WO2021143544A1 - 一种改性陶瓷隔膜及其制备方法和应用 - Google Patents

一种改性陶瓷隔膜及其制备方法和应用 Download PDF

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WO2021143544A1
WO2021143544A1 PCT/CN2020/142329 CN2020142329W WO2021143544A1 WO 2021143544 A1 WO2021143544 A1 WO 2021143544A1 CN 2020142329 W CN2020142329 W CN 2020142329W WO 2021143544 A1 WO2021143544 A1 WO 2021143544A1
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urea
ceramic
formaldehyde resin
epoxy resin
ceramic diaphragm
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PCT/CN2020/142329
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English (en)
French (fr)
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赵金保
张鹏
李航
彭龙庆
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厦门大学
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Priority claimed from CN202010061673.3A external-priority patent/CN113224459A/zh
Priority claimed from CN202010151280.1A external-priority patent/CN113437438A/zh
Application filed by 厦门大学 filed Critical 厦门大学
Publication of WO2021143544A1 publication Critical patent/WO2021143544A1/zh

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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
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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

Definitions

  • the invention relates to battery diaphragms, batteries, capacitors and other products, in particular to high-temperature resistant ceramic diaphragms, preparation methods and applied batteries.
  • Lithium-ion battery as a chemical power system with high energy density, high output voltage, no memory effect, excellent cycle performance, and environmentally friendly, has good economic benefits, social benefits and strategic significance. It has been widely used in mobile communications, Digital products and other fields are very likely to become the most important power supply system in the field of energy storage and electric vehicles.
  • lithium-ion batteries are mainly composed of positive electrode, negative electrode, separator, and electrolyte.
  • the separator mainly plays a role in preventing the positive and negative electrodes from contacting and allowing ion conduction, and is an important part of the battery.
  • commercial lithium-ion batteries mainly use polyolefin separator materials with a microporous structure, such as single-layer or multi-layer films of polyethylene (PE) and polypropylene (Polypropylene, PP). Due to the low melting temperature of the polyolefin membrane, the thermal stability is not good (PE is about 130°C, PP is about 160°C).
  • polyolefin membrane can provide sufficient mechanical strength and chemical stability at room temperature, it can provide sufficient mechanical strength and chemical stability under high temperature conditions.
  • the lower part shows greater thermal shrinkage, which leads to a short circuit between the positive and negative electrodes and causes thermal runaway, aggravates heat accumulation, generates high pressure inside the battery, and causes the battery to burn or explode.
  • Ceramic-coated Separator is a safety function formed by coating a uniform protective layer composed of ceramic microparticles on one or both sides on the surface of the existing polyolefin microporous membrane substrate Diaphragm.
  • a uniform protective layer composed of ceramic microparticles on one or both sides on the surface of the existing polyolefin microporous membrane substrate Diaphragm.
  • the thermal stability of existing ceramic diaphragms is still very limited.
  • the main reason is that the inorganic ceramic particles adhere to the surface of the polyolefin diaphragm base film through the adhesive. When the temperature reaches the melting point of the base film, the base film melts. Although the existence of ceramic particles can hinder the shrinkage of the diaphragm to a certain extent, it cannot Completely inhibit its contraction.
  • the AI 2 O 3 ceramic diaphragm with PE as the base film when the temperature rises to 130 °C, the PE base film melts, due to the shrinkage resistance of the Al 2 O 3 ceramic particles, the ceramic diaphragm does not shrink, but when the temperature continues to rise
  • the temperature is higher than 150°C, the Al 2 O 3 ceramic coating layer will shrink along with the base film.
  • the mechanical properties of the separator are also greatly reduced. Since the ceramic layer cannot be self-supporting to form a film, the separator will eventually become powdered, which will still cause a short circuit between the positive and negative electrodes. Obviously, a simple ceramic separator cannot meet the requirements of high-safety battery applications.
  • the lithium ion battery separator provided by CN107785520A includes a porous base film and a heat-resistant layer covering at least one side surface of the porous base film; the heat-resistant layer contains a high-temperature resistant polymer and inorganic nanoparticles, and the heat-resistant The layer has a fiber network structure.
  • the provided lithium-ion battery separator not only has good stability at high temperature (>160°C), the high-temperature heat shrinkage rate is small, and the high-temperature mechanical strength is better, which is more resistant than the composite separator obtained by pure high-temperature polymer spinning.
  • Thermal and high-temperature mechanical strength are much better, while ordinary ceramic (CCL) diaphragms, due to the use of heat-labile polymers, either show great thermal shrinkage at high temperatures, or the polymer melts at high temperatures and the ceramic particles are loosely connected. As a result, the entire lithium-ion battery separator does not have high mechanical strength.
  • the heat-resistant layer adopts a fiber mesh structure, which is difficult to realize and a complicated preparation process.
  • the present invention proposes a modified ceramic diaphragm developed on the basis of a ceramic diaphragm.
  • An object of the present invention is to provide a modified ceramic diaphragm prepared by this inventive method, which can effectively inhibit the thermal shrinkage of the base film, and maintain the basic film morphology of the modified ceramic diaphragm when the melting temperature of the base film is reached.
  • the epoxy resin modified ceramic diaphragm provided by the present invention has extremely excellent thermal stability and mechanical properties.
  • the invention has low cost, simple operation in the preparation process, and is suitable for large-scale production.
  • Another object of the present invention is to provide a lithium ion battery containing the modified ceramic separator prepared by the above method.
  • Another object of the present invention is to provide the application of the ceramic modified diaphragm prepared by the inventive method in a chemical power system, especially in a lithium ion battery.
  • a technical solution of the present invention is to use epoxy resin modified ceramic diaphragm, and the specific solution is as follows:
  • the epoxy resin modified ceramic diaphragm provided by the present invention includes a porous base film.
  • the epoxy resin penetrates into the ceramic diaphragm and solidifies on the surface of the inorganic ceramic particles, the surface of the porous base film and the microporous pore walls of the ceramic diaphragm.
  • An epoxy protective layer is formed. Due to the characteristics of epoxy resin, the protective layer is thin and uniform, and will not block the micropores of the porous base film.
  • the epoxy resin protective layer can be formed by coating and curing the epoxy ceramic slurry on the single-layer or double-layer surface of the porous base film, or it can be formed by polymerizing the epoxy resin in situ on the ceramic-coated porous base film. It can also be formed by coating a layer of epoxy resin solution on the prepared ceramic diaphragm and curing it; the single-sided thickness of the epoxy resin protective layer is 0.5 nm-40 nm, preferably 3-10 nm.
  • epoxy resin and ceramic slurry can be mixed to prepare epoxy resin ceramic slurry, and then the epoxy ceramic slurry can be coated on one side or both sides of the porous base film;
  • the ceramic slurry can be coated on the porous base film to make a ceramic diaphragm, and then the prepared epoxy resin solution can be coated on the ceramic diaphragm, and then cured to form an epoxy modified ceramic diaphragm.
  • the porous base film includes polyolefin porous polymers (polyethylene, polypropylene, etc.), polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinyl chloride, poly Ethylene terephthalate, polybutylene terephthalate, polymethylmethacrylate, polyacrylonitrile, polyimide, polyvinylpyrrolidone, polyethylene oxide, polyvinyl alcohol or the above At least one of polymer-derived blending and copolymerization systems.
  • polyolefin porous polymers polyethylene, polypropylene, etc.
  • polytetrafluoroethylene polyvinylidene fluoride
  • polyvinylidene fluoride-hexafluoropropylene copolymer polyvinyl chloride
  • poly Ethylene terephthalate polybutylene terephthalate
  • the size of the inorganic ceramic particles is 10-1000 nm, preferably 50-500 nm, and the thickness of the ceramic layer is 0.1-10 ⁇ m, preferably 2-5 ⁇ m.
  • the ceramic slurry contains 5 to 80% of the base material by weight percentage, and the remainder is the solvent.
  • the base material is composed of the following parts by mass: 0.1-20 parts by mass of the binder, and 80-99.9 parts by mass of the ceramic particles.
  • the epoxy resin ceramic slurry contains 5 to 80% of the base material by weight percentage, and the remainder is the solvent.
  • the base material is composed of the following parts by mass: 0.1-20 parts by mass of binder, 60-99 parts by mass of ceramic particles, 0.1-20 parts by mass of epoxy resin, 0-5 parts by mass of curing agent, and 0 parts by mass of curing accelerator. -5 parts by mass, 0-5 parts by mass of surfactant, 0-5 parts by mass of modifier.
  • the epoxy resin refers to an organic compound containing two or more epoxy groups in a chemical structure, and can form a thermosetting high molecular polymer through the ring-opening reaction of the epoxy groups.
  • the molecular weight of the epoxy resin is 100-5000 as measured by gel permeation chromatography.
  • epoxy resin polymerization monomers are divided into compounds that can be introduced or can generate epoxy groups (referred to as component A) and compounds with two or more active hydrogens, prepolymers or compounds containing Compounds and prepolymers with two or more unsaturated double bonds (referred to as component B).
  • the mixed solution of component A and component B contains 0.1-40% of component A, 0.1-40% of component B, 0.01-8% of catalyst, and 0.01-5% of curing agent. %, curing accelerator 0.01 to 5%, surfactant 0.01 to 5%, additive 0 to 5%, the balance is solvent.
  • the catalyst includes but is not limited to sodium carbonate, potassium carbonate, pyridine, triethylamine, sodium acetate, sodium hydroxide, potassium hydroxide, quaternary ammonium salt, quaternary phosphate salt, choline and the like.
  • the curing agent can be selected from addition polymerization curing agents such as polyamines, acid anhydrides, phenolic aldehydes, mercaptans, etc., or other visible curing agents such as catalytic curing agents, or latent curing agents such as imidazoles. Hardener.
  • addition polymerization curing agents such as polyamines, acid anhydrides, phenolic aldehydes, mercaptans, etc.
  • other visible curing agents such as catalytic curing agents
  • latent curing agents such as imidazoles. Hardener.
  • the curing accelerator is selected according to the nucleophilic and electrophilic properties of the curing agent (the nucleophilic curing agent matches the electrophilic curing accelerator, and the electrophilic curing agent matches the nucleophilic curing accelerator).
  • the nucleophilic curing agent matches the electrophilic curing accelerator
  • the electrophilic curing agent matches the nucleophilic curing accelerator.
  • Commonly used curing accelerators are amines, phenols, acids, amides, etc.
  • the surfactant is stearic acid, sodium dodecylbenzene sulfonate, quaternary ammonium compound, sodium cetyl sulfonate, lecithin, amino acid type, betaine type, fatty acid glyceride, fatty acid At least one of sorbitan and polysorbate.
  • urea-formaldehyde resin to improve the ceramic diaphragm, which is specifically as follows:
  • a urea-formaldehyde resin modified ceramic diaphragm includes inorganic ceramic particles and a porous base film.
  • the surface of the inorganic ceramic particles, the surface of the porous base film and the side walls of the micropores of the porous base film form a continuous urea-formaldehyde resin layer.
  • the thickness of the urea-formaldehyde resin layer is 0.1nm-30nm.
  • the urea-formaldehyde resin layer is formed by coating a urea-formaldehyde resin solution or a urea-formaldehyde resin ceramic slurry.
  • the concentration of the urea-formaldehyde resin in the urea-formaldehyde resin solution or urea-formaldehyde resin ceramic slurry is 1g/L ⁇ 100g/L, the weight average molecular weight of urea-formaldehyde resin is 100-5000.
  • the thickness of the urea-formaldehyde resin layer is 2-10nm
  • the concentration of the urea-formaldehyde resin in the urea-formaldehyde resin solution or urea-formaldehyde resin ceramic slurry is 5g/L-50g/L
  • the weight average of the urea-formaldehyde resin The molecular weight is 500-2000.
  • the urea-formaldehyde resin layer can be formed by coating urea-formaldehyde resin ceramic slurry on the surface of the porous base film, or formed by in-situ polymerization of urea-formaldehyde resin on a ceramic-coated porous base film; more specifically, The urea-formaldehyde resin and ceramic slurry can be mixed to prepare the urea-formaldehyde resin ceramic slurry, and then the urea-formaldehyde resin ceramic slurry can be coated on the single-layer or double-layer surface of the porous base film; or firstly on the single-layer or double-layer surface of the porous base film The ceramic slurry is coated to prepare a ceramic diaphragm, and then the ceramic diaphragm is immersed in a mixed solution of urea and formaldehyde to polymerize and coat the urea-formaldehyde resin in situ.
  • the material of the aforementioned porous base film is polyolefin or its derivatives, polyesters or its derivatives, polynitrile or its derivatives, polyamide or its derivatives, polyalkylene oxide or its derivatives, polyolefin At least one of alcohol or its derivatives.
  • the above-mentioned ceramic slurry is composed of an organic solvent and 5 to 80 parts by mass of a base material, and the solid-to-liquid ratio of the ceramic slurry is preferably 10%, 12%, or 15%; the composition of the base material is 0.1-20 parts by mass of binder and 60-99.9 parts by mass of ceramic particles.
  • the urea-formaldehyde resin ceramic slurry contains 5 to 80 parts by mass of a base material, and the balance is an organic solvent.
  • the base material is composed of 0.1-20 parts by mass of binder, 60-99.9 parts by mass of ceramic particles, and 0.1-20 parts by mass of urea-formaldehyde resin. 0-5 parts by mass of curing agent, 0-5 parts by mass of curing accelerator, 0-5 parts by mass of surfactant, and 0-5 parts by mass of modifier.
  • the urea-formaldehyde resin is a mixed solution of urea and aldehyde compounds, which includes 0.1 to 80 parts by mass of a mixture of urea and aldehyde compounds, 0.01 to 8 parts by mass of catalyst, and 0.01 to 5 parts by mass of curing agent. Parts, 0-5 parts by mass of curing accelerator, 0-5 parts by mass of surfactant, and 0-5 parts by mass of modifier.
  • the molar ratio of the aldehyde compound/urea is 0.6 to 3.0; the aldehyde compound is at least one of formaldehyde, acetaldehyde, propionaldehyde, furfural, and paraformaldehyde;
  • the above-mentioned catalyst is an acidic catalyst or a basic catalyst;
  • the acidic catalyst is organic acid, inorganic acid such as formic acid, hydrochloric acid, ammonium chloride, ammonium persulfate, ammonium sulfate, oxalic acid, sulfuric acid, phosphoric acid, etc.
  • alkali catalysts are sodium hydroxide, potassium hydroxide, barium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, calcium oxide, ammonia, magnesium oxide, calcium oxide, aniline, sodium carbonate , At least one of organic bases such as tertiary amine compounds, inorganic bases, alkaline oxides, alkaline salts, etc.;
  • the curing agent is acid salts such as ammonium hexachloride, ammonium hexafluoride, ammonium sulfate, ammonium nitrate, ammonium persulfate, etc., or active materials such as resorcinol, tannin, melamine, etc. At least one substance;
  • the above-mentioned curing accelerator is at least one of zinc sulfate, trimethyl phosphate, diethyl oxalate, etc.;
  • the above-mentioned surfactant is stearic acid, sodium dodecylbenzene sulfonate, quaternary amine, sodium cetyl sulfonate, lecithin, amino acid type, betaine type, At least one of fatty acid glyceride, fatty acid sorbitan, and polysorbate;
  • the above-mentioned modifier can enhance the heat resistance and water resistance of the urea-formaldehyde resin-modified ceramic separator.
  • the ceramic diaphragm in the above two technical solutions can be the same, including the following:
  • the ceramic particles are selected from among aluminum oxide, titanium dioxide, silicon dioxide, zirconium dioxide, tin dioxide, magnesium oxide, zinc oxide, barium sulfate, boron nitride, aluminum nitride, and magnesium nitride. At least one.
  • the particle size of the ceramic particles is 5nm-10um.
  • the binder is a water-based binder or an organic-based binder
  • the water-based binder is at least one of sodium methyl cellulose, styrene butadiene rubber, gelatin, polyvinyl alcohol, and polyacrylate terpolymer latex;
  • the organic binder is at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, and polymethyl methacrylate.
  • the solvent is methanol, ethanol, isopropanol, n-butanol, acetone, ethyl acetate, n-butyl acetate, xylene, acetonitrile, dimethyl formamide, dimethyl sulfoxide, dimethyl ethyl
  • organic solvents such as amide, N-methylpyrrolidone, dichloromethane, and chloroform.
  • additives are various additives that can improve the performance of the epoxy resin, and are not particularly limited.
  • the preparation scheme of an epoxy resin modified ceramic diaphragm provided by the present invention is as follows:
  • Synthetic epoxy resin In terms of mass percentage, the mixed solution of component A: 1-40%, component B: 1-40%, alkaline catalyst 0.2-8%, and solvent 10-95% is mixed in 25- React at 110°C for 0.5-24h (reaction can be done in stages at different temperatures, or at a fixed temperature without stage reaction, you can choose to add alkaline catalyst at a time, or you can choose to add alkaline catalyst in batches), separate washing and drying , Get epoxy resin.
  • Preparation of ceramic diaphragm mixing ceramic particles and binder in a certain proportion to form a ceramic slurry, and coating the prepared ceramic slurry on the surface of the porous base membrane on one or both sides, and drying to remove the solvent. The ceramic diaphragm is obtained.
  • Preparation of ceramic diaphragm mixing ceramic particles and binder in a certain proportion to form a ceramic slurry, and coating the prepared ceramic slurry on the surface of the porous base film on one or both sides, and drying to remove the solvent.
  • the ceramic diaphragm is obtained.
  • Preparation of epoxy resin modified ceramic diaphragm prepare a mixed solution of component A and component B at a certain concentration, and adjust the concentration to control the total mass fraction of the two components A and B within 1-10%.
  • the concentration value is preferably 3-8%.
  • the ceramic diaphragm prepared in step 1 is fully immersed in the above-mentioned component A and component B mixed solution, taken out and reacted at 25-110°C for 0.5-24h (the reaction can be divided at different temperatures, or the temperature can be fixed regardless of temperature. Stage reaction), washing and drying, to obtain epoxy resin modified ceramic diaphragm.
  • Step 1 Synthesis of urea-formaldehyde resin: After mixing aldehyde compounds, urea, alkaline catalyst and appropriate amount of water, perform polycondensation reaction at pH 8-9 and 85-95°C for 25-35 minutes.
  • the above-mentioned aldehyde compounds, urea and alkaline The mass ratio of the catalyst is 1 ⁇ 40:1 ⁇ 40:0.1 ⁇ 1; the aqueous solution containing the above-mentioned aldehyde compounds, urea, acid catalyst and modifier is added, and the polycondensation reaction is carried out at pH 5 ⁇ 6 and 85 ⁇ 95°C React for 25 to 35 minutes, the mass ratio of the above-mentioned aldehyde compound, urea, acid catalyst and modifier is 1-40:1-40:0.5-1:0.2-2; until a smog-like cloud point appears, then add alkaline catalyst Terminate the polycondensation reaction; then add an appropriate amount of urea at 85-95°C to eliminate the free aldehyde compounds in it, and the urea-formaldehyde resin can be obtained after cooling;
  • Step two preparing a ceramic diaphragm: mix inorganic ceramic particles, binder, sodium carboxymethyl cellulose and an appropriate amount of solvent to form a ceramic slurry, apply the ceramic slurry on the surface of the porous base film, and dry it That is, the ceramic diaphragm is obtained; the mass ratio of the inorganic ceramic particles, the binder, and the sodium carboxymethyl cellulose is 60-99:0.1-20:1-10;
  • Step 3 Preparation of urea-formaldehyde resin-modified ceramic diaphragm: mix the urea-formaldehyde resin, curing agent, curing accelerator and appropriate amount of solvent to prepare a urea-formaldehyde resin solution, coat the urea-formaldehyde resin solution on the ceramic diaphragm, and cure at 25-110°C 0.5-24 hours to obtain the above-mentioned urea-formaldehyde resin modified ceramic diaphragm; the mass ratio of the above-mentioned urea-formaldehyde resin, curing agent, and curing accelerator is 1-20:0.01-5:0-5;
  • the solvents in the above step 2 and step 3 are all mixed solutions of organic solvent and water, and the volume of the organic solvent is divided into 10-100.
  • Step 1 synthesize urea-formaldehyde resin: the method is the same as above;
  • Step two preparing the urea-formaldehyde resin modified ceramic diaphragm: mix the urea-formaldehyde resin, curing agent, curing accelerator, binder, catalyst, inorganic ceramic particles and an appropriate amount of solvent to prepare the urea-formaldehyde resin ceramic slurry, and coat the urea-formaldehyde resin ceramic slurry.
  • urea-formaldehyde resin modified ceramic diaphragm Cover the surface of the porous base film and stand for 1 to 24 hours at 25-100°C to obtain the urea-formaldehyde resin modified ceramic diaphragm; the above-mentioned urea-formaldehyde resin, curing agent, curing accelerator, binder, catalyst, inorganic ceramic
  • the mass ratio of the particles is 1-20:0.01-5:0-5:1-3:0.1-2:60-99.
  • the solvents in the above step two are all mixed solutions of organic solvents and water, and the volume of the organic solvents is 10-100.
  • Step one prepare a ceramic diaphragm: mix inorganic ceramic particles, binder, sodium carboxymethyl cellulose and an appropriate amount of solvent to form a ceramic slurry, coat the ceramic slurry on the surface of the porous base film, and dry it That is, the ceramic diaphragm is obtained; the mass ratio of the inorganic ceramic particles, the binder, and the sodium carboxymethyl cellulose is 60-99:0.1-20:1-10;
  • Step two react the mixture of aldehyde compound, urea, alkaline catalyst and appropriate amount of organic solvent to an appropriate viscosity at pH 8-9, 25-110°C, add curing agent, curing accelerator, and surfactant after cooling; Then add the above-mentioned ceramic diaphragm, fully soak the ceramic diaphragm, take it out, and cure it at 25-110°C for 0.5-24 hours to obtain the urea-formaldehyde resin modified ceramic diaphragm; the above-mentioned aldehyde compound, urea, alkaline catalyst, curing agent
  • the mass ratio of curing accelerator and surfactant is 1-40:1-40:0.0.1-2:0-5:0-5:0-5.
  • the solvent in the above step 1 is a mixed solution of an organic solvent and water, and the volume of the organic solvent is 10-100.
  • the total mass fraction of the aldehyde compound and urea is 1%-40%, preferably 5%-20%.
  • the above-mentioned organic solvent is at least one of lower alcohol, acetone, dimethylformamide, dimethylsulfoxide, dimethylacetamide and N-methylpyrrolidone.
  • the coating method of the present invention is not limited, and includes spraying, knife coating, rolling coating and the like.
  • Another object of the present invention is to provide an application of the above-mentioned epoxy resin and urea-formaldehyde resin modified ceramic diaphragm in the field of chemical power sources, especially lithium ion batteries.
  • Another object of the present invention is to provide a lithium ion battery, including a positive electrode material and a negative electrode material, characterized in that there is the epoxy resin and urea-formaldehyde resin modified ceramic separator provided by the present invention between the positive electrode material and the negative electrode material.
  • the positive electrode materials used in lithium ion batteries can be used in the present invention.
  • the positive electrode active material involved in the positive electrode can be a compound capable of reversibly intercalating and deintercalating Li + , for example, Li x MO 2 or Li y M 2 O 4 (where M is a transition metal, 0 ⁇ x ⁇ 1, 0 ⁇ y ⁇ 2) represented by lithium-containing composite oxides, spinel-like oxides, layered structured metal chalcogenides, olivine structures, and the like.
  • the negative electrode active material for the negative electrode a compound capable of inserting and extracting lithium metal or lithium can be used.
  • various materials such as alloys or oxides such as aluminum, silicon, and tin, and carbon materials can be used as the negative electrode active material.
  • oxides include titanium dioxide and the like
  • carbon materials include graphite, pyrolytic carbons, cokes, glassy carbons, fired bodies of organic polymer compounds, mesophase carbon beads, and the like.
  • conductive additives such as carbon black and acetylene black, or binders such as polyvinylidene fluoride and polyethylene oxide are appropriately added to the above-mentioned negative electrode active material.
  • a negative electrode mixture is prepared, and it is used after coating it on a strip-shaped molded body with a current collector material such as copper foil as a core material.
  • the manufacturing method of the negative electrode is not limited to the above example.
  • non-aqueous solvent organic solvent
  • Non-aqueous solvents include carbonates, ethers, and the like.
  • non-aqueous solvents such as methyl propionate, chain phosphate triesters such as trimethyl phosphate; nitrile solvents such as 3-methoxypropionitrile; and dendrimers
  • chain alkyl esters such as methyl propionate, chain phosphate triesters such as trimethyl phosphate
  • nitrile solvents such as 3-methoxypropionitrile
  • dendrimers Representative non-aqueous solvents (organic solvents) such as branched compounds having ether bonds.
  • fluorine-based solvents can also be used.
  • lithium perchlorate organic boron lithium salt, lithium salt of fluorine-containing compound, lithium imide salt, and the like are preferable.
  • the concentration of the electrolyte lithium salt in the non-aqueous electrolyte for example, 0.3 mol/L (mole/liter) or more is preferable, more preferably 0.7 mol/L or more, preferably 1.7 mol/L or less, and more preferably 1.2 mol/L or less .
  • concentration of the electrolyte lithium salt is too low, the ion conductivity is too low, and when it is too high, there is a fear of precipitation of the electrolyte salt that has not been completely dissolved.
  • various additives that can improve the performance of the battery using it can also be added, and it is not particularly limited.
  • the epoxy resin or urea-formaldehyde resin-modified ceramic separator and the non-aqueous electrolyte secondary battery using the epoxy resin or urea-formaldehyde resin-modified ceramic separator of the present invention have excellent physical and chemical properties. Therefore, by taking advantage of this characteristic, the non-aqueous electrolyte secondary battery of the present invention can be applied not only to secondary batteries for driving power sources of mobile information devices such as mobile phones and notebook computers, but also to various devices such as electric vehicles. Power supply.
  • the ceramic diaphragm is coated with epoxy resin or urea-formaldehyde resin, and the ceramic particle layer, the surface of the porous base film and the pore wall can be bonded and connected into a whole through epoxy resin and urea-formaldehyde resin.
  • the three-dimensional composite protective layer composed of epoxy resin or aldehyde resin and ceramic particle layer improves the heat treatment stability of the separator and maintains strong mechanical strength at 200°C, which can effectively block the contact between the positive and negative electrodes and protect the battery The safety performance.
  • the porous base film melts and closes the cells at a temperature of 130 ⁇ 140°C to form a dense layer, which cuts off the transmission channel of lithium ions in the diaphragm.
  • the three-dimensional protective layer composed of epoxy resin or urea resin ceramic layer maintains dimensional stability. Prevent the negative terminal of the battery from contacting and short-circuit.
  • the synergistic effect of epoxy resin, urea-formaldehyde resin protective layer, ceramic layer and porous base membrane gives the epoxy resin and urea-formaldehyde resin modified ceramic separator a thermal blocking function to prevent further thermal runaway of the battery at high temperatures.
  • the epoxy resins and urea-formaldehyde resin materials selected in the present invention there are O atoms that can hydrogen bond with the H atoms on the porous base film such as pp, and the hydrogen bonding interaction between the epoxy resin and urea-formaldehyde resin and the base film It can better make the epoxy resin or urea-formaldehyde resin three-dimensional coating layer adhere to the base film.
  • its O atoms and the hydroxyl groups on the surface of the ceramic particles may also have similar interactions, strengthening the interaction between the resin layer and the ceramic particle layer. effect.
  • the epoxy resin and urea-formaldehyde resin materials selected in the present invention can penetrate into the pores of the porous base membrane well under the action of the polar functional groups, and form a thin layer on the wall surface of the pores of the diaphragm.
  • the uniform polymer coating layer, epoxy resin and urea-formaldehyde resin have a low curing shrinkage rate, generally 1-2%, which will not block the micropores of the diaphragm, and affect the porosity and air permeability of the diaphragm.
  • the coating can ensure sufficient ion conduction channels so as not to negatively affect the battery performance.
  • the preparation method used in the present invention is simple and low in cost.
  • epoxy resin and urea-formaldehyde resin are cheap and easy to obtain, can be cured at low temperatures, and have good electrochemical stability.
  • the prepared epoxy resin modified ceramic separator can be directly used in batteries without cleaning, and is easy to realize industrialization. Production, it is expected to replace the existing ceramic diaphragm, realize industrial application, and improve the safety performance of lithium-ion power batteries.
  • Figure 1 is a comparison diagram of Example 1 (right) and Comparative Example 1 (left) after heat treatment at 160°C for 30 min.
  • Example 4 is a comparison diagram of scanning electron microscopes of Example 1 and Comparative Example 1;
  • Example 5 is a histogram of the pore size distribution of the diaphragm of Example 1 and Comparative Example 1;
  • Fig. 7 is a comparison diagram of Example 4 before (left) and after (right) heat treatment at 160°C for 30 min.
  • Example 1 and Example 4 Example 5 and Example 6 in comparison of the thickness of the coating layer.
  • Figure 8 is a scanning electron micrograph of Example 10 and Comparative Example 6
  • Figure 9 is a histogram of the pore size distribution of the diaphragm in Example 10 and Comparative Example 6
  • Example 10 is a comparison diagram of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 10 and the silica ceramic diaphragm prepared in Comparative Example 6 after heat treatment at 165° C. for 30 minutes.
  • Fig. 11 is a test diagram of mechanical properties of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 10 after heat treatment at 200° C. for 30 min.
  • Figure 12 is a graph showing the adhesion test between the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 10 and the silica ceramic diaphragm prepared in Comparative Example 6
  • FIG. 13 is a comparison diagram of the thermal interruption function test of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 13 of the present invention and the magnesium oxide ceramic diaphragm prepared in Comparative Example 7.
  • FIG. 13 is a comparison diagram of the thermal interruption function test of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 13 of the present invention and the magnesium oxide ceramic diaphragm prepared in Comparative Example 7.
  • FIG. 14 is a cycle performance test diagram of a battery equipped with a urea-formaldehyde resin modified ceramic separator (prepared in Example 10) in Example 14 of the present invention and a battery equipped with a silica ceramic separator in Comparative Example 8 (prepared in Comparative Example 6).
  • the thickness of the coating or protective layer referred to in this specification refers to the thickness in the pores of the diaphragm or the thickness on the plane of the outer coating or protective layer of the ceramic layer of the diaphragm.
  • the calculation method in this manual is to estimate the thickness of the coating layer through the reduction of the average pore diameter.
  • the above synthesized epoxy resin is dissolved in acetone solvent to prepare a solution with a mass dispersion of 5%, adding 0.5% of the curing agent diethylene triamine and 0.1% of the curing accelerator resorcinol to obtain an epoxy resin solution Coated on a silicon dioxide ceramic diaphragm, dried and cured in an oven at 45°C for 12 hours.
  • the epoxy resin modified ceramic diaphragm is obtained.
  • magnesium oxide ceramic particles with a particle size of about 200nm, 6 parts by mass of styrene-butadiene rubber, 4 parts by mass of sodium carboxymethyl cellulose, and a water/acetone mixture with a volume ratio of 2:1 to prepare solid content 10% (mass fraction) of ceramic slurry is coated on the surface of a single layer of a commercial polyethylene (PE) diaphragm, and dried to remove the solvent to obtain a magnesium oxide ceramic diaphragm.
  • PE polyethylene
  • the above-mentioned synthetic epoxy resin is dissolved in xylene solvent, and it is configured into a 5% (mass fraction) solution.
  • the epoxy resin modified ceramic diaphragm is obtained.
  • the above-mentioned synthetic epoxy resin is dissolved in acetone solvent to prepare a solution with a mass dispersion of 3%, adding 0.5% of the curing agent diethylene triamine and 0.1% of the curing accelerator resorcinol to obtain an epoxy resin solution Coated on a silicon dioxide ceramic diaphragm, dried and cured in an oven at 45°C for 12 hours.
  • the epoxy resin modified ceramic diaphragm is obtained.
  • the above-mentioned synthetic epoxy resin is dissolved in acetone solvent to prepare a solution with a mass dispersion of 10%, adding 0.5% of the curing agent diethylene triamine and 0.1% of the curing accelerator resorcinol to obtain an epoxy resin solution Coated on a silicon dioxide ceramic diaphragm, dried and cured in an oven at 45°C for 12 hours.
  • the epoxy resin modified ceramic diaphragm is obtained.
  • a battery includes a positive electrode material and a negative electrode material, and the epoxy resin modified ceramic separator prepared in Example 1 is arranged between the positive electrode material and the negative electrode material.
  • a battery includes a positive electrode material and a negative electrode material, and the epoxy resin modified ceramic separator prepared in Example 2 is arranged between the positive electrode material and the negative electrode material.
  • a battery includes a positive electrode material and a negative electrode material, and the epoxy resin modified ceramic separator prepared in Example 3 is arranged between the positive electrode material and the negative electrode material.
  • magnesium oxide ceramic particles with a particle size of about 200nm, 6 parts by mass of styrene-butadiene rubber, 4 parts by mass of sodium carboxymethyl cellulose, and a water/acetone mixture with a volume ratio of 2:1 to prepare solid content 10% (mass fraction) of ceramic slurry is coated on the double-layer surface of a commercial polyethylene (PE) diaphragm, and dried to remove the solvent to obtain a magnesium oxide ceramic diaphragm.
  • PE polyethylene
  • the above-mentioned synthetic epoxy resin was dissolved in acetone solvent and prepared into a 30% solution by mass fraction.
  • the curing agent diethylene triamine 0.5% (mass fraction) was added, and the curing accelerator resorcinol 0.1% (mass fraction) ), the obtained epoxy resin solution was coated on the silica ceramic diaphragm, dried and cured in an oven at 45° C. for 12 hours.
  • the epoxy resin modified ceramic diaphragm is obtained.
  • a battery includes a positive electrode material and a negative electrode material, and there is a silica ceramic separator prepared in Comparative Example 1 between the positive electrode material and the negative electrode material.
  • Figure 1 is a comparison diagram of Example 1 (right) and Comparative Example 1 (left) after heat treatment at 160°C for 30 minutes. As can be seen from the figure, the epoxy resin modified ceramic diaphragm of Example 1 and the ceramic diaphragm of Comparative Example 1 were heat-treated at 160° C. for 30 minutes. The epoxy resin-modified diaphragm of Example 1 did not shrink, while the ceramic diaphragm of Comparative Example 1 had already shrunk significantly.
  • Figure 2 is a graph showing the tensile strength properties of Example 2 and Comparative Example 2 at different temperatures. As can be seen from the figure, as the temperature increases, Comparative Example 2 quickly loses its mechanical strength. At 150°C, it only has a tensile strength of 20MPa. When the temperature exceeds 180°C, it melts completely and loses its mechanical strength. . In contrast, Example 2 maintained a tensile strength exceeding 35 MPa at 150°C, and maintained a tensile strength of about 15 MPa between 170°C and 220°C.
  • Fig. 3 is a comparison diagram of the thermal interruption function test of Example 3 and Comparative Example 3.
  • the PE base film melts and blocks the pores, blocking the lithium ion channel in the battery, and the impedance rapidly increases by 10,000 times.
  • the ceramic diaphragm of Comparative Example 3 shrinks, resulting in a short circuit between the positive and negative electrodes, and the impedance is rapidly reduced.
  • the epoxy resin modified ceramic diaphragm still maintains good dimensional stability and can effectively block the positive and negative electrodes. Contact short circuit to prevent further thermal runaway of the battery.
  • Example 4 is a scanning electron microscope image of the epoxy resin modified ceramic diaphragm prepared in Example 1 and the silica ceramic diaphragm prepared in Comparative Example 1 without ceramic slurry surface. It can be seen from the figure that after the epoxy resin is coated, the pores of the diaphragm are not significantly reduced. This proves that the epoxy resin has good film-forming properties and the thickness of the epoxy resin coating layer is thin under the parameter conditions described in the examples.
  • Figure 5 is a histogram of the pore size distribution of the epoxy resin modified ceramic diaphragm prepared in Example 1 and the silica ceramic diaphragm prepared in Comparative Example 1.
  • the pore size distribution of both conforms to the normal distribution, which can be seen As a whole, the pore diameter of the epoxy resin-modified ceramic diaphragm in Example 1 is slightly smaller than the pore diameter of the silica ceramic diaphragm in Comparative Example 1.
  • the average pore diameter of Example 1 is 103 nm
  • the average pore diameter of Comparative Example 1 is 114 nm.
  • the average thickness of the epoxy resin coating layer in Example 1 is about 5.5 nm.
  • Example 7 and Comparative Example 5 Cycle performance test diagrams of Example 7 and Comparative Example 5. As can be seen from the figure, both Example 7 and Comparative Example 5 have relatively good cycle performance. Compared with Comparative Example 5, the 100-cycle cycle performance of Example 7 is not significantly different. It shows that the epoxy resin modified ceramic diaphragm prepared by the present invention has no negative influence on the battery performance.
  • Table 1 is the air permeability comparison table of Example 1, Comparative Example 1, and Comparative Example 4. As shown in the table, the epoxy resin-modified ceramic diaphragm prepared in Example 1 is compared with the two prepared in Comparative Example 1. The permeability and conductivity of the silicon oxide ceramic diaphragm have decreased, but the degree of decrease is extremely limited. The epoxy resin coating layer of the epoxy resin modified diaphragm is thin and uniform, and there is no problem of blocking the pores of the diaphragm. The air permeability and electrical conductivity of the diaphragm cause too much influence. In Comparative Example 4, the air permeability and conductivity of the high-concentration epoxy-modified ceramic diaphragm decreased sharply.
  • the epoxy resin cannot form a thin and uniform epoxy resin layer on the ceramic diaphragm. It will block the pores of the diaphragm and severely degrade the permeability and conductivity of the diaphragm. It can be seen from the above results.
  • the preferred epoxy resin coating material of the present invention can form a coating layer with a suitable thickness on the ceramic diaphragm without affecting the key performance air permeability and electrical conductivity of the diaphragm.
  • Table 2 is a comparison table of the thickness of the pore coating layer of Example 1, Example 4, Example 5, and Example 6. Table 2 is intended to illustrate how different epoxy resin concentrations affect the average thickness of the epoxy resin layer coated on the pores of the diaphragm.
  • the average thickness of the epoxy resin coating layer is calculated by calculating the average pore size of the epoxy resin modified diaphragm and the unmodified diaphragm (the specific method has been described in detail in the description of FIG. 5). It can be seen from the table that as the concentration of epoxy resin increases, the thickness of the epoxy resin coating layer also increases. When the epoxy concentration is low (Example 4), the average thickness of the epoxy resin coating layer is also correspondingly increased. It is thinner and cannot support the diaphragm, and its high temperature resistance is limited.
  • the heat resistance test result is shown in Figure 7.
  • the epoxy concentration is high, the average thickness of the epoxy coating layer is correspondingly relatively thick.
  • a coating that is too thin will affect the effect of the epoxy resin coating to inhibit the thermal shrinkage of the ceramic diaphragm and improve the mechanical strength, while a coating that is too thick will affect the permeability of the ceramic diaphragm and further reduce its electrical conductivity.
  • aqueous solution containing 30% formaldehyde, 25% urea, and 0.3% alkaline catalyst adjust the pH to 9, react at 90°C for 30 minutes, and then add 10% formaldehyde, 15% urea, and 0.8% acidity.
  • Catalyst, 1% aqueous solution of modifier adjust the pH to 5, react at 90°C for about 25 minutes until the viscosity appears turbid, add alkaline catalyst to terminate the polycondensation reaction, and at the same time, add appropriate amount of urea to react with the free formaldehyde in the solution , Keep the reaction temperature at 90°C. After the reaction is over, cool and discharge.
  • Step three preparation of urea-formaldehyde resin modified ceramic diaphragm:
  • the urea-formaldehyde resin synthesized above is dissolved in a 1:1 water/ethanol solvent and configured into a 50g/L solution, 0.5 parts by mass of the curing agent resorcinol and 0.1 parts by mass of the curing accelerator trimethyl phosphate are added to obtain The urea-formaldehyde resin solution is coated on the silica ceramic diaphragm, dried and cured in an oven at 70° C. for 12 hours to obtain a urea-formaldehyde resin modified ceramic diaphragm.
  • Example 8 is a scanning electron microscope image of the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 10 and the silica ceramic diaphragm prepared in Comparative Example 6 on the uncoated surface of the ceramic slurry. It can be seen from the figure that the pores of the diaphragm are not significantly reduced after being coated with urea-formaldehyde resin. This proves that the urea-formaldehyde resin has good film-forming properties and the thickness of the urea-formaldehyde resin coating layer is thin under the parameter conditions described in the examples.
  • Figure 9 is a histogram of the pore size distribution of the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 10 and the silica ceramic diaphragm prepared in Comparative Example 1.
  • the pore size distribution of both conforms to the normal distribution. It can be seen that, On the whole, the pore diameter of the urea-formaldehyde resin-modified ceramic diaphragm in Example 10 is slightly smaller than the pore diameter of the silica ceramic diaphragm in Comparative Example 6. According to statistics, the average pore diameter of Example 10 is 143 nm, and the average pore diameter of Comparative Example 1 is 156 nm. It can be estimated that the average thickness of the urea-formaldehyde resin coating layer in Example 10 is about 6.5 nm.
  • Example 11 is a comparison diagram of the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 10 (right) and the unmodified silica ceramic diaphragm prepared in Comparative Example 6 (left) after heat treatment at 165°C for 30 minutes.
  • the urea-formaldehyde resin-modified ceramic diaphragm of Example 10 and the silica-ceramic diaphragm of Comparative Example 6 were heat-treated at 160°C for 30 minutes, and the urea-formaldehyde resin-modified ceramic diaphragm of Example 10 did not shrink, while the urea-formaldehyde resin-modified ceramic diaphragm of Comparative Example 6 did not shrink.
  • the silica ceramic diaphragm has shrunk significantly.
  • Fig. 12 is a test diagram of mechanical properties of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 10 after heat treatment at 200° C. for 30 min. As can be seen from the figure, after heat treatment at 200°C for 30 minutes, the urea-formaldehyde resin-modified ceramic separator of Example 10 still maintains a relatively high mechanical strength, which can effectively block the contact between the positive and negative electrodes and ensure the safety performance of the battery.
  • FIG. 13 is a graph showing the adhesion test between the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 10 and the silica ceramic diaphragm prepared in Comparative Example 6.
  • FIG. 13 the urea-formaldehyde resin-modified ceramic diaphragm of Example 10 has improved adhesion of the ceramic layer compared with the silica ceramic diaphragm of Comparative Example 6.
  • the urea-formaldehyde resin-modified ceramic diaphragm of Example 10 The resin three-dimensional protective layer has better adhesion and can better adhere the ceramic particle layer to the base film.
  • Step one synthesize urea-formaldehyde resin: prepare an aqueous solution containing 40% acetaldehyde, 25% urea, and 0.5% alkaline catalyst in terms of mass percentage, adjust the pH to 8.5, react at 90°C for 30 minutes, and then add acetaldehyde 10 %, urea 20%, 0.5% acidic catalyst, 1% modifier aqueous solution, adjust the pH to 5.5, react at 90°C for about 25 minutes to the point where the viscosity appears turbidity, add alkaline catalyst to terminate the polycondensation reaction, at the same time, Add an appropriate amount of urea to react with free acetaldehyde in the solution, keeping the reaction temperature at 90°C. After the reaction is over, cool and discharge.
  • Step 2 Preparation of urea-formaldehyde resin modified ceramic diaphragm: 6 parts by mass of urea-formaldehyde resin, 2 parts by mass of gelatin, 2 parts by mass of polyvinyl alcohol, 0.5 parts by mass of ammonium sulfate, 0.1 parts by mass of zinc sulfate, and particles with a particle size of about 200 nm are prepared.
  • urea-formaldehyde resin ceramic slurry with a solid content of 15%, and the above-mentioned urea-formaldehyde resin ceramic slurry is coated on a commercial polyethylene (PE) diaphragm Single layer surface. After standing and aging at 75°C for 10h, a urea-formaldehyde resin modified ceramic diaphragm was obtained.
  • PE polyethylene
  • a water/ethanol volume ratio 2:1 mixed solution containing 10% formaldehyde, 10% urea, and 0.6% alkaline catalyst is prepared, the pH value is adjusted to 8, and the solution is reacted to an appropriate viscosity at 95°C.
  • magnesium oxide ceramic particles with a particle size of about 500nm 100 parts by mass of magnesium oxide ceramic particles with a particle size of about 500nm
  • PP polypropylene
  • FIG. 13 is a comparison diagram of the thermal interruption function test of the urea-formaldehyde resin modified ceramic diaphragm prepared in Example 13 of the present invention and the magnesium oxide ceramic diaphragm prepared in Comparative Example 7.
  • FIG. 13 As can be seen from the figure, when the temperature rises to about 157°C, the PP base film melts and blocks the pores, blocking the lithium ion channel in the battery, and the impedance rapidly increases to several thousand ohms. When the temperature continued to rise to 178°C, the magnesium oxide ceramic separator of Comparative Example 7 contracted, resulting in a short circuit between the positive and negative electrodes, and the impedance rapidly decreased. However, the urea-formaldehyde resin-modified ceramic separator of Example 13 still maintained good dimensional stability and performance. Effectively block the short circuit of the positive and negative electrodes to prevent further thermal runaway of the battery.
  • magnesium oxide ceramic particles with a particle size of about 500nm 100 parts by mass of magnesium oxide ceramic particles with a particle size of about 500nm
  • PP polypropylene
  • a lithium ion battery includes a positive electrode material and a negative electrode material, and a silica aluminum ceramic separator prepared in Comparative Example 1 is provided between the positive electrode material and the negative electrode material.
  • silica ceramic diaphragm is immersed in a polyurethane solution, dried and cured in an oven at 70° C. for 12 hours to obtain a polyurethane modified ceramic diaphragm.
  • Step one prepare urea-formaldehyde resin: prepare an aqueous solution containing 30% formaldehyde, 25% urea, and 0.3% alkaline catalyst based on mass percentage, adjust the pH to 9, react at 90°C for 30 minutes, and then add 10% formaldehyde, An aqueous solution of 15% urea, 0.8% acid catalyst, and 1% modifier, adjust the pH to 5, and react at 90°C for about 25 minutes to the point where the viscosity appears turbid. Add alkaline catalyst to terminate the polycondensation reaction, and at the same time, add an appropriate amount Urea reacts with free formaldehyde in the solution, keeping the reaction temperature at 90°C. After the reaction is over, cool and discharge.
  • Step two prepare a ceramic diaphragm: mix 95 parts by mass of silica ceramic particles with a particle size of about 300 nm, 3 parts by mass of styrene butadiene rubber, 2 parts by mass of sodium carboxymethyl cellulose, and the solvent is water/volume ratio 1:1.
  • the ethanol mixture is formulated into a ceramic slurry with a solid content of 10%, coated on the surface of a single layer of a commercial polyethylene (PE) diaphragm, and dried to remove the solvent to obtain a silica ceramic diaphragm.
  • PE polyethylene
  • Step three preparing the urea-formaldehyde resin modified ceramic diaphragm: dissolve the synthetic urea-formaldehyde resin in a 1:1 water/ethanol solvent, configure it into a 300g/L solution, add 0.5 parts by mass of the curing agent resorcinol to promote curing 0.1 parts by mass of trimethyl phosphate, the obtained urea-formaldehyde resin solution was coated on the silica ceramic diaphragm, dried and cured in an oven at 70° C. for 12 hours to obtain a urea-formaldehyde resin modified ceramic diaphragm.
  • Table 1 The air permeability and electrical conductivity of urea-formaldehyde resin modified ceramic diaphragm, silica ceramic diaphragm, and polyurethane modified ceramic diaphragm are shown in Table 1.
  • the urea-formaldehyde resin-modified ceramic diaphragm prepared in Example 1 has decreased air permeability and electrical conductivity compared to the silica ceramic diaphragm prepared in Comparative Example 6, but the degree of decrease is extremely limited. This shows that under reasonable parameter conditions, the urea-formaldehyde resin coating layer of the urea-formaldehyde resin-modified membrane is thin and uniform, there is no problem of blocking the pores of the membrane, and it will not cause much influence on the air permeability and electrical conductivity of the membrane.
  • the polyurethane-modified ceramic diaphragm prepared in Comparative Example 9 has a sharp decrease in air permeability and electrical conductivity. This shows that the modification of polyurethane did not form a thinner coating layer, but seriously blocked the pores of the diaphragm.
  • Comparative Example 10 a urea-formaldehyde resin modified ceramic diaphragm made of a high-concentration urea-formaldehyde resin was used for air permeability and conductivity. The rate has also been greatly reduced.
  • non-preferred polymer coating materials may cause problems such as membrane blockage, which will seriously affect the air permeability and electrical conductivity of the modified membrane.
  • the coating modification of urea-formaldehyde resin needs to be reasonably controlled. Key parameters such as concentration, so as to avoid the formation of too thick urea-formaldehyde resin coating.
  • a lithium ion battery includes a positive electrode material and a negative electrode material, and the urea-formaldehyde resin modified ceramic separator prepared in Example 1 is arranged between the positive electrode material and the negative electrode material.
  • FIG. 14 is a cycle performance test diagram of a battery equipped with a urea-formaldehyde resin modified ceramic separator (prepared in Example 10) in Example 14 of the present invention and a battery equipped with a silica ceramic separator in Comparative Example 8 (prepared in Comparative Example 01).
  • the battery equipped with a urea-formaldehyde resin-modified ceramic separator (prepared in Example 10) in Example 14 and the battery equipped with a silica ceramic separator in Comparative Example 8 (prepared in Comparative Example 10) have relatively good cycle performance.
  • the 100-cycle capacity retention rate is above 98%, and the coulombic efficiency is close to 100%, indicating that the urea-formaldehyde resin-modified ceramic separator prepared by the invention has no negative impact on battery performance.
  • a lithium ion battery includes a positive electrode material and a negative electrode material, and the urea-formaldehyde resin modified ceramic separator prepared in Example 2 is arranged between the positive electrode material and the negative electrode material.
  • a lithium ion battery includes a positive electrode material and a negative electrode material. Between the positive electrode material and the negative electrode material, there is the urea-formaldehyde resin modified ceramic separator prepared in Example 3.
  • a lithium ion battery includes a positive electrode material and a negative electrode material, and the urea-formaldehyde resin modified ceramic separator prepared in Example 4 is arranged between the positive electrode material and the negative electrode material.
  • the epoxy resin or urea-formaldehyde resin modified ceramic diaphragm provided by the present invention includes a porous base membrane.
  • the epoxy resin or urea-formaldehyde resin infiltrates into the ceramic diaphragm and solidifies on the surface of the inorganic ceramic particles, the surface of the porous base membrane and the micropores of the ceramic diaphragm.
  • a protective layer of epoxy resin or urea-formaldehyde resin is formed between the walls of the holes. Due to the characteristics of epoxy resin or urea-formaldehyde resin, the protective layer is uniform and will not block the micropores of the porous base film.
  • the epoxy resin or urea-formaldehyde resin protective layer can be formed by coating and curing the epoxy or urea-formaldehyde resin ceramic slurry on the single-layer or double-layer surface of the porous base film, or it can be formed by in-situ polymerization of the ceramic-coated porous base film.
  • Epoxy resin or urea-formaldehyde resin can also be formed by coating a layer of epoxy resin or urea-formaldehyde resin solution on the prepared ceramic diaphragm and curing it, which has industrial practicability.

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Abstract

一种环氧树脂或脲醛树脂改性陶瓷隔膜，包括多孔基膜，环氧树脂或脲醛树脂渗入陶瓷隔膜中固化，在陶瓷隔膜的无机陶瓷颗粒表面、多孔基膜表面和微孔孔壁并其之间形成了环氧树脂或脲醛树脂保护层。由于环氧树脂或脲醛树脂本身的特性，该保护层是均匀的，且不会堵住多孔基膜的微孔。所述的环氧树脂或脲醛树脂保护层可以通过在多孔基膜单层或者双层表面涂覆环氧或脲醛树脂陶瓷浆料并固化形成，也可以通过陶瓷涂覆的多孔基膜原位聚合环氧树脂或脲醛树脂形成，还可以通过在制备好的陶瓷隔膜上涂覆一层环氧树脂或脲醛树脂溶液并固化形成。

Description

一种改性陶瓷隔膜及其制备方法和应用 技术领域
本发明涉及电池隔膜，及电池，电容器等产品，具体是耐高温陶瓷隔膜、制备方法及所应用的电池。
背景技术
锂离子电池作为一种能量密度高、输出电压高、无记忆效应、循环性能优异、环境友好的化学电源体系，具有很好的经济效益、社会效益和战略意义，已被广泛应用于移动通讯、数码产品等各个领域，并极有可能成为储能和电动汽车领域最主要的电源系统。
常规锂离子电池主要有正极，负极，隔膜，电解液几部分组成。其中，隔膜主要起到防止正负极接触并允许离子传导的作用，是电池重要的组成部分。目前，商品化的锂离子电池中采用的主要是具有微孔结构的聚烯烃类隔膜材料，如聚乙烯(Polyethylene,PE)、聚丙烯(Polypropylene,PP)的单层或多层膜。由于聚烯烃隔膜的熔融温度低，热稳定性不好(PE约为130℃,PP约为160℃)，虽然聚烯烃隔膜在常温下可以提供足够的机械强度和化学稳定性，但在高温条件下则表现出较大的热收缩，从而导致正负极接触短路并引发热失控，加剧热量积累，产生电池内部高气压，引起电池燃烧或爆炸。
为了满足大容量锂离子电池发展的需要，开发高安全性隔膜已成为行业的当务之急。陶瓷隔膜优异的耐温性和高安全性使其成为取代传统聚烯烃隔膜的主要选择之一。
陶瓷隔膜(Ceramic-coated Separators)是在现有的聚烯烃微孔膜基材的表面上，单面或双面涂布一层均匀的、由陶瓷微颗粒等构成的保护层形成的安全性功能隔膜。在保证聚烯烃微孔隔膜原有基本特性的基础上，通过陶瓷层的引入赋予隔膜高耐热功能，拉开隔膜闭孔温度和熔融温度之间的温度差，从而更有效地减少锂离子电池内部短路，防止因电池内部短路而引起的电池热失控。
然而，现有的陶瓷隔膜热稳定还是非常有限。主要是由于无机陶瓷颗粒通过粘结剂粘附在聚烯烃隔膜基膜表面，当温度到达基膜熔点时，基膜熔化，陶瓷颗粒的存在虽然对隔膜的收缩起到一定的阻碍作用，但是不能完全抑制其收缩。例如以PE为基膜的AI 2O 3陶瓷隔膜,当温度升高到130℃时，PE基膜融化，由于Al 2O 3陶瓷颗粒的收缩阻力作用使陶瓷隔膜不收缩，但是当温度继续升高到在150℃以上时Al 2O 3陶瓷涂覆层就会跟随基膜一起收缩。而且随着基膜的融化，隔膜的机械性能也大幅降低，由于陶瓷层无法自支撑成膜，最终导致隔膜粉化，仍然会引起正负极接触短路。显然，单纯的陶瓷隔膜无法满足电池高安全性的应用的需求。
CN107785520A提供的锂离子电池隔膜包括多孔基膜以及覆盖在所述多孔基膜的至少一侧表面上的耐热层；所述耐热层含有耐高温聚合物以及无机纳米颗粒，且所述耐热层具有纤维网络状结构。提供的锂离子电池隔膜在高温下(＞160℃)不仅具有很好的稳定性，高温热收缩率很小，而且高温机械强度好，比单纯采用耐高温聚合物纺 丝得到的复合隔膜的耐热性和高温机械强度要好很多，而普通陶瓷(CCL)隔膜由于采用不耐热聚合物，在高温下要么表现出很大的热收缩，要么高温下出现聚合物融化而陶瓷颗粒之间连接松散的现象，从而使得整个锂离子电池隔膜不具有很高的机械强度。其耐热层采用纤维网结构，实现难度大，制备过程复杂。
发明内容
为了解决以上问题，本发明提出一种在陶瓷隔膜基础上研发的改性陶瓷隔膜。本发明的一个目的是提供由这种发明方法制备的改性陶瓷隔膜，可以有效抑制基膜的热缩，在达到基膜熔融温度时，仍保持改性陶瓷隔膜的基本膜形态。本发明提出的环氧树脂改性陶瓷隔膜具有极其优异的热稳定性和机械性能。同时，本发明成本低廉，制备过程操作简单，适合大规模生产。
本发明的另一个目的在于提供一种含有上述方法制备的改性陶瓷隔膜的锂离子电池。
本发明的另一个目的是提供由这种发明方法制备的陶瓷改性隔膜在化学电源体系的应用，尤其是在锂离子电池中的应用。
为实现上述目的，本发明的一种技术方案是采用环氧树脂改性陶瓷隔膜，具体方案如下：
本发明提供的一种环氧树脂改性陶瓷隔膜，包括多孔基膜，环氧树脂渗入陶瓷隔膜中固化，在陶瓷隔膜的无机陶瓷颗粒表面、多孔基膜表面和微孔孔壁并其之间形成了环氧树脂保护层。由于环氧树脂本身的特性，该保护层是薄而均匀的，且不会堵住多孔基膜的微孔。所述的环氧树脂保护层可以通过在多孔基膜单层或者双层表面涂覆环氧树脂陶瓷浆料并固化形成，也可以通过陶瓷涂覆的多孔基膜原位聚合环氧树脂形成，还可以通过在制备好的陶瓷隔膜上涂覆一层环氧树脂溶液并固化形成；所述的环氧树脂保护层的单面厚度为0.5nm～40nm,优选3-10nm。
更具体的，可以将环氧树脂与陶瓷浆料混合制备环氧树脂陶瓷浆料，然后将环氧树脂陶瓷浆料涂覆于多孔基膜的单面或者双面；
也可以先在多孔基膜单层或者双层表面涂覆陶瓷浆料，制备陶瓷隔膜，再将陶瓷隔膜浸渍在环氧树脂聚合单体的混合溶液中，原位聚合包覆环氧树脂；还可以先在多孔基膜上涂覆陶瓷浆料制成陶瓷隔膜，再在陶瓷隔膜上涂覆配制好的环氧树脂溶液，再固化形成环氧改性陶瓷隔膜。
进一步的，所述多孔基膜包括聚烯烃类多孔聚合物(聚乙烯、聚丙烯等)、聚四氟乙烯、聚偏氟乙烯、聚偏氟乙烯-六氟丙烯共聚物、聚氯乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰亚胺、聚乙烯吡咯烷酮、聚环氧乙烷、聚乙烯醇或者上述聚合物衍生的共混、共聚体系中的至少一种。
进一步的，所述的无机陶瓷颗粒的大小为10-1000nm,优选50-500nm，陶瓷层厚度为0.1-10μm,优选为2-5μm。
进一步的，所述的陶瓷浆料按重量百分比计含有5～80％的基料，余量为溶剂。所述基料由以下质量份的物质组成：粘结剂0.1-20质量份、陶瓷颗粒80-99.9质量份。
进一步的，所述的环氧树脂陶瓷浆料按重量百分比计含有5～80％的基料，余量为 溶剂。所述基料由以下质量份的物质组成：粘结剂0.1-20质量份、陶瓷颗粒60-99质量份、环氧树脂0.1-20质量份、固化剂0-5质量份，固化促进剂0-5质量份、表面活性剂0-5质量份，改性剂0-5质量份。
进一步的，所述环氧树脂是指在化学结构中，含有两个或者两个以上环氧基团的有机化合物，且通过环氧基团的开环反应，可形成热固性的高分子聚合物。所述环氧树脂的分子量用凝胶渗透色谱法测定重均分子量为100～5000。
进一步的，所述的环氧树脂聚合单体分为能导入或者能生成环氧基团的化合物(称为组分A)和具有两个或两个以上活泼氢的化合物、预聚物或含有两个或两个以上不饱和双键的化合物、预聚物(称为组分B)。
进一步的，所述的组分A，组分B混合溶液按重量百分比计，含组分A0.1～40％、组分B0.1～40％、催化剂0.01～8％、固化剂0.01～5％、固化促进剂0.01～5％、表面活性剂0.01～5％，添加剂0～5％，余量为溶剂。
进一步的，所述的催化剂包括但不限于碳酸钠、碳酸钾、吡啶、三乙胺、醋酸钠、氢氧化钠、氢氧化钾、季铵盐、季磷盐、胆碱等。
进一步的，所述的固化剂可选择多元胺，酸酐，酚醛，硫醇等加成聚合型固化剂，也可以选择催化型固化剂等其他显在型固化剂，还可以选择咪唑类等潜伏型固化剂。
进一步的，所述的固化促进剂根据固化剂的亲核、亲电性进行选择(亲核固化剂匹配亲电固化促进剂，亲电固化剂匹配亲核固化促进剂)。常用的固化促进剂有胺类，酚类，酸类，酰胺类等。
进一步的，所述的表面活性剂为硬脂酸、十二烷基苯磺酸钠、季铵化物、十六烷基磺酸钠、卵磷脂、氨基酸型、甜菜碱型、脂肪酸甘油酯，脂肪酸山梨坦、聚山梨酯中的至少一种。
本发明的另一技术方案是采用脲醛树脂改进陶瓷隔膜，具体如下：
一种脲醛树脂改性陶瓷隔膜，包括无机陶瓷颗粒和多孔基膜，该无机陶瓷颗粒的表面、多孔基膜的表面和多孔基膜的微孔的侧壁形成一连续的脲醛树脂层，该该脲醛树脂层的厚度为0.1nm～30nm，该脲醛树脂层通过涂覆脲醛树脂溶液或脲醛树脂陶瓷浆料而形成，该脲醛树脂溶液或脲醛树脂陶瓷浆料中脲醛树脂的浓度为1g/L～100g/L，脲醛树脂的重均分子量为100～5000。
在本发明的一个优选实施方案中，上述脲醛树脂层的厚度为2～10nm，上述脲醛树脂溶液或脲醛树脂陶瓷浆料中脲醛树脂的浓度5g/L～50g/L，上述脲醛树脂的重均分子量为500～2000。
在本发明的一个优选实施方案中，该脲醛树脂层可通过该多孔基膜表面涂覆脲醛树脂陶瓷浆料形成，或通过陶瓷涂覆的多孔基膜原位聚合脲醛树脂形成；更具体的，可以将脲醛树脂与陶瓷浆料混合制备脲醛树脂陶瓷浆料，然后将脲醛树脂陶瓷浆料涂覆于多孔基膜的单层或者双层表面；也可以先在多孔基膜单层或者双层表面涂覆陶瓷浆料，制备陶瓷隔膜，再将陶瓷隔膜浸渍在尿素、甲醛的混合溶液中，原位聚合包覆 脲醛树脂。
进一步地，上述多孔基膜的材料为聚烯烃或其衍生物、聚酯类或其衍生物、聚腈或其衍生物、聚酰胺或其衍生物、聚环氧烷烃或其衍生物、聚烯醇或其衍生物中的至少一种。
在本发明的一个优选实施方案中，上述陶瓷浆料由有机溶剂和5～80质量份基料组成，该陶瓷浆料的固液比优选10％、12％、15％；该基料成分为粘结剂0.1～20质量份、陶瓷颗粒60～99.9质量份。脲醛树脂陶瓷浆料含有5～80质量份的基料，余量为有机溶剂，该基料由粘结剂0.1～20质量份、陶瓷颗粒60～99.9质量份、脲醛树脂0.1～20质量份、固化剂0～5质量份，固化促进剂0～5质量份、表面活性剂0～5质量份，改性剂0～5质量份。
在本发明的一个优选实施方案中，脲醛树脂是尿素和醛类化合物的混合溶液，其中包括尿素与醛类化合物的混合物0.1～80质量份、催化剂0.01～8质量份、固化剂0.01～5质量份、固化促进剂0～5质量份、表面活性剂0～5质量份、改性剂0～5质量份。上述醛类化合物/尿素之摩尔比为0.6～3.0；该醛类化合物为甲醛、乙醛、丙醛、糠醛、多聚甲醛中的至少一种；
在本发明的一个优选实施方案中，上述催化剂为酸性催化剂或碱性催化剂；酸性催化剂为甲酸、盐酸、氯化铵、过硫酸铵、硫酸铵、草酸、硫酸、磷酸等中有机酸、无机酸或酸性盐类的至少一种；碱类催化剂为氢氧化钠、氢氧化钾、氢氧化钡、氢氧化钙、碳酸钠、碳酸钾、氧化钙、氨水、氧化镁、氧化钙、苯胺、碳酸钠、叔胺类化合物等有机碱、无机碱、碱性氧化物、碱性盐类等中的至少一种；
在本发明的一个优选实施方案中，上述固化剂为六氯化铵、六氟化铵、硫酸铵、硝酸铵、过硫酸铵等酸性盐类，或者间苯二酚、单宁、三聚氰胺等活性物质的至少一种；
在本发明的一个优选实施方案中，上述固化促进剂为硫酸锌、磷酸三甲酯、草酸二乙酯等中的至少一种；
在本发明的一个优选实施方案中，上述表面活性剂为硬脂酸、十二烷基苯磺酸钠、季胺化物、十六烷基磺酸钠、卵磷脂、氨基酸型、甜菜碱型、脂肪酸甘油酯、脂肪酸山梨坦、聚山梨酯中的至少一种；
在本发明的一个优选实施方案中，上述改性剂能够增强该脲醛树脂改性陶瓷隔膜的耐热性和耐水性。
在上述二种技术方案陶瓷隔膜可以是同样的，包括如下：
进一步的，所述的陶瓷颗粒为三氧化二铝、二氧化钛、二氧化硅、二氧化锆、二氧化锡、氧化镁、氧化锌、硫酸钡、氮化硼、氮化铝、氮化镁中的至少一种。所述陶瓷颗粒的粒径为5nm～10um。
进一步的，所述粘结剂为水系粘结剂或有机系粘结剂；
所述水系粘结剂是甲基纤维素钠和丁苯橡胶、明胶和聚乙烯醇、聚丙烯酸酯类三元共聚物乳胶中的至少一种；
所述有机系粘结剂是聚偏氟乙烯、聚偏氟乙烯-六氟丙烯、聚甲基丙烯酸甲酯中的至少一种。
进一步的，所述溶剂为甲醇、乙醇、异丙醇、正丁醇、丙酮、乙酸乙酯、乙酸正丁酯、二甲苯、乙腈、二甲基甲酰胺、二甲亚砜、二甲基乙酰胺、N-甲基吡咯烷酮，二氯甲烷、三氯甲烷等一种或多种有机溶剂。
进一步的，添加剂为能提高环氧树脂性能的各种添加剂，未作特别限定。
本发明提供的一种环氧树脂改性陶瓷隔膜的制备方案如下：
方案一：
1、合成环氧树脂：按质量百分比计，将组分A：1-40％、组分B：1-40％、碱性催化剂0.2-8％、溶剂10-95％的混合溶液在25-110℃下反应0.5-24h(可在不同温度下分段反应，也可以固定温度不分段反应，可以选择一次加碱性催化剂，也可以选择分批次加入碱性催化剂)，分离洗涤烘干，得到环氧树脂。
2、制备陶瓷隔膜：将陶瓷颗粒、粘结剂按一定比例混匀制成陶瓷浆料，并将制得的陶瓷浆料单面或双面涂覆于多孔基膜表面，烘干除去溶剂，即得到陶瓷隔膜。
3、配置质量分数为1-10％的环氧树脂溶液，优选为3-8％，加入0.01-5％的固化剂，0.01-5％的固化促进剂，0-5％的添加剂。通过喷涂，浸泡等方式使环氧树脂溶液充分浸润陶瓷隔膜，在25℃-110℃下烘干、固化0.5-24h。
方案二：
1.制备陶瓷隔膜：将陶瓷颗粒、粘结剂按一定比例混匀制成陶瓷浆料，并将制得的陶瓷浆料单面或双面涂覆于多孔基膜表面，烘干除去溶剂，即得到陶瓷隔膜。
2.制备环氧树脂改性陶瓷隔膜：配制一定浓度的组分A、组分B混合溶液，通过浓度调节，将A、B两组分总质量分数控制在1-10％之内的某个浓度值，优选为3-8％。将步骤1制备的陶瓷隔膜充分浸泡于上述组分A、组分B混合溶液中，取出并于25-110℃下反应0.5-24h(可在不同温度下分段反应，也可以固定温度不分段反应)，洗涤烘干，得到环氧树脂改性陶瓷隔膜。
本发明提供的一种脲醛树脂改性陶瓷隔膜的制备方案如下：
脲醛树脂改性陶瓷隔膜的制备方法一：
步骤一，合成脲醛树脂：将醛类化合物、尿素、碱性催化剂和适量水混合后，在pH 8～9、85～95℃下进行缩聚反应25～35min，上述醛类化合物、尿素和碱性催化 剂的质量比为1～40:1～40:0.1～1；再加入含有上述醛类化合物、尿素、酸性催化剂、改性剂的水溶液，在pH 5～6、85～95℃下进行缩聚反应反应25～35min，上述醛类化合物、尿素、酸性催化剂和改性剂的质量比为1～40:1～40:0.5～1:0.2～2；直至出现烟雾状浑浊点，接着加入碱性催化剂终止缩聚反应；然后在85～95℃下，加入适量的尿素，以消除其中游离的醛类化合物，冷却后即得该脲醛树脂；
步骤二，制备陶瓷隔膜：将无机陶瓷颗粒、粘结剂、羧甲基纤维素钠和适量溶剂混匀制成陶瓷浆料，将该陶瓷浆料涂覆于上述多孔基膜表面，烘干后即得该陶瓷隔膜；上述无机陶瓷颗粒、粘结剂、羧甲基纤维素钠的质量比为60～99:0.1～20:1～10；
步骤三，制备脲醛树脂改性陶瓷隔膜：将上述脲醛树脂、固化剂、固化促进剂和适量溶剂混合配制脲醛树脂溶液，将该脲醛树脂溶液涂覆在上述陶瓷隔膜上，在25～110℃固化0.5～24小时，即得上述脲醛树脂改性陶瓷隔膜；上述脲醛树脂、固化剂、固化促进剂的质量比为1～20:0.01～5:0～5；
上述步骤二和步骤三中的溶剂均为有机溶剂与水的混合溶液，该有机溶剂的体积分为10～100。
脲醛树脂改性陶瓷隔膜的制备方法二：
步骤一，合成脲醛树脂：方法同上；
步骤二，制备脲醛树脂改性陶瓷隔膜：将脲醛树脂、固化剂、固化促进剂、粘结剂、催化剂、无机陶瓷颗粒和适量溶剂混合配制脲醛树脂陶瓷浆料，将该脲醛树脂陶瓷浆料涂覆于多孔基膜表面，于25～100℃静置陈化1～24小时，即得该脲醛树脂改性陶瓷隔膜；上述脲醛树脂、固化剂、固化促进剂、粘结剂、催化剂、无机陶瓷颗粒的质量比为1～20:0.01～5:0～5:1～3:0.1～2:60～99。
上述步骤二中的溶剂均为有机溶剂与水的混合溶液，所述有机溶剂的体积分为10～100。
方法三：
步骤一，制备陶瓷隔膜：将无机陶瓷颗粒、粘结剂、羧甲基纤维素钠和适量溶剂混匀制成陶瓷浆料，将该陶瓷浆料涂覆于上述多孔基膜表面，烘干后即得该陶瓷隔膜；上述无机陶瓷颗粒、粘结剂、羧甲基纤维素钠的质量比为60～99:0.1～20:1～10；
步骤二，将醛类化合物、尿素、碱性催化剂和适量有机溶剂的混合液在pH 8～9、25～110℃下反应至适当粘度，冷却后加入固化剂、固化促进剂、表面活性剂；然后加入上述陶瓷隔膜，将该陶瓷隔膜充分浸泡后取出，在25～110℃下固化0.5～24小 时，即得该脲醛树脂改性陶瓷隔膜；上述醛类化合物、尿素、碱性催化剂、固化剂、固化促进剂、表面活性剂的质量比为1～40:1～40:0.0.1～2:0～5:0～5:0～5。
上述步骤一中的溶剂为有机溶剂与水的混合溶液，所述有机溶剂的体积分为10～100。
上述步骤二中混合液，醛类化合物与尿素的总质量分数为1％～40％，优选为5％～20％。
在本发明的一个优选实施方案中，上述有机溶剂为低级醇、丙酮、二甲基甲酰胺、二甲亚砜、二甲基乙酰胺和N-甲基吡咯烷酮中的至少一种。
本发明所述的涂覆方式不限，包括喷涂、刮涂、滚涂等方式。
本发明的另一个目的在于提供一种上述环氧树脂、脲醛树脂改性陶瓷隔膜在化学电源领域的应用，尤其是锂离子电池。
本发明的另一个目的在于提供一种锂离子电池，包括正极材料、负极材料，其特征在于：在正极材料和负极材料之间有本发明提供的环氧、脲醛树脂改性陶瓷隔膜。
通常锂离子电池使用的正极材料都可以在本发明中使用。正极涉及的正极活性物质，可以使用能可逆地嵌入与脱嵌Li +的化合物，例如，可以举出用Li xMO 2或Li yM 2O 4(式中，M为过渡金属，0≤x≤1，0≤y≤2)表示的含锂复合氧化物、尖晶石状的氧化物、层状结构的金属硫族化物、橄榄石结构等。
通常锂离子电池使用的负极材料都可以在本发明中使用。负极涉及的负极活性物质可以使用能够嵌入-脱嵌锂金属、锂的化合物。例如铝、硅、锡等的合金或氧化物、碳材料等各种材料等可以用作负极活性物质。氧化物可以举出二氧化钛等，碳材料可以举出石墨、热解碳类、焦炭类、玻璃状碳类、有机高分子化合物的烧成体、中间相碳微珠等。
用于构成非水电解液二次电池的负极，例如，在上述负极活性物质中适当添加炭黑、乙炔黑等导电助剂，或聚偏氟乙烯、聚环氧乙烷等粘合剂等，配制负极合剂，将其在以铜箔等集电材料作为芯材的带状成型体上涂布后使用。但是，负极的制作方法不仅仅限于上例。
在本发明提供的非水电解液二次电池中，使用非水溶剂(有机溶剂)作为非水电解液。非水溶剂包括碳酸酯类、醚类等。
另外，除上述非水溶剂外，可以采用丙酸甲酯等链状烷基酯类、磷酸三甲酯等链状磷酸三酯；3-甲氧基丙腈等腈类溶剂；以树枝状化合物为代表的具有醚键的支链型化合物等非水溶剂(有机溶剂)。
另外，也可采用氟类溶剂。
作为非水电解液中使用的电解质盐，优选锂的高氯酸盐、有机硼锂盐、含氟化合物的锂盐、锂酰亚胺盐等锂盐。
电解质锂盐在非水电解液中的浓度，例如，0.3mol/L(摩尔/升)以上是优选的，更优选0.7mol/L以上，优选1.7mol/L以下，更优选1.2mol/L以下。当电解质锂盐的浓度过低时，离子传导度过小，过高时，担心未能溶解完全的电解质盐析出。
另外，在非水电解液中，也可以添加能提高采用它的电池的性能的各种添加剂，未作特别限定。
本发明的上述环氧树脂或脲醛树脂改性陶瓷隔膜和利用上述环氧树脂或脲醛树脂改性陶瓷隔膜的非水电解液二次电池具有优异的物化特性。从而，利用这种特性，本发明的非水电解液二次电池不仅可以应用于手机、笔记本电脑等移动信息机器的驱动电源用二次电池，而且还可以广泛地应用于电动汽车等各种机器的电源。
通过采用上述技术方案，本发明的有益效果在于：
1、通过陶瓷隔膜基础上包覆环氧树脂或脲醛树脂，可以通过环氧树脂、脲醛树脂将陶瓷颗粒层，多孔基膜表面和孔壁，粘合联结成一个整体，环氧树脂固化收缩率低，一般为1-2％，环氧树脂或和脲醛树脂陶瓷颗粒层形成一个三维复合保护层，提高了隔膜的拉伸强度、剥离强度等机械性能。
2、环氧树脂或醛树脂和陶瓷颗粒层组成的三维复合保护层，提高了隔膜的热处理稳定性，并且在200℃下仍旧保持较强的机械强度，能有效阻隔正负极接触，保障电池的安全性能。
3、多孔基膜在130～140℃的温度下熔融闭孔，形成致密层，切断锂离子在隔膜中的传输通道，同时环氧树脂或脲醛树脂陶瓷层组成的三维保护层保持尺寸稳定性，防止电池负极接触短路。环氧树脂、脲醛树脂保护层、陶瓷层与多孔基膜的协同作用赋予环氧树脂、脲醛树脂改性陶瓷隔膜热遮断功能，防止电池高温下进一步热失控。
4、本发明所选的环氧树脂、脲醛树脂类材料中，具有能与pp等多孔基膜上H原子发生氢键作用的O原子，环氧树脂、脲醛树脂与基膜的氢键相互作用能够更好的使环氧树脂或脲醛树脂三维包覆层粘附结合与基膜上，同时，其O原子与陶瓷颗粒表面的羟基也可能存在类似相互作用，加强树脂层与陶瓷颗粒层的相互作用。
5、本发明所选择的环氧树脂、脲醛树脂类材料，在极性官能团的作用下，能够很好的渗入多孔基膜的微孔内，并在优先在隔膜微孔壁面附着形成一层薄而均匀的聚合物包覆层，环氧树脂、脲醛树脂固化收缩率低，一般为1-2％，不会堵住隔膜微孔，对隔膜的孔隙率、透气度的影响，在较薄的涂层上能确保足够的离子传导通道，从而不会对电池性能产生负面影响。
6、本发明所用的制备方法简单，成本低廉。特别的，环氧树脂、脲醛树脂廉价易得，可以在低温下固化，具有良好的电化学稳定性，所制备的环氧树脂改性陶瓷隔膜无需清洗即可直接应用于电池中，易于实现工业化生产，有望取代现有的陶瓷隔膜，实现工业化应用，提高锂离子动力电池的安全性能。
附图说明
图1实施例1(右)与对比例1(左)在160℃下热处理30min后对比图。
图2实施例2与对比例2在不同温度下的拉伸强度对比图
图3实施例3与对比例3热遮断功能测试对比图。
图4是实施例1和对比例1的扫描电镜对比图；
图5是实施例1和对比例1的隔膜孔径分布直方图；
图6实施例7与对比例5的循环性能测试图。
图7实施例4在160℃下热处理30min前(左)后(右)对比图。
表1实施例1与对比例1、对比例4的透气度、电导率比较表；
表2实施例1与实施例4、实施例5、实施例6的包覆层厚度比较表。
图8为实施例10与对比例6的扫描电镜图
图9是实施例10与对比例6中隔膜孔径分布直方图
图10为实施例10制得的脲醛树脂改性陶瓷隔膜与对比例6中制得的二氧化硅陶瓷隔膜在165℃下热处理30min后对比图。
图11为实施例10制得的脲醛树脂改性陶瓷隔膜在200℃热处理30min后的机械性能测试图。
图12为实施例10制得的脲醛树脂改性陶瓷隔膜与对比例6中制得的二氧化硅陶瓷隔膜的粘附力测试图
图13为本发明实施例13中所制得的脲醛树脂改性陶瓷隔膜与对比例7中制得的氧化镁陶瓷隔膜的热遮断功能测试对比图。
图14为本发明实施例14中具备脲醛树脂改性陶瓷隔膜(实施例10制备)的电池与对比例8中具备二氧化硅陶瓷隔膜(对比例6制备)的电池的循环性能测试图。
具体实施方式
下面将通过实施例进行更详细的描述，但本发明的保护范围并不受限于这些实施例。
本说明书中所指包覆层或保护层的厚度是指在隔膜的孔隙内的厚度或和隔膜陶瓷层外包覆层或保护层平面上的厚度。本说明书计算方法是通过孔隙孔径平均值的减小来推测包覆层的厚度
实施例1：
制备环氧树脂：
按双酚A：环氧氯丙烷＝1:6的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.08倍)，反应3h后，抽真空并继续滴加50％的NaOH水溶液，滴加时间在1.5-3h，滴加完碱性催化剂后，继续反应20min，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于丙酮溶剂中，配置成质量分散5％的溶液，加入固化剂二亚乙基三胺0.5％，固化促进剂间苯二酚0.1％，将得到环氧树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在45℃下烘干、固化12h。得到环氧树脂改性陶瓷隔膜。
实施例2
制备陶瓷隔膜：
将粒径约为400nm的三氧化二铝陶瓷颗粒92质量份、丁苯橡胶5质量份、羧甲基纤维素钠3质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量12％(质量分数)的陶瓷浆料，涂覆在商品化的聚丙烯(PP)隔膜双层表面，烘干除去溶剂，即得到三氧化二铝陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
按双酚F：环氧氯丙烷＝1:10的摩尔比将双酚F溶于环氧氯丙烷中，在氮气氛围下，升温到60℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚F分子的0.01倍)，反应6h,冷却。加入固化剂三亚乙基四胺2％(质量分数)，改性剂1％(质量分数)，加入20％的乙酸乙酯做溶剂(稀释剂)将环氧树脂溶液的浓度稀释到3％(质量分数)，将前述制备好的三氧化二铝陶瓷隔膜浸入环氧树脂溶液中，带环氧树脂溶液充分浸润陶瓷隔膜后，将隔膜取出，置于烘箱中在50℃下烘干、固化24h。得到环氧树脂改性陶瓷隔膜。
实施例3：
制备环氧树脂：
按双酚A：环氧氯丙烷＝1：8的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.12倍)，反应6h后，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为200nm的氧化镁陶瓷颗粒90质量份、丁苯橡胶6质量份、羧甲基纤维素钠4质量份，溶剂为体积比2:1的水/丙酮混合液，配制成固含量10％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到氧化镁陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于二甲苯溶剂中，配置成5％(质量分数)的溶液，加入固化剂邻苯二甲酸酐4％(质量分数)，固化促进剂季铵盐2％(质量分数)，将得到环 氧树脂溶液喷涂在二氧化硅陶瓷隔膜上，置于烘箱中在55℃下烘干、固化48h。得到环氧树脂改性陶瓷隔膜。
实施例4
制备环氧树脂：
按双酚A：环氧氯丙烷＝1:6的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.08倍)，反应3h后，抽真空并继续滴加50％的NaOH水溶液，滴加时间在1.5-3h，滴加完碱性催化剂后，继续反应20min，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于丙酮溶剂中，配置成质量分散0.1％的溶液，加入固化剂二亚乙基三胺0.5％，固化促进剂间苯二酚0.1％，将得到环氧树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在45℃下烘干、固化12h。得到环氧树脂改性陶瓷隔膜。
实施例5
制备环氧树脂：
按双酚A：环氧氯丙烷＝1:6的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.08倍)，反应3h后，抽真空并继续滴加50％的NaOH水溶液，滴加时间在1.5-3h，滴加完碱性催化剂后，继续反应20min，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于丙酮溶剂中，配置成质量分散3％的溶液，加入固化剂二亚乙基三胺0.5％，固化促进剂间苯二酚0.1％，将得到环氧树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在45℃下烘干、固化12h。得到环氧树脂改性陶瓷隔膜。
实施例6
制备环氧树脂：
按双酚A：环氧氯丙烷＝1:6的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.08倍)，反应3h后，抽真空并继续滴加50％的NaOH水溶液，滴加时间在1.5-3h，滴加完碱性催化剂后，继续反应20min，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于丙酮溶剂中，配置成质量分散10％的溶液，加入固化剂二亚乙基三胺0.5％，固化促进剂间苯二酚0.1％，将得到环氧树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在45℃下烘干、固化12h。得到环氧树脂改性陶瓷隔膜。
实施例7
一种电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例1制备的环氧树脂改性陶瓷隔膜。
实施例8
一种电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例2制备的环氧树脂改性陶瓷隔膜。
实施例9
一种电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例3制备的环氧树脂改性陶瓷隔膜。
对比例1
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
对比例2
将粒径约为400nm的三氧化二铝陶瓷颗粒92质量份、丁苯橡胶5质量份、羧甲基纤维素钠3质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量12％(质量分数)的陶瓷浆料，涂覆在商品化的聚丙烯(PP)隔膜双层表面，烘干除去溶剂，即得到三氧化二铝陶瓷隔膜。
对比例3
将粒径约为200nm的氧化镁陶瓷颗粒90质量份、丁苯橡胶6质量份、羧甲基纤维素钠4质量份，溶剂为体积比2:1的水/丙酮混合液，配制成固含量10％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜双层表面，烘干除去溶剂，即得到氧化镁陶瓷隔膜。
对比例4
制备环氧树脂：
按双酚A：环氧氯丙烷＝1:6的摩尔比将双酚A溶于环氧氯丙烷中，在氮气氛围下，升温到55℃，并加入50％(质量分数)的NaOH水溶液(加入量为双酚A分子的0.08倍)，反应3h后，抽真空并继续滴加50％的NaOH水溶液，滴加时间在1.5-3h，滴加完碱性催化剂后，继续反应20min，分离并提纯得到液态双酚A环氧树脂。
制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量11％(质量分数)的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
制备环氧树脂改性陶瓷隔膜：
将上述合成的环氧树脂溶于丙酮溶剂中，配置成质量分数30％的溶液，加入固化剂二亚乙基三胺0.5％(质量分数)，固化促进剂间苯二酚0.1％(质量分数)，将得到环氧树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在45℃下烘干、固化12h。得到环氧树脂改性陶瓷隔膜。
对比例5
一种电池，包括正极材料和负极材料，在正极材料和负极材料之间有对比例1制备的二氧化硅陶瓷隔膜。
测试结果分析：
图1是实施例1(右)和对比例1(左)在160℃下热处理30min后对比图。如图可知，实施例1环氧树脂改性陶瓷隔膜和对比例1陶瓷隔膜在160℃下热处理30min后。实施例1环氧树脂改性隔膜不收缩，而对比例1陶瓷隔膜已经明显收缩。
图2是实施例2和对比例2在不同温度下的拉伸强度性能图。如图可知，随着温度的升高，对比例2迅速的失去了其机械强度，在150℃时，就仅有20MPa的拉伸强度，当温度超过180℃时，就彻底熔融而失去机械强度。相对地，实施例2在150℃下保持着超过35MPa的拉伸强度，且在170℃到220℃间都保持着约15MPa的拉伸强度。
图3是实施例3与对比例3热遮断功能测试对比图。如图可知，当温度升高到130℃时，PE基膜融化堵孔，阻断电池中的锂离子通道，阻抗迅速提高1万倍。当温度继续升到147℃时，对比例3陶瓷隔膜收缩，导致正负极接触短路，阻抗迅速降低，而环氧树脂改性陶瓷隔膜仍旧保持良好的尺寸稳定性，能有效的阻隔正负极接触短路，防止电池进一步热失控。
图4是实施例1中制得的环氧树脂改性陶瓷隔膜和对比例1中制得的二氧化硅陶瓷隔膜未涂覆陶瓷浆料面的扫描电镜图。从图中可以看出，包覆了环氧树脂后，隔膜的孔并没有明显减小。这证明环氧树脂具有良好的成膜性且在实施例所述参数条件下环氧树脂包覆层的厚度薄。
图5是实施例1中制得的环氧树脂改性陶瓷隔膜和对比例1中制得的二氧化硅陶瓷隔膜的孔径分布直方图，二者的孔径分布都符合正态分布，可以看出，整体上，实施例1中环氧树脂改性陶瓷隔膜孔隙的孔径整体上略小于对比例1中二 氧化硅陶瓷隔膜孔隙的孔径。经统计，实施例1的孔径平均值为103nm，对比例1的孔径平均值为114nm，经推算，实施例1中环氧树脂包覆层的平均厚度约为5.5nm。
图6实施例7与对比例5的循环性能测试图。如图可知，实施例7与对比例5都具有较良好的循环性能，相较对比例5，实施例7的100圈循环性能并无明显差别。表明本发明制备的环氧树脂改性陶瓷隔膜对电池性能没有负面影响。
表1
实验例 实施例1 对比例1 对比例4
透气度(s/100ml) 280 260 2700
电导率(mS/cm) 0.81 0.95 0.06
表1是实施例1，对比例1，对比例4的透气度比较表，如表可知，实施例1中所制得的环氧树脂改性陶瓷隔膜相比于对比例1中制得的二氧化硅陶瓷隔膜，透气性和电导率有所下降，但下降程度极为有限，环氧树脂改性隔膜的环氧树脂包覆层是薄而均匀的，不存在堵塞隔膜孔隙的问题，不会对隔膜的透气度、电导率造成太大影响。而对比例4中高浓度环氧树脂改性陶瓷隔膜的透气性和电导率都急剧下降，这说明，高浓度下，环氧树脂无法在陶瓷隔膜上形成薄而均匀的环氧树脂层，而是会堵塞隔膜孔隙，使隔膜的透气性和电导率发生严重劣化。由以上结果可知。在合适的参数调控下，本发明所优选的环氧树脂包覆材料，可以在在陶瓷隔膜上形成合适厚度的包覆层，而几乎不会影响隔膜的关键性能透气度、电导率。
表2
实验例 环氧浓度(％) 包覆层厚度(nm)
实施例4 0.1 ＜0.5
实施例5 3 2.4
实施例1 5 5.5
实施例6 10 32
表2为实施例1、实施例4、实施例5、实施例6的孔隙包覆层厚度比较表。 表2旨在说明，不同的环氧树脂浓度如何影响隔膜孔隙上所包覆的环氧树脂层的平均厚度。环氧树脂包覆层的平均厚度通过将环氧树脂改性隔膜与未改性隔膜的隔膜平均孔隙大小的变化计算得到(具体方法已于图5的说明中详细阐述)。由表可知，随着环氧树脂的浓度增加，环氧树脂包覆层的厚度也相应增加，当环氧浓度较低时(实施例4)，环氧树脂包覆层的平均厚度也对应地较薄，对隔膜起不到支撑作用，其耐高温性能受限，其耐热性测试结果如图7所示。当环氧浓度较高时，环氧树脂包覆层的平均厚度也对应地相对较厚。过薄的包覆层会影响环氧树脂包覆层抑制陶瓷隔膜热缩和提高机械强度的效果，而过厚的包覆层则会影响陶瓷隔膜的透气性并进一步降低其电导率。
实施例10：
步骤一，制备脲醛树脂：
按质量百分比计，配制含有甲醛30％、尿素25％、碱性催化剂0.3％的水溶液，调节pH值至9，在90℃下反应30min，再加入含有甲醛10％、尿素15％，0.8％酸性催化剂，改性剂1％的水溶液，调节pH值至5，在90℃下反应25min左右至黏度出现烟雾状浑浊点，加入碱性催化剂终止缩聚反应，同时，加入适量尿素与溶液中游离甲醛反应，保持反应温度为90℃。待反应结束，冷却出料。
步骤二，制备陶瓷隔膜：
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量10％的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
步骤三，制备脲醛树脂改性陶瓷隔膜：
将上述合成的脲醛树脂溶于水/乙醇1:1的溶剂中，配置成50g/L的溶液，加入固化剂间苯二酚0.5质量份，固化促进剂磷酸三甲酯0.1质量份，将得到脲醛树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在70℃下烘干、固化12h，得到脲醛树脂改性陶瓷隔膜。
图8是实施例10中制得的脲醛树脂改性陶瓷隔膜和对比例6中制得的二氧化硅陶瓷隔膜未涂覆陶瓷浆料面的扫描电镜图。从图中可以看出，包覆了脲醛树脂后，隔膜的孔并没有明显减小。这证明脲醛树脂具有良好的成膜性且在实施例所述参数条件下脲醛树脂包覆层的厚度薄。
图9是实施例10中制得的脲醛树脂改性陶瓷隔膜和对比例1中制得的二氧化硅陶瓷隔膜的孔径分布直方图，二者的孔径分布都符合正态分布，可以看出，整体上，实施例10中脲醛树脂改性陶瓷隔膜孔隙的孔径整体上略小于对比例6中二氧化硅陶瓷隔膜孔隙的孔径。经统计，实施例10的孔径平均值为143nm，对比例1的孔径平均值为156nm，可以估计，实施例10中脲醛树脂包覆层的平均厚度约为6.5nm。
图11是实施例10中制得的脲醛树脂改性陶瓷隔膜(右)与对比例6中制得的未改性二氧化硅陶瓷隔膜(左)在165℃下热处理30min后对比图。如图可知，实施例10的脲醛树脂改性陶瓷隔膜和对比例6的二氧化硅陶瓷隔膜在160℃下热处理30min后，实施例10的脲醛树脂改性陶瓷隔膜不收缩，而对比例6的二氧化硅陶瓷隔膜已经明显收缩。
图12为实施例10制得的脲醛树脂改性陶瓷隔膜在200℃热处理30min后的机械性能测试图。如图可知，200℃热处理30min后，实施例10的脲醛树脂改性陶瓷隔膜仍旧保持较高的机械强度，能有效阻挡正负极接触，保障电池的安全性能。
图13为实施例10制得的脲醛树脂改性陶瓷隔膜与对比例6中制得的二氧化硅陶瓷隔膜的粘附力测试图。如图可知，实施例10的脲醛树脂改性陶瓷隔膜相较于对比例6的二氧化硅陶瓷隔膜，其陶瓷层的粘附力有所提高，实施例10的脲醛树脂改性陶瓷隔膜的脲醛树脂三维保护层具有较好的粘结性，能够将陶瓷颗粒层更好的粘附于基膜上。
实施例11
制备脲醛树脂改性陶瓷隔膜：
步骤一，合成脲醛树脂：按质量百分比计，配制含有乙醛40％、尿素25％、碱性催化剂0.5％的水溶液，调节pH值至8.5，在90℃下反应30min，再加入含有乙醛10％、尿素20％，0.5％酸性催化剂，改性剂1％的水溶液，调节pH值至5.5，在90℃下反应25min左右至黏度出现烟雾状浑浊点，加入碱性催化剂终止缩聚反应，同时，加入适量尿素与溶液中游离乙醛反应，保持反应温度为90℃。待反应结束，冷却出料。
步骤二，制备脲醛树脂改性陶瓷隔膜：将上述合成的脲醛树脂6质量份、明胶2质量份、聚乙烯醇2质量份、硫酸铵0.5质量份、硫酸锌0.1质量份，粒径 约200nm的二氧化钛89.4质量份和体积比1:1.5的水、异丙醇混合溶剂配制成固含量15％的脲醛树脂陶瓷浆料，将上述脲醛树脂陶瓷浆料涂覆于商品化的聚乙烯(PE)隔膜单层表面。于75℃下静置陈化10h,得到脲醛树脂改性陶瓷隔膜。
实施例12
步骤一，制备陶瓷隔膜：
将粒径约为400nm的三氧化二铝陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量10％的陶瓷浆料，涂覆在商品化的聚丙烯(PP)隔膜单层表面，烘干除去溶剂，即得到三氧化二铝陶瓷隔膜。
步骤二，制备脲醛树脂改性陶瓷隔膜：
按质量百分比计，配制含有甲醛10％、尿素10％、碱性催化剂0.6％的水/乙醇体积比2:1的混合溶液，调节pH值至8，在95℃下反应至适当粘度。冷却后，加入适量固化剂六氟化铵，将上述三氧化二铝陶瓷隔膜充分浸泡在该混合溶液中，待混合溶液浸润充分后，取出隔膜，置于烘箱中在45℃下烘干、固化24h。
实施例13
步骤一，制备陶瓷隔膜：
将粒径约为500nm的氧化镁陶瓷颗粒90质量份、丁苯橡胶5质量份、羧甲基纤维素钠5质量份，溶剂为体积比2:1的水/丙酮混合液，配制成固含量12％的陶瓷浆料，涂覆在商品化的聚丙烯(PP)隔膜双层表面，烘干除去溶剂，即得到氧化镁陶瓷隔膜。
步骤二，制备脲醛树脂改性陶瓷隔膜：
按质量百分比计，配制含多聚甲醛6％、尿素11％、氢氧化钡1％、氢氧化钙0.5％的、三聚氰胺1％、草酸二乙酯0.1％、十六烷基磺酸钠0.1％的水/丙酮体积比2:1的混合溶液。将上述氧化镁陶瓷隔膜浸泡在该混合溶液中于65℃反应0.5h，再在90℃反应2h，洗涤烘干，得到脲醛树脂改性陶瓷隔膜。
图13为本发明实施例13中所制得的脲醛树脂改性陶瓷隔膜与对比例7中制得的氧化镁陶瓷隔膜的热遮断功能测试对比图。如图可知，当温度升高到约157℃时，PP基膜融化堵孔，阻断电池中的锂离子通道，阻抗迅速提高到几千欧姆。当温度继续升到178℃时，对比例7的氧化镁陶瓷隔膜收缩，导致正负极接触短路， 阻抗迅速降低，而实施例13的脲醛树脂改性陶瓷隔膜仍旧保持良好的尺寸稳定性，能有效的阻隔正负极接触短路，防止电池进一步热失控。
对比例6
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量10％的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
对比例7
将粒径约为500nm的氧化镁陶瓷颗粒90质量份、丁苯橡胶5质量份、羧甲基纤维素钠5质量份，溶剂为体积比2:1的水/丙酮混合液，配制成固含量12％的陶瓷浆料，涂覆在商品化的聚丙烯(PP)隔膜双层表面，烘干除去溶剂，即得到氧化镁陶瓷隔膜。
对比例8
一种锂离子电池，包括正极材料和负极材料，在正极材料和负极材料之间有对比例1制备的二氧化硅铝陶瓷隔膜。
对比例9
将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量10％的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
将上述二氧化硅陶瓷隔膜浸泡在聚氨酯溶液中，并与70℃烘箱中烘干、固化12h，得到聚氨酯改性陶瓷隔膜。
对比例10
步骤一，制备脲醛树脂：按质量百分比计，配制含有甲醛30％、尿素25％、碱性催化剂0.3％的水溶液，调节pH值至9，在90℃下反应30min，再加入含有甲醛10％、尿素15％，0.8％酸性催化剂，改性剂1％的水溶液，调节pH值至5，在90℃下反应25min左右至黏度出现烟雾状浑浊点，加入碱性催化剂终止缩聚反应，同时，加入适量尿素与溶 液中游离甲醛反应，保持反应温度为90℃。待反应结束，冷却出料。
步骤二，制备陶瓷隔膜：将粒径约为300nm的二氧化硅陶瓷颗粒95质量份、丁苯橡胶3质量份、羧甲基纤维素钠2质量份，溶剂为体积比1:1的水/乙醇混合液，配制成固含量10％的陶瓷浆料，涂覆在商品化的聚乙烯(PE)隔膜单层表面，烘干除去溶剂，即得到二氧化硅陶瓷隔膜。
步骤三，制备脲醛树脂改性陶瓷隔膜：将上述合成的脲醛树脂溶于水/乙醇1:1的溶剂中，配置成300g/L的溶液，加入固化剂间苯二酚0.5质量份，固化促进剂磷酸三甲酯0.1质量份，将得到脲醛树脂溶液涂覆在二氧化硅陶瓷隔膜上，置于烘箱中在70℃下烘干、固化12h，得到脲醛树脂改性陶瓷隔膜。脲醛树脂改性陶瓷隔膜、二氧化硅陶瓷隔膜、聚氨酯改性陶瓷隔膜的透气性和电导率比较详见表1。
表3脲醛树脂改性陶瓷隔膜的透气度比较表
实验例 实施例10 对比例6 对比例9 对比例10
透气度(s/100mL) 285 253 2440 1049
电导率(mS/cm) 0.8 0.9 0.009 0.3
由上表可知，实施例1中所制得的脲醛树脂改性陶瓷隔膜相比于对比例6中制得的二氧化硅陶瓷隔膜，透气性和电导率有所下降，但下降程度极为有限，这说明在合理的参数条件下，脲醛树脂改性隔膜的脲醛树脂包覆层是薄而均匀的，不存在堵塞隔膜孔隙的问题，不会对隔膜的透气度、电导率造成太大影响。对比例9中制得的聚氨酯改性陶瓷隔膜相对于实施例10中所制得的脲醛树脂改性陶瓷隔膜和对比例6中制得的二氧化硅陶瓷隔膜，透气性和电导率性急剧下降，这说明聚氨酯的改性并未形成较薄的包覆层，而是严重的堵塞了隔膜的孔隙，对比例10中使用高浓度脲醛树脂制得的脲醛树脂改性陶瓷隔膜，透气性和电导率也都有较大减小。这说明较高的浓度下，脲醛树脂层的厚度过厚，严重影响了隔膜孔隙的大小，从而降低了透气性和电导率。由以上结果对比可知，采用本发明所优选的脲醛树脂为高分子包覆材料具有良好的成膜性，通过合理参数调控制得的脲醛树脂改性陶瓷隔膜，脲醛树脂包覆层具有足够薄的厚度，几乎不会影响所改性隔膜的透气度、电导率等关键参数。而选用其他非优选高分子包覆材料，则可能会导致隔膜堵孔等问题，严重影响改性隔膜的透气度，电导率等性能，同时，对于脲醛树脂的包覆改性，也需要合理控制浓度等关键参数，以免形成过厚的脲醛树脂包覆层。
实施例14
一种锂离子电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例1制备的脲醛树脂改性陶瓷隔膜。
图14为本发明实施例14中具备脲醛树脂改性陶瓷隔膜(实施例10制备)的电池与对比例8中具备二氧化硅陶瓷隔膜(对比例01制备)的电池的循环性能测试图。如图可知，实施例14中具备脲醛树脂改性陶瓷隔膜(实施例10制备)的电池与对比例8中具备二氧化硅陶瓷隔膜(对比例10制备)的电池都具有较良好的循环性能，100圈容量保持率在98％以上，库伦效率接近100％，表明本发明制备的脲醛树脂改性陶瓷隔膜对电池性能没有负面影响。
实施例15
一种锂离子电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例2制备的脲醛树脂改性陶瓷隔膜。
实施例16
一种锂离子电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例3制备的脲醛树脂改性陶瓷隔膜。
实施例17
一种锂离子电池，包括正极材料和负极材料，在正极材料和负极材料之间有实施例4制备的脲醛树脂改性陶瓷隔膜。
以上详细描述了本发明的优选实施方式，但是，本发明并不限于上述实施方式中的具体细节，在本发明的技术构思范围内，可以对本发明的技术方案进行多种简单变型，这些简单变型均属于本发明的保护范围。另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。为了避免不必要的重复，本发明对各种可能的组合方式不再另行说明。此外，本发明的各种不同的实施方式之间也可以进行任意组合，只要其不违背本发明的思想，其同样应当视为本发明所公开的内容。
工业实用性
本发明提供的一种环氧树脂或脲醛树脂改性陶瓷隔膜，包括多孔基膜，环氧树脂或脲醛树脂渗入陶瓷隔膜中固化，在陶瓷隔膜的无机陶瓷颗粒表面、多孔基膜表面和微孔孔壁并其之间形成了环氧树脂或脲醛树脂保护层。由于环氧树脂或脲醛树脂本身 的特性，该保护层是均匀的，且不会堵住多孔基膜的微孔。所述的环氧树脂或脲醛树脂保护层可以通过在多孔基膜单层或者双层表面涂覆环氧或脲醛树脂陶瓷浆料并固化形成，也可以通过陶瓷涂覆的多孔基膜原位聚合环氧树脂或脲醛树脂形成，还可以通过在制备好的陶瓷隔膜上涂覆一层环氧树脂或脲醛树脂溶液并固化形成,具有工业实用性。

Claims (24)

  1. 一种环氧树脂改性陶瓷隔膜，包括多孔基膜，及涂布在基膜上单层或双层的陶瓷层，其特征在于在陶瓷层至少一面涂布或浸润或喷涂上环氧树脂，所述单面的环氧树脂层的厚度为0.5nm～40nm。
  2. 根据权利要求1所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述环氧树脂配制成重量浓度为1％-10％。
  3. 根据权利要求1所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述多孔基膜包括聚烯烃类多孔聚合物、聚四氟乙烯、聚偏氟乙烯、聚偏氟乙烯-六氟丙烯共聚物、聚氯乙烯、聚对苯二甲酸乙二醇酯、聚对苯二甲酸丁二醇酯、聚甲基丙烯酸甲酯、聚丙烯腈、聚酰亚胺、聚乙烯吡咯烷酮、聚环氧乙烷、聚乙烯醇或者上述聚合物衍生的共混、共聚体系中的至少一种。
  4. 根据权利要求1所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的陶瓷颗粒的平均粒径为10-1000nm,优选50-500nm，陶瓷层厚度为0.1-10μm。
  5. 根据权利要求1所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述环氧树脂是指在化学结构中，含有两个或者两个以上环氧基团的有机化合物，且通过环氧基团的开环反应，可形成热固性的高分子聚合物；所述环氧树脂的分子量用凝胶渗透色谱法测定重均分子量为100～5000。
  6. 根据权利要求1或2所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的环氧树脂聚合单体分为能导入或者能生成环氧基团的化合物称为组分A和具有两个或两个以上活泼氢的化合物、预聚物或含有两个或两个以上不饱和双键的化合物、预聚物称为组分B。
  7. 根据权利要求6所述的一种环氧树脂改性陶瓷隔膜，特征在于所述的组分A，组分B混合溶液按重量百分比计，含组分A0.1～40％、组分B0.1～40％、催化剂0.01～8％、固化剂0.01～5％、固化促进剂0.01～5％、表面活性剂0.01～5％，添加剂0～5％，余量为溶剂。
  8. 根据权利要求7所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的催化剂包括碳酸钠、碳酸钾、吡啶、三乙胺、醋酸钠、氢氧化钠、氢氧化钾、季铵盐、季磷盐、胆碱的一种。
  9. 根据权利要求7所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的固化剂包括多元胺，酸酐，酚醛，硫醇类加成聚合型固化剂，或催化型固化剂或其他显在型固化剂，或选择咪唑类类潜伏型固化剂。
  10. 根据权利要求7所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的固化促进剂根据固化剂的亲核、亲电性进行选择，亲核固化剂匹配亲电固化促进剂，亲电固化剂匹配亲核固化促进剂。
  11. 根据权利要求7所述的一种环氧树脂改性陶瓷隔膜，其特征在于所述的表面活性剂为硬脂酸、十二烷基苯磺酸钠、季铵化物、十六烷基磺酸钠、卵磷脂、氨基酸型、甜菜碱型、脂肪酸甘油酯，脂肪酸山梨坦、聚山梨酯中的至少一种。
  12. 一种环氧树脂改性陶瓷隔膜，包括多孔基膜，及涂布在基膜上单层或双层的陶瓷层，其特征在于在陶瓷层至少一面涂布或浸润或喷涂环氧树脂，所形成的隔膜孔隙率大于40％；所述的环氧树脂与陶瓷层复合，环氧树脂增加厚度小于40nm。
  13. 根据权利要求12述的锂电池隔膜，其特征在于在所述的多孔基膜单层或者双 层表面涂覆陶瓷浆料，制备陶瓷隔膜，再将陶瓷隔膜浸渍在环氧树脂聚合单体的混合溶液中，原位聚合包覆环氧树脂；或在多孔基膜上涂覆陶瓷浆料制成陶瓷隔膜，再在陶瓷隔膜上涂覆配制好的环氧树脂溶液，再固化形成环氧改性陶瓷隔膜。
  14. 根据权利要求13所述的锂电池隔膜，其特征在于所述的环氧树脂配置质量分数为1-10％的环氧树脂溶液。
  15. 一种锂电池隔膜的制备方法，其特征在于：
    环氧树脂聚合单体分为能导入或者能生成环氧基团的化合物称为组分A和具有两个或两个以上活泼氢的化合物、预聚物或含有两个或两个以上不饱和双键的化合物、预聚物称为组分B；
    步骤1、合成环氧树脂：按质量百分比计，将组分A：1-40％、组分B：1-40％、碱性催化剂0.2-8％、溶剂10-95％的混合溶液在25-110℃下反应0.5-24h，分离洗涤烘干，得到环氧树脂；
    步骤2、制备陶瓷隔膜：将陶瓷颗粒、粘结剂按一定比例混匀制成陶瓷浆料，并将制得的陶瓷浆料单面或双面涂覆于多孔基膜表面，烘干除去溶剂，即得到陶瓷隔膜；
    步骤3、配置质量分数为1-10％的环氧树脂溶液，加入0.01％-5％的固化剂，0.01-5％的固化促进剂，0～5％的添加剂；通过喷涂，浸泡或其它方式，使环氧树脂溶液浸润陶瓷隔膜，在25℃-110℃下烘干、固化0.5-24h。
  16. 一种脲醛树脂改性陶瓷隔膜，包括无机陶瓷颗粒和多孔基膜，其特征在于：无机陶瓷颗粒的表面、多孔基膜的表面和多孔基膜的微孔的侧壁形成一连续的脲醛树脂层，该脲醛树脂层的厚度为0.1nm～30nm，该脲醛树脂层通过在上述多孔基膜和无机陶瓷颗粒的表面涂覆脲醛树脂溶液或在上述多孔基膜的表面涂覆含有上述无机陶瓷颗粒的脲醛树脂陶瓷浆料而形成，该脲醛树脂溶液或脲醛树脂陶瓷浆料中脲醛树脂浓度为1g/L～100g/L，该脲醛树脂的重均分子量为100～5000。
  17. 根据权利要求16所述的一种脲醛树脂改性陶瓷隔膜，其特征在于，所述脲醛树脂层的厚度为2～10nm，所述脲醛树脂溶液或脲醛树脂陶瓷浆料中脲醛树脂浓度为5g/L～50g/L，所述脲醛树脂的重均分子量为500～2000。
  18. 根据权利要求16或17所述的一种脲醛树脂改性陶瓷隔膜，其特征在于，所述多孔基膜的材料为聚烯烃或其衍生物、聚酯类或其衍生物、聚腈或其衍生物、聚酰胺或其衍生物、聚环氧烷烃或其衍生物、聚烯醇或其衍生物中的至少一种。
  19. 根据权利要求16或17所述的一种脲醛树脂改性陶瓷隔膜，其特征在于，所述无机陶瓷颗粒为三氧化二铝、二氧化钛、二氧化硅、二氧化锆、二氧化锡、氧化镁、氧化锌、硫酸钡、氮化硼、氮化铝、氮化镁中的至少一种，所述无机陶瓷颗粒的粒径为 5nm～1μm。
  20. 如权利要求16至19中任一权利要求所述的一种脲醛树脂改性陶瓷隔膜的制备方法，其特征在于，包括：
    步骤一，合成脲醛树脂：将醛类化合物、尿素、碱性催化剂和适量水混合后，在pH 8～9、85～95℃下进行缩聚反应25～35分钟，上述醛类化合物、尿素和碱性催化剂的质量比为1～40:1～40:0.1～1；再加入含有所述醛类化合物、尿素、酸性催化剂、改性剂的水溶液，在pH 5～6、85～95℃下进行缩聚反应反应25～35分钟，上述醛类化合物、尿素、酸性催化剂和改性剂的质量比为1～40:1～40:0.5～1:0.2～2；直至出现烟雾状浑浊点，接着加入所述碱性催化剂终止缩聚反应；然后在85～95℃下，加入适量的尿素，以消除其中游离的醛类化合物，冷却后即得所述脲醛树脂；
    步骤二，制备陶瓷隔膜：将无机陶瓷颗粒、粘结剂、羧甲基纤维素钠和适量溶剂混匀制成陶瓷浆料，将该陶瓷浆料涂覆于所述多孔基膜表面，烘干后即得所述陶瓷隔膜；上述无机陶瓷颗粒、粘结剂、羧甲基纤维素钠的质量比为60～99:0.1～20:1～10；
    步骤三，制备脲醛树脂改性陶瓷隔膜：将所述脲醛树脂、固化剂、固化促进剂和适量溶剂混合配制脲醛树脂溶液，将该脲醛树脂溶液涂覆在所述陶瓷隔膜上，在25～110℃固化0.5～24小时，即得所述脲醛树脂改性陶瓷隔膜；上述脲醛树脂、固化剂、固化促进剂的质量比为1～20:0.01～5:0～5；
    上述步骤二和步骤三中的溶剂均为有机溶剂与水的混合溶液，所述有机溶剂的体积分为10～100。
  21. 如权利要求16至19中任一权利要求所述的一种脲醛树脂改性陶瓷隔膜的制备方法，其特征在于，包括：
    步骤一，合成脲醛树脂：将醛类化合物、尿素、碱性催化剂和适量水混合后，在pH 8～9、85～95℃下进行缩聚反应25～35分钟，上述醛类化合物、尿素和碱性催化剂的质量比为1～40:1～40:0.1～1；再加入含有所述醛类化合物、尿素、酸性催化剂、改性剂的水溶液，在pH 5～6、85～95℃下进行缩聚反应反应25～35分钟，上述醛类化合物、尿素、酸性催化剂和改性剂的质量比为1～40:1～40:0.5～1:0.2～2；直至出现烟雾状浑浊点，接着加入所述碱性催化剂终止缩聚反应；然后在85～95℃下，加入适量的尿素，以消除其中游离的醛类化合物，冷却后即得所述脲醛树脂；
    步骤二，制备脲醛树脂改性陶瓷隔膜：将所述脲醛树脂、固化剂、固化促进剂、粘结剂、催化剂、所述无机陶瓷颗粒和适量有机溶剂混合配制脲醛树脂陶瓷浆料，将该脲醛树脂陶瓷浆料涂覆于所述多孔基膜表面，于25～100℃静置陈化1～24小时，即得所述脲醛树脂改性陶瓷隔膜；上述脲醛树脂、固化剂、固化促进剂、粘结剂、催化剂、所述无机陶瓷颗粒的质量比为1～20:0.01～5:0～5:1～3:0.1～2:60～99；所述溶剂为有机溶剂与水的混合溶液，所述有机溶剂的体积分为10～100。
  22. 如权利要求16至19中任一权利要求所述的一种脲醛树脂改性陶瓷隔膜的制备方法，其特征在于，包括：
    步骤一，制备陶瓷隔膜：制备陶瓷隔膜：将无机陶瓷颗粒、粘结剂、羧甲基纤维素钠和适量溶剂混匀制成陶瓷浆料，将该陶瓷浆料涂覆于所述多孔基膜表面，烘干后即得所述陶瓷隔膜；上述无机陶瓷颗粒、粘结剂、羧甲基纤维素钠的质量比为60～99:0.1～20:1～10；
    步骤二，制备脲醛树脂改性陶瓷隔膜：将醛类化合物、尿素、碱性催化剂和适量有机溶剂的混合液在pH 8～9、25～110℃下反应至适当粘度，冷却后加入固化剂、固化促进剂、表面活性剂；然后加入所述陶瓷隔膜，将所述陶瓷隔膜充分浸泡后取出，在25～110℃下固化0.5～24小时，即得所述脲醛树脂改性陶瓷隔膜；上述醛类化合物、尿素、碱性催化剂、固化剂、固化促进剂、表面活性剂的质量比为1～40:1～40:0.0.1～2:0～5:0～5:0～5。
    上述步骤一中的溶剂为有机溶剂与水的混合溶液，所述有机溶剂的体积分为10～100。
    上述步骤二中混合液，醛类化合物与尿素的总质量分数为1％～40％。
  23. 如权利要求16至19中任一权利要求所述的一种脲醛树脂改性陶瓷隔膜在锂离子电池中的应用。
  24. 一种锂离子电池，其特征在于：其具有权利要求16至19中任一权利要求所述的一种脲醛树脂改性陶瓷隔膜。
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