CN108878960B - Solid electrolyte positive electrode and solid battery - Google Patents

Solid electrolyte positive electrode and solid battery Download PDF

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Publication number
CN108878960B
CN108878960B CN201810719121.XA CN201810719121A CN108878960B CN 108878960 B CN108878960 B CN 108878960B CN 201810719121 A CN201810719121 A CN 201810719121A CN 108878960 B CN108878960 B CN 108878960B
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positive electrode
solid electrolyte
ceramic
lithium
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CN108878960A (en
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周素霞
王晓明
徐远新
杨浩田
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Ningde Zhuogao New Material Technology 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
    • 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
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • 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
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • 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
    • 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
    • H01M2300/0082—Organic polymers
    • 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
    • H01M2300/0088—Composites
    • H01M2300/0091—Composites in the form of mixtures
    • 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 present disclosure relates to a solid electrolyte positive electrode and a solid battery. The solid electrolyte positive electrode includes: the positive plate is coated with a positive active material layer, and the conductive ceramic composite coating is coated on the outer surface of the positive active material layer, wherein the thickness of the conductive ceramic composite coating is 1-50 mu m; the conductive ceramic composite coating comprises an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a macromolecular graft modified ceramic, a binder and a wetting agent, wherein based on the total weight of the conductive ceramic composite coating, the content of the organic polymer is 5-80 wt%, the content of the lithium salt is 5-50 wt%, the content of the nano inorganic solid electrolyte is 10-85 wt%, the content of the macromolecular graft modified ceramic is 1-20 wt%, the content of the binder is 1-12 wt%, and the content of the wetting agent is 0.1-0.5 wt%.

Description

Solid electrolyte positive electrode and solid battery
Technical Field
The disclosure relates to the field of battery anodes, and particularly relates to a solid electrolyte anode and a solid battery comprising the same.
Background
In recent years, in the field of new energy automobiles, the demand for lithium ion batteries has increased year by year. At present, the lithium ion battery generally adopts liquid organic electrolyte to conduct ions, but the organic electrolyte is easy to have accidents of liquid leakage, electrode corrosion, combustion explosion and the like, and has larger potential safety hazard.
Solid electrolyte batteries are gradually coming into the public view because of their organic liquid battery characteristics and high safety. The solid electrolyte comprises polymer electrolyte, inorganic electrolyte and composite electrolyte, the conductivity of the polymer electrolyte is lower at normal temperature, the cost of the inorganic solid electrolyte is higher, and the existing composite electrolyte has poorer mechanical property and larger resistance with the interface between the positive plate and the negative plate.
Disclosure of Invention
The inventor of the application finds that the interface stability and the electrochemical working window between an electrolyte and a pole piece can be improved and the lithium ion cycle performance can be improved by coating a conductive ceramic composite coating with a specific composition on the surface of the conventional positive electrode of the solid electrolyte battery to prepare the solid electrolyte positive electrode, and the prepared solid electrolyte battery has excellent thermal stability and mechanical strength performance and high ionic conductivity and lithium ion transference number at normal temperature.
One aspect of the present disclosure provides a solid electrolyte positive electrode, including:
a positive electrode sheet coated with a positive electrode active material layer, and
a conductive ceramic composite coating coated on the outer surface of the positive active material layer,
the conductive ceramic composite coating comprises an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a macromolecular graft modified ceramic, a binder and a wetting agent, wherein based on the total weight of the conductive ceramic composite coating, the content of the organic polymer is 5-80 wt%, the content of the lithium salt is 5-50 wt%, the content of the nano inorganic solid electrolyte is 10-85 wt%, the content of the macromolecular graft modified ceramic is 1-20 wt%, the content of the binder is 1-12 wt%, and the content of the wetting agent is 0.1-0.5 wt%.
Another aspect of the present disclosure relates to a method of preparing the above solid electrolyte positive electrode, comprising:
(1) mixing the high-molecular graft modified ceramic, the nano inorganic solid electrolyte, the organic polymer, the binder, the wetting agent and the solvent to obtain composite ceramic slurry;
(2) and coating the composite ceramic slurry on the outer surface of the positive active material layer of the positive plate coated with the positive active material layer, and drying to obtain the conductive ceramic composite coating.
Yet another aspect of the present disclosure relates to a solid-state battery including the above solid-state electrolyte positive electrode.
Advantageous effects
In the solid electrolyte positive electrode according to the present disclosure, the conductive ceramic composite coating is formed by mixing an organic polymer, a lithium salt, a nano inorganic solid electrolyte and a submicron ceramic and coating at one time, and the process is simple and easy to operate. The nano inorganic solid electrolyte and the submicron modified ceramic are added into the organic polymer solid electrolyte, so that a smooth path is provided for lithium ion conduction, and the high-rate charge and discharge performance is good. In addition, the conductive ceramic composite coating enables lithium ions to be transferred and distributed uniformly, reduces lithium ion loss caused by formation of lithium dendrites, can improve interface stability and an electrochemical working window between an electrolyte and a pole piece, and improves the lithium ion cycle performance. Moreover, the polymer grafted modified ceramic is introduced into the conductive ceramic composite coating, so that polymer chains can be disordered, the crystallinity of the polymer is reduced, the mechanical strength of an electrolyte is improved, and the mechanical property and the electrochemical property of the coating are improved. The polymer grafted modified ceramic has a uniform surface structure with interconnected micropores, a plurality of rapid lithium ion channels are formed, lithium ion diffusion is facilitated, and meanwhile the heat stability of the anode can be improved due to the high-temperature resistance of the ceramic. The adopted nano inorganic solid electrolyte has large specific surface area and high conductivity, increases the lithium ion transfer capacity and improves the ionic conductivity. The solid electrolyte anode has high ionic conductivity, high thermal stability, high mechanical property and high safety.
The solid-state battery according to the present disclosure has excellent thermal stability and mechanical strength properties, high ionic conductivity and lithium ion transport number at normal temperature.
Detailed Description
The present disclosure will be described in more detail below.
One aspect of the present disclosure provides a solid electrolyte positive electrode, including:
a positive electrode sheet coated with a positive electrode active material layer, and
a conductive ceramic composite coating coated on the outer surface of the positive active material layer,
the conductive ceramic composite coating comprises an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a macromolecular graft modified ceramic, a binder and a wetting agent, wherein based on the total weight of the conductive ceramic composite coating, the content of the organic polymer is 5-80 wt%, the content of the lithium salt is 5-50%, the content of the nano inorganic solid electrolyte is 10-85 wt%, the content of the macromolecular graft modified ceramic is 1-20 wt%, the content of the binder is 1-12 wt%, and the content of the wetting agent is 0.1-0.5 wt%.
The positive electrode active material layer may be coated on one or both surfaces of the positive electrode sheet. The thickness of each positive electrode active material layer may be 0.5 to 50 μm independently.
In the case where the positive electrode active material layers are coated on both sides of the positive electrode sheet, the conductive ceramic composite coating may be coated on only the outer surface of one positive electrode active material layer, or may be coated on both the outer surfaces of both positive electrode active material layers.
The thickness of the conductive ceramic composite coating is independently 1-100 μm, such as 5-60 μm, preferably 10-50 μm.
In the present disclosure, there is no particular limitation on the material of the positive electrode sheet as long as it is a material that can be generally used for the positive electrode sheet in the art. For example, the positive electrode sheet may be an aluminum foil, and the thickness may be 8 to 15 μm.
The positive electrode active material layer comprises a positive electrode active material, a conductive agent and a binder, and preferably consists essentially of the positive electrode active material, the conductive agent and the binder, wherein the content of the positive electrode active material can be 50-95%, and preferably 60-85%, based on the total weight of the positive electrode active material layer; the content of the conductive agent can be 1-20%, preferably 5-15%; the content of the binder may be 2 to 30%, preferably 10 to 25%.
In the present disclosure, the positive electrode active material is not particularly limited as long as it is a positive electrode active material generally used for a lithium battery. For example, the positive electrode active material may be one or more selected from lithium manganate, lithium cobaltate, lithium iron phosphate, and ternary positive electrode materials.
In the present disclosure, the conductive agent is not particularly limited as long as it is a conductive agent generally used for a positive electrode. For example, the conductive agent may be one or more selected from acetylene black, conductive carbon black, carbon fiber, and graphene.
In the present disclosure, the binder is not particularly limited as long as it is a binder generally used for a positive electrode. For example, the binder may be at least one selected from polyvinylidene fluoride, styrene-butadiene rubber, styrene-acrylic emulsion, acrylic resin, polyacrylonitrile, and sodium carboxymethylcellulose.
The positive electrode active material layer may further include a thickener, for example, one or more selected from the group consisting of carboxymethyl cellulose (CMC), carboxyethyl cellulose, polyacrylamide, and polyurethane, wherein the content of the thickener may be 1 to 10 wt% based on the total weight of the positive electrode active material layer.
In the solid electrolyte positive electrode according to the present disclosure, the conductive ceramic composite coating may include an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a high molecular graft modified ceramic, a binder, and a wetting agent. In some embodiments, the conductive ceramic composite coating consists essentially of an organic polymer, a lithium salt, a nano-inorganic solid electrolyte, a polymeric graft modified ceramic, a binder, and a wetting agent. By "consisting essentially of an organic polymer, a lithium salt, a nano-inorganic solid electrolyte, a polymeric graft modified ceramic, a binder, and a wetting agent" is meant that the organic polymer, lithium salt, nano-inorganic solid electrolyte, polymeric graft modified ceramic, binder, and wetting agent comprise greater than 95 wt%, greater than 97 wt%, or, in some aspects, greater than 99 wt% of the conductive ceramic composite coating.
In the conductive ceramic composite coating, the organic polymer is used for forming a matrix of an organic polymer electrolyte, so that the problems of electrolyte leakage, poor safety, short circuit and the like easily occurring in a liquid lithium ion battery are solved. The organic polymer may be at least one selected from the group consisting of polyoxyethylene (also referred to as polyethylene oxide (PEO) or polyethylene glycol (PEG)), polyvinylidene fluoride-hexafluoropropylene, and polyethylene carbonate.
The content of the organic polymer may be 5 to 80 wt%, preferably 15 to 45 wt%, and more preferably 20 to 35 wt%, based on the total weight of the conductive ceramic composite coating. Within the above quantity range, the organic polymer can play a role in improving the safety and flexibility of the battery, and the obtained conductive ceramic composite coating finally improves the safety of the solid electrolyte battery. In the case where the content of the organic polymer is less than 5% by weight, no polymer advantage is exerted. When the content of the organic polymer is more than 80 wt%, the inorganic solid electrolyte and the modified ceramic have a small proportion, which may cause a decrease in ion conductivity, an increase in high-temperature shrinkage, and the like.
In the conductive ceramic composite coating, the lithium salt can generate a certain degree of dissociation of positive and negative ions in a polymer medium through interaction with a polymer and form a complex through complexation with a polar group of the polymer. In the creeping process of the polymer chain segment, positive and negative ions are continuously dissociated from the original groups and are complexed with the adjacent groups, and the ions can be directionally moved under the action of an external electric field, so that the conduction of the positive and negative ions is realized.
The lithium salt is not particularly limited, and a lithium salt suitable for preparing a lithium ion battery may be used without limitation. For example, the lithium salt may be at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium biethanate borate, and lithium oxalyldifluoroborate.
The content of the lithium salt may be 5 to 50 wt%, preferably 10 to 40 wt%, and more preferably 15 to 35 wt%, based on the total weight of the conductive ceramic composite coating. Within the above amount range, the lithium salt may mainly function to conduct ions.
In one embodiment, the weight ratio of the lithium salt to the organic polymer in the conductive ceramic composite coating is 0.05 to 10:1, preferably 0.3 to 3: 1.
In the conductive ceramic composite coating, the nano inorganic solid electrolyte has the advantages of large specific surface area and high conductivity, can increase the lithium ion transfer capacity, has good high-temperature resistance and processability, and has good application prospect in large-scale power lithium ion batteries with high specific energy.
The nano inorganic solid electrolyte may be at least one selected from Lithium Lanthanum Zirconium Oxide (LLZO), titanium aluminum lithium phosphate (LATP), aluminum lithium germanium phosphorus (LAGP).
The content of the nano inorganic solid electrolyte may be 10 to 85 wt%, preferably 30 to 60 wt%, and more preferably 35 to 45 wt%, based on the total weight of the conductive ceramic composite coating. Within the above quantity range, the nano inorganic solid electrolyte can play a role in conducting lithium ions, the internal resistance of the obtained conductive ceramic composite coating is low, the lithium ion loss caused by the formation of interface lithium dendrites is reduced, and the cycle performance of the solid electrolyte battery is improved finally. In the case where the nano inorganic solid electrolyte content is less than 10 wt%, the conductivity may be caused to be low. In the case where the nano inorganic solid electrolyte content is more than 85 wt%, it may result in poor mechanical strength of the composite separator, large interfacial resistance upon contact with an electrode active material, and an insufficiently wide electrochemical window.
The particle size of the nano inorganic solid electrolyte, expressed as D50, can be 80-500 nm, preferably 150-250 nm. Within the above quantity range, the nano inorganic solid electrolyte has the advantages of large specific surface area and high conductivity, can increase the lithium ion transfer capacity, improve the ionic conductivity, enable the internal resistance of the obtained conductive ceramic composite coating to be smaller, reduce the lithium ion loss caused by the formation of interface lithium dendrites, and finally enable the stability and the cycle performance of the solid electrolyte battery to be improved. In the case where the particle size is less than 80nm, the pore blocking phenomenon of the inorganic solid electrolyte particles may be caused, and the particle size is small, the specific surface area is large, and the deposition is easy, which is not favorable for the coating of the separator. Under the condition that the particle size is larger than 500nm, the structure stability and the density of the material are possibly caused, and lithium ion migration is not facilitated.
There is no particular limitation on the method for preparing the nano inorganic solid electrolyte as long as it can have the above particle diameter. For example, the submicron inorganic electrolyte can be pulverized by planetary ball milling and/or high-energy ball milling to obtain the nano inorganic solid electrolyte meeting the requirement of particle size.
The polymer graft modified ceramic may be ceramic particles graft-modified with an acrylic polymer. Here, the acrylic polymer refers to a homopolymer or a copolymer formed by homopolymerization or copolymerization of acrylic monomers.
The glass transition temperature (Tg) of the acrylic polymer can be 50-200 ℃, and preferably 80-180 ℃. For example, the acrylic polymer may be polymethyl methacrylate, or a copolymer of methyl methacrylate and one or more selected from methacrylic acid, ethacrylic acid, ethyl acrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate.
The ceramic particles may be at least one selected from alumina, magnesium oxide, magnesium hydroxide, boehmite, and calcium carbonate, and the particle size thereof, represented by D50, may be 0.1 to 8 μm, and preferably 0.5 to 1 μm.
In the high-molecular graft modified ceramic, the weight ratio of the acrylic polymer to the ceramic particles can be 0.01-0.4: 1, preferably 0.05-0.2: 1. in a weight ratio of less than 0.01: 1, the grafting amount on the surface of the ceramic may be low, which is not favorable for lithium ion transfer, and the mechanical and electrochemical properties of the solid electrolyte may not be improved significantly, and the electrochemical stability and interface stability may not be improved effectively. The weight ratio is more than 0.4:1, the grafting amount on the surface of the ceramic may be too large, and the closely interlaced structure may obstruct lithium ion channels, which is not favorable for lithium ion transfer.
The particle size of the polymer graft modified ceramic, expressed as D50, may be 0.5 to 10 μm, preferably 1 to 6 μm.
In the present disclosure, D50 refers to the particle size corresponding to a cumulative distribution of 50% in the particle size distribution curve, and can be measured using a laser particle size tester, such as BetterSize2000 by dandong baite instruments ltd.
Without being limited by any theory, in the conductive ceramic composite coating, the macromolecular grafting modified ceramic has a uniform surface structure with micropores interconnected, lithium ion diffusion is facilitated, and meanwhile, the heat stability of the anode can be improved due to the high-temperature resistance of the ceramic. The polymer modified ceramic can break up polymer chains, reduce the crystallinity of the polymer and improve the mechanical strength of electrolyte.
The content of the polymer graft modified ceramic may be 1 to 20 wt%, preferably 5 to 15 wt%, and more preferably 5 to 10 wt%, based on the total weight of the conductive ceramic composite coating. In the case where the content of the polymer graft-modified ceramic is less than 1% by weight, a decrease in thermal stability may result. In the case where the content of the polymer graft-modified ceramic is more than 20 wt%, a decrease in lithium ion transferring ability may be caused.
The method for producing the polymer graft-modified ceramic is not particularly limited as long as the polymer can be grafted to the surface of the ceramic particle.
In one embodiment, the preparation of the polymer graft modified ceramic is performed as follows: acrylic acid monomer is subjected to free radical graft polymerization reaction in the presence of ceramic particles to obtain the polymer graft modified ceramic. For example, the radical graft polymerization reaction may be carried out as follows: the modified ceramic particles are obtained by initiating the solution polymerization of acrylic monomers with a radical initiator in an organic solvent in the presence of ceramic particles under an inert gas (e.g., nitrogen, argon) environment. In the polymerization reaction, the weight ratio of the acrylic monomer to the ceramic fine particles may be 0.01 to 0.4:1, preferably 0.05-0.2: 1. the amount of the organic solvent to be used is not particularly limited as long as it is suitable for solution polymerization. For example, the organic solvent may be used in an amount such that the solid content in the mixture when solution polymerization is carried out is 5 to 90 wt%, preferably 10 to 80 wt%.
In the present disclosure, the acrylic monomer refers to a compound represented by the following formula I:
Figure BDA0001718250650000061
wherein R is1Selected from H and C1-C4 alkyl, R2Selected from H and C1-C10 alkyl.
In embodiments, the acrylic monomers include acrylic acid, acrylic esters, methacrylic acid, methacrylic esters, ethacrylic acid, and ethacrylic esters. In embodiments, the (meth) acrylic monomer may be polymethyl methacrylate or a mixture of methyl methacrylate and one or more selected from methacrylic acid, ethacrylic acid, ethyl methacrylate, propyl methacrylate, and butyl methacrylate.
The initiator is not particularly limited, and a radical initiator commonly used in the art, for example, a thermal initiator or an ultraviolet initiator, for example, a peroxide-based initiator such as persulfate (e.g., ammonium persulfate, etc.), benzoyl peroxide (e.g., benzoyl peroxide, bis (2, 4-dichlorobenzoyl) peroxide, diacetyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, etc.), alkyl peroxide (e.g., dicumyl peroxide, di-t-butyl peroxide, etc.), peroxyester (e.g., t-butyl peroxybenzoate, t-butyl peroxypivalate, etc.), hydroperoxide (e.g., cumene hydroperoxide, t-butyl hydroperoxide, etc.), peroxydicarbonate (e.g., diisobutyl peroxydicarbonate IBP, dicyclohexyl peroxydicarbonate DCPD, di (p-t-butylcyclohexyl) peroxydicarbonate, etc.), etc., can be used, Ketone peroxides (e.g., methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), azo initiators (e.g., azobisisobutyronitrile, azobisisoheptonitrile, azobisisobutyramidine, azobisdiisopropylamidine oxazoline, etc.), redox initiators, and the like. The amount of the initiator may be 0.5 to 10 wt%, preferably 1 to 5 wt%, based on the weight of the ceramic.
The reaction temperature of the radical graft polymerization reaction is not particularly limited, and may be appropriately selected depending on the selected initiator, and for example, may be 40 to 160 ℃, and preferably 60 to 120 ℃. The reaction time may be 0.5 to 24 hours, preferably 1 to 10 hours.
The organic solvent is not particularly limited as long as the above-mentioned radical graft polymerization reaction can be carried out in the organic solvent. For example, the organic solvent may be one or more selected from tetrahydrofuran, cyclohexane, petroleum ether, acetone, Dimethylacetamide (DMAC), N-Dimethylformamide (DMF).
After the free radical graft polymerization reaction, cooling, suction filtration, drying and other steps can be carried out according to needs.
In the conductive ceramic composite coating, the wetting agent is used for reducing the surface energy of slurry, improving the wettability of the slurry and a porous membrane and avoiding the bad phenomena of missing coating and the like. The wetting agent is not particularly limited, and a wetting agent suitable for preparing a coating layer of a positive electrode of a lithium battery may be used without limitation. For example, the wetting agent may be one or more selected from the group consisting of fluoroalkyl methoxy alcohol ether, polyoxyethylene alkylamine, sodium butylnaphthalene sulfonate, sodium arylnaphthalene sulfonate, sodium dodecylbenzene sulfonate, and sodium alkyl sulfate. The content of the wetting agent may be 0.1 to 0.5 wt%, preferably 0.1 to 0.4 wt%, and more preferably 0.15 to 0.3 wt%, based on the total weight of the conductive ceramic composite coating. Within the above quantity range, the wetting agent can play a role in reducing the surface energy of the slurry, and the obtained conductive ceramic composite coating is uniform and good in consistency, so that the solid electrolyte battery is good in cycle performance and good in adhesion between the coating and a pole piece. In the case where the content of the wetting agent is less than 0.1 wt%, there is a possibility that the slurry may be blown during the coating process, and defects such as spot-like or large-area missing coating may occur. In the case of a wetting agent content of more than 0.5 wt%, it may result in a greater increase in the permeability of the coating, which is detrimental to lithium ion cycling.
In the conductive ceramic composite coating, the binder is used for binding the coating material and the porous base membrane, so that the coating is prevented from falling off when the battery is impacted by the outside, and the safety performance of the battery is prevented from being influenced. The binder is not particularly limited, and a binder suitable for preparing a coating layer of a positive electrode of a lithium battery may be used without limitation. For example, the binder may be at least one selected from styrene-butadiene rubber (including styrene-butadiene latex), styrene-acrylic emulsion, polyethylacrylate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyvinyl acetate, and polyurethane. The content of the binder may be 1 to 12 wt%, preferably 4 to 10 wt%, and more preferably 6 to 9 wt%, based on the total weight of the conductive ceramic composite coating. Within the above quantity range, the binder mainly can play a role in binding the coating and the porous membrane, and the obtained conductive ceramic composite coating has a stable structure, so that the safety performance of the solid electrolyte battery is improved finally. In the case where the binder content is less than 1 wt%, poor adhesion, i.e., "dusting", may result. In the case where the binder content is more than 12 wt%, it may result in a high permeability value of the coating, which is disadvantageous for lithium ion transfer.
In addition, the conductive ceramic composite coating layer may further include additives such as a dispersant (e.g., polyacrylamide, sodium polyacrylate, polyoxyethylene dioleate, etc.), a thickener (e.g., carboxyethyl cellulose, carboxymethyl cellulose (CMC), etc.), and the like, as necessary. The amount of the additive may be determined by those skilled in the art as needed, for example, 0 to 0.3 wt% based on the total weight of the conductive ceramic composite coating.
The solid electrolyte positive electrode according to the present disclosure may further include other layers, for example, an electrospun layer, a thermal closure layer, a nano flame retardant layer.
Another aspect of the present disclosure relates to a method of preparing the above solid electrolyte positive electrode, comprising:
(1) mixing high-molecular graft modified ceramic, nano inorganic solid electrolyte, organic polymer, lithium salt, binder, wetting agent and solvent to obtain composite ceramic slurry;
(2) and coating the composite ceramic slurry on the outer surface of the positive active material layer of the positive plate coated with the positive active material layer, and drying to obtain the conductive ceramic composite coating.
In the step (1), the descriptions of the polymer graft modified ceramic, the nano inorganic solid electrolyte, the organic polymer, the lithium salt, the binder and the wetting agent are the same as those of the above description, and are not repeated here.
The solvent is not particularly limited as long as the solvent can uniformly disperse the high molecular graft modified ceramic, the lithium salt, the organic polymer, the binder and the wetting agent. For example, the solvent may be one or more selected from deionized or distilled water, tetrahydrofuran, cyclohexane, petroleum ether, acetone, Dimethylacetamide (DMAC), N-Dimethylformamide (DMF).
The amount of the solvent used is not particularly limited as long as it enables the resulting composite ceramic slurry to be suitable for coating on a positive electrode sheet. In one embodiment, the solvent is used in an amount such that the solids content of the slurry is from 10 to 60 wt%, for example from 15 to 50 wt%, preferably from 20 to 45 wt%.
In the above step (1), there is no particular limitation on the method of mixing the components to prepare the composite ceramic slurry, as long as the components can be uniformly mixed. For example, stirring may be performed by a planetary stirrer, a homogenizer, or the like.
In the above step (2), there is no particular limitation on the method of applying the composite ceramic slurry to the outer surface of the positive electrode active material layer, as long as a uniform coating layer can be obtained. For example, the coating may be applied by microgravure coating. After coating, there is no particular limitation on the method of drying the coating layer, as long as the solvent can be removed without adversely affecting the coating layer. For example, drying, vacuum drying, or the like may be employed.
In one embodiment, the step (2) is carried out by coating the composite ceramic slurry on one side or both sides of the positive plate coated with the positive active material layer at a coating speed of 20-80 m/min, and drying in an oven at 30-60 ℃ to obtain the conductive ceramic composite coating.
The thickness of the conductive composite ceramic coating is 1 to 100 μm, such as 5 to 60 μm, preferably 10 to 50 μm.
In the above step (2), the description about the positive electrode sheet coated with the positive electrode active material layer is the same as the foregoing, and is not repeated here. The method for preparing the positive electrode sheet coated with the positive electrode active material layer is not particularly limited, and may be prepared by a method known in the art.
In one embodiment, the positive electrode sheet coated with the positive electrode active material layer may be prepared as follows:
1) uniformly mixing a positive active substance, N-methylpyrrolidone (NMP), a binder and a conductive agent to obtain positive active substance slurry,
2) the positive electrode active material slurry is applied to one side or both sides of a positive electrode sheet to form a positive electrode active material layer and dried, thereby obtaining a positive electrode sheet coated with the positive electrode active material layer.
In one embodiment, in the step 1), for example, the positive electrode active material and NMP may be mixed and stirred at a temperature of 25 to 40 ℃, a rotation speed of 500 to 2500rpm/min, and a time of 1 to 3 hours; and then adding a binder and a conductive agent, keeping the temperature at 25-40 ℃, and stirring at 1000-2000 rpm/min for 0.5-2 h to obtain the anode active material slurry.
In the above step 2), there is no particular limitation on the method of applying the positive electrode active material slurry to the positive electrode sheet as long as a uniform coating layer can be obtained. For example, the coating may be applied by microgravure coating. After coating, there is no particular limitation on the method of drying the coating layer, as long as the solvent can be removed without adversely affecting the coating layer. For example, drying, vacuum drying, or the like may be employed.
The method for preparing a solid electrolyte positive electrode according to the present disclosure may further include operations of preparing an electrostatic spinning layer, a thermal closure layer, a nano flame retardant layer, etc., as necessary. The above-described operations for preparing the electrospun layer, the thermal closure layer, the nano flame-retardant layer, and the like may be performed using conventional operations in the art for preparing such layers.
The method for preparing the solid electrolyte anode can also perform operations such as pole piece compression roller, slitting, sheet making and the like as required. The operations of pressing, slitting, flaking and the like of the pole piece can be carried out by the conventional operations in the field for preparing the positive electrode, for example, the operations can be carried out according to the compaction density of 3.85g/cm3And carrying out pole piece compression roller.
Yet another aspect of the present disclosure provides a solid-state battery including the above solid-state electrolyte positive electrode.
The solid-state battery may have a structure and components conventional in solid-state batteries in the art, for example, a negative electrode, an aluminum plastic film, and the like, in addition to the above-described solid-state electrolyte positive electrode.
The negative electrode and the aluminum plastic film are not particularly limited, and any negative electrode and aluminum plastic film known in the art to be used for a solid-state battery may be used.
In one embodiment, the negative electrode may include a negative electrode sheet and a negative electrode active material layer coated on the negative electrode sheet.
In one embodiment, the negative electrode sheet is a copper foil and has a thickness of 5 to 20 μm.
The anode active material is not particularly limited as long as it is an active material for an anode commonly used in the art. For example, the negative active material may be one or more selected from artificial graphite and natural graphite.
In one embodiment, the solid-state battery is a solid-state lithium battery.
Further, there is no particular limitation in the structure and assembly method of the solid-state battery, and any structure and assembly method known in the art that can be used for a lithium battery may be employed. For example, the solid-state battery may be assembled into a button battery, a square battery, or the like.
The present disclosure has been described in detail hereinabove, but the above embodiments are merely exemplary in nature and are not intended to limit the present disclosure. Furthermore, there is no intention to be bound by any theory presented in the preceding prior art or the summary or the following examples.
Unless expressly stated otherwise, a numerical range throughout this specification includes any sub-range therein and any numerical value incremented by the smallest sub-unit within a given value. Unless expressly stated otherwise, numerical values throughout this specification represent approximate measures or limitations to the extent that such deviations from the given values, as well as embodiments having approximately the stated values and having the exact values stated, are included. Other than in the operating examples provided at the end of the detailed description, all numbers expressing quantities or conditions of parameters (e.g., quantities or conditions) used in the specification (including the appended claims) are to be understood as being modified in all instances by the term "about" whether or not "about" actually appears before the number. "about" means that the numerical value so stated is allowed to be somewhat imprecise (with some approach to exactness in that value; about or reasonably close to that value; approximately). As used herein, "about" refers to at least variations that can be produced by ordinary methods of measuring and using such parameters, provided that the imprecision provided by "about" is not otherwise understood in the art with this ordinary meaning. For example, "about" can include less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5% variation, and in some aspects, less than or equal to 0.1% variation.
Unless otherwise expressly stated, the terms "comprising," "including," "having," "containing," or any other similar term in this specification are intended to be open-ended terms that indicate that a composition or article may include other elements not expressly listed or inherent to such composition or article. Furthermore, in this document, the terms "comprising," including, "" having, "" containing, "and" containing "are to be construed as specifically disclosed and to cover both closed and semi-closed conjunctions, such as" consisting of … "and" consisting essentially of …. By "consisting essentially of …," it is meant that the elements listed herein constitute greater than 95%, greater than 97%, or in some aspects, greater than 99% of the composition or article.
Examples
The technical solution of the present disclosure is further illustrated by the following examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present disclosure and should not be construed as the specific limitations of the present disclosure.
Reagent and apparatus
Unless otherwise indicated, all reagents used are commercially available reagents suitable for use in lithium batteries. Unless otherwise indicated, like terms refer to like materials. Polyvinylidene fluoride was obtained from Dongguan, Heng Plastic materials Ltd. Lithium iron phosphate and lithium manganate were purchased from Guizhou Anda scientific and technological energy resources Co. The ternary cathode material is purchased from Hu nan fir new material Co. The particle size D50 was measured using a laser particle sizer (BetterSize 2000, Inc., Dandong Baite instruments Co., Ltd.).
Preparation examples
Preparation of the negative electrode
1) Mixing 32g of natural graphite, 6g of polyvinylidene fluoride and 60g of deionized water, and carrying out planetary stirring at the temperature of 35 ℃ and the rotating speed of 1500rpm/min for 2 h; then 2g of acetylene black is added, the temperature is kept at 35 ℃, and stirring is carried out at 1000rpm/min for 1h, so as to obtain aqueous graphite slurry;
2) and (3) passing the aqueous graphite slurry through a 300-mesh screen, coating the aqueous graphite slurry on one side or two sides of a copper foil to form a graphite coating, and drying the graphite coating, wherein the coating thickness is 20 microns. And rolling, slitting and flaking to obtain the cathode.
Example 1
Preparation of lithium iron phosphate-containing positive plate
1) Mixing and stirring 50g of lithium iron phosphate and 130g N-methyl pyrrolidone (NMP) at the temperature of 30 ℃ and the rotation speed of 1500rpm/min for 3 h; then adding 20g of styrene-acrylic emulsion with the solid content of 50 wt% and 6g of carbon fiber, keeping the temperature at 30 ℃, and stirring at 1000rpm/min for 1.5h to obtain composite anode slurry;
2) and coating the composite anode slurry on one side or two sides of an aluminum foil with the thickness of 10 mu m, and then drying to obtain a single-coating thickness of 42 mu m, thereby obtaining the anode plate containing the lithium iron phosphate.
Preparing the polymer grafted modified ceramic:
after adding 1.5g of benzoyl peroxide to 100ml of tetrahydrofuran under a nitrogen atmosphere and stirring until the benzoyl peroxide is completely dissolved, 7.5g of methyl methacrylate and 75g of alumina fine particles (D50 ═ 1.0 μm) are added, and the mixture is refluxed at 80 ℃ for 5 hours, cooled, filtered with suction, and dried under vacuum for 10 hours to obtain modified ceramic fine particles (D50 ═ 1.5 μm).
Preparing a nano inorganic solid electrolyte:
and the submicron-sized LLZO is crushed by planetary ball milling and high-energy ball milling to obtain the nano-sized LLZO with the particle size D50 of 210 nm.
Preparing a solid electrolyte anode:
20g of polyoxyethylene serving as an organic polymer and 6.85g of polyvinyl acetate serving as a binder are uniformly dispersed in 150ml of DMAC, then lithium hexafluorophosphate (30g), the prepared high-molecular graft modified ceramic particles (6g) and nano-LLZO (35g) are added, and finally 0.15g of polyoxyethylene alkylamine serving as a wetting agent is added and mixed and stirred in a 1L reaction kettle for 3 hours to obtain the composite ceramic slurry.
Coating the composite ceramic slurry on one side or two sides of the prepared lithium iron phosphate-containing positive plate, and performing vacuum drying at 120 ℃ for 48 hours to obtain a conductive ceramic composite coating, wherein the thickness of the final coating is 40 mu m; then the pressed solid density is 3.85g/cm3And rolling, slitting and flaking to obtain the solid electrolyte anode.
Preparation of solid-state batteries:
the above solid electrolyte positive electrode and the above prepared negative electrode were sequentially wound into 10 layers to form a lithium ion prismatic solid-state battery.
Example 2
Preparation of positive plate containing lithium manganese oxide
1) Mixing and stirring 50g of lithium manganate and 130g N-methyl pyrrolidone (NMP), wherein the temperature is 30 ℃, the rotating speed is 1500rpm/min, and the time is 3 h; then adding 20g of styrene-acrylic emulsion with the solid content of 50 wt% and 6g of carbon fiber, keeping the temperature at 30 ℃, and stirring at 1000rpm/min for 1.5h to obtain composite anode slurry;
2) and coating the composite anode slurry on one side or two sides of an aluminum foil with the thickness of 10 mu m, and then drying to obtain a single-coating thickness of 42 mu m, thereby obtaining the lithium manganese oxide-containing anode sheet.
Preparing the polymer grafted modified ceramic:
after adding 1.5g of benzoyl peroxide to 100ml of acetone under a nitrogen atmosphere and stirring until the benzoyl peroxide is completely dissolved, 7.5g of methyl methacrylate, ethyl acrylic acid (ratio 1:1) and 75g of magnesium oxide particles (D50 ═ 0.9 μm) are added, and the mixture is refluxed at 80 ℃ for 6 hours, cooled, filtered by suction, and dried under vacuum for 8 hours to obtain modified ceramic particles (D50 ═ 1.3 μm).
Preparing a nano inorganic solid electrolyte:
and the submicron-level LLZO is subjected to planetary ball milling and high-energy ball milling to obtain the nano-level LLZO with the particle size D50 of 240 nm.
Preparing a solid electrolyte anode:
20g of polyvinylidene fluoride as an organic polymer and 6.85g of polyvinyl acetate as a binder were uniformly dispersed in 150ml of N, N-dimethylformamide, and then lithium hexafluorophosphate (30g), the prepared polymer graft modified ceramic fine particles (6g) and nano-LLZO (35g) were further added, and then 0.2g of polyoxyethylenealkylamine as a wetting agent was added to the mixture and stirred in a 1L reactor for 3 hours to obtain a composite ceramic slurry.
Coating the composite ceramic slurry on one side or two sides of a positive plate containing lithium manganese oxide, and performing vacuum drying at 120 ℃ for 48 hours to obtain a conductive ceramic composite coating, wherein the thickness of the final single coating is 35 mu m; then the pressed solid density is 3.85g/cm3Rolling the mixture,And (4) slitting and flaking to obtain the solid electrolyte anode.
Preparation of solid-state batteries:
the above solid electrolyte positive electrode and the above prepared negative electrode were sequentially wound in 10 layers to prepare a lithium ion prismatic solid state battery.
Example 3
Preparation of positive plate containing ternary positive material
1) Mixing and stirring 50g of ternary cathode material and 130g N-methyl pyrrolidone (NMP), wherein the temperature is 30 ℃, the rotating speed is 1500rpm/min, and the time is 3 h; then adding 20g of styrene-acrylic emulsion with the solid content of 50 wt% and 6g of carbon fiber, keeping the temperature at 30 ℃, and stirring at 1000rpm/min for 1.5h to obtain composite anode slurry;
2) and coating the composite anode slurry on one side or two sides of an aluminum foil with the thickness of 10 mu m, and then drying to obtain a single-coating thickness of 42 mu m, thereby obtaining the anode plate containing the ternary anode material.
Preparing the polymer grafted modified ceramic:
after adding 1.5g of benzoyl peroxide to 100ml of tetrahydrofuran under a nitrogen atmosphere and stirring until the benzoyl peroxide is completely dissolved, 15g of ethyl methacrylate, methacrylic acid (ratio 1:1) and 75g of boehmite particles (D50 ═ 0.9 μm) were added, and the mixture was refluxed at 80 ℃ for 10 hours, cooled, filtered with suction, and dried under vacuum for 6 hours to obtain modified ceramic particles (D50 ═ 1.4 μm).
Preparing a nano inorganic solid electrolyte:
the submicron LATP is pulverized by planetary ball milling and high-energy ball milling to obtain the nanometer LATP, and the particle size D50 is 200 nm.
Preparing a solid electrolyte anode:
20g of polyethylene carbonate as an organic polymer and 6.85g of polyvinyl acetate as a binder were uniformly dispersed in 150ml of N, N-dimethylformamide, and then lithium hexafluorophosphate (30g), the polymer graft-modified ceramic fine particles (6g) prepared above, and nano-LLZO (35g) were further added, and then 0.2g of polyoxyethylenealkylamine as a wetting agent was added to the mixture and mixed in a 1L reactor for 3 hours to obtain a composite ceramic slurry.
Coating the composite ceramic slurry on the positive electrode containing the ternary positive electrode materialVacuum drying one or two sides of the pole piece at 150 ℃ for 24 hours to obtain a conductive ceramic composite coating, wherein the thickness of the final single coating is 35 mu m; then the pressed solid density is 3.85g/cm3And rolling, slitting and flaking to obtain the solid electrolyte anode.
Preparation of solid-state batteries:
the above solid electrolyte positive electrode and the above prepared negative electrode were sequentially wound into 10 layers to form a lithium ion prismatic solid-state battery.
Comparative example 1
Preparing a nano inorganic solid electrolyte:
and the submicron-sized LLZO is crushed by planetary ball milling and high-energy ball milling to obtain the nano-sized LLZO with the particle size D50 of 210 nm.
Preparing a solid electrolyte anode:
32g of the nano-LLZO is dissolved in 70ml of DMAC, and then 3.8g of polyvinyl acetate serving as a binder and 0.2g of polyoxyethylene alkylamine serving as a wetting agent are added to be mixed and stirred in a 1L reaction kettle for 3 hours to obtain inorganic electrolyte slurry.
35g of polyoxyethylene as an organic polymer and 30g of lithium hexafluorophosphate were added to 105ml of DMAC and uniformly stirred, and then 10g of polyvinyl acetate as a binder and 0.2g of polyoxyethylene alkylamine as a wetting agent were added and mixed in a 1L reactor for 3 hours to obtain an organic polymer electrolyte slurry.
The organic polymer electrolyte slurry was coated on one side or both sides of the lithium iron phosphate-containing positive electrode sheet of example 1, and vacuum-dried at 150 ℃ for 24 hours to obtain an organic polymer electrolyte coating, and the final single coating thickness was 20 μm.
Coating the inorganic electrolyte slurry on the outer surface of an organic polymer electrolyte coating, and performing vacuum drying at 120 ℃ for 36 hours to obtain an inorganic electrolyte coating, wherein the thickness of the final single coating is 15 mu m; then the mixture is compacted according to the compaction density of 3.85g/cm3Rolling, slitting and flaking to obtain the solid electrolyte anode.
Preparation of solid-state batteries
The above solid electrolyte positive electrode and the above prepared negative electrode were sequentially wound into 10 layers to form a lithium ion prismatic solid-state battery.
Comparative example 2
Preparation of alumina ceramic diaphragm
Adding 30g of alumina with the particle size of 1 mu m into 200g of deionized water, uniformly stirring, then adding 20g of styrene-butadiene latex with the solid content of 50 wt% as a binder and 1g of polyoxyethylene alkylamine as a wetting agent, and uniformly dispersing by stirring for 2.5h to obtain the ceramic slurry.
Coating the ceramic slurry on a PE (polyethylene) base film with the thickness of 12 mu m, drying in a 50 ℃ oven to obtain an alumina ceramic diaphragm, wherein the thickness of the single ceramic coating is 4 mu m, and the coating weight is 5g/m2。
Preparation of the Battery
The lithium iron phosphate-containing positive electrode sheet of example 1, the above-described alumina ceramic separator, and the above-described prepared negative electrode were wound in this order by 10 layers to form a prismatic aluminum can battery.
Then the battery is dried in vacuum and vacuumized to remove water, and electrolyte (containing 1mol/L LiPF) is injected into the shell6The organic electrolytic solution of (1), wherein the solvent is dimethyl carbonate: diethyl carbonate: 1:1:1) and sealing. And obtaining the organic solution lithium ion battery.
Examples of the experiments
The batteries of examples 1 to 3 and comparative examples 1 to 2 (including 5 cells) were extracted and subjected to a cycle performance test after full charge. The lithium ion battery is charged at normal temperature by adopting 1C multiplying power, discharged at 1C multiplying power, and sequentially circulated for 500 times, and the battery capacity before and after each circulation is recorded (5 battery data average values are taken in each group).
The capacity retention ratio after n cycles is (battery capacity after n cycles/battery capacity before cycles) × 100%.
The results of capacity retention after 500 cycles are shown in table 1:
TABLE 1500 Capacity Retention (% after cycles)
Item Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2
Capacity retention ratio% 97.42％ 96.85％ 96.31％ 91.43％ 89.48％
The results in table 1 show that the batteries of examples 1 to 3 have high capacity retention rate, and may reduce the irreversible loss of lithium ions during the cycle process, have high ionic conductivity, reduce the influence of shuttle effect, and avoid the formation of lithium dendrites. The battery of comparative example 1 has inferior capacity retention rate, and the organic electrolyte coating is sandwiched between the high-conductivity inorganic electrolyte coating and the positive electrode active material layer, thereby improving the cycle performance of the battery to a certain extent. The battery of comparative example 2 has lower capacity retention rate and higher internal resistance in the circulation process, and is not beneficial to the cycle performance of the lithium ion battery.

Claims (18)

1. A solid electrolyte cathode, comprising:
a positive electrode sheet coated with a positive electrode active material layer, and
the conductive ceramic composite coating coated on the outer surface of the positive active material layer has a thickness of 1-100 μm,
the conductive ceramic composite coating comprises an organic polymer, a lithium salt, a nano inorganic solid electrolyte, a macromolecular graft modified ceramic, a binder and a wetting agent, wherein based on the total weight of the conductive ceramic composite coating, the content of the organic polymer is 5-80 wt%, the content of the lithium salt is 5-50%, the content of the nano inorganic solid electrolyte is 10-85 wt%, the content of the macromolecular graft modified ceramic is 1-20 wt%, the content of the binder is 1-12 wt%, and the content of the wetting agent is 0.1-0.5 wt%, wherein,
the organic polymer is at least one selected from polyoxyethylene, polyvinylidene fluoride-hexafluoropropylene and polyethylene carbonate;
the lithium salt is at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (oxalato) borate and lithium oxalato difluoro borate;
the nano inorganic solid electrolyte is at least one selected from lithium lanthanum zirconium oxide, lithium titanium aluminum phosphate and lithium aluminum germanium phosphorus;
the wetting agent is one or more selected from fluoroalkyl methoxy alcohol ether, polyoxyethylene alkylamine, butyl sodium naphthalene sulfonate, aryl sodium naphthalene sulfonate, sodium dodecyl benzene sulfonate or alkyl sodium sulfate;
the binder is at least one selected from styrene butadiene rubber, styrene-acrylic emulsion, polyethylacrylate, polyvinyl alcohol, ethylene-vinyl acetate copolymer, polyvinyl acetate and polyurethane;
the high molecular graft modified ceramic is ceramic particles graft-modified by acrylic acid polymer, wherein
The glass transition temperature of the acrylic polymer is 50-200 ℃;
the acrylic polymer is polymethyl methacrylate, or a copolymer of methyl methacrylate and one or more selected from methacrylic acid, ethacrylic acid, ethyl acrylate, ethyl methacrylate, propyl methacrylate and butyl methacrylate;
the ceramic particles are at least one selected from aluminum oxide, magnesium hydroxide, boehmite or calcium carbonate, and the particle size, expressed as D50, of the ceramic particles is 0.1-8 μm;
in the high-molecular graft modified ceramic, the weight ratio of acrylic polymer to ceramic particles is 0.01-0.4: 1;
the particle size of the polymer graft modified ceramic is 0.5 to 10 μm expressed as D50.
2. The solid electrolyte cathode according to claim 1, wherein the conductive ceramic composite coating has a thickness of 5 to 60 μm.
3. The solid electrolyte cathode according to claim 1, wherein the conductive ceramic composite coating has a thickness of 10 to 50 μm.
4. The solid electrolyte positive electrode according to claim 1, wherein the nano inorganic solid electrolyte has a particle size, expressed as D50, of 80 to 500 nm.
5. The solid electrolyte positive electrode according to claim 1, wherein the nano inorganic solid electrolyte has a particle size, expressed as D50, of 150 to 250 nm.
6. The solid electrolyte cathode according to claim 1, wherein the conductive ceramic composite coating layer comprises, based on the total weight of the conductive ceramic composite coating layer,
the content of the organic polymer is 15-45 wt%; and/or
The content of the lithium salt is 10-40 wt%; and/or
The content of the nano inorganic solid electrolyte is 30-60 wt%; and/or
The content of the polymer graft modified ceramic is 5-15 wt%; and/or
The content of the wetting agent is 0.1-0.4 wt%; and/or
The content of the binder is 4-10 wt%; and/or
In the conductive ceramic composite coating, the weight ratio of lithium salt to organic polymer is 0.05-10: 1.
7. The solid electrolyte cathode according to claim 6, wherein the conductive ceramic composite coating layer comprises, based on the total weight of the conductive ceramic composite coating layer,
the content of the organic polymer is 20-35 wt%; and/or
The content of the lithium salt is 15-35 wt%; and/or
The content of the nano inorganic solid electrolyte is 35-45 wt%; and/or
The content of the polymer graft modified ceramic is 5-10 wt%; and/or
The content of the wetting agent is 0.15-0.3 wt%; and/or
In the conductive ceramic composite coating, the weight ratio of lithium salt to organic polymer is 0.3-3: 1.
8. The solid-state electrolyte positive electrode according to claim 1,
the glass transition temperature of the acrylic polymer is 80-180 ℃;
the particle size of the ceramic particles is 0.5-1 μm expressed as D50;
in the high-molecular graft modified ceramic, the weight ratio of acrylic polymer to ceramic particles is 0.05-0.2: 1;
the particle size of the polymer graft modified ceramic is 1-6 μm expressed by D50.
9. The solid electrolyte positive electrode according to claim 1, wherein the polymer graft modified ceramic is prepared by: carrying out free radical graft polymerization reaction on acrylic monomers in the presence of ceramic particles to obtain high-molecular graft modified ceramic;
in the polymerization reaction, the weight ratio of the acrylic monomer to the ceramic particles is 0.01-0.4: 1;
the acrylic monomer is methyl methacrylate, or a mixture of methyl methacrylate and one or more of methacrylic acid, ethacrylic acid, ethyl methacrylate, propyl methacrylate and butyl methacrylate;
the amount of the initiator is 0.5-10% of the weight of the ceramic.
10. The solid electrolyte positive electrode according to claim 9, wherein a weight ratio of the acrylic monomer to the ceramic fine particles in the polymerization reaction is 0.05 to 0.2: 1; the amount of the initiator is 1-5% of the weight of the ceramic.
11. The solid-state electrolyte positive electrode according to claim 1,
the positive electrode active material layer is coated on one surface or two surfaces of the positive electrode sheet, and the thickness of each positive electrode active material layer is 0.5-50 mu m independently; and/or
The positive plate is an aluminum foil, and the thickness of the positive plate is 8-15 mu m; and/or
The positive electrode active material layer comprises a positive electrode active material, a conductive agent and a binder, wherein the content of the positive electrode active material is 50-95% based on the total weight of the positive electrode active material layer; the content of the conductive agent is 1-20%; the content of the binder is 2-30%; and/or
The positive active material is one or more selected from lithium manganate, lithium cobaltate, lithium iron phosphate and ternary positive materials; and/or
The conductive agent is one or more selected from acetylene black, conductive carbon black, carbon fiber and graphene; and/or
The binder is at least one selected from polyvinylidene fluoride, styrene butadiene rubber, styrene-acrylic emulsion, acrylic resin, polyacrylonitrile and sodium carboxymethylcellulose.
12. The solid electrolyte positive electrode according to claim 11, wherein the content of the positive electrode active material is 60 to 85% based on the total weight of the positive electrode active material layer; the content of the conductive agent is 5-15%; the content of the binder is 10-25%.
13. A method of making the solid electrolyte cathode of any one of claims 1-12, comprising:
(1) mixing high-molecular graft modified ceramic, nano inorganic solid electrolyte, organic polymer, lithium salt, binder, wetting agent and solvent to obtain composite ceramic slurry;
(2) and coating the composite ceramic slurry on the outer surface of the positive active material layer of the positive plate coated with the positive active material layer, and drying to obtain the conductive ceramic composite coating.
14. The method of claim 13, wherein,
the solvent is one or more selected from deionized water or distilled water, tetrahydrofuran, cyclohexane, petroleum ether, acetone, dimethylacetamide and N, N-dimethylformamide;
the solvent is used in an amount such that the slurry has a solid content of 10 to 60 wt%.
15. The method according to claim 14, wherein the solvent is used in an amount such that the slurry has a solid content of 15 to 50 wt%.
16. The method of claim 14, wherein the solvent is used in an amount such that the slurry has a solids content of 20 to 45 wt%.
17. A solid-state battery comprising the solid-state electrolyte positive electrode of any one of claims 1 to 12.
18. The solid-state battery according to claim 17, which is a solid-state lithium battery.
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CN107645013A (en) * 2016-07-22 2018-01-30 中国科学院物理研究所 Compound quasi-solid electrolyte, its preparation method and the lithium battery or lithium ion battery containing it
CN106785009A (en) * 2016-12-09 2017-05-31 北京科技大学 A kind of all solid state composite electrolyte of organic-inorganic and its methods for making and using same
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