CN116666550A - Preparation methods of positive plate, solid electrolyte and battery thereof - Google Patents

Preparation methods of positive plate, solid electrolyte and battery thereof Download PDF

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Publication number
CN116666550A
CN116666550A CN202310509094.4A CN202310509094A CN116666550A CN 116666550 A CN116666550 A CN 116666550A CN 202310509094 A CN202310509094 A CN 202310509094A CN 116666550 A CN116666550 A CN 116666550A
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positive electrode
lithium
parts
polyethylene oxide
content
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丁意军
胡大林
李辉
黄圣华
李璐
方凯斌
侯林玲
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Guangdong Highpower New Energy Technology Co Ltd
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Guangdong Highpower New Energy Technology Co Ltd
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    • H—ELECTRICITY
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    • 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
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    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
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    • H01M4/04—Processes of manufacture in general
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
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    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1397—Processes of manufacture of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
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    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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
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Abstract

In order to solve the problems that the ion polarization is large and the thickness of the positive plate is difficult to increase in the existing solid positive plate, the application provides a preparation method of the positive plate, the solid electrolyte and a battery thereof, wherein the positive plate comprises a current collector and a plurality of layers of positive electrode coatings, and the plurality of layers of positive electrode coatings comprise metal salt, positive electrode active materials, polyethylene oxide, conductive agents and plasticizers; the particle size of the positive electrode active material, the molecular weight of the polyethylene oxide, the content of the plasticizer and the content of the metal salt in the multilayer positive electrode coating are distributed in a gradient manner, and the particle size of the positive electrode active material is in a decreasing trend along the direction close to the current collector; the molecular weight of the polyethylene oxide, the plasticizer content and the metal salt-containing content show an increasing trend; the anode sheet provided by the application optimizes the ion migration path of the inner layer of the anode sheet by adopting a multilayer coating mode, reduces the polarization of the inner layer ions, and combines the battery performance and the energy density.

Description

Preparation methods of positive plate, solid electrolyte and battery thereof
Technical Field
The application relates to the technical field of batteries, in particular to a positive plate, a solid electrolyte and a preparation method of a battery thereof.
Background
Solid-state batteries have many advantages of nonflammability, high safety, matchability to alkali metal cathodes, high energy density, and the like, and have gradually attracted public attention in recent years. However, the solid electrolyte does not have better fluidity as the liquid electrolyte, and can effectively wet the positive electrode active material, so that the ion normal-temperature performance polarization in the discharging process is larger, and the migration rate of lithium ions in the positive electrode plate of the solid battery is slower at normal temperature. The solid-state positive electrode cell generally selects polyethylene oxide as a binder and an alkali metal element carrier, and the alkali metal element is conducted in the positive electrode sheet through the polyethylene oxide. However, the polyethylene oxide glass has high transformation temperature and high normal-temperature crystallinity, so that the ion conductivity of the polyethylene oxide glass is low at normal temperature, the ion polarization in the positive electrode plate is large, and the thickening of the positive electrode plate and the improvement of the energy density of the battery are hindered to a certain extent. As is known by those skilled in the art, the lower the molecular weight of polyethylene oxide, the lower the glass transition temperature, the mobile short chain is contained in the polyethylene oxide, the high ionic conductivity is realized, but the cohesiveness is low, when the polyethylene oxide is used as a positive binder, the pole piece is easy to fall off, the higher the molecular weight of the polyethylene oxide, the viscosity is increased, but the ionic conductivity is lower; therefore, how to overcome the above-mentioned technical problems and drawbacks becomes an important problem to be solved.
Disclosure of Invention
Aiming at the problems that the ion polarization in the solid-state positive plate is large and the thickness of the positive plate is difficult to increase, the application provides a preparation method of the positive plate, a solid-state electrolyte and a battery thereof.
The technical scheme adopted by the application for solving the technical problems is as follows: the application provides a positive plate, which comprises a current collector and a plurality of positive electrode coatings, wherein the positive electrode coatings comprise metal salt, positive electrode active materials, polyethylene oxide, conductive agents and plasticizers; the particle size of the positive electrode active material, the molecular weight of the polyethylene oxide, the content of the plasticizer and the content of the metal salt in the multilayer positive electrode coating are distributed in a gradient manner, and the particle size of the positive electrode active material is in a decreasing trend along the direction close to the current collector; the molecular weight of the polyethylene oxide, the plasticizer content and the metal salt-containing content show an increasing trend.
Optionally, the metal-containing salt comprises lithium/sodium salt comprising one or more of lithium bis (trifluoromethanesulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, lithium perchlorate, sodium perchlorate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium hexafluoroarsenate, sodium hexafluoroarsenate, lithium tetrafluoroborate, sodium tetrafluoroborate, lithium bis (fluorosulfonamide), sodium bis (fluorosulfonamide), lithium difluoro (oxalato) borate, and sodium difluoro (oxalato) borate.
Optionally, the positive electrode active material comprises one or more of lithium iron phosphate, lithium cobalt oxide, lithium battery ternary positive electrode, prussian blue, prussian white, sodium battery layered oxide positive electrode active material and sodium battery polyanion positive electrode active material.
Optionally, the plasticizer comprises one or more of dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, butyl benzyl phthalate, di (2-ethyl) hexyl phthalate, and diisononyl phthalate.
Optionally, the conductive agent comprises one or more of conductive carbon black, carbon nanotubes, graphene, carbon fibers, acetylene black and ketjen black.
The application provides a preparation method of a positive plate, which comprises the following steps:
polyethylene oxide a and metal salt containing a are mixed according to the mass ratio of 15-17:1 dispersing in a first organic solvent, uniformly stirring to prepare a glue solution a, wherein the solid content of the glue solution a is 3-30%; mixing 85-95 parts of positive electrode active material a, 1.5-5 parts of plasticizer a, 2.0-15 parts of conductive agent and 2.0-15 parts of glue solution a according to the weight ratio, and uniformly stirring and dispersing to prepare positive electrode slurry a;
polyethylene oxide b monomer EO and metal salt b are mixed according to the mass proportion of 18-20:1, dispersing in a first organic solvent, uniformly stirring to prepare a glue solution b, wherein the solid content of the glue solution b is 3-30%; mixing, stirring and dispersing evenly, 85-94.9 parts of positive electrode active material b, 0.1-1.5 parts of plasticizer b, 2.0-15.0 parts of conductive agent and 2.0-8.5 parts of glue solution b according to the weight ratio, and preparing positive electrode slurry b;
dispersing 10-20 parts of conductive carbon black, 10-20 parts of carbon nano tubes in 1-20 parts of polyvinylidene fluoride glue solution, uniformly mixing the polyvinylidene fluoride glue solution with the mass content of 1.2-20% in the polyvinylidene fluoride glue solution, and marking the mixture as slurry c;
coating the slurry c on a current collector, and drying to prepare a carbon-coated current collector for later use;
and (3) sequentially coating positive electrode slurry a and positive electrode slurry b on the surface of the carbon-coated current collector, and drying to obtain the positive electrode plate.
Optionally, the molecular weight of the polyethylene oxide is 30 ten thousand to 200 ten thousand, and the molecular weight of the polyethylene oxide a is larger than that of the polyethylene oxide b; the average particle size of the positive electrode active material is 2-30 um, and the particle size of the positive electrode active material a is smaller than that of the positive electrode active material b; the weight proportion of the plasticizer in the positive electrode coating is 0.1-5.0%, the content of the plasticizer a is larger than the content of the plasticizer b, and the weight proportion of the metal salt in the positive electrode coating is 0.3-3%; the content of the lithium/sodium salt a is higher than the content of the lithium/sodium salt b.
In another aspect, the present application provides a method for preparing a solid electrolyte, comprising the steps of:
mixing 35-70 parts of polyethylene oxide, 1-10 parts of lithium salt/sodium salt, 3-35 parts of filler, 1-10 parts of plasticizer and 20-100 parts of second organic solvent uniformly by weight, and stirring to prepare polymer electrolyte slurry, namely a slurry d;
and then directly pouring the slurry d on the surface of the positive plate prepared by any one of the above steps, and scraping, drying and hot-pressing the slurry d to prepare the solid electrolyte.
Optionally, the filler is Lithium Aluminum Germanium Phosphate (LAGP), and the second organic solvent is N-methyl pyrrolidone.
In a further aspect, the present application provides a method for preparing a solid-state battery, which comprises the prepared positive electrode sheet, the solid-state electrolyte and the alkali metal element metal negative electrode sheet;
the preparation method comprises the following preparation steps: and placing a lithium/sodium metal sheet on the surface of the solid electrolyte of the positive plate, hot-pressing by a hot press, and packaging to prepare the solid-state battery.
According to the positive plate provided by the application, a multilayer coating type positive plate is adopted, and the particle size gradient of the positive active material, the molecular weight gradient of polyethylene oxide and the content gradient of plasticizer are arranged in the positive plate, namely, the particle size of the positive active material is in a decreasing trend in the direction perpendicular to the positive plate and close to a current collector; the molecular weight of polyethylene oxide, the content of plasticizer and the content of metal salt show increasing trend; the thickness of the positive plate is increased by adopting a multilayer coating mode, so that the energy density of the solid-state battery is effectively improved; and the inner-layer ion polarization is reduced by optimizing the inner-layer ion migration path of the positive plate, and the battery performance and the energy density are both considered.
Drawings
FIG. 1 is a schematic view of a positive plate according to an embodiment of the present application;
reference numerals in the drawings of the specification are as follows:
1-a current collector; 2-coating a layer of slurry c; 3-coating a layer of slurry a; 4-slurry b coating layer.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects solved by the application more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
In order to make the technical problems, technical schemes and beneficial effects solved by the application more clear, the application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The test methods used in the following examples are conventional methods unless otherwise specified; the materials, reagents and the like used, unless otherwise specified, are those commercially available.
The embodiment provides a positive electrode sheet, which comprises a current collector and a plurality of layers of positive electrode coatings, wherein the positive electrode coatings comprise metal salt, positive electrode active materials, polyethylene oxide, conductive agents and plasticizers; the particle size of the positive electrode active material, the molecular weight of the polyethylene oxide, the content of the plasticizer and the content of the metal salt in the multilayer positive electrode coating are distributed in a gradient manner, and the particle size of the positive electrode active material is in a decreasing trend along the direction close to the current collector; the molecular weight of the polyethylene oxide, the plasticizer content and the metal salt-containing content show an increasing trend.
Specifically, the positive electrode active material of the positive electrode sheet provides the charge and discharge capacity of the battery; the conductive agent plays a role in electronic conduction; polyethylene oxide is used as a binder and simultaneously plays a role in conducting lithium/sodium ions together with alkali metal salts; the plasticizer can improve the ionic conductivity of the positive plate.
Furthermore, the positive plate adopts a multilayer coating mode, and the particle size gradient, the alkali metal salt content gradient, the polyethylene oxide molecular weight gradient and the plasticizer content gradient of the positive active material are arranged in the positive plate, so that the migration speed of alkali metal element ions at the position of the positive plate close to the current collector is improved, the polarization of a thick positive electrode is reduced, the thickness of the positive plate is increased, and the positive plate has substantial significance in improving the energy density of the solid-state battery.
Specifically, the current collector is selected from aluminum foil, and carbon-coated aluminum foil is adopted for the current collector, so that the stripping force between the anode coating and the current collector can be effectively improved, meanwhile, the corrosion of partial alkali metal salt in the anode to the current collector is reduced, and the good interface of the current collector and the anode is ensured.
Further, current collectors include, but are not limited to, aluminum foils, aluminum meshes, aluminum foils coated with a conductive carbon layer, aluminum coated polymer films, conductive polymer films, and any other conductive film that has corrosion stability for use in a battery.
In one embodiment, the positive electrode sheet further comprises a current collector coating layer located between the positive electrode coating layer and the current collector, the current collector coating layer comprising the following weights:
10-20 parts of conductive carbon black, 10-20 parts of carbon nano tube and 0.5-5 parts of polyethylene oxide.
In one embodiment, the molecular weight of the polyethylene oxide is 30-200 ten thousand, the average particle size of the positive electrode active material is 2-30 um, the weight proportion of the plasticizer in the positive electrode coating is 0.1-5.0%, and the weight proportion of the metal salt in the positive electrode coating is 0.3-3%.
In one embodiment, the metal-containing salt comprises lithium/sodium salt comprising one or more of lithium bis (trifluoromethanesulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, lithium perchlorate, sodium perchlorate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium hexafluoroarsenate, sodium hexafluoroarsenate, lithium tetrafluoroborate, sodium tetrafluoroborate, lithium bis (fluorosulfonamide), sodium bis (fluorosulfonamide), lithium difluoro (oxalato) borate, and sodium difluoro (oxalato) borate.
In an embodiment, the positive electrode active material includes one or more of lithium iron phosphate, lithium cobalt oxide, lithium battery ternary positive electrode, prussian blue, prussian white, sodium battery layered oxide positive electrode active material, and sodium battery polyanion positive electrode active material.
In one embodiment, the plasticizer comprises one or more of dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, butyl benzyl phthalate, di (2 ethyl) hexyl phthalate, and diisononyl phthalate.
In an embodiment, the conductive agent includes one or more of conductive carbon black, carbon nanotubes, graphene, carbon fibers, acetylene black, and ketjen black.
The application provides a preparation method of a positive plate, which comprises the positive plate prepared by any one of the above steps:
polyethylene oxide a and metal salt containing a are mixed according to the mass ratio of 15-17:1 dispersing in a first organic solvent, uniformly stirring to prepare a glue solution a, wherein the solid content of the glue solution a is 3-30%; mixing 85-95 parts of positive electrode active material a, 1.5-5 parts of plasticizer a, 2.0-15 parts of conductive agent and 2.0-15 parts of glue solution a according to the weight ratio, and uniformly stirring and dispersing to prepare positive electrode slurry a;
polyethylene oxide b monomer EO and metal salt b are mixed according to the mass proportion of 18-20:1, dispersing in a first organic solvent, uniformly stirring to prepare a glue solution b, wherein the solid content of the glue solution b is 3-30%; mixing, stirring and dispersing evenly, 85-94.9 parts of positive electrode active material b, 0.1-1.5 parts of plasticizer b, 2.0-15.0 parts of conductive agent and 2.0-8.5 parts of glue solution b according to the weight ratio, and preparing positive electrode slurry b;
dispersing 10-20 parts of conductive carbon black, 10-20 parts of carbon nano tubes in 1-20 parts of polyvinylidene fluoride glue solution, uniformly mixing the polyvinylidene fluoride glue solution with the mass content of 1.2-20% in the polyvinylidene fluoride glue solution, and marking the mixture as slurry c;
coating the slurry c on a current collector, and drying to prepare a carbon-coated current collector for later use;
and (3) sequentially coating positive electrode slurry a and positive electrode slurry b on the surface of the carbon-coated current collector, and drying to obtain the positive electrode plate.
In the present application, the first organic solvent includes one or more of acetonitrile, N dimethylformamide, N dimethylacetamide, N-methyl-2-pyrrolidone, acetone, butanone, ethanol, propanol, isopropanol, butanol, toluene, xylene, methyl ethyl ketone, dimethyl sulfoxide, tetrahydrofuran, dioxane, ethyl acetate, methyl formate, chloroform, dimethyl carbonate, diethyl carbonate, acetic acid, acrylic acid, chloroacetic acid, ethylene glycol, glycerin.
The outer layer of the positive plate prepared by the method adopts low molecular weight polyethylene, which is beneficial to improving the ionic conductivity of the outer positive coating, ensuring an ion channel, reducing the use of plasticizer to a certain extent and improving the effective load of positive active substances; the inner layer adopts the small-particle-size positive electrode active material, which is beneficial to reducing the ion polarization of the inner layer and improving the rate capability of the battery; the high molecular weight polyethylene oxide is adopted in the inner layer of the positive plate, so that the stripping force between the positive plate coating and the current collector can be enhanced, and the powder on the surface of the plate is prevented from falling off; meanwhile, the high-content plasticizer is adopted, so that the glass transition temperature of the high-molecular-weight polyethylene oxide can be reduced, and the ionic conductivity of the inner-layer positive electrode coating can be improved; the carbon-coated aluminum foil is adopted for the current collector, so that the stripping force between the anode coating and the current collector can be effectively improved, meanwhile, the corrosion of partial lithium/sodium salt in the anode to the current collector is reduced, and the good interface between the current collector and the anode is ensured.
In one embodiment, the molecular weight of the polyethylene oxide is 30 ten thousand to 200 ten thousand, and the molecular weight of the polyethylene oxide a is greater than the molecular weight of the polyethylene oxide b; the average particle size of the positive electrode active material is 2-30 um, and the particle size of the positive electrode active material a is smaller than that of the positive electrode active material b; the weight proportion of the plasticizer in the positive electrode coating is 0.1-5.0%, the content of the plasticizer a is larger than the content of the plasticizer b, and the weight proportion of the metal salt in the positive electrode coating is 0.3-3%; the content of the lithium/sodium salt a is higher than the content of the lithium/sodium salt b.
Specifically, the molecular weight of the polyethylene oxide a is 80-200 ten thousand, and the molecular weight of the polyethylene oxide b is 30-60 ten thousand; the slurry b is coated on the outermost layer, and the slurry b adopts low molecular weight polyethylene oxide, so that the ionic conductivity of the outer positive electrode coating can be improved, an ion channel is ensured, the use of a plasticizer can be reduced to a certain extent, and the effective loading of a positive electrode active substance is improved.
Specifically, the average particle size of the positive electrode active material is 2um-30um, the particle size of the positive electrode active material a is 2um-12um, and the particle size of the positive electrode active material b is 12um-30 um.
Specifically, the weight proportion of the plasticizer in the solid powder of the positive plate is 0.1-5.0%, the content of the plasticizer a is 1.5-5.0%, and the content of the plasticizer b is 0.1-1.5%; the high molecular weight polyethylene oxide is adopted in the positive plate slurry a layer, so that the stripping force between the positive electrode coating and the current collector can be enhanced, and the powder on the surface of the pole piece is prevented from falling off; meanwhile, the high-content plasticizer is adopted, so that the glass transition temperature of the high-molecular-weight polyethylene oxide can be reduced, and the ionic conductivity of the inner-layer positive electrode coating can be improved.
Specifically, the content of the lithium/sodium salt a is higher than the content of the lithium/sodium salt b, the polyethylene oxide is used as a binder, and simultaneously plays a role in conducting lithium ions together with the lithium/sodium salt, the plasticizer can improve the ion conductivity of the lithium/sodium salt, the content of the lithium/sodium salt a is higher than the content of the lithium/sodium salt b, the lithium ion conduction rate of a slurry layer a can be improved, the inner layer ion migration path of a positive plate is optimized, the inner layer ion polarization is reduced, and the battery performance is improved.
In another aspect, the present application provides a method for preparing a solid electrolyte, comprising the steps of:
mixing 35-70 parts of polyethylene oxide, 1-10 parts of lithium salt/sodium salt, 3-35 parts of filler, 1-10 parts of plasticizer and 20-100 parts of second organic solvent uniformly by weight, and stirring to prepare polymer electrolyte slurry, namely a slurry d;
and then directly pouring the slurry d on the surface of the positive plate prepared by any one of the above steps, and scraping, drying and hot-pressing the slurry d to prepare the solid electrolyte.
Specifically, the paste d is applied to the surface of the positive electrode sheet by a method including, but not limited to, a doctor blade method, an extrusion coating method, a transfer coating method, a screen printing method, or an inkjet printing method.
In one embodiment, the filler is Lithium Aluminum Germanium Phosphate (LAGP) and the second organic solvent is N-methylpyrrolidone.
In the present application, the second organic solvent further includes one or more of acetonitrile, N dimethylformamide, N dimethylacetamide, acetone, butanone, ethanol, propanol, isopropanol, butanol, toluene, xylene, methyl ethyl ketone, dimethyl sulfoxide, tetrahydrofuran, dioxane, ethyl acetate, methyl formate, chloroform, dimethyl carbonate, diethyl carbonate, acetic acid, acrylic acid, chloroacetic acid, ethylene glycol, and glycerin.
In a further aspect, the present application provides a method for preparing a solid-state battery, comprising the positive electrode sheet prepared in any one of the above steps, a solid-state electrolyte, and an alkali metal element metal negative electrode sheet;
the preparation method comprises the following preparation steps: and placing a lithium/sodium metal sheet on the surface of the solid electrolyte of the positive plate, hot-pressing by a hot press, and packaging to prepare the solid-state battery.
Example 1:
a preparation method of a positive plate and a solid-state battery comprises the following steps:
(1) 100 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =17:1) in acetonitrile to prepare a gum solution, and the average particle size of the lithium cobalt oxide positive electrode with 12um, conductive carbon black, gum and dimethyl phthalate were mixed according to 90.0% by weight: 3.0% wt.%: 3.0% wt.%: 4.0% wt weight ratioMixing to prepare positive electrode slurry, and recording the positive electrode slurry as slurry a for later use;
(2) 50 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =18:1) in acetonitrile, to prepare a gum solution, the average particle size of positive electrode lithium cobaltate, conductive carbon black, gum, and dimethyl phthalate was mixed according to 93.0% by weight: 3.0% wt.%: 3.0% wt.%: mixing 1.0 wt% of the positive electrode slurry to prepare a positive electrode slurry b for later use;
(3) Conducting carbon black, carbon nano tubes and polyvinylidene fluoride glue solution are mixed according to the weight percentage of 30: 50% by weight: mixing 20% by weight to prepare a slurry c for later use;
(4) Coating the slurry c on a current collector, and drying to prepare a carbon-coated current collector for later use;
(5) Coating positive electrode slurry a on a carbon-coated current collector, wherein the coating surface density is 65g/m 2 Then, the positive electrode slurry b was applied again to a surface density of 130g/m 2 And (5) drying for later use.
Example 2:
a preparation method of a positive plate and a solid-state battery comprises the following steps:
(1) 100 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =17:1) in acetonitrile to prepare a gum solution, and the average particle size of the lithium cobalt oxide positive electrode with 12um, conductive carbon black, gum and dimethyl phthalate were mixed according to 90% by weight: 10% by weight: 8% by weight: mixing 2% by weight of the mixture to prepare positive electrode slurry which is recorded as slurry a for later use;
(2) 50 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =18:1) in acetonitrile to prepare a gum solution, and the average particle size of the lithium cobalt oxide positive electrode with 15um, conductive carbon black, gum and dimethyl phthalate were mixed according to 80% by weight: 10% by weight: 9% by weight: mixing 1% by weight of the positive electrode slurry to prepare a positive electrode slurry b for later use;
(3) Conducting carbon black, carbon nano tubes and polyvinylidene fluoride glue solution are mixed according to the weight percentage of 30: 50% by weight: mixing 20% by weight to prepare a slurry c for later use;
(4) Coating the slurry c on a current collector, and drying to prepare a carbon-coated current collector for later use;
(5) The carbon-coated current collector is coated with positive electrode slurry a, and the coating surface density is 90g/m 2 Then, the positive electrode slurry b was applied again to a coating surface density of 170g/m 2 And (5) drying for later use.
Comparative example 1:
a preparation method of a positive plate and a solid-state battery comprises the following steps:
(1) 100 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =18:1) uniformly stirring in acetonitrile to prepare a glue solution;
(2) Positive electrode lithium cobaltate with average particle diameter of 15um, conductive carbon black and glue according to 90 percent by weight: 5% by weight: mixing 5% by weight of the mixture to prepare anode slurry for later use;
(3) Coating the positive electrode slurry on a current collector, wherein the coating surface density is 130g/m 2 ；
Comparative example 2:
a preparation method of a positive plate and a solid-state battery comprises the following steps:
(1) 50 ten thousand molecular weight polyethylene oxide and LiTFSI (EO: li) + =18:1) uniformly stirring in acetonitrile to prepare a glue solution;
(2) Positive electrode lithium cobaltate with average particle diameter of 15um, conductive carbon black and glue according to 90 percent by weight: 5% by weight: mixing 5% by weight of the mixture to prepare anode slurry for later use;
(3) Coating the positive electrode slurry on a current collector, wherein the coating surface density is 130g/m 2 ；
And (5) drying for later use.
And (3) battery assembly:
50 ten thousand molecular weight polyethylene oxide, liTFSI salt, LAGP and dimethyl phthalate according to 65 percent by weight: 4% by weight: 25% by weight: adding 6% by weight of the electrolyte into acetonitrile, uniformly stirring to prepare polymer electrolyte slurry, pouring the polymer electrolyte slurry on the surfaces of the positive plates of the comparative example 1, the comparative example 2, the example 1 and the example 2 respectively, carrying out hot pressing, placing a lithium sheet on the surface of a solid electrolyte to form a lithium sheet/solid electrolyte/lithium cobaltate structure, and carrying out encapsulation to be tested.
The testing method comprises the following steps:
cycling at 25℃: charging the battery to 4.20V at constant current and constant voltage of 0.5C, and stopping charging until the current is 0.05C; standing for 10min, and discharging at 0.5C constant current.
Test results:
case (B) Whether the surface falls off powder Roll stripping force (N/m) Capacity retention (100T)
Comparative example 1 Whether or not 12.6 85.4％
Comparative example 2 Is that 10.5 84.6％
Example 1 Whether or not 15.8 88.9％
Example 2 Whether or not 15.3 88.6％
Conclusion: compared with comparative examples 1 and 2, the positive electrode sheet surfaces of examples 1 and 2 are not subjected to powder falling, and the stripping force of the electrode sheet and the capacity retention rate of the battery core are improved to a certain extent, which shows that the application has practical effects and effects on improving the cycle performance of the solid-state battery.
The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the application.

Claims (10)

1. The positive plate is characterized in that: the positive plate comprises a current collector and a plurality of positive electrode coatings, wherein the positive electrode coatings comprise metal salt, positive electrode active materials, polyethylene oxide, conductive agents and plasticizers; the particle size of the positive electrode active material, the molecular weight of the polyethylene oxide, the content of the plasticizer and the content of the metal salt in the multilayer positive electrode coating are distributed in a gradient manner, and the particle size of the positive electrode active material is in a decreasing trend along the direction close to the current collector; the molecular weight of the polyethylene oxide, the plasticizer content and the metal salt-containing content show an increasing trend.
2. The positive electrode sheet according to claim 1, wherein: the metal-containing salt comprises lithium/sodium salt, and the lithium/sodium salt comprises one or more of lithium bis (trifluoromethanesulfonyl) imide, sodium bis (trifluoromethanesulfonyl) imide, lithium perchlorate, sodium perchlorate, lithium hexafluorophosphate, sodium hexafluorophosphate, lithium hexafluoroarsenate, sodium hexafluoroarsenate, lithium tetrafluoroborate, sodium tetrafluoroborate, lithium bis (fluorosulfonamide), sodium bis (fluorosulfonamide), lithium bis (oxalato) borate and sodium bis (oxalato) borate.
3. The positive electrode sheet according to claim 1, wherein: the positive electrode active material comprises one or more of lithium iron phosphate, lithium cobaltate, lithium battery ternary positive electrode, prussian blue, prussian white, sodium battery layered oxide positive electrode active material and sodium battery polyanion positive electrode active material.
4. The positive electrode sheet according to claim 1, wherein: the plasticizer comprises one or more of dimethyl phthalate, diethyl phthalate, di-n-butyl phthalate, dioctyl phthalate, butyl benzyl phthalate, di (2-ethyl) hexyl phthalate and diisononyl phthalate.
5. The positive electrode sheet according to claim 1, wherein: the conductive agent comprises one or more of conductive carbon black, carbon nano tubes, graphene, carbon fibers, acetylene black and ketjen black.
6. The method for preparing the positive electrode sheet prepared according to any one of claims 1 to 5, characterized in that: the method comprises the following steps:
polyethylene oxide a and metal salt containing a are mixed according to the mass ratio of 15-17:1 dispersing in a first organic solvent, uniformly stirring to prepare a glue solution a, wherein the solid content of the glue solution a is 3-30%; mixing 85-95 parts of positive electrode active material a, 1.5-5 parts of plasticizer a, 2.0-15 parts of conductive agent and 2.0-15 parts of glue solution a according to the weight ratio, and uniformly stirring and dispersing to prepare positive electrode slurry a;
polyethylene oxide b monomer EO and metal salt b are mixed according to the mass proportion of 18-20:1, dispersing in a first organic solvent, uniformly stirring to prepare a glue solution b, wherein the solid content of the glue solution b is 3-30%; mixing, stirring and dispersing evenly, 85-94.9 parts of positive electrode active material b, 0.1-1.5 parts of plasticizer b, 2.0-15.0 parts of conductive agent and 2.0-8.5 parts of glue solution b according to the weight ratio, and preparing positive electrode slurry b;
dispersing 10-20 parts of conductive carbon black, 10-20 parts of carbon nano tubes in 1-20 parts of polyvinylidene fluoride glue solution, uniformly mixing the polyvinylidene fluoride glue solution with the mass content of 1.2-20% in the polyvinylidene fluoride glue solution, and marking the mixture as slurry c;
coating the slurry c on a current collector, and drying to prepare a carbon-coated current collector for later use;
and (3) sequentially coating positive electrode slurry a and positive electrode slurry b on the surface of the carbon-coated current collector, and drying to obtain the positive electrode plate.
7. The method for preparing the positive electrode sheet according to claim 6, wherein: the molecular weight of the polyethylene oxide is 30 ten thousand to 200 ten thousand, and the molecular weight of the polyethylene oxide a is larger than that of the polyethylene oxide b; the average particle size of the positive electrode active material is 2-30 um, and the particle size of the positive electrode active material a is smaller than that of the positive electrode active material b; the weight proportion of the plasticizer in the positive electrode coating is 0.1-5.0%, the content of the plasticizer a is larger than the content of the plasticizer b, and the weight proportion of the metal salt in the positive electrode coating is 0.3-3%; the content of the lithium/sodium salt a is higher than the content of the lithium/sodium salt b.
8. A method for preparing a solid electrolyte, characterized by: the method comprises the following steps:
mixing 35-70 parts of polyethylene oxide, 1-10 parts of lithium salt/sodium salt, 3-35 parts of filler, 1-10 parts of plasticizer and 20-100 parts of second organic solvent uniformly by weight, and stirring to prepare polymer electrolyte slurry, namely a slurry d;
and then directly pouring the slurry d on the surface of the positive plate prepared by any one of claims 1-7, and scraping, drying and hot-pressing the slurry d to prepare the solid electrolyte.
9. The method for preparing a solid electrolyte according to claim 8, wherein: the filler is Lithium Aluminum Germanium Phosphate (LAGP), and the second organic solvent is N-methyl pyrrolidone.
10. A method of preparing a solid state battery, characterized by: comprising the positive electrode sheet prepared according to any one of claims 1 to 7, the solid electrolyte prepared according to any one of claims 8 to 9, and an alkali metal element metal negative electrode sheet;
the preparation method comprises the following preparation steps: and placing a lithium/sodium metal sheet on the surface of the solid electrolyte of the positive plate, hot-pressing by a hot press, and packaging to prepare the solid-state battery.
CN202310509094.4A 2023-05-08 2023-05-08 Preparation methods of positive plate, solid electrolyte and battery thereof Pending CN116666550A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117117087A (en) * 2023-10-24 2023-11-24 宁德时代新能源科技股份有限公司 Positive plate, battery monomer, battery and power utilization device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117117087A (en) * 2023-10-24 2023-11-24 宁德时代新能源科技股份有限公司 Positive plate, battery monomer, battery and power utilization device

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