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CN-122025773-A - Coating preparation method of ultrathin high-toughness high-pressure-resistant block polyurethane solid electrolyte and application of lithium ion battery

CN122025773ACN 122025773 ACN122025773 ACN 122025773ACN-122025773-A

Abstract

A coating preparation method of ultrathin high-toughness high-pressure-resistant block polyurethane solid electrolyte and application of a lithium ion battery belong to the field of solid batteries. Mixing polycarbonate-based polyol solution, polyisocyanate solution, conductive lithium salt and catalyst, defoaming to form uniform precursor solution, coating the precursor solution poured on a substrate by using a coating machine, and drying the obtained wet film. The multi-functional isocyanate with the three-dimensional cross-linked structure is used as a hard segment, is segmented with a polyester long-chain soft segment, adjusts and controls the mass ratio of the soft segment to the hard segment, and constructs a continuous microphase separation ion channel, so that the multi-functional isocyanate has excellent flexibility, an ultra-wide electrochemical window, and the electrochemical window is higher than 5.30v, can be matched with a high-voltage positive electrode material, and further improves the energy density of a battery.

Inventors

  • WEI HAIJUN
  • Cui hongda
  • WU LINGQIAO

Assignees

  • 北京工业大学

Dates

Publication Date
20260512
Application Date
20260109

Claims (9)

  1. 1. The coating preparation method of the ultrathin high-toughness high-pressure-resistant block polyurethane solid electrolyte is characterized by comprising the following steps of: S1, firstly, drying polycarbonate-based polyol, dissolving the dried polycarbonate-based polyol in N-methyl pyrrolidone (NMP) solvent, and stirring until the dried polycarbonate-based polyol is completely dissolved; S2, dissolving the three-dimensional chain diisocyanate 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 three-dimensional chain diisocyanate solution 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; s5 the obtained wet film is dried in vacuum, for example, in a vacuum oven at 60 ℃ for 14 hours, to obtain a 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; The selected isocyanate is one or more of ① high-functionality system obtained by modifying traditional polyisocyanate polymeric MDI, HDI trimer, IPDI trimer, TDI trimer and triphenylmethane triisocyanate ②, wherein the isocyanate comprises hyperbranched polyisocyanate, dendritic macromolecular isocyanate and isocyanate derivative of isocyanate ④ based on rotaxane/chordin for synthesizing interpenetrating polymer network, wherein the isocyanate has a topological structure of urethane modified polyisocyanate ③; 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 (LiPF 6 ), lithium perchlorate (LiCIO), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) and bis (trifluoromethanesulfonyl) methyllithium [ LiC (SO 2 CF 3 ) 3 ].
  4. 4. The method according to claim 1, wherein the mass percentage of the polycarbonate-based polyol, the polyisocyanate, the initiator or catalyst, the conductive lithium salt is 10-40%, 10-25%, 2-5%, 30-65%.
  5. 5. A block polyurethane solid state electrolyte prepared according to the method of any one of claims 1-4.
  6. 6. Use of the block polyurethane solid electrolyte prepared according to the method of any one of claims 1 to 4 for solid lithium batteries with electrochemical windows higher than 5.30v.
  7. 7. A solid lithium battery, characterized by comprising the block polyurethane solid electrolyte prepared by the 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 7, 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; (d) Drying the coated pole piece in a drying oven to obtain a positive electrode; the active material of the positive electrode is selected from one or more of lithium iron phosphate, lithium nickel cobalt aluminate, lithium-rich manganese-based material, lithium cobaltate, vanadium lithium fluorophosphate, lithium nickel cobalt manganate, lithium manganese iron phosphate and lithium nickelate; the negative electrode active material is selected from one or more of metal lithium, metal lithium alloy, lithium metal nitride and lithium titanate; the preparation method of the negative electrode is characterized by comprising 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, namely grinding an anode active material accounting for 30-90% of the total mass of the anode material and an electroconductive 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) Coating the negative electrode slurry obtained in the step (b) on the surface of a copper foil current collector; (d) And (5) drying the coated pole piece in vacuum, such as drying in a vacuum drying oven at 120 ℃ for 6 hours, and obtaining the negative electrode.
  9. 9. A method of preparing a solid state lithium battery as claimed in claim 7 or 8, 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.

Description

Coating preparation method of ultrathin high-toughness high-pressure-resistant block polyurethane solid electrolyte and application of lithium ion battery 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 especially relates to an ultrathin high-toughness high-pressure-resistant block polyurethane-based polymer solid electrolyte membrane prepared based on a coating method and application of the polymer solid electrolyte membrane in a solid lithium battery. Background All-solid-state lithium batteries of solid electrolyte are considered as one of the important development directions of next-generation lithium batteries because of their remarkable advantages in energy density, cycle life, safety, and the like, as compared to conventional liquid-electrolyte lithium batteries. Most all-solid-state lithium batteries use solid polymer electrolytes because of their advantages of good flexibility, simple processing and forming, and good compatibility with electrodes. The polyurethane solid electrolyte membrane realizes breakthrough balance among high ionic conductivity, strong mechanical barrier property and wide electrochemical window through the molecular-level rigid-flexible cooperative design, has the industrial advantages of customization, easy processing, high safety and the like, and becomes one of key material systems for promoting the landing of the high-energy-density and high-safety solid battery. The CN202010230287.2 patent reports a polyurethane of high mechanical strength, but the thickness still does not meet the requirements of high energy density lithium ion batteries, and previous studies have not reported polyurethane electrolytes adapted to high voltage positive electrodes. Therefore, the patent aims to prepare three-dimensional reticular polyurethane by selecting triisocyanate, and the polyurethane solid electrolyte which is ultrathin, still has high mechanical strength and is suitable for a high-voltage positive electrode to realize a high-energy-density lithium ion battery is prepared by simplifying the preparation process. Based on the above, the invention selects polycarbonate polyol with excellent oxidation resistance and three-dimensional network polyisocyanate with high crosslinking degree and toughness as main raw materials, adjusts and controls a microphase separation structure of a soft segment and a hard segment through molecular design, combines the synergistic effect of the three-dimensional network crosslinking hard segment and a flexible long-chain soft segment, and prepares the ultrathin Polyurethane-based composite solid electrolyte (Polyurethane-based Composite Solid Electrolyte, PUCSE) with excellent comprehensive performance. The electrolyte aims to overcome the short performance plate of the existing polymer electrolyte and simplify the preparation process. Disclosure of Invention The invention relates to the technical field of solid electrolyte, and particularly provides an ultrathin, high-toughness and high-pressure-resistant block polyurethane-based polymer solid electrolyte membrane prepared based on a coating method and application thereof in a solid lithium battery. The technical scheme of the invention is as follows: 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 three-dimensional chain-like triisocyanate in an N-methylpyrrolidone (NMP) solvent, and stirring until the triisocyanate is completely dissolved; S3, mixing the polycarbonate-based polyol solution obtained in the step S1, the three-dimensional chain-like triisocyanate solution 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; s5, drying the obtained wet film in vacuum, such as in a vacuum oven at 60 ℃ for 14 hours, to obtain a dried polyurethane-based solid electrolyte film having a thickness of 30-40 micrometers, preferably 30-35 micrometers. 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. The selected isocyanate is one or more of ① traditional polyisocyanates, such as diphenylmethane diisocyanate trimer (MDIt), hexame