiAl _0.05 Co _0.15 Ni _0.80 O ₂ , LiCoO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , at least one of LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , LiNi _0.5 Mn _1.5 O ₄ , Li ₃ V ₃ (PO ₄ ) ₃ or the like.

When the positive electrode active material is the above lithium salt active material, the corresponding negative electrode in the battery may be a negative electrode conventionally used in the art, such as a graphite negative electrode, a silicon carbon negative electrode, a metal lithium negative electrode or a lithium-indium alloy negative electrode.

According to the all-solid-state lithium ion battery positive electrode composite material proposed by the present invention, preferably, the positive electrode active material is at least one selected from the group consisting of V ₂ O ₅ , MnO ₂ , TiS ₂ , and FeS ₂ .

When the positive electrode active material is at least one of the above-mentioned V ₂ O ₅ , MnO ₂ , TiS ₂ , and FeS ₂ , the corresponding negative electrode in the battery should be an anode active material capable of extracting lithium ions, for example, lithium metal can be used. A negative electrode or a lithium-indium alloy negative electrode.

According to a second aspect of the present invention, the present invention also provides a method for preparing an all-solid lithium ion battery positive electrode composite. According to an embodiment of the invention, the method comprises:

(1) preparing a polymer electrolyte by dissolving a polymer and a lithium salt in an organic solvent according to a mass ratio of (20 to 85): (80 to 15);

(2) mixing the polymer electrolyte in the step (1) with a sulfide solid electrolyte to obtain an emulsion;

(3) A positive electrode active material having a core-shell structure is obtained by adding a positive electrode active material to the emulsion of the step (2), wherein the core includes a positive electrode active material, and the shell includes a polymer electrolyte and a sulfide solid electrolyte.

According to the method for preparing a positive electrode composite material for a lithium ion battery according to the present invention, preferably, the polymer in the step (1) is selected from the group consisting of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate and poly At least one of ethylene; the lithium salt is selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiClO ₄ , LiBF ₆ , LiN(CF ₃ SO ₃ ) ₂ , LiCF ₃ SO ₃ , LiC(CF ₃ SO ₃ ) ₂ , LiN ( At least one of C ₄ F ₉ SO ₂ )(CF ₃ SO ₃ ).

Thus, the polymer electrolyte prepared by using the above polymer and lithium salt can further improve the lithium ion conductivity of the shell layer, and at the same time, the shell has good bonding properties, thereby reducing non-ion conductance during coating of the cathode material. The use of the component binder, and the polymer electrolyte component also has certain elastomeric properties, which can alleviate the volume expansion effect of the positive electrode active material during charging and discharging to some extent.

According to the method for preparing a positive electrode composite material for a lithium ion battery according to the present invention, preferably, the step (1) comprises dissolving the polymer and the lithium salt in an organic ratio according to a ratio of (20 to 85): (80 to 15). After the solvent is stirred and mixed for 1-48 hours, the polymer and the lithium salt can be sufficiently subjected to a complexation reaction by using the above ratio and stirring for 1 to 48 hours, thereby efficiently preparing a polymer electrolyte. The step (2) includes adding a sulfide solid electrolyte to the polymer electrolyte, and stirring and mixing for 1-48 hours to obtain an emulsion. Thereby, the polymer electrolyte can be uniformly mixed with the sulfide solid electrolyte.

According to the method for preparing a positive electrode composite material for a lithium ion battery according to the present invention, preferably, the mass of the sulfide solid electrolyte added in the step (2) satisfies the mass ratio between the polymer electrolyte and the sulfide solid electrolyte. a ratio of 1:99 to 99:1; further preferably, the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 2:8 to 1:99; or the mass between the polymer electrolyte and the sulfide solid electrolyte a ratio of 8:2 to 99:1; still more preferably, the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 1:9 to 1:99; or the polymer electrolyte and the sulfide solid electrolyte The mass ratio between 9:1 and 99:1. Thus, by using the polymer electrolyte of the above ratio, the lithium ion conductivity of the shell layer can be further improved, and the adhesion property of the shell can be improved, and the use of the nonionic conductive component binder in the coating process of the cathode material can be reduced. In addition, the ionic conductivity of the shell polymer electrolyte can be further increased, and the electrochemical window of the shell polymer electrolyte can be increased, so that the obtained cathode composite can match the high ion. The conductivity of the inorganic solid electrolyte and the negative electrode give the battery a higher safety and a longer cycle life.

According to a third aspect of the present invention, the present invention further provides an all-solid lithium ion battery positive electrode material, comprising a positive electrode composite material and a positive electrode conductive material, wherein the positive electrode composite material is an all-solid lithium ion battery positive electrode composite material proposed by the present invention. .

The lithium ion positive electrode material proposed in the present application includes the positive electrode composite material described in the present application, the core of the positive electrode composite material includes a positive electrode active material, and the shell includes a polymer electrolyte and a sulfide solid electrolyte.

Wherein, the above positive electrode material may also optionally comprise a positive electrode binder; since the polymer electrolyte of the shell layer of the positive electrode composite material provided by the present application not only has good ionic conductivity, but also has adhesive properties, and thus is used in the positive electrode material. It may be free of a positive binder or, optionally, a very small amount of a positive binder. The positive electrode binder may be used as a binder in a positive electrode of a high-voltage lithium ion battery. Specifically, the positive electrode binder may be selected from a fluorine-containing resin and a polyolefin compound such as polyvinylidene fluoride (PVDF) and polytetraethylene. At least one of vinyl fluoride (PTFE) and styrene-butadiene rubber (SBR); preferably, the positive electrode binder is contained in an amount of from 0 to 5%.

The positive electrode conductive agent is a conductive agent used in a positive electrode of a high-voltage lithium ion battery. Specifically, the positive electrode conductive agent may be at least one selected from the group consisting of acetylene black, carbon nanotubes, HV, and carbon black.

A cathode material for a lithium ion battery according to the present invention is characterized in that the content of the positive electrode conductive agent is from 0.5% to 5% based on the mass of the positive electrode composite material.

According to the embodiment of the present invention, the positive electrode composite material of the above embodiment of the present invention is used in the positive electrode material because the polymer electrolyte of the shell layer of the positive electrode composite material itself has good bonding properties, and therefore, the positive electrode material is prepared. In the process, it is only necessary to add a small amount of the positive electrode binder after adding the non-active positive electrode binder, and the corresponding addition amount of the positive electrode conductive agent in the positive electrode material can also be reduced.

According to a fourth aspect of the present invention, the present application further provides an all-solid-state lithium ion battery positive electrode comprising the all-solid lithium ion battery positive electrode material of the above embodiment of the present invention.

The preparation method of the positive electrode of the present invention is not particularly limited, and is a method for preparing a positive electrode which is conventional in the art, comprising mixing the positive electrode composite material, the positive electrode conductive agent and the organic solvent according to the present invention to prepare a positive electrode slurry for coating the positive electrode current collector. Drying to obtain a positive electrode; or mixing the positive electrode composite material, the positive electrode binder and the positive electrode conductive agent described in the present application with an organic solvent to prepare a positive electrode slurry coated on the positive electrode current collector to be dried to obtain a positive electrode.

The positive electrode of the all-solid lithium ion battery described in the present application may also adopt the following methods, including:

(1) preparing a polymer electrolyte by dissolving a polymer and a lithium salt in an organic solvent according to a ratio of (20 to 85): (80 to 15);

(2) mixing the polymer electrolyte in the step (1) with a sulfide solid electrolyte to obtain an emulsion;

(3) The positive electrode active material and the positive electrode conductive agent are added to the surface of the step (2), and then coated on the surface of the positive electrode current collector to be dried to obtain the positive electrode described in the present application.

Wherein the polymer in the step (1) is at least one selected from the group consisting of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate and polyethylene; the lithium salt is selected from the group consisting of LiPF ₆ , At least one of LiAsF ₆ , LiClO ₄ , LiBF ₆ , LiN(CF ₃ SO ₃ ) ₂ , LiCF ₃ SO ₃ , LiC(CF ₃ SO ₃ ) ₂ , LiN(C ₄ F ₉ SO ₂ )(CF ₃ SO ₃ ) One type;

The step (1) comprises dissolving the polymer and the lithium salt in an organic solvent according to a ratio of (20-85): (80-15), and stirring and mixing for 1-48 hours. In the process, the polymer and the lithium salt are generated. The complexation reaction results in a polymer electrolyte; the step (2) comprises adding a sulfide solid electrolyte to the step (1), and stirring and mixing for 1-48 hours to obtain an emulsion; the positive electrode conductive agent is well known to those skilled in the art. The conductive agent in the positive electrode of the high-voltage lithium ion battery, wherein the positive electrode conductive agent may be at least one selected from the group consisting of acetylene black, carbon nanotubes, HV, and carbon black.

According to the method for preparing a positive electrode of an all-solid-state lithium ion battery according to the present invention, preferably, the mass of the sulfide solid electrolyte added in the step (2) satisfies the mass ratio between the polymer electrolyte and the sulfide solid electrolyte. a ratio of 1:99 to 99:1; further preferably, the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 2:8 to 1:99; or the mass between the polymer electrolyte and the sulfide solid electrolyte a ratio of 8:2 to 99:1; still more preferably, the mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 1:9 to 1:99; or the polymer electrolyte and the sulfide solid electrolyte The mass ratio between 9:1 and 99:1.

According to an embodiment of the present invention, in the method for preparing a positive electrode of an all-solid-state lithium ion battery, preferably, the quality of the added positive electrode conductive agent satisfies: adding in step (3) based on the total mass of the obtained positive electrode material. The content of the positive electrode conductive agent is from 1% to 5%.

The cathode current collector is a cathode current collector well known to those skilled in the art, and for example, may be selected from aluminum foil, carbon paper, carbon nanotube paper, graphene paper or stainless steel foil.

According to a fifth aspect of the present invention, the present invention further provides an all-solid-state lithium ion battery comprising a battery case and a battery cell located in the battery case, the battery core including a positive electrode, a negative electrode, and a positive electrode and a negative electrode An inorganic solid electrolyte layer, which is the positive electrode proposed in the present application.

The inorganic solid electrolyte layer includes an inorganic solid electrolyte and a binder; the present invention has no special requirements on the inorganic solid electrolyte and the binder in the inorganic solid electrolyte layer, and the inorganic solid electrolyte and the binder which are conventional in the art can be used. Preferably, the inorganic solid electrolyte is selected from a sulfide solid electrolyte; preferably, the sulfide solid electrolyte is selected from the group consisting of Li ₂ SP ₂ S _{5 in a} glass state, Li _{x '} M _y' PS _{z' in a} crystalline state or At least one of glass-ceramic state Li ₂ SP ₂ S ₅ , wherein M is at least one of Si, Ge, and Sn, x′+4y′+5=2z′, 0≤y′≤1; further preferably The glassy Li ₂ SP ₂ S _{5 is} selected from at least one of glassy 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ , 80Li ₂ S-20P ₂ S ₅ ; The glass-ceramic state of Li ₂ SP ₂ S _{5 is} selected from at least one of 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ , 80Li ₂ S-20P ₂ S ₅ in a glass-ceramic state; The crystalline state of Li _{x '} M _y' PS _{z' is} selected from the group consisting of Li ₃ PS ₄ , Li ₄ SnS ₄ , Li ₄ GeS ₄ , Li ₁₀ SnP ₂ S ₁₂ , Li ₁₀ GeP ₂ S ₁₂ , Li ₁₀ SiP ₂ S _{In 12} One less. The binder is selected from at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and styrene butadiene rubber (SBR). The present invention has no special requirements on the thickness of the inorganic solid electrolyte layer and the ratio of the inorganic solid electrolyte to the binder in the inorganic solid electrolyte layer, and the thickness of the inorganic solid electrolyte layer conventional in the art and the inorganic in the conventional inorganic solid electrolyte layer. The ratio of the solid electrolyte to the binder is not described in the present application.

According to the all-solid-state lithium ion battery proposed by the present invention, preferably, the positive electrode active material is selected from the group consisting of LiFe _x Mn _y M _z PO ₄ (0 ≤ x ≤ ₁ , 0 _{≤ y ≤ 1} , 0 ≤ _z ≤ ₁ , x + y+z=1, wherein M is at least one of Al, Mg, Ga, Ti, Cr, Cu, Zn, Mo), Li ₃ V ₂ (PO ₄ ) ₃ , Li ₃ V ₃ (PO ₄ ) ₃ LiNi _0.5-x Mn _1.5-y M _x+y O ₄ (-0.1≤x≤0.5, 0≤y≤1.5, M is Li, Co, Fe, Al, Mg, Ca, Ti, Mo, Cr, Cu At least one of Zn, LiVPO ₄ F, Li _1+x L _1-y-z M _y N _z O ₂ (L, M, N are Li, Co, Mn, Ni, Fe, Al, Mg At least one of Ga, Ti, Cr, Cu, Zn, Mo, F, I, S, B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z At least one of ≤1.0), Li ₂ CuO ₂ , and Li ₅ FeO ₄ ; preferably, the cathode active material is selected from the group consisting of LiAl _0.05 Co _0.15 Ni _0.80 O ₂ , LiCoO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiMnPO ₄ , LiNiPO ₄ , LiCoPO ₄ , LiNi _0.5 Mn _1.5 O ₄ , Li ₃ V ₃ (PO ₄ ) ₃ and the like; at this time, the negative electrode is not particularly limited, and the corresponding negative electrode in the battery can be used conventionally in the art. Negative electrode, such as stone A negative electrode, a negative electrode silicon carbon, lithium metal or a lithium anode - the negative electrode can be indium alloy; Specifically, the negative electrode includes a negative current collector and a negative electrode material in said negative electrode current collector surface. The negative current collector is a negative current collector known to those skilled in the art, for example, may be selected from copper foil.

The negative electrode material includes a negative electrode active material and a negative electrode binder; the negative electrode active material may be a negative electrode active material conventional in the art; specifically, the negative electrode active material is selected from the group consisting of carbon materials, tin alloys, silicon alloys, silicon, At least one of tin and antimony; further, the carbon material may be selected from the group consisting of natural graphite, naturally modified graphite, artificial graphite, petroleum coke, organic cracked carbon, mesocarbon microbeads, carbon fiber, tin alloy, and silicon alloy. At least one of them is preferably artificial graphite and natural modified graphite; at the same time, the negative electrode active material may also be metal lithium, lithium-indium alloy or the like; generally, the negative electrode material may further contain a negative electrode conductive agent according to actual use. The negative electrode conductive agent is not particularly limited and may be a conventional negative electrode conductive agent in the art, and may be, for example, at least one of carbon black, acetylene black, furnace black, carbon fiber VGCF, conductive carbon black, and conductive graphite; The fourth binder is a binder known in the art for use in a negative electrode of a lithium ion battery. Specifically, the fourth binder may be selected from the group consisting of polythiophene and poly. Oxide, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polystyrene, polyacrylamide, ethylene-propylene-diene copolymer resin, styrene butadiene rubber, polybutadiene, fluororubber, Polyethylene oxide, polyvinylpyrrolidone, polyester resin, acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, carboxypropyl cellulose, ethyl cellulose, sodium carboxymethyl cellulose, styrene-butadiene latex At least one.

The content of the negative electrode active material and the negative electrode binder in the above negative electrode material is known to those skilled in the art, and specifically, the content of the negative electrode conductive agent is 0.5 to 10% by weight based on the weight of the negative electrode active material; The content of the negative electrode binder is 0.01 to 10% by weight.

According to the all-solid-state lithium ion battery proposed by the present invention, preferably, the positive electrode active material is selected from at least one of V ₂ O ₅ , MnO ₂ , TiS ₂ , and FeS ₂ ; As the negative electrode of lithium ion, for example, lithium pre-calined graphite or a silicon negative electrode may be used, or metal lithium, lithium-indium alloy or the like may be used as it is; preferably, the corresponding negative electrode is metal lithium, lithium-indium alloy or the like.

The preparation method of the negative electrode of the battery in the present invention is not particularly limited, and the preparation method of the negative electrode conventional in the art may be used. Preferably, the negative electrode slurry containing the negative electrode active and negative electrode binder is coated on the negative electrode current collector. A negative electrode material layer is formed on the negative electrode current collector.

The specific preparation method of lithium ion in the present invention is not particularly limited, and is a preparation method of an all-solid lithium ion battery which is conventional in the art; and the battery core is sealed in a battery case; the preparation of the battery core is conventional in the art. The preparation method of the electric core in the all-solid lithium ion battery is not particularly limited; the preparation of the positive electrode is first prepared, and then the solid electrolyte layer is prepared on the surface of the positive electrode. The solid electrolyte layer in the present application is an inorganic solid electrolyte layer; The method of injecting an inorganic solid electrolyte layer comprises: drying an inorganic solid electrolyte slurry on a surface of the positive electrode to form an inorganic solid electrolyte layer on the surface of the positive electrode; the inorganic solid electrolyte slurry comprising an inorganic solid electrolyte and a binder; The inorganic solid electrolyte is preferably a sulfide solid electrolyte; the kind of the binder and the ratio of the inorganic solid electrolyte to the binder are well known to those skilled in the art, and are not specifically limited herein.

After the inorganic solid electrolyte layer is formed on the surface of the positive electrode, the negative electrode is laminated on the solid electrolyte layer to obtain a lithium ion battery of the present application.

In the present application, after the solid electrolyte layer is formed on the surface of the negative electrode, the positive electrode and the solid electrolyte are bonded together to obtain a lithium ion battery according to the present application.

The lithium ion battery provided by the present application adopts the positive electrode active material described in the present application, and the positive electrode has high ionic conductivity, and the interface between the positive electrode and the inorganic solid electrolyte layer has little influence, and the prepared battery has high safety. Good cycle performance.

The invention is further illustrated in detail below by way of examples.

Example 1

(1) Weighing 7.0 g of polyoxyethylene (molecular weight: 600,000) in anhydrous acetonitrile, and then adding 5.0 g of LiN(CF ₃ SO ₃ ) ₂ thereto, and then magnetically stirring at room temperature for 20 hours, and then adding thereto 228.0 g of a glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ (a glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S _{5 was} prepared by high-energy ball milling), and then magnetically stirred at room temperature for 6 hours to obtain an emulsion;

(2) adding 750.0 g of LiNi _0.5 Mn _1.5 O ₄ and 10.0 g of carbon nanotubes to the emulsion of step (1), and continuing magnetic stirring for 2 h, after forming a stable and uniform positive electrode slurry, coating on the aluminum foil current collector, and then After drying at 80 ° C, the positive electrode sheet A1 was obtained after being pressed by a roll press.

(3) 490 g of a sulfide solid electrolyte Li ₁₀ SnP ₂ S ₁₂ and 10 g of SBR were added to anhydrous n-heptane, and then stirred in a vacuum mixer to form a stable and uniform electrolyte slurry; the electrolyte slurry was uniformly intermittently It was coated on the positive electrode sheet A1 prepared above, and dried in an oven at 80 ° C to form an inorganic solid electrolyte layer on the surface of the positive electrode; the lithium foil was attached to the surface of the inorganic solid electrolyte layer, and a pressure of 240 MPa was applied to press it. Then, the package is obtained to obtain an all-solid lithium ion battery S1.

Example 2

(1) Weighing 7.0 g of PEO (molecular weight: 600,000) was dissolved in anhydrous acetonitrile, and then 5.0 g of LiN(CF ₃ SO ₃ ) _{2 was} added thereto, followed by magnetic stirring at room temperature for 20 hours, and 228.0 g of glass was added thereto. a sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ (a glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ is prepared by high-energy ball milling), and then magnetically stirred at room temperature for 6 hours to obtain an emulsion;

(2) adding 750.0 g of LiNi _0.5 Mn _1.5 O _{4 to} the emulsion of the step (1), magnetically stirring for 2 hours, drying to obtain a positive electrode active material B by ball milling; and adding the positive electrode active material B490.0 g to the organic solvent anhydrous acetonitrile Then, 5.0 g of carbon nanotubes were added and fully dispersed to obtain a positive electrode slurry, and the positive electrode slurry was coated on an aluminum foil current collector, and then dried at 80 ° C, and a positive electrode sheet A2 was obtained after being pressed by a roll press.

(3) 490.0 g of a sulfide solid electrolyte Li ₁₀ SnP ₂ S ₁₂ and 10.0 g of SBR were added to anhydrous n-heptane, and then stirred in a vacuum mixer to form a stable and uniform electrolyte slurry; The mixture was intermittently coated on the positive electrode sheet A1 prepared above, and dried in an oven at 80 ° C to form an inorganic solid electrolyte layer on the surface of the positive electrode; the lithium foil was attached to the surface of the inorganic solid electrolyte layer, and a pressure of 240 MPa was applied thereto. The compaction is followed by encapsulation to obtain an all-solid lithium ion battery S2.

Comparative example 1

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that the glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ was not added in the step (1); And an all-solid-state lithium-ion battery DS1.

Comparative example 2

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that the lithium salt LiN(CF ₃ SO ₃ ) ₂ was not added in the step (1); the positive electrode sheet DA2 and the all solid lithium were prepared. Ion battery DS2.

Example 3

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that step (1) used 7.0 g of polyvinylidene fluoride instead of polyoxyethylene, acetone was used instead of acetonitrile, and step (3) was added. 490.0 g of a glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ ; A positive electrode sheet A3 and an all-solid lithium ion battery S3 were prepared.

Example 4

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that step (1) used 7.0 g of polyacrylonitrile instead of polyoxyethylene, acetone was used instead of acetonitrile, and step (3) used 490.0. g Crystalline sulfide solid electrolyte Li ₃ PS ₄ replaces glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ ; A positive electrode sheet A4 and an all-solid lithium ion battery S4 were prepared.

Example 5

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that step (1) used 7.0 g of polymethyl methacrylate instead of polyoxyethylene, and acetone was used instead of acetonitrile. Step (3) A 228.0 g crystalline sulfide solid electrolyte Li ₄ SnS _{4 was used in} place of the glassy sulfide solid electrolyte 75Li ₂ S-25P ₂ S ₅ ; a positive electrode sheet A5 and an all-solid lithium ion battery S5 were prepared.

Example 6

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that step (1) used 7.0 g of polyethylene instead of polyoxyethylene and 5.0 g of LiPF ₆ instead of LiN (CF ₃ SO ₃ ). ₂ ; A positive electrode sheet A6 and an all-solid lithium ion battery S6 were prepared.

Example 7

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that 750.0 g of LiFePO _{4 was used in} place of LiNi _0.5 Mn _1.5 O ₄ in the step (2); the positive electrode sheet A7 and the all solid lithium were prepared. Ion battery S7.

Comparative example 3

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 7, except that the sulfide solid electrolyte Li ₂ SP ₂ S ₅ was not added in the step (1); the positive electrode sheet DA3 and the all solid lithium were prepared. Ion battery DS3.

Comparative example 4

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 7, except that the lithium salt LiN(CF ₃ SO ₃ ) ₂ was not added in the step (1); the positive electrode sheet DA4 and the all solid lithium were prepared. Ion battery DS4.

Example 8

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that 750.0 g of LiCoO _{2 was used in} place of LiNi _0.5 Mn _1.5 O ₄ in the step (2); the positive electrode sheet A8 and the all solid lithium were prepared. Ion battery S8.

Comparative example 5

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 8, except that the sulfide solid electrolyte Li ₂ SP ₂ S ₅ was not added in the step (1); the positive electrode sheet DA5 and the all solid lithium were prepared. Ion battery DS5.

Comparative example 6

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 8, except that the lithium salt LiN(CF ₃ SO ₃ ) ₂ was not added in the step (1); the positive electrode sheet DA6 and the all solid lithium were prepared. Ion battery DS6.

Example 9

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that 750.0 g of V ₂ O _{5 was used in} place of LiNi _0.5 Mn _1.5 O ₄ in the step (2); the positive electrode sheet A9 and the whole were prepared. Solid state lithium ion battery S9.

Comparative example 7

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 9, except that the sulfide solid electrolyte Li ₂ SP ₂ S ₅ was not added in the step (1); the positive electrode sheet DA7 and the all solid lithium were prepared. Ion battery DS7.

Comparative example 8

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 9, except that the lithium salt LiN(CF ₃ SO ₃ ) ₂ was not added in the step (1); the positive electrode sheet DA8 and the all solid lithium were prepared. Ion battery DS8.

Example 10

A positive electrode sheet and an all-solid lithium ion battery were prepared in the same manner as in Example 1, except that 750.0 g of TiS _{2 was used in} place of LiNi _0.5 Mn _1.5 O ₄ in the step (2); the positive electrode sheet A10 and the all solid lithium were prepared. Ion battery S10.

Performance Testing

(1) AC impedance test

Under the open circuit potential, the frequency range is 100KHz-0.1Hz, the amplitude is 50mV; the impedance of all solid-state lithium-ion batteries S1-S10 and DS1-DS8 before charging and discharging is tested. The test results are shown in Table 1;

The specific test conditions are: charging the batteries S1-S10 and DS1-DS8 constant current 0.01C to a certain voltage cut-off at 25±1°C (the cut-off voltage of the S1-S6 and DS1-DS2 batteries is set to 5.0V; S7) The cutoff voltage of the DS3 and DS4 batteries is set to 3.8V; the cutoff voltage of the S8, DS5 and DS6 batteries is set to 4.2V; the cutoff voltage of the S9, DS7 and DS8 batteries is set to 4.0V; the cutoff voltage of the S10 battery Set to 3.0V); set aside for 10 minutes; constant current 0.01C discharge to a certain voltage cutoff (S1-S8 and DS1-DS6 battery cut-off voltage is set to 3.0V; S9, S10, DS7 and DS8 battery cut-off voltage setting The cycle was set to 1.5 V. The battery was charged and discharged for 30 cycles, and the impedance after 30 cycles of the battery was recorded. The test results are shown in Table 1.

Table 1

(2) charge and discharge cycle test

Using the LAND CT2001C secondary battery performance detecting device, the batteries S1-S10 and DS1-DS8 were subjected to a charge and discharge cycle test at 0.01 C under conditions of 25 ± 1 °C. The specific test procedure is: set aside for 10 minutes, constant current 0.01C charge to a certain voltage cutoff (S1-S6 and DS1-DS2 battery cut-off voltage is set to 5.0V; S7, DS3 and DS4 battery cut-off voltage is set to 3.8V The cutoff voltage of the S8, DS5, and DS6 batteries is set to 4.2V; the cutoff voltage of the S9, DS7, and DS8 batteries is set to 4.0V; the cutoff voltage of the S10 battery is set to 3.0V);; 10 minutes on hold; constant current Discharge to a certain voltage cutoff (S1-S8 and DS1-DS6 battery cut-off voltage is set to 3.0V; S9, S10, DS7 and DS8 battery cut-off voltage is set to 1.5V), which is 1 cycle, so the battery Charge and discharge 30 cycles, record the first The secondary charge and discharge capacity, and calculate the coulombic efficiency (%). After 30 cycles, the discharge capacity at the 30th cycle was recorded, and the capacity retention ratio after the cycle (%) = discharge capacity at the 30th cycle / initial discharge capacity × 100%; the test results are shown in Table 2.

Table 2

As can be seen from Fig. 1, a mixture of a polymer electrolyte and a sulfide solid electrolyte is coated on the surface of the positive electrode active material.

It can be seen from Table 1 that the initial impedance values of the batteries S1-S10 and the impedance values after the cycles in the examples 1-10 are smaller than the impedance values of the corresponding comparative examples DS1-DS8, indicating that the battery is covered by the composite electrolyte. The polarization inside the positive electrode is reduced.

It can be seen from Table 2 that the discharge specific capacity and the charge-discharge cycle stability of the batteries S1-S10 in Examples 1-10 are also superior to the discharge specific capacity and the charge-discharge cycle stability energy of the corresponding comparative examples DS1-DS8, indicating Composite electrolyte It only acts well as a conductor for lithium ion transport, improves the activity of the positive active material, and effectively alleviates the volume shrinkage and expansion effect of the positive active material during charge and discharge, and improves the dynamic contact interface between the positive active material and the electrolyte material. The expected results were achieved.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification, as well as features of various embodiments or examples, may be combined and combined.

Although the embodiments of the present invention have been shown and described, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the invention. The embodiments are subject to variations, modifications, substitutions and variations.

Claims (19)

1. An all-solid-state lithium ion battery positive electrode composite material having a core-shell structure, characterized in that the core comprises a positive electrode active material, and the shell comprises a polymer electrolyte and a sulfide solid electrolyte.
2. The cathode composite according to claim 1, wherein the polymer electrolyte is selected from the group consisting of a polyoxyethylene polymer electrolyte, a polyvinylidene fluoride polymer electrolyte, a polyacrylonitrile-based polymer electrolyte, and a polymethyl group. At least one of a methyl acrylate-based polymer electrolyte and a polyvinyl polymer electrolyte.
3. The cathode composite according to claim 2, wherein the polymer electrolyte is at least selected from the group consisting of a polyoxyethylene polymer electrolyte, a polyvinylidene fluoride polymer electrolyte, and a polyacrylonitrile-based polymer electrolyte. One.
4. The positive electrode composite according to any one of claims 1 to 3, wherein the sulfide solid electrolyte is Li ₂ SP ₂ S ₅ selected from a glassy state, and Li _{x '} M _y' PS _{z in a} crystalline state. _'and Li in the glass-ceramic state ₂ SP ₂ S ₅ at least one, wherein the crystalline Li _x' M _{y 'PS z',} M is Si, Ge and Sn, at least one, x '+ 4y '+5=2z', 0≤y'≤1.
5. The cathode composite according to claim 4, wherein the glassy state of Li ₂ SP ₂ S ₅ is 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ and selected from the glass state. At least one of 80Li ₂ S-20P ₂ S ₅ ; the glass-ceramic state of Li ₂ SP ₂ S ₅ is 70Li ₂ S-30P ₂ S ₅ , 75Li ₂ S-25P ₂ S ₅ selected from the group consisting of glass ceramics And at least one of 80Li ₂ S-20P ₂ S ₅ ; the crystalline state of Li _{x '} M _y' PS _z' is selected from the group consisting of Li ₃ PS ₄ , Li ₄ SnS ₄ , Li ₄ GeS ₄ , Li ₁₀ SnP At least one of ₂ S ₁₂ , Li ₁₀ GeP ₂ S ₁₂ and Li ₁₀ SiP ₂ S ₁₂ .
6. The positive electrode composite according to any one of claims 1 to 5, wherein a mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 1:99 to 99:1.
7. The positive electrode composite according to claim 6, wherein a mass ratio between the polymer electrolyte and the sulfide solid electrolyte is 1:9 to 1:99.
8. The positive electrode composite according to claim 6, wherein a mass ratio between the polymer electrolyte and the sulfide solid electrolyte is from 9:1 to 99:1.
9. The positive electrode composite according to any one of claims 1 to 8, wherein a mass ratio of the total mass of the polymer electrolyte and the sulfide solid electrolyte to the positive electrode active material is (40 to 5) : (60 ~ 95).
10. The cathode composite material according to any one of claims 1 to 9, wherein the cathode active material is selected from the group consisting of LiFe _x Mn _y M _z PO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Li ₃ V ₃ (PO ₄ ) ₃ , LiNi _0.5-x Mn _1.5-y M _x+y O ₄ , LiVPO ₄ F, Li _{1+ x} L _1-y-z M _y N _z O ₂ , Li ₂ CuO ₂ and Li ₅ At least one of FeO ₄ ,

    Wherein, in the LiFe _x Mn _y M _z PO ₄ , 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, x + y + z = 1, wherein M is selected from the group consisting of Al, Mg, Ga At least one of Ti, Cr, Cu, Zn, and Mo;

    In the LiNi _0.5-x Mn _1.5-y M _x+y O ₄ , -0.1≤x≤0.5, 0≤y≤1.5, M is selected from the group consisting of Li, Co, Fe, Al, Mg, Ca, Ti, Mo At least one of Cr, Cu, and Zn;

    In the Li _1+x L _1-y-z M _y N _z O ₂ , L, M, and N are each independently selected from the group consisting of Li, Co, Mn, Ni, Fe, Al, Mg, Ga, Ti, and Cr. At least one of Cu, Zn, Mo, F, I, S, and B, -0.1≤x≤0.2, 0≤y≤1, 0≤z≤1, 0≤y+z≤1.0.
11. The cathode composite material according to any one of claims 1 to 9, wherein the cathode active material is at least one selected from the group consisting of V ₂ O ₅ , MnO ₂ , TiS ₂ , and FeS ₂ .
12. A method for preparing a positive electrode composite material for an all-solid lithium ion battery according to any one of claims 1 to 11, comprising:

    (1) dissolving the polymer and the lithium salt in an organic solvent in a mass ratio of (20 to 85): (80 to 15) to obtain a polymer electrolyte;

    (2) mixing the polymer electrolyte with a sulfide solid electrolyte to obtain an emulsion;

    (3) adding a positive electrode active material to the emulsion, wrapping the emulsion with the positive electrode composite material, and drying to obtain a positive electrode composite material having a core-shell structure, wherein the core includes a positive electrode active material, The shell includes a polymer electrolyte and a sulfide solid electrolyte.
13. The method according to claim 12, wherein said polymer is at least one selected from the group consisting of polyoxyethylene, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, and polyethylene; The lithium salt is selected from the group consisting of LiPF ₆ , LiAsF ₆ , LiClO ₄ , LiBF ₆ , LiN(CF ₃ SO ₃ ) ₂ , LiCF ₃ SO ₃ , LiC(CF ₃ SO ₃ ) ₂ , LiN(C ₄ F ₉ SO ₂ ) ( At least one of CF ₃ SO ₃ ).
14. An all-solid-state lithium ion battery positive electrode material comprising a positive electrode composite material and a positive electrode conductive material, wherein the positive electrode composite material is the positive electrode composite material according to any one of claims 1 to 11.
15. The positive electrode material according to claim 14, wherein the positive electrode conductive agent is contained in an amount of from 0.5% to 5% based on the mass of the positive electrode composite.
16. An all-solid-state lithium ion battery positive electrode, characterized in that the positive electrode comprises the positive electrode material according to any one of claims 14-15.
17. An all-solid-state lithium ion battery comprising a battery case and a battery core located in the battery case, the battery core comprising a positive electrode, a negative electrode and an inorganic solid electrolyte layer between the positive electrode and the negative electrode, wherein the positive electrode is The positive electrode of claim 16.
18. The all-solid-state lithium ion battery according to claim 17, wherein the inorganic solid electrolyte in the inorganic solid electrolyte layer is selected from the group consisting of sulfide solid electrolytes.
19. The all-solid-state lithium ion battery according to claim 17 or 18, wherein the positive electrode active material is one or more selected from the group consisting of V ₂ O ₅ , MnO ₂ , TiS ₂ , and FeS ₂ ; Extremely metallic lithium or lithium-indium alloy.

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