[0046] The third aspect of the present invention is a method for preparing a polymer electrolyte, the method comprising:
[0047] (1) Provide a polymerization solution containing a crosslinkable copolymer, a lithium salt, a crosslinking agent, inorganic nanoparticles modified by a silane coupling agent, and a photoinitiator;
[0048] (2) The polymerization solution is cast and molded to obtain a semi-dry film;
[0049] (3) Cross-linking and curing the semi-dry film under ultraviolet light irradiation;
[0050] Wherein, the crosslinkable copolymer contains a structural unit represented by formula (1), a structural unit represented by formula (2), and a structural unit represented by formula (3);
[0051] Formula 1): Formula (2): Formula (3):
[0052] Among them, R is H or C1-C4 alkyl, L is C0-C4 alkylene or -R 1 -O-R 2 -, R 1 Is a C0-C4 alkylene group, R 2 Is a C0-C4 alkylene group;
[0053] The crosslinking agent is one or more of acrylate crosslinking agents containing at least two acrylate groups, and the acrylate group is a group represented by formula (4): -OC (O)-C(R')=CH 2 , R'is H or C1-C4 alkyl;
[0054] The silane coupling agent is a silane coupling agent containing an unsaturated carbon-carbon double bond at the end.
[0055] According to the present invention, the group and type selection of the above-mentioned crosslinkable copolymer, the group and type selection of the crosslinking agent, and the type selection of the silane coupling agent-modified inorganic nanoparticles are as described above, and the present invention is here No longer.
[0056] According to the present invention, the cross-linkable copolymer may be prepared by a conventional method in the field, or may be a commercially available product. According to the present invention, the present invention is not particularly limited.
[0057] According to the present invention, the inorganic nanoparticles modified by the silane coupling agent can be prepared by conventional methods in the art. For example, the preparation method may include: mixing the inorganic nanoparticles with the silane coupling agent in an organic solvent ( For example, ultrasonic dispersion for 20-40min), and then heat treatment (for example, heating at 90-120°C for 10-24h). Wherein, the organic solvent can be, for example, one or more of ethanol, methanol, propanol, propylene glycol, ethylene glycol, and isopropanol. Relative to 100 parts by weight of inorganic nanoparticles, the amount of the organic solvent may be 500-5000 parts by weight, for example. Wherein, relative to 100 parts by weight of inorganic nanoparticles, the amount of the silane coupling agent is 5-20 parts by weight.
[0058] The amount of the crosslinkable copolymer, the crosslinking agent, and the silane coupling agent-modified inorganic nanoparticles can be selected according to the content of each of the crosslinked polymers described above. Preferably, the The total weight of the crosslinked copolymer, the crosslinking agent and the inorganic nanoparticles modified by the silane coupling agent is based on the total weight, and the content of the crosslinkable copolymer is 55-90% by weight, preferably 60-80% by weight, and more It is preferably 65-78% by weight, for example, 18.5-21.5% by weight. Preferably, the content of the crosslinking agent is 5-30% by weight, preferably 10-25% by weight, more preferably 15-22% by weight, for example 68-76% by weight. Preferably, the content of the inorganic nanoparticles modified by the silane coupling agent is 1-20% by weight, preferably 2-15% by weight, more preferably 3-12% by weight, for example 3.5-11.5% by weight.
[0059] According to the present invention, the selection of the lithium salt is as described above, and the present invention will not be repeated here. The amount of the lithium salt can be selected according to the description of the lithium salt content in the polymer electrolyte above. Preferably, the cross-linked polymer and the cross-linked polymer in terms of the structural unit represented by formula (1) in the cross-linked polymer The molar ratio of the lithium salt in terms of Li is 5-20:1, preferably 8-20:1.
[0060] According to the present invention, preferably, the photoinitiator is 2-hydroxy-2-methylpropiophenone, ethyl (2,4,6-trimethylbenzoyl)phosphonate, 4-dimethylaminobenzene One or more of ethyl formate, 1-hydroxycyclohexyl phenyl ketone, benzoin dimethyl ether, methyl phthaloyl benzoate and 4-chlorobenzophenone. The amount of the photoinitiator can vary within a wide range. Preferably, based on the total weight of the crosslinkable copolymer, the crosslinking agent and the inorganic nanoparticles modified by the silane coupling agent, the photoinitiator The amount of initiator used is 2-15% by weight, preferably 4-10% by weight, more preferably 5-8% by weight.
[0061] According to the present invention, the organic solvent used in the polymerization solution needs to be capable of sufficiently dissolving the raw materials of step (1), preferably N,N-dimethylformamide, N,N-dimethylacetamide, and One or more of methyl sulfoxide, tetrahydrofuran, chloroform, dichloromethane and acetonitrile, wherein the amount of the organic solvent can vary within a wide range, preferably, relative to 10g of crosslinkable copolymer, The total weight of the inorganic nanoparticles modified by the crosslinking agent and the silane coupling agent, and the amount of the organic solvent used is 20-100 mL, preferably 30-80 mL, more preferably 35-60 mL.
[0062] According to the present invention, in step (1), it is preferable to first dissolve the crosslinkable copolymer in an organic solvent, then add the lithium salt and mix it thoroughly (for example, mixing for 10-20h), and then add the inorganic silane coupling agent modified The nanoparticles are finally added with a crosslinking agent and a photoinitiator for mixing (for example, mixing for 1-4 hours) to obtain the polymerization solution.
[0063] According to the present invention, the method of pouring the polymerization solution in step (2) can be performed in a conventional manner in the art, for example, adding the polymerization solution to a PTFE mold for pouring, and then drying (for example, at 40-70 Bake at ℃ for 8-15h) to obtain a semi-dry film that is not completely dried.
[0064] According to the present invention, in step (3), ultraviolet light can be used to irradiate the photoinitiator to initiate polymerization free radicals, so that the cross-linkable copolymer and the cross-linking agent can undergo cross-linking polymerization to obtain the above-described A cross-linked polymer with a three-dimensional network structure. Among them, preferably, in step (3), the crosslinking and curing time is 30s-15min, preferably 2-10min. The ultraviolet light irradiation can be performed by a conventional ultraviolet irradiation method in the art, and the present invention has no particular limitation on this.
[0065] According to the present invention, a transparent cross-linked polymer film can be obtained by the above method. The method may also include drying the film obtained in step (3) to remove residual solvents and moisture, for example, at 40-80°C Dry for 8-20h.
[0066] The fourth aspect of the present invention provides a polymer electrolyte prepared by the above method.
[0067] The polymer electrolyte prepared by the above method of the present invention may be the same as the polymer electrolyte described above, of course, as long as the polymer electrolyte prepared by the above method belongs to this aspect.
[0068] The above method of the present invention has simple procedures and lower cost, and the obtained polymer electrolyte has higher ion conductivity, lower crystallinity and suitable flexibility. Specifically, the ionic conductivity of the resulting polymer electrolyte at 30°C can reach 5.4×10 -5 S/cm or more, preferably 6×10 -5 Above S/cm, especially 8×10 -5 S/cm to 1×10 -4 S/cm; the ionic conductivity at 60℃ can reach 5×10 -4 S/cm or more, preferably 6×10 -5 Above S/cm, especially 7×10 -4 S/cm to 8.5×10 -4 S/cm; The tensile strength is 1.5MPa or more, preferably 4MPa or more, especially 6-8MPa.
[0069] The fifth aspect of the present invention provides a lithium ion battery including the above-mentioned polymer electrolyte.
[0070] The lithium ion battery may be a conventional structure in the field, as long as it includes the polymer electrolyte of the present invention as a polymer electrolyte membrane.
