Polyoxymethylene-based all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization and application
A polyoxymethylene-based all-solid-state polymer electrolyte prepared by in-situ ring-opening polymerization is used in forming an all-solid-state secondary lithium battery. A trioxymethylene monomer, an additive and lithium salt initiates in-situ ring-opening polymerization on a porous support material through a catalyst to form the all-solid-state polymer electrolyte, which has a 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.
1 . 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 R 1 , R 2 , and R 3 is identical or different and are selected from —H, —F, —Cl, —Br, —I, and —C x H 2x+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—(CH 2 ) 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.
2 . An all-solid-state secondary lithium battery, comprising the all-solid-state polymer electrolyte according to claim 1 , wherein the all-solid-state secondary lithium battery is an all-solid-state lithium ion battery, an all-solid-state lithium metal battery, or an all-solid-state lithium-sulfur battery.
3 . The all-solid-state secondary lithium battery of claim 2 , further comprising a cathode or an anode, wherein the all-solid-state polymer electrolyte according is disposed between the cathode and the anode.
4 . A preparation method for the all-solid-state polymer electrolyte according to claim 1 , comprising
a) uniformly mixing the trioxymethylene monomer and the additive according to a ratio, and then adding the lithium salt and the optional catalyst to obtain a mixture;
b) adding the mixture on the porous support;
and c) heating the porous support carrying the mixture for 0.05 h-100 hrs at 40° C.-110° C. to conduct in-situ ring-opening polymerization to obtain the all-solid-state polymer electrolyte.
5 . The preparation method according to claim 4 , wherein under the condition of 40° C.-110° C. in the step a), the trioxymethylene monomer and the additive are stirred for 0.1 h-10 hrs and uniformly mixed; and then the lithium salt and the catalyst are added and stirred for 0.01 h-10 hrs under the condition of 40° C.-100° C. for uniform mixing to obtain the mixture for later use.
6 . The method according to claim 4 , comprising placing the porous support carrying the mixture between the cathode and the anode prior to the heating step.