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CN-122025772-A - Method for preparing polyurethane-based solid electrolyte with high thermal stability based on coating method and application

CN122025772ACN 122025772 ACN122025772 ACN 122025772ACN-122025772-A

Abstract

A method for preparing polyurethane-based solid electrolyte with high thermal stability based on a coating method, application and the technical field of solid lithium batteries. Mixing polycarbonate-based polyol solution, aromatic isocyanate solution, conductive lithium salt, initiator or catalyst, performing one-pot mixing and defoaming in a vacuum defoaming machine to form uniform precursor solution, coating the precursor solution poured on a substrate by using a coating machine, and performing vacuum drying to obtain the polyurethane-based solid electrolyte membrane. The method is used for lithium ion batteries, metal lithium batteries and flexible battery devices, and particularly used for lithium battery application scenes in high-temperature environments, so that thermal runaway of the lithium batteries is greatly reduced, and safety is ensured.

Inventors

  • WU LINGQIAO
  • Cui hongda
  • WEI HAIJUN

Assignees

  • 北京工业大学

Dates

Publication Date
20260512
Application Date
20260109

Claims (10)

  1. 1. A method for preparing a polyurethane-based solid electrolyte with high thermal stability based on a coating method, which is characterized by comprising the following steps: s1, firstly, drying polycarbonate-based polyol at 120 ℃ for 12 hours, dissolving the dried polycarbonate-based polyol in an N-methylpyrrolidone (NMP) solvent, and stirring until the dried polycarbonate-based polyol is completely dissolved; S2, dissolving the diisocyanate of aryl in an N-methyl pyrrolidone (NMP) solvent, and stirring until the diisocyanate is completely dissolved; S3, mixing the polycarbonate-based polyol solution obtained in the step S1, the aryl diisocyanate obtained in the step S2, conductive lithium salt, an initiator or a catalyst, and performing one-pot mixing and defoaming in a vacuum defoaming machine to form a uniform precursor solution; S4, pouring the precursor solution on the substrate, coating the precursor solution poured on the substrate by using a coating machine, and controlling coating parameters to obtain wet films with different thicknesses; And S5, vacuum drying the obtained wet film to obtain the dried polyurethane-based solid electrolyte film.
  2. 2. The method according to claim 1, wherein the polyurethane-based solid electrolyte membrane has a thickness of 30-40 microns, preferably 30-35 microns.
  3. 3. The method of claim 1, wherein the polycarbonate-based polyol is one or more of polycarbonate diol, poly (1, 6-hexanediol carbonate) diol, poly (1, 4-butanediol carbonate) diol, poly (1, 5-pentanediol carbonate) diol, poly (3-methyl-1, 5-pentanediol carbonate) diol, poly (cyclohexanedimethanol carbonate) diol, poly (propylene carbonate) diol, and poly (cyclohexene carbonate) diol.
  4. 4. The aryl diisocyanate is one or more of Toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene Diisocyanate (XDI), naphthalene-1, 5-diisocyanate (NDI), terephthalyl diisocyanate (PPDI), polymeric MDI, liquefied MDI, TDI prepolymer, TDI trimer (TDI polyisocyanate), HDI/TDI (mixed trimer) The initiator or the catalyst is selected from one or more of dibutyl tin dilaurate, dibutyl tin bis (acetylacetonate), azodiisobutyronitrile (AIBN), dimethyl Azodiisobutyrate (AIBME), benzoyl Peroxide (BPO) and a platinum catalyst (Pt); The conductive lithium salt is selected from one or more of lithium hexafluorophosphate ) Lithium perchlorate ) Bis (trifluoromethanesulfonyl) lithium imide (LiTFSI), bis (trifluoromethanesulfonyl) methyllithium [ sic ] ]。
  5. 5. The method according to claim 1, wherein the mass percentage of polycarbonate-based polyol, isocyanate, initiator or catalyst, conductive lithium salt is 10-40% (preferably 12-15%), 10-25% (preferably 15-18%), 2-5% (preferably 5%), 30-65% (preferably 65%).
  6. 6. Use of the polyurethane-based solid electrolyte prepared based on the coating method according to any one of claims 1 to 4 for lithium ion batteries, lithium metal batteries, flexible battery devices, operating at a temperature of room temperature to 80 ℃.
  7. 7. A solid-state lithium battery comprising the polyurethane-based solid electrolyte prepared based on the coating method according to any one of claims 1 to 4, comprising a positive electrode, a negative electrode, and the polyurethane-based solid electrolyte having both separator and electrolyte functions interposed between the positive electrode and the negative electrode.
  8. 8. A solid state lithium battery according to claim 6, characterized in that the method for preparing the positive electrode comprises the steps of: (a) Grinding and mixing an anode active material accounting for 50-85% of the total mass of the anode material and an electroconductive agent acetylene black accounting for 10-40% of the total mass of the anode material; (b) Adding binder polyvinylidene fluoride (PVDF) and N-methyl pyrrolidone (NMP) accounting for 5-20% of the total mass of the positive electrode material into the mixture in the step (a), grinding and blending to obtain positive electrode slurry, wherein the positive electrode material is a mixture of which the positive electrode slurry is not calculated by the amount of the N-methyl pyrrolidone (NMP); (c) Coating the positive electrode slurry obtained in the step (b) on the surface of an aluminum current collector, and drying the coated pole piece in a 120 ℃ vacuum drying oven for 6 hours to obtain a positive electrode; The active material of the positive electrode is selected from one or more of lithium iron phosphate (LiFePO 4), lithium nickel cobalt aluminate (LiNiCoAIO, NCA), lithium-rich manganese base material (xLi 2MnO 3- (1-x) LiMO2, LLOs), lithium cobalt oxide (LiCoO 2), vanadium lithium fluorophosphate (LiVPO 4F), lithium nickel cobalt manganate (LiNiCoMnO 2, NCM), lithium manganate (LiMn 2O 4), lithium manganese iron phosphate (LiMnxFe-xPO 4) and lithium nickelate (LiNiO 2); The negative electrode active material is selected from one or more of lithium metal (Li), lithium metal alloy, lithium metal nitride (such as Li 3N), lithium titanate (Li 4Ti5O 12); The preparation method of the negative electrode comprises the following steps: when the negative electrode active material is metallic lithium or a lithium alloy, it can be used as a negative electrode directly, or When the anode active material is other material, comprising the steps of: (a) The preparation of the anode slurry comprises grinding anode active material accounting for 30-90% of the total mass of the anode material and conductive agent acetylene black accounting for 5-30% of the total mass of the anode material (B) Adding binder polyvinylidene fluoride (PVDF) accounting for 5-25% of the total mass of the anode material and a proper amount of N-methylpyrrolidone (NMP) into the mixture in the step (a), and grinding and mixing to obtain anode slurry, wherein the anode material is a mixture of which the anode slurry is not counted by the amount of the N-methylpyrrolidone (NMP); (c) And (3) coating the negative electrode slurry obtained in the step (b) on the surface of a copper foil current collector, and vacuum drying the coated pole piece, such as drying the pole piece in a vacuum drying oven at 120 ℃ for 6 hours, so as to obtain the negative electrode.
  9. 9. The method for preparing a solid-state lithium battery as claimed in claims 6 to 7, characterized by comprising one of the following two processes: (1) In-situ assembling process, the prepared positive electrode, negative electrode and solid polymer electrolyte membrane corresponding to the invention are directly stacked and assembled; or (2) a composite electrode assembly process: (a) Pouring the polymer electrolyte precursor solution prepared in the step S3 onto the surface of a positive electrode, and vacuum drying for 14 hours at 60 ℃ to prepare a positive electrode @ polymer electrolyte composite; (b) Pouring the polymer electrolyte precursor solution prepared in the step S3 onto the surface of a negative electrode, and vacuum drying for 14 hours at 60 ℃ to prepare a negative electrode@polymer electrolyte composite; (c) And stacking and assembling the positive electrode@polymer electrolyte composite and the negative electrode@polymer electrolyte composite.
  10. 10. Use of a solid state lithium battery according to any of the claims 6-7, characterized in that the use temperature is room temperature to 80 ℃.

Description

Method for preparing polyurethane-based solid electrolyte with high thermal stability based on coating method and application Technical Field The invention relates to the technical field of solid lithium batteries, in particular to a preparation method and application of a polymer solid electrolyte membrane, and particularly relates to a polyurethane-based polymer solid electrolyte membrane with high thermal stability prepared based on a coating method and application of the polyurethane-based polymer solid electrolyte membrane in a solid lithium battery. Background The lithium ion battery has become the dominant power source technology of portable electronic equipment, electric tools, electric automobiles and large-scale energy storage systems because of the remarkable advantages of high energy density, high working voltage, low self-discharge rate, no memory effect, long cycle life, environmental friendliness and the like. However, the conventional lithium ion battery generally adopts flammable organic liquid electrolyte, has potential safety hazards such as leakage, combustion, explosion and the like, and severely restricts the application of the lithium ion battery in scenes with high safety requirements. Solid-state electrolytes (Solid-State Electrolytes, SSEs) are considered as a critical path to solve the above-mentioned safety problems. The lithium dendrite lithium electrolyte has the advantages of 1) being high in intrinsic safety, completely eliminating combustible organic solvents, avoiding leakage and combustion risks, 2) inhibiting lithium dendrites, being high in mechanical strength, being capable of physically blocking growth and penetration of lithium dendrites and reducing internal short circuit probability, 3) being excellent in thermal stability, being higher than 200 ℃ in thermal decomposition temperature, remarkably widening a working temperature window of a battery, 4) being huge in energy density potential, being capable of matching high-voltage/high-capacity anode materials (such as lithium cobalt oxide LCO, high-nickel ternary NMC/NCA, lithium-rich manganese LLOs and the like) in a wide electrochemical window (up to more than 5V), being capable of directly using a metal lithium cathode, breaking through the specific capacity bottleneck of the traditional graphite cathode, being capable of integrating a diaphragm function, simplifying the battery structure and improving the volume energy density. However, current solid state electrolytes, particularly polymer systems, still face significant challenges: 1. The ionic conductivity is insufficient, the ionic conductivity of most polymer solid electrolytes at room temperature is generally lower than 10- 4 S/cm, the performance attenuation is serious at low temperature, and the internal resistance of the battery is high and the multiplying power performance is poor. 2. Solid-solid interface problem (core bottleneck): physical contact difference, namely that the solid electrolyte is in rigid point contact with the electrodes, the effective contact area is small, and the interface impedance is far higher than that of a liquid system (1-2 orders of magnitude higher). Poor interface stability, and easy chemical/electrochemical side reaction, leading to interface degradation. Lithium dendrite control is difficult-even in solid state systems, uneven deposition of lithium may still lead to dendrite growth. 3. The high temperature resistance is poor, and the problems of short circuit, electrolyte leakage and the like of the battery are easy to occur at high temperature in the prior art. 4. The preparation process (such as high-temperature high-pressure sintering and precise film deposition) is often harsh, and the key process (such as large-area uniform film formation and low-impedance interface construction) is still immature, so that the production cost is far higher than that of a liquid battery. Aiming at the defects of the prior art, in particular to the comprehensive performance bottleneck of polyurethane electrolyte in the aspects of room temperature ion conductivity, mechanical strength, electrochemical window, thermal stability and the like, and the high cost problem caused by complex preparation technology, the invention aims to provide a new solution. The scheme is as follows: Simple process and convenient mass production. Excellent performance, high thermal stability, wide electrochemical window, high room temperature ionic conductivity and other key characteristics. The reaction has the advantages of low cost, simple synthesis process, mild reaction condition, high yield, less side reaction and the like. In addition, the previous report has not applied polyurethane with high thermal stability to lithium batteries to ensure the safety of the batteries operated at high temperature, reduce thermal runaway, and improve the safety of the batteries used in high temperature environments. Based on the above, the invention selects polycarbonat