Polyoxymethylene-based all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization and application

An all-solid-state polymer electrolyte, comprising a polyoxymethylene polymer supported on a porous support,

• wherein the polyoxymethylene polymer is prepared by in-situ ring-opening polymerization of a trioxymethylene monomer in the presence of an additive, a lithium salt, and optionally in the presence of a catalyst,
• wherein the all-solid-state polymer electrolyte has thickness of 10 μm-800 μm, an ionic conductivity of 4×10−5 S/cm-8×10−3 S/cm at room temperature, and an electrochemical window not lower than 4.2 V,
• wherein the trioxymethylene monomer is of general formula 1:
• wherein R1, R2, and R3 is identical or different and are selected from —H, —F, —Cl, —Br, —I, and —CxH2x+1, x being 1-5,
• the lithium salt is one or more selected from lithium bis(oxalate) borate, lithium tetrafluoroborate, and lithium difluorophosphate,
• the additive is NC—(CH2)y—CN, a value range of y being 1-16,
• the optional catalyst is one or more selected from ferric chloride, niobium pentachloride, titanium tetrachloride, zinc chloride, bismuth chloride, perchloric acid, tyrosine, boric acid, and acetic acid, and
• the porous support is a polyethylene separator, a polypropylene separator, nylon non-woven membrane, an alginate fiber non-woven membrane, a cellulose non-woven membrane, bacterial cellulose, glass fiber, a polyethylene terephthalate membrane, a polyimide non-woven membrane, a polyamide membrane, a spandex membrane, or an aramid membrane, and
• wherein a mass fraction of the polyoxymethylene polymer in the polymer electrolyte is 20%-40%;
• a mass fraction of the lithium salt in the polymer electrolyte is 5%-20%;
• a mass fraction of the additive in the polymer electrolyte is 5%-25%;
• a mass fraction of the porous support in the polymer electrolyte is 50%-60%;
• and a mass fraction of the catalyst in the polymer electrolyte is less than 5%, and
• the polymerization of the trioxymethylene monomer is carried out without a solvent to form the all-solid-state electrolyte.