Polymer and preparation thereof, and electrolyte film and preparation thereof

A method of preparing a polymer electrolyte film, the method comprising:

• reacting monomer 1, monomer 2, monomer 3, monomer 4, a lithium salt, and an initiator at 30-100° C. for 0.2-24 h to obtain product 1,
• wherein monomer 1 has a structure of formula 1, monomer 2 has a structure of formula 2, monomer 3 has a structure of formula 3, and monomer 4 has a structure of formula 4:
• wherein
• R1 and R3 are each independently selected from hydrogen or C1-10 alkyl;
• R4 is selected from C1-10 hydrocarbyl or C1-10 hydrocarbyl containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus;
• R2 and R5 are each independently selected from hydrogen, C1-10 hydrocarbyl, or hydrocarbyl containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus, having a carbon atom count of less than or equal to 10, and containing C═C or C≡C;
• Rf is selected from hydrogen, or ethoxy segment containing one or more elements of fluorine, chlorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus and having a carbon atom count of less than or equal to 16;
• x is the number of repeating units of methylene, and 0≤x≤20;
• A+ is selected from one of functional groups with nitrogen, sulfur, or phosphorus as a cationic center;
• Q− is one, two or more anions selected from halide ion, haloborate, halo(oxalate) borate, perhalate, halophosphate, and halosulfonimide, and optionally Q is one, two or more anions selected from chloride ion, tetrafluoroborate, difluorooxalate borate, perchlorate, hexafluorophosphate, and bis(fluorosulfonyl)imide;
• and
• E is selected from structures of (1) to (3):
• R6 is selected from hydrogen or C1-10 alkyl,
• R7 is selected from hydrogen, or hydrocarbyl with a carbon atom count of less than 7 that is unsubstituted or substituted by one or more elements of fluorine, bromine, iodine, nitrogen, oxygen, sulfur, silicon, boron, and phosphorus,
• the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium difluorooxalate borate, lithium perchlorate, lithium bis(oxalate) borate.