CN115172653A - Composite positive electrode, solid-state lithium ion secondary battery, and electric device - Google Patents

Composite positive electrode, solid-state lithium ion secondary battery, and electric device Download PDF

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CN115172653A
CN115172653A CN202210867370.XA CN202210867370A CN115172653A CN 115172653 A CN115172653 A CN 115172653A CN 202210867370 A CN202210867370 A CN 202210867370A CN 115172653 A CN115172653 A CN 115172653A
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positive electrode
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active material
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冯静
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Sunwoda Electronic Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
    • H01M10/0562—Solid materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M2300/00—Electrolytes
    • H01M2300/0017—Non-aqueous electrolytes
    • H01M2300/0065—Solid electrolytes
    • H01M2300/0068—Solid electrolytes inorganic
    • H01M2300/008—Halides
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention discloses a composite positive electrode, a solid-state lithium ion secondary battery and an electric device. The composite positive electrode comprises a current collector, a positive active material layer and a halide solid electrolyte layer; the positive electrode active material layer is located between the current collector and the halide solid state electrolyte layer; the halide solid state electrolyte layer includes a halide solid state electrolyte a. The composite positive electrode is used for a sulfide all-solid-state battery, can completely isolate direct contact between a high-voltage positive electrode material and a sulfide solid-state electrolyte, inhibits formation of a space charge layer, and further improves the cycling stability of the battery.

Description

Composite positive electrode, solid-state lithium ion secondary battery, and electric device
Technical Field
The invention belongs to the field of solid lithium ion batteries, and particularly relates to a composite anode, a solid lithium ion secondary battery and electric equipment.
Background
Solid-state batteries have been extensively studied by enterprises and universities due to their excellent safety and high energy density. The solid electrolyte is used in the solid battery to replace volatile and combustible liquid electrolyte and a diaphragm in the traditional lithium ion battery. Compared with liquid electrolyte, the solid electrolyte has the advantages of no exertion, nonflammability, no corrosion, high mechanical strength and the like, avoids the dangers of electrolyte leakage, electrode short circuit and the like in the traditional lithium ion battery, reduces the sensitivity of the battery pack to temperature, can effectively prevent the growth of lithium dendrites due to the high mechanical strength of the solid electrolyte, and has extremely high safety in the use process.
Currently, solid-state electrolytes mainly include sulfide, halide, oxide, and polymer solid-state electrolytes. The ionic conductivity of oxide and polymer solid electrolyte is lower, 10 -6 -10 -4 S/cm; halide solid electrolyte ionic conductivity of 10 -3 About S/cm; the sulfide solid electrolyte has excellent ionic conductivity of 10 -3 -10 -2 S/cm, some of which have even higher ionic conductivity than commercial liquid electrolytes. The sulfide solid electrolyte is suitable for high energy density energy storage devices, and thus becomes one of very promising technical routes for developing all-solid-state lithium ion batteries.
However, in an all-solid battery, when a transition metal oxide is used as a positive electrode and a sulfide is used as a solid electrolyte, since the potential of lithium ions in the oxide is higher than that in the sulfide, lithium ions migrate from the sulfide solid electrolyte into the oxide solid electrolyte positive electrode under the driving of an electric field force until the potentials at both ends of the interface are balanced, and when the balance is reached, a low lithium ion concentration region, i.e., a space charge layer, is formed at the interface of the sulfide solid electrolyte and the oxide positive electrode material, which causes the impedance of the positive electrode/sulfide electrolyte layer interface to increase sharply.
Therefore, it is highly desirable to develop a solid-state battery having more excellent electrochemical properties to solve the above problems.
Disclosure of Invention
The invention aims to provide a composite positive electrode, a solid lithium ion secondary battery and electric equipment, which are used for solving the problems that the interface stability of a sulfide solid electrolyte and a high-voltage positive electrode is poor, and space charge is easy to generate at the interface, so that the interface resistance is increased continuously.
The invention provides a composite anode, which comprises a current collector, an anode active material layer and a halide solid electrolyte layer, wherein the current collector is arranged on the anode active material layer;
the positive electrode active material layer is located between the current collector and the halide solid state electrolyte layer;
the halide solid state electrolyte layer includes a halide solid state electrolyte a.
In the composite positive electrode, the particle diameter D of the halide solid electrolyte a 50 It may be 1 to 15 μm, specifically 1 μm, 10 μm or 15 μm. The grain size of the halide solid electrolyte A affects the grain boundary of the formed electrolyte layer, when the grain size D of the halide solid electrolyte A 50 When the thickness is 1-15 mu m, the formed electrolyte layer has fewer grain boundaries, so that the grain boundary resistance is smaller, and lithium ion transmission is facilitated.
In the composite positive electrode, the thickness of the halide solid electrolyte layer may be 5 to 30 μm, specifically 5 μm, 10 μm, 15 μm, 20 μm, or 30 μm, and preferably 10 to 20 μm.
In the invention, the halide solid electrolyte layer cannot be too thin, and cannot effectively isolate the positive active material layer in the composite positive electrode from the sulfide solid electrolyte layer in the solid secondary battery when the composite positive electrode is used as the positive electrode of the solid secondary battery; it should not be too thick, which would be detrimental to lithium ion transport.
In the composite positive electrode described above, the positive electrode active material layer includes a positive electrode active material, a halide solid electrolyte B, a conductive agent, and a binder.
In the composite positive electrode, the positive active material layer comprises the following components in parts by mass:
Figure BDA0003759972170000021
in the composite positive electrode, the particle diameter D of the halide solid electrolyte B 50 Can be 0.5 to 5 μm.
In the composite positive electrode, the thickness of the positive active material layer is 100-500 mu m, the positive active material layer is too thin, the active material load is less, and the capacity is low; the positive electrode active material layer is too thick, and the active layer has a large resistance, specifically, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 100 to 200 μm, 100 to 300 μm, 100 to 400 μm, 400 to 500, 200 to 300 μm, or 200 to 400 μm.
In the composite positive electrode, the positive active material comprises at least one of lithium iron phosphate, lithium cobaltate, lithium manganate, a nickel-cobalt-manganese ternary material and a nickel-cobalt-aluminum ternary material;
the conductive agent comprises one or more of Super P, acetylene black, ketjen black, carbon nanotubes, graphene and vapor-grown carbon fibers;
the binder comprises one or more of PTFE, SBS, SEBS, PVDF, PTFE, PAALi, SBR, NBR, butylene rubber, styrene rubber and polyurethane.
In the composite positive electrode, the molecular formulas of the halide solid electrolyte A and the halide solid electrolyte B are both Li 3 MX 6 Wherein M comprises at least one of In, Y, sc, er, mg, zr, and Al, and X comprises at least one of Cl, F, br, and I; the molecular formula of the halide solid electrolyte A is the same as or different from that of the halide solid electrolyte B.
The halide solid electrolyte a and the halide solid electrolyte B may specifically contain Li 3 YCl 6 、Li 3 ErCl 6 、Li 3 YBr 6 、Li 3 InBr 6 And Li 3 InCl 6 At least one of (1).
The invention also provides a preparation method of the composite anode, which comprises the following steps:
1) Preparing the positive active material, a binder, a conductive agent and an organic solvent A according to a certain proportion into slurry a, coating the slurry a on the surface of the current collector, and drying and rolling to form the positive active material layer;
2) And preparing the halide solid electrolyte, the binder and the organic solvent B into slurry B according to a certain proportion, coating the slurry B on the surface of the positive active material layer, and drying and rolling to form the composite positive electrode.
According to the preparation method of the composite positive electrode, halide solid electrolyte slurry is coated on the surface of the positive electrode active material layer, and a halide electrolyte layer is formed on the surface of the positive electrode active material layer after drying, so that the electrolyte layer can isolate direct contact between a high-voltage positive electrode material and sulfide solid electrolyte and inhibit formation of a space charge layer; on the other hand, the halide electrolyte layer has higher ionic conductivity, which is beneficial to the transmission of lithium ions; in addition, the interface contact between the positive electrode and the halide electrolyte can be effectively improved by in-situ wet coating, and meanwhile, the interface contact between the halide electrolyte and the sulfide electrolyte is also improved due to the good flexibility of the halide.
In the above preparation method, the organic solvent a comprises at least one of N-methylpyrrolidone, dimethyl carbonate, ethyl acetate, absolute ethyl alcohol, acetone, diethyl carbonate, and methyl propionate;
in the preparation method, the positive active material in the slurry a accounts for 70-95%; 2 to 27 percent of binder; the conductive agent accounts for 3-28 percent.
In the preparation method, the solid content of the slurry a can be 40-60%.
In the above preparation method, the organic solvent B includes at least one of a polar solvent and a non-polar solvent.
The polar solvent comprises at least one of N-methyl pyrrolidone, dimethyl carbonate, ethyl acetate, absolute ethyl alcohol, acetone, diethyl carbonate and methyl propionate; the non-polar solvent comprises at least one of toluene, p-xylene, cyclohexane and isopropanol.
The invention further provides a solid-state lithium ion secondary battery, which comprises the composite positive electrode, the solid-state electrolyte layer and the negative electrode.
In the solid-state lithium ion secondary battery, the solid electrolyte layer is made of sulfide solid electrolyte;
the negative electrode comprises at least one of metal lithium, metal indium, lithium-indium alloy, silicon carbon, silicon, graphite and lithium titanate.
In the present invention, the sulfide solid electrolyte is xLi 2 S·(100–x)P 2 S 5 (x is more than or equal to 20 and less than or equal to 80) glass, li-P-S glass ceramic, lithium fast ion conductor type, li 6 PS 5 X (X = Cl, br and I) Geranite, li 11-c M 2-c P 1+c S 12 (M = Ge, sn, and Si); the sulfide is in a solid stateThe electrolyte is preferably of the lithium fast ion conductor type, li 6 PS 5 X (X = Cl, br and I) Geranite, li 11 -cM 2-c P 1+c S 12 (M = Ge, sn, and Si).
In the solid-state lithium ion secondary battery, the density of the solid-state electrolyte layer is 85-95%;
particle diameter D of the sulfide solid electrolyte 50 Is 1 to 10 μm.
In the present invention, the negative electrode may be any one conventional in the art, and specifically, the negative electrode may include at least one of metal lithium, metal indium, lithium-indium alloy, silicon carbon, silicon, graphite, and lithium titanate.
In the present invention, the positive electrode active material layer in the solid-state lithium ion secondary battery is generally prepared by coating a slurry obtained by mixing a positive electrode active material, a solid-state electrolyte, a conductive agent, and a binder. The solid electrolyte affects lithium ion transport, and when the halide solid electrolyte B is used, the positive active material does not need to be coated.
The invention further provides an electric device comprising the solid-state lithium ion secondary battery.
Compared with the prior art, the invention has the beneficial effects that:
the composite positive electrode is used for a sulfide all-solid-state battery, can completely isolate direct contact between a high-voltage positive electrode material and a sulfide solid-state electrolyte, inhibits formation of a space charge layer, and further improves the cycling stability of the battery. The halide solid electrolyte with high oxidation potential is used as the anode coating material, on one hand, the halide solid electrolyte has higher ionic conductivity and is beneficial to the transmission of lithium ions in the electrochemical process; on the other hand, the formed slurry b may fill the voids of the positive electrode active material layer, promoting the transport of lithium ions in the positive electrode active material layer. The preparation of the composite anode avoids the process that the anode active material needs to be coated in the use of the sulfide all-solid-state battery, and simplifies the anode preparation process. In addition, the interface contact between the positive electrode and the halide electrolyte can be effectively improved by in-situ wet coating, and meanwhile, the interface contact between the halide electrolyte and the sulfide electrolyte is also improved due to the good flexibility of the halide.
Drawings
Fig. 1 is a schematic structural view of a solid-state lithium ion secondary battery according to example 1 of the present invention.
The individual labels in the figure are as follows:
1 composite anode pole piece, 2 solid electrolyte layer and 3 lithium indium cathode.
Detailed Description
The experimental procedures used in the following examples are all conventional procedures unless otherwise specified.
Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.
The invention provides a composite anode, aiming at the problems that the interface stability of a sulfide solid electrolyte and a high-voltage anode is poor, and space charge is easy to generate at the interface, so that the interface resistance is increased continuously, and the composite anode comprises a current collector, an anode active material layer and a halide solid electrolyte layer which are sequentially stacked;
the halide solid state electrolyte layer includes a halide solid state electrolyte a.
In a specific example, the particle size D of the halide solid electrolyte a may affect the grain boundary of the formed electrolyte layer because the particle size of the halide solid electrolyte a may affect the grain boundary of the formed electrolyte layer 50 And when the thickness of the electrolyte layer is 1-15 micrometers, specifically 1 micrometer, 10 micrometers or 15 micrometers, the formed electrolyte layer has fewer grain boundaries, so that the grain boundary resistance is smaller, and lithium ion transmission is facilitated.
In a specific embodiment, when the composite positive electrode is used as a positive electrode of a solid-state secondary battery, the halide solid-state electrolyte layer cannot be too thin, and the positive active material layer in the composite positive electrode cannot be effectively isolated from the halide solid-state electrolyte layer in the solid-state secondary battery; it is not too thick, which may be unfavorable for lithium ion transport, and therefore, the thickness of the halide solid electrolyte layer may be 5 to 30 μm, and more preferably, the thickness of the halide solid electrolyte layer may be 10 to 20 μm, and in specific embodiments, may be 10 μm, 15 μm, 20 μm, and 30 μm, which may be favorable for lithium ion transport.
In a specific embodiment, the positive electrode active material layer comprises the following components in parts by mass: 25-85 parts of a positive electrode active material; 2-20 parts of halide solid electrolyte B; 1 part of a conductive agent; 0.25-2 parts of a binder.
Preferably, the particle diameter D of the halide solid electrolyte B 50 Can be 0.5 to 5 μm.
The thickness of the positive electrode active material layer is 100 to 500 μm.
Preferably, the halide solid state electrolyte a and the halide solid state electrolyte B may be selected from Li in particular 3 YCl 6 、Li 3 ErCl 6 、Li 3 YBr 6 、Li 3 InBr 6 And Li 3 InCl 6 At least one of (a).
In a specific embodiment, because the positive electrode active material layer is too thin, the active material loading is small and the capacity is low; the positive electrode active material layer is too thick and has a large resistance, and the thickness of the positive electrode active material layer may be 100 to 500 μm, specifically 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 100 to 200 μm, 100 to 300 μm, 100 to 400 μm, 400 to 500, 200 to 300 μm, or 200 to 400 μm.
Preferably, the positive active material is at least one selected from lithium iron phosphate, lithium cobaltate, lithium manganate, a nickel cobalt manganese ternary material and a nickel cobalt aluminum ternary material;
the conductive agent is selected from one or more of Super P, acetylene black, ketjen black, carbon nanotubes, graphene and vapor-grown carbon fibers;
the binder is selected from one or more of PTFE, SBS, SEBS, PVDF, PTFE, PAALi, SBR, NBR, butylene rubber, styrene rubber and polyurethane.
Preferably, the halide solid electrolyte A and the halide solid electrolyte B have the molecular formula Li 3 MX 6 Wherein M is selected from at least one of In, Y, sc, er, mg, zr and Al, and X is selected from at least one of Cl, F, br and I; the molecular formula of the halide solid electrolyte A is the same as or different from that of the halide solid electrolyte B.
The invention also provides a preparation method of the composite anode, which comprises the following steps:
1) Preparing the positive active material, a binder, a conductive agent and an organic solvent A according to a certain proportion into slurry a, coating the slurry a on the surface of the current collector, and drying and rolling to form the positive active material layer;
2) And preparing the halide solid electrolyte, the binder and the organic solvent B into slurry B according to a certain proportion, coating the slurry B on the surface of the positive active material layer, and drying and rolling to form the composite positive electrode.
According to the preparation method of the solid-state battery composite positive electrode, halide solid electrolyte slurry is coated on the surface of a positive electrode active material layer, and a halide electrolyte layer is formed on the surface of the positive electrode active material layer after drying, so that the electrolyte layer can isolate direct contact between a high-voltage positive electrode material and sulfide solid electrolyte, and formation of a space charge layer is inhibited; on the other hand, the halide electrolyte layer has higher ionic conductivity, which is beneficial to the transmission of lithium ions; in addition, the interface contact between the positive electrode and the halide electrolyte can be effectively improved by in-situ wet coating, and meanwhile, the interface contact between the halide electrolyte and the sulfide electrolyte is also improved due to the good flexibility of the halide.
Preferably, the organic solvent A is at least one of N-methyl pyrrolidone, dimethyl carbonate, ethyl acetate, absolute ethyl alcohol, acetone, diethyl carbonate and methyl propionate;
preferably, the positive active material accounts for 70-95% of the slurry a; 2 to 27 percent of binder; the conductive agent accounts for 3-28 percent.
Preferably, the solid content of the slurry a is 40-60%.
Preferably, the organic solvent B is at least one of a polar solvent and a non-polar solvent.
The polar solvent is at least one of N-methyl pyrrolidone, dimethyl carbonate, ethyl acetate, absolute ethyl alcohol, acetone, diethyl carbonate and methyl propionate; the nonpolar solvent is at least one of toluene, p-xylene, cyclohexane and isopropanol.
The invention further provides a solid-state lithium ion secondary battery, which comprises the composite positive electrode, the solid-state electrolyte layer and the negative electrode.
Preferably, the solid electrolyte layer comprises a sulfide solid electrolyte;
the negative electrode is selected from at least one of metal lithium, metal indium, lithium-indium alloy, silicon carbon, silicon, graphite and lithium titanate.
In the present invention, the sulfide solid electrolyte is xLi 2 S·(100–x)P 2 S 5 (x is more than or equal to 20 and less than or equal to 80) glass, li-P-S glass ceramic, lithium fast ion conductor type, li 6 PS 5 X (X = Cl, br and I) Geranite, li 11-c M 2-c P 1+c S 12 (M = Ge, sn, and Si); the sulfide solid electrolyte is preferably of the lithium fast ion conductor type, li 6 PS 5 X (X = Cl, br and I) Geranite, li 11-c M 2-c P 1+c S 12 (M = Ge, sn, and Si).
Preferably, the density of the solid electrolyte layer is 85% -95%;
particle diameter D of the sulfide solid electrolyte 50 Is 1 to 10 μm.
In the invention, the negative electrode can be any one of the negative electrodes conventional in the art, and the negative electrode can be specifically selected from at least one of metal lithium, metal indium, lithium-indium alloy, silicon carbon, silicon, graphite and lithium titanate.
In the present invention, the positive electrode active material layer in the solid-state lithium ion secondary battery is generally prepared by coating a slurry obtained by mixing a positive electrode active material, a solid electrolyte, a conductive agent, and a binder. The solid electrolyte affects lithium ion transport, and when the halide solid electrolyte B is used, the positive active material does not need to be coated.
Example 1
The embodiment provides a preparation method of a solid-state lithium ion secondary battery, which comprises the following steps:
s1, a preparation process of the composite anode comprises the following steps:
s11, carrying out gas phase growth on a positive electrode active material NCM622, a binder PVDF, a conductive agent carbon fiber and an electrolyte Li 3 InCl 6 According to the mass ratio of 85:0.5:1.5:13, weighing and mixing, adding N-methyl pyrrolidone (NMP) solution to form slurry with solid content of 45%, coating the slurry on the surface of a current collector aluminum foil (with the thickness of 10 mu m), drying in vacuum at 80 ℃, rolling to form a positive active material layer, wherein the thickness of the positive active material layer after rolling is 300 mu m, and electrolyte Li is 3 InCl 6 D of (1) 50 Is 3 μm;
s12, preparing a halide solid electrolyte Li 3 InCl 6 And the NBR as a binder in a mass ratio of 98.5:1.5, weighing and mixing, then adding dimethylbenzene to form slurry with 60% of solid content, coating the slurry on the surface of a positive electrode active material layer, drying and rolling to form a composite positive electrode, wherein the thickness of the rolled composite positive electrode (without the thickness of a current collector) is 315 mu m (namely the thickness of a halide electrolyte layer is 15 mu m), and the thickness of the halide solid electrolyte Li is 3 InCl 6 D of (1) 50 Is 10 μm.
S2, preparing a solid lithium ion secondary battery:
s21, preparing a composite positive plate: cutting the composite positive electrode prepared in the step S1 into pieces, and cutting the pieces to form a composite positive electrode piece with the diameter of 10 mm;
s22, preparing a solid electrolyte layer: 70mg of sulfide solid electrolyte Li with the particle size D50 of 5 mu m 6 PS 5 Cl, and forming a solid electrolyte sheet with the density of 85% and the diameter of 10mm under the pressure of 8 MPa;
s23, assembling the solid-state battery: matching with the lithium indium cathode 3, sequentially assembling the composite anode plate 1, the solid electrolyte plate (i.e. the solid electrolyte layer) 2 and the lithium indium cathode 3 in a solid battery testing mold, and applying a pressure of 2MPa to prepare the all-solid battery, wherein the structural schematic diagram of the all-solid battery is shown in fig. 1.
Example 2
This example differs from example 1 in that the thickness of the halide solid state electrolyte layer was 20 μm.
Example 3
This example differs from example 1 in that the thickness of the halide solid state electrolyte layer was 10 μm.
Example 4
This example differs from example 1 in that the halide solid state electrolyte layer has a thickness of 5 μm.
Example 5
This example differs from example 1 in that the halide solid state electrolyte layer has a thickness of 30 μm.
Example 6
This example differs from example 1 in that the halide solid state electrolyte layer has a thickness of 4.5 μm.
Example 7
This example differs from example 1 in that the thickness of the halide solid state electrolyte layer was 35 μm.
Example 8
This example differs from example 1 in that the halide solid electrolyte Li in step S12 3 InCl 6 Particle diameter D of 50 And was 15 μm.
Example 9
This example differs from example 1 in that the halide solid electrolyte Li in step S12 3 InCl 6 Particle diameter D of 50 Is 1 μm.
Example 10
This example differs from example 1 in that the halide solid electrolyte Li in step S12 3 InCl 6 Particle diameter D of 50 Is 0.5. Mu.m.
Example 11
This example differs from example 1 in that the halide solid electrolyte Li in step S12 3 InCl 6 Particle diameter D of 50 And 20 μm.
Example 12
This example differs from example 1 in that LATP is used instead of the electrolyte Li in step S11 3 InCl 6 。
Example 13
This example differs from example 1 in that Li is used 3 InBr 6 Instead of electricity in step S11Electrolyte Li 3 InCl 6 。
Example 14
This example differs from example 1 in that Li is used 3 ErCl 6 Instead of the electrolyte Li in step S11 3 InCl 6 。
Example 15
This example differs from example 1 in that the electrolyte Li in step S11 3 InCl 6 The particle diameter D50 of (2) was 0.5. Mu.m.
Example 16
This example differs from example 1 in that the electrolyte Li in step S11 3 InCl 6 Has a particle diameter D50 of 5 μm.
Example 17
This example differs from example 1 in that the electrolyte Li in step S11 3 InCl 6 The particle diameter D50 of (2) was 0.1. Mu.m.
Example 18
This example differs from example 1 in that the electrolyte Li in step S11 3 InCl 6 Has a particle diameter D50 of 10 μm.
Example 19
This embodiment is different from embodiment 1 in that the thickness of the positive electrode active material layer in step S11 is 100 μm.
Example 20
This embodiment is different from embodiment 1 in that the thickness of the positive electrode active material layer in step S11 is 500 μm.
Example 21
This embodiment is different from embodiment 1 in that the thickness of the positive electrode active material layer in step S11 is 50 μm.
Example 22
This embodiment is different from embodiment 1 in that the thickness of the positive electrode active material layer in step S11 is 700 μm.
Comparative example 1
This comparative example differs from example 1 in that the halide solid state electrolyte layer is not included in the composite positive electrode.
Performance testing
The tests of the solid-state lithium ion secondary batteries described in examples 1 to 22 and comparative example 1 were conducted by using a novyi test cabinet for a long cycle test of rate charge and discharge, the battery test rate was 0.1C (1c = 180ma/g), the test voltage range was 1.9 to 3.7V, and the cycle was 100 cycles. The test results are shown in table 1.
From the results analysis in table 1, it can be seen that:
1. effect of the thickness of the halide electrolyte layer on the Performance of solid-State lithium ion Secondary batteries
Firstly, compared with the solid-state lithium ion secondary battery prepared by the thickness of 4.5 μm of the halide electrolyte layer in the embodiment 6 and the thickness of 35 μm of the halide electrolyte layer in the embodiment 7 in the embodiments 1 to 5, the first charging specific capacity, the first discharging specific capacity, the first efficiency and the data effect of the capacity retention rate after 100 cycles in the embodiments 1 to 5 are better than those in the embodiments 6 to 7, so that the optimized thickness range of the halide solid-state electrolyte layer is 5 to 30 μm;
next, by comparing the effects of the data in examples 1-3 and 4-5, a more preferable thickness range of the halide solid electrolyte layer is obtained in the range of 10 to 20 μm.
Finally, as can be seen from comparison of data in examples 1 to 7 of the present invention and comparative example 1, the solid-state lithium ion secondary battery prepared by using the composite anode having the halide solid-state electrolyte layer of the present invention has the first charge specific capacity, the first discharge specific capacity, the first efficiency and the capacity retention rate data after 100 cycles superior to those of the comparative example, which indicates that the composite anode of the present invention is beneficial to the capacity exertion of the solid-state lithium ion secondary battery and the improvement of the cycle performance.
2. Particle diameter D of halide solid electrolyte A in S12 50 Effect on the Performance of solid-State lithium ion Secondary batteries
Li in examples 1, 8 and 9 of the present invention 3 InCl 6 D of (A) 50 10 μm, 15 μm, 1 μm and Li in examples 10 to 11 of the present invention, respectively 3 InCl 6 D of (A) 50 The above examples 1, 8 and 9 of the present invention are superior to the solid state lithium ion secondary batteries obtained at 0.5 μm and 20 μm, respectively, in performance, and therefore the particle diameter D of the halide solid state electrolyte a preferred in the present invention is 50 Is 1-15 μm. Moreover, as can be seen from comparison of the data in examples 1 and 8 to 11 of the present invention and the comparative example, the first charge specific capacity, the first discharge specific capacity, the first efficiency and the 100-cycle capacity retention rate data of the solid-state lithium ion secondary battery prepared by using the composite anode having the halide solid electrolyte layer are superior to those of the comparative example, which indicates that the present invention is beneficial to the capacity exertion of the solid-state lithium ion secondary battery and the improvement of the cycle stability of the battery.
3. Step S11 Effect of selecting different halide solid electrolytes B on the Performance of solid lithium ion Secondary batteries
Comparing examples 1, 12-14 with comparative examples shows that the effects of different electrolytes selected by the invention are better than those of the comparative examples, thereby showing that the invention is beneficial to the capacity exertion of the solid-state lithium ion secondary battery and improving the cycling stability of the battery.
4. Step S11 particle diameter D of halide solid electrolyte B 50 Effect on the Performance of solid-State lithium ion Secondary batteries
Halide solid electrolyte B Li selected in example 1 of the present invention 3 InCl 6 Particle diameter D of 50 At 3 μm, the performance data of the solid-state lithium ion secondary batteries prepared in examples 15 to 16 were all better than those of examples 17 to 18, and thus the particle diameter D of the halide solid-state electrolyte B preferred in the present invention was found to be better than that of examples 17 to 18 50 0.5 to 5 μm. However, the effects of the embodiments 1 and 15 to 18 of the present invention are significantly superior to those of the comparative examples, which shows that the present invention is advantageous for the capacity exertion of the solid-state lithium ion secondary battery and the improvement of the cycle stability of the secondary battery.
5. Effect of thickness of positive electrode active material layer on Performance of solid-State lithium ion Secondary Battery in step S11
As is clear from comparison of the data in example 1 (300 μm), example 19 (100 μm), example 20 (500 μm) and examples 21 to 22 (50, 700 μm) of the present invention, it is preferable that the thickness of the positive electrode active material layer of the present invention is 100 to 500 μm; compared with the comparative examples, the effects of the examples 1 and 19 to 22 of the present invention are significantly superior to those of the comparative examples, which shows that the solid-state lithium ion secondary battery prepared with the positive electrode active material layer of the present invention having a thickness of 100 to 500 μm is advantageous for the capacity exertion and the cycle performance improvement of the solid-state lithium ion secondary battery.
Table 1 performance test results of solid-state lithium ion secondary battery
Figure BDA0003759972170000101
Figure BDA0003759972170000111

Claims (10)

1. A composite positive electrode, characterized in that it comprises a current collector, a positive active material layer and a halide solid electrolyte layer;
the positive electrode active material layer is located between the current collector and the halide solid state electrolyte layer;
the halide solid state electrolyte layer includes a halide solid state electrolyte a.
2. The composite positive electrode according to claim 1, wherein the particle diameter D of the halide solid electrolyte A 50 Is 1-15 μm.
3. The composite positive electrode according to claim 1 or 2, wherein the halide solid state electrolyte layer has a thickness of 5 to 30 μm;
preferably, the halide solid state electrolyte layer has a thickness of 10 to 20 μm.
4. The composite positive electrode according to claim 1, wherein the positive electrode active material layer comprises a positive electrode active material, a halide solid electrolyte B, a conductive agent, and a binder.
5. The composite positive electrode according to claim 4, wherein the particle diameter D of the halide solid electrolyte B 50 0.5 to 5 μm.
6. The composite positive electrode according to claim 1, wherein the thickness of the positive electrode active material layer is 100 to 500 μm.
7. The composite positive electrode according to claim 4, wherein the positive electrode active material comprises at least one of lithium iron phosphate, lithium cobaltate, lithium manganate, a nickel cobalt manganese ternary material, and a nickel cobalt aluminum ternary material;
the conductive agent comprises one or more of SuperP, acetylene black, ketjen black, carbon nanotubes, graphene and vapor-grown carbon fibers;
the binder comprises one or more of PTFE, SBS, SEBS, PVDF, PTFE, PAALi, SBR, NBR, butylene rubber, styrene rubber and polyurethane;
the molecular formulas of the halide solid electrolyte A and the halide solid electrolyte B are both Li 3 MX 6 Wherein M comprises at least one of In, Y, sc, er, mg, zr, and Al, and X comprises at least one of Cl, F, br, and I; the molecular formula of the halide solid electrolyte A is the same as or different from that of the halide solid electrolyte B.
8. A solid-state lithium ion secondary battery comprising the composite positive electrode according to any one of claims 1 to 7, a sulfide solid electrolyte layer, and a negative electrode.
9. The solid-state lithium ion secondary battery according to claim 8, wherein the negative electrode comprises at least one of metallic lithium, metallic indium, a lithium-indium alloy, silicon carbon, silicon, graphite, lithium titanate.
10. An electric device comprising the solid-state lithium-ion secondary battery according to claim 8 or 9.
CN202210867370.XA 2022-07-22 2022-07-22 Composite positive electrode, solid-state lithium ion secondary battery, and electric device Pending CN115172653A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115911532A (en) * 2023-01-17 2023-04-04 天祥安氢(上海)科技有限公司 All-solid-state battery and preparation method thereof
CN117080542A (en) * 2023-10-18 2023-11-17 清陶(昆山)能源发展股份有限公司 Composite solid electrolyte membrane, preparation method thereof and lithium ion battery

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115911532A (en) * 2023-01-17 2023-04-04 天祥安氢(上海)科技有限公司 All-solid-state battery and preparation method thereof
CN117080542A (en) * 2023-10-18 2023-11-17 清陶(昆山)能源发展股份有限公司 Composite solid electrolyte membrane, preparation method thereof and lithium ion battery
CN117080542B (en) * 2023-10-18 2024-01-30 清陶(昆山)能源发展股份有限公司 Composite solid electrolyte membrane, preparation method thereof and lithium ion battery

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