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CN-122025782-A - Flame-retardant CO2Polyurethane-based solid polymer electrolyte and preparation method thereof

CN122025782ACN 122025782 ACN122025782 ACN 122025782ACN-122025782-A

Abstract

The invention discloses a flame-retardant CO 2 -based polyurethane solid polymer electrolyte and a preparation method thereof, and belongs to the technical field of lithium ion batteries and the technical field of flame-retardant polymer electrolytes. According to the invention, CO 2 , an epoxy compound, diamine and a functionalized ionic liquid are used as raw materials, flame-retardant CO 2 -based polyurethane is synthesized in one step, and the polyurethane solid electrolyte with flame retardant property and conductivity is obtained by compounding with lithium salt, so that the safety of the battery under the condition of thermal runaway is effectively improved. By blending the structure and the proportion of the raw materials, the processability of the polymer and the interfacial compatibility of the solid electrolyte are improved.

Inventors

  • SHI LIJUAN
  • YI QUN
  • GAO YANAN
  • MA QIAN
  • CHEN SHANGQING
  • HUANG YI
  • HU HUI
  • Cheng Fanpeng
  • CHENG LIWEI

Assignees

  • 武汉工程大学

Dates

Publication Date
20260512
Application Date
20260226

Claims (10)

  1. 1. The preparation method of the flame-retardant CO 2 -based polyurethane solid polymer electrolyte is characterized by comprising the following steps of: 1) Carrying out ion exchange reaction on the intermediate and a phosphorus-containing compound in an organic solvent B, so that halogen ions in the intermediate are replaced by phosphorus-containing anions to obtain phosphorus-series functionalized ionic liquid; , Wherein R 1 represents any one of triphenylphosphine, triisopropylphosphine, tri-tert-butylphosphine, imidazole, 1-methylimidazole, pyrrole and pyridine, R 2 represents any one of ethyl, propyl and butyl, X represents Cl or Br element, R IL + represents a cation formed by covalent connection and ionization of R 1 and R 2 , and Y - represents any one of PO 4 3- 、H 2 PO 2 - 、P 2 O 7 4- and PF 6 ⁻ ; 2) CO 2 , an epoxy compound, diamine and phosphorus functionalized ionic liquid are used as raw materials, and react for 12-30 hours at a reaction temperature of 60-120 ℃ under the action of a catalyst to synthesize flame-retardant CO 2 -based polyurethane; , Wherein R represents any one of bisphenol F group, linear fatty chain and cycloalkyl, R' represents any one of fatty chain, carboxyl/guanidine functional fatty chain and cycloalkyl, R IL + is defined in the same step 1), n is between 64 and 93, and m is between 48 and 76; 3) And dispersing lithium salt into the flame-retardant CO 2 -based polyurethane to obtain the flame-retardant CO 2 -based polyurethane solid electrolyte.
  2. 2. The preparation method of the flame-retardant CO 2 -based polyurethane solid polymer electrolyte according to claim 1, wherein in the step 1), the molar ratio of the organic phosphine/nitrogen compound to the halogenated hydrocarbon is 1:1-6, the reaction temperature is 50-120 ℃, the reaction time is 24-48 h, and the molar ratio of the intermediate to the phosphorus-containing compound is 1:1-1.5.
  3. 3. The method for preparing a flame retardant CO 2 -based polyurethane solid polymer electrolyte according to claim 1, wherein the organic solvent a comprises at least one of anhydrous acetonitrile, ethyl acetate and acetone, and the organic solvent B comprises at least one of anhydrous ethanol, dimethyl sulfoxide, tetrahydrofuran and toluene.
  4. 4. The preparation method of the flame-retardant CO 2 -based polyurethane solid polymer electrolyte according to claim 1, wherein in the step 2), the epoxy compound comprises one or more of bisphenol F diglycidyl ether, 1, 4-butanediol diglycidyl ether and dicyclopentadiene dioxide, the diamine comprises one or more of 1, 5-pentanediamine, lysine, ornithine, arginine and isophorone diamine, and the catalyst is any one of ZIF-9, ZIF-67 and ZIF-68.
  5. 5. The preparation method of the flame-retardant CO 2 -based polyurethane solid polymer electrolyte according to claim 1 or 4, wherein the molar ratio of the epoxy compound to the CO 2 to the diamine is 1-2:0.1-2, and the mass fraction of the phosphorus-based functionalized ionic liquid in the reaction system is 2-15 wt%.
  6. 6. The preparation method of the flame-retardant CO 2 -based polyurethane solid polymer electrolyte is characterized in that in the step 3), lithium salt is dispersed into flame-retardant polyurethane, wherein the flame-retardant CO 2 -based polyurethane is dissolved in an organic solvent, stirring is carried out for 2-12 hours at 20-80 ℃ to obtain flame-retardant CO 2 -based polyurethane solution, then the lithium salt is dissolved into the flame-retardant CO 2 -based polyurethane solution according to the mass ratio of the lithium salt to the flame-retardant polyurethane of 1:2-50 to obtain casting solution, finally the casting solution is cast into a polytetrafluoroethylene mold, and the casting solution is solidified for 24-36 hours at 80-120 ℃ to obtain the flame-retardant CO 2 -based polyurethane solid polymer electrolyte.
  7. 7. The method for preparing a flame retardant CO 2 based polyurethane solid polymer electrolyte according to claim 6, wherein the organic solvent comprises any one of N, N-dimethylformamide, N-methylpyrrolidone and dimethylsulfoxide.
  8. 8. The method for preparing a flame retardant CO 2 based polyurethane solid polymer electrolyte according to claim 6, wherein the lithium salt comprises any one of lithium bis (trifluoromethanesulfonyl imide), lithium bis (fluorosulfonyl imide) and lithium bis (oxalato) borate.
  9. 9. The flame-retardant CO 2 -based polyurethane solid polymer electrolyte is characterized in that the flame-retardant CO 2 -based polyurethane solid polymer electrolyte is prepared by the preparation method of any one of claims 1-8.
  10. 10. A lithium ion battery comprising the flame retardant CO 2 -based polyurethane solid polymer electrolyte of claim 9.

Description

Flame-retardant CO 2 -based polyurethane solid polymer electrolyte and preparation method thereof Technical Field The invention belongs to the technical field of new energy materials, and particularly relates to a flame-retardant solid polymer electrolyte for a lithium ion battery, in particular to a polyurethane-based solid polymer electrolyte synthesized by taking carbon dioxide (CO 2) as a raw material and a preparation method thereof. Background Lithium ion batteries are ubiquitous as efficient energy storage systems due to their high energy density and long cycle life. However, its security problem is always a challenge to be solved. The commonly adopted organic liquid electrolyte (such as a carbonic ester mixture containing LiPF 6) has the characteristics of easy volatilization, inflammability and easy leakage, and when the battery suffers thermal shock, internal short circuit or mechanical abuse, the battery is extremely easy to cause thermal runaway, so that the battery burns and even explodes, and seriously threatens the safety of life and property. The adoption of a solid electrolyte to replace a liquid electrolyte is recognized as a key path for fundamentally improving the safety of the battery. The solid electrolyte can not only eliminate the risks of liquid leakage and volatilization, but also be expected to match with a high-capacity lithium metal anode, so that the energy density of the battery is remarkably improved. Currently, the solid electrolytes under development mainly include inorganic ceramic/sulfide electrolytes and solid polymer electrolytes. Among them, solid Polymer Electrolytes (SPEs) have been attracting attention because of their light weight, good flexibility, close contact with electrode interfaces, and the like. However, existing SPEs (e.g., polyethylene oxide PEO-based electrolytes) generally have two major bottlenecks, namely, low ionic conductivity at room temperature and difficult mechanical strength to inhibit lithium dendrite growth. Even more serious, most polymer matrices are inherently flammable, which introduces new safety hazards to the battery system. Polyurethane (PU) is used as a polymer with extremely high molecular design flexibility, and the mechanical property and the electrochemical property of the polyurethane can be regulated and controlled in a wide range by regulating the proportion of soft and hard segments of the polyurethane. Polyurethane generally exhibits superior mechanical strength, toughness, and chemical stability compared to flexible polymers such as PEO, and is considered a potential SPE matrix material. However, the synthesis of conventional polyurethanes relies heavily on highly toxic isocyanate monomers, which present safety and environmental risks to the production process. In addition, polyurethane itself is flammable and releases highly toxic isocyanic compounds easily after combustion, resulting in limited application in batteries as well. To improve the flame retardancy of polymers, the introduction of flame retardants is a common means. Among the various types of flame retardants, halogen-containing flame retardants are being phased out due to the release of toxic and corrosive gases upon combustion. The phosphorus flame retardant, in particular the organic phosphorus flame retardant, can play a role in flame retardance by promoting the formation of a carbon layer, capturing free radicals and other mechanisms during combustion, has the advantages of low smoke, low toxicity, environmental protection and the like, and becomes a key development direction. Ionic Liquids (ILs), particularly those containing phosphorus, which combine non-volatility, nonflammability, high thermal stability, and high ionic conductivity, are considered ideal "multi-functional" flame retardant additives. However, how to stably and uniformly disperse the ionic liquid flame retardant in the polymer matrix, and avoid migration or phase separation of the ionic liquid flame retardant in long-term use, so as to realize both durable flame retardance and high ionic conductivity, is a core challenge faced by the current technology. Simple physical blending often makes this difficult. Based on the analysis, the technical problem to be solved in the prior art is how to prepare the solid polymer electrolyte which has excellent mechanical property, high ionic conductivity and flame retardance by an environment-friendly synthesis process so as to meet the requirements of the lithium ion battery with high safety and high performance on key materials. Disclosure of Invention In view of the above, the invention aims to overcome the defects of the prior art and provide a flame-retardant CO 2 -based polyurethane solid polymer electrolyte and a preparation method thereof. The method aims to solve the core problems of the reduction of the comprehensive performance of the electrolyte caused by low mechanical strength and poor compatibility with the flame retardant of the existing