CN-121546150-B - Composite solid electrolyte membrane, preparation method thereof and secondary battery

CN121546150BCN 121546150 BCN121546150 BCN 121546150BCN-121546150-B

Abstract

The application provides a composite solid electrolyte membrane, a preparation method thereof and a secondary battery. The composite solid electrolyte membrane comprises a modified pyrochlore type oxide solid electrolyte, a polymer matrix and lithium salt, wherein the modified pyrochlore type oxide solid electrolyte comprises a pyrochlore type oxide solid electrolyte and a polymer coating layer coated on the surface of the pyrochlore type oxide solid electrolyte, the polymer coating layer and the pyrochlore type oxide solid electrolyte are connected through covalent bonds, the polymer coating layer is formed by in-situ polymerization of polymer monomers on the surface of the pyrochlore type oxide solid electrolyte, and the polymer monomers are selected from monomers with trifluoroacetamide functional groups and/or monomers with carbamate functional groups. The composite solid electrolyte membrane of the present application has excellent lithium ion conductivity.

Inventors

ZHU XINGBAO
ZHOU XUEFENG
ZHANG WENQIANG

Assignees

合肥国轩高科动力能源有限公司

Dates

Publication Date: 20260508
Application Date: 20260121

Claims (10)

1. The composite solid electrolyte membrane is characterized by comprising a modified pyrochlore type oxide solid electrolyte, a polymer matrix and lithium salt, wherein the modified pyrochlore type oxide solid electrolyte comprises a pyrochlore type oxide solid electrolyte and a polymer coating layer coated on the surface of the pyrochlore type oxide solid electrolyte, the polymer coating layer and the pyrochlore type oxide solid electrolyte are connected through covalent bonds, the polymer coating layer is formed by in-situ polymerization of polymer monomers on the surface of the pyrochlore type oxide solid electrolyte, and the polymer monomers are selected from monomers with trifluoroacetamide functional groups and/or monomers with carbamate functional groups.
2. The composite solid electrolyte membrane according to claim 1, wherein the mass content of the modified pyrochlore oxide solid electrolyte in the composite solid electrolyte membrane is 15-60%.
3. The composite solid electrolyte membrane according to claim 1, wherein the mass ratio of the pyrochlore oxide solid electrolyte to the polymer coating layer is 1 (0.4-10), and/or the average particle diameter of the pyrochlore oxide solid electrolyte is 100-5000 nm, and/or the weight average molecular weight of the polymer in the polymer coating layer is 2000-50000 g/mol, and/or the weight average molecular weight of the polymer matrix is 60000-1200000 g/mol.
4. The composite solid electrolyte membrane according to any one of claims 1 to 3, wherein the polymer monomer is a combination of the monomer having a trifluoroacetamide functional group and the monomer having a urethane functional group, and the mass ratio of the monomer having a trifluoroacetamide functional group and the monomer having a urethane functional group is 1 (2 to 3).
5. A composite solid electrolyte membrane according to any one of claims 1 to 3, wherein the monomer having a trifluoroacetamide functional group is selected from N-allyl-2, 2 trifluoroacetamide and/or N, N-diallyl-2, 2-trifluoroacetamide; and/or the monomer with carbamate functional group is selected from any one or more of N, N-diallyl carbamate, allyl (2-oxo ethyl) carbamate tert-butyl and tert-butyl allyl (pent-4-enyl) carbamate; And/or the pyrochlore oxide solid state electrolyte has a chemical formula (Li a A1 b ) x (La c A2 d ) y (Nb e A3 f ) 2 O 6 F,, wherein A1 is selected from any one or more of Na, K, rb, cs and Fr, A2 is selected from any one or more of Be, mg, ca, sr, ba and Ra, A3 is selected from any one or more of Ta, zr, W, hf, mo and V, 0≤x≤2, y is used for balancing valence, a+b≤1, 0< a≤1, 0≤b≤1, c+d≤1, 0≤c≤1, 0≤d≤1, e+f≤1, 0≤f≤1; And/or the polymer matrix is selected from any one or more of polyvinylidene fluoride, polyvinylidene fluoride-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropylene copolymer, polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride-hexafluoropropylene-trifluoroethylene copolymer, polyvinylidene fluoride-tetrafluoroethylene-hexafluoropropylene terpolymer, polyacrylonitrile, polymethyl methacrylate, polyurethane, polyurea, polyvinylpyrrolidone, polypropylene carbonate, polyethylene carbonate, polyimide, polyethylene carbonate, nylon, polyethylene terephthalate and polyvinyl alcohol; and/or the lithium salt is selected from any one or more of LiPF 6 、LiBF 4 、LiCl、LiI、LiBr、LiClO 4 、LiAsF 6 、CH 3 CO 2 Li、CF 3 SO 3 Li、N(CF 3 SO 2 ) 2 Li、N(FSO 2 ) 2 Li、C(CF 2 SO 2 ) 3 Li、C 2 BF 4 O 4 Li、B(C 2 O 4 ) 2 Li.
6. The composite solid electrolyte membrane according to any one of claims 1 to 3, wherein the lithium ion conductivity of the composite solid electrolyte membrane is 1.8 to 2.7ms·cm -1 .
7. A method for producing the composite solid electrolyte membrane according to any one of claims 1 to 6, characterized by comprising: step S1, mixing raw materials comprising pyrochlore type oxide solid electrolyte, an aminosilane coupling agent and a first organic solvent, and then performing hydrolysis-condensation reaction to obtain the aminosilane coupling agent modified pyrochlore type oxide solid electrolyte; Step S2, mixing raw materials comprising the amino silane coupling agent modified pyrochlore oxide solid electrolyte, a halogenated acyl halide initiator, a first catalyst and a second organic solvent, and then carrying out substitution reaction to obtain the initiator modified pyrochlore oxide solid electrolyte; Step S3, mixing the raw materials comprising the initiator modified pyrochlore type oxide solid electrolyte, a polymer monomer, a second catalyst and a third organic solvent, and then performing polymerization reaction to form a polymer coating layer on the surface of the pyrochlore type oxide solid electrolyte, so as to obtain a modified pyrochlore type oxide solid electrolyte; And S4, mixing the modified pyrochlore oxide solid electrolyte, a polymer matrix, lithium salt and a fourth organic solvent, and then sequentially pouring the mixture into a film and drying the film to obtain the composite solid electrolyte film.
8. The method according to claim 7, wherein the hydrolysis-condensation reaction is carried out at a temperature of 120 to 140 ℃ and/or the hydrolysis-condensation reaction time is 8 to 12 hours; and/or the temperature of the substitution reaction is-5~0 ℃, and/or the time of the substitution reaction is 8-12 hours; And/or the temperature of the polymerization reaction is 45-55 ℃, and/or the time of the polymerization reaction is 8-12 hours; And/or the mass ratio of the pyrochlore oxide solid electrolyte to the aminosilane coupling agent is 1 (0.5-1.5); And/or the mass ratio of the pyrochlore oxide solid electrolyte, the halogenated acyl halide initiator and the first catalyst is 1 (0.2-1.5): 0.1-2; And/or the mass ratio of the pyrochlore oxide solid electrolyte, the polymer monomer and the second catalyst is 1 (0.4-10): 0.005-0.03.
9. The production method according to claim 7 or 8, wherein the aminosilane coupling agent is selected from any one or more of γ3-aminopropyl trimethoxysilane, trimethoxy [3- (methylamino) propyl ] silane, 3- [2- (2-aminoethylamino) ethylamino ] propyl-trimethoxysilane, [3- (6-aminohexylamino) propyl ] trimethoxysilane, N- (3- (trimethoxysilyl) propyl) ethylenediamine, N- (3- (trimethoxysilyl) propyl) butan-1-amine, 3- (2-aminoethylamino) propyltriethoxysilane, (3-aminopropyl) dimethylmethoxysilane, N- (β -aminoethyl- γ -aminopropyl) methyldimethoxysilane, N-methylaminopropyl dimethoxysilane and aminoethylamino isobutyl methyldimethoxysilane; and/or the halogenated acyl halide initiator is selected from any one or more of 2-bromoisobutyryl bromide, 2-bromobutyryl bromide, 2-bromopropionyl bromide and 3-bromopropionyl chloride; And/or the first catalyst is selected from any one or more of triethylamine, 2 '-bipyridine, tri (2-aminoethyl) amine, tetramethyl ethylenediamine tri (2-picolyl) amine, N, N, N', N '', N '' -pentamethyl diethylenetriamine, hexamethyltriethylenetetramine, 1 '-dimethyl-2, 2' -biimidazole; And/or the second catalyst is selected from any one or more of cuprous chloride dihydrate, cupric chloride tetrahydrate, cuprous bromide and cupric bromide.
10. A secondary battery comprising the composite solid electrolyte membrane according to any one of claims 1 to 6.

Description

Composite solid electrolyte membrane, preparation method thereof and secondary battery Technical Field The invention relates to the technical field of batteries, in particular to a composite solid electrolyte membrane, a preparation method thereof and a secondary battery. Background Along with the continuous improvement of the requirements of the fields of new energy automobiles, energy storage systems and the like on the energy density and the safety of secondary batteries, the short circuit risk caused by the inflammability, the easy leakage and the growth of lithium dendrites of the traditional liquid electrolyte has become a key bottleneck for restricting the development of the industry. Solid-state electrolytes are recognized as an ultimate solution by virtue of their inherent safety as core components of next-generation secondary batteries, and are largely classified into two major categories, solid-state inorganic electrolytes and solid-state polymer electrolytes. Although the inorganic solid electrolyte has higher lithium ion conductivity, the characteristics of higher rigidity, brittleness and the like are unfavorable for forming good interface contact, the processability is poor, the sulfide solid electrolyte with the highest lithium ion conductivity is unstable in the environment, toxic hydrogen sulfide gas is generated by easy decomposition in the air, and the cost is higher. The polymer solid electrolyte has good flexibility, can achieve good interface contact effect, and can be processed in a thin film mode, but lithium ion transmission is required to depend on movement of a high molecular chain segment, the lithium ion transmission capacity is weak, the lithium ion conductivity is often lower than 10 -4 S/cm, and the mechanical property is weak. The existing composite system mostly adopts a blending strategy of inorganic filler and polymer matrix, but still faces key technical challenges: 1. the inorganic phase is unevenly dispersed and easy to form agglomerates, and the interface energy between the organic phase and the inorganic phase is higher, so that phase separation is easy to form, and the transmission of lithium ions is seriously hindered. 2. The inorganic phase is agglomerated to easily form a stress concentration point, so that the mechanical property of the composite solid electrolyte is reduced. Disclosure of Invention The invention mainly aims to provide a composite solid electrolyte membrane, a preparation method thereof and a secondary battery, so as to solve the problem of low ionic conductivity of the solid electrolyte membrane in the prior art. In order to achieve the above object, according to one aspect of the present invention, there is provided a composite solid electrolyte membrane comprising a modified pyrochlore-type oxide solid electrolyte, a polymer matrix, and a lithium salt, the modified pyrochlore-type oxide solid electrolyte comprising a pyrochlore-type oxide solid electrolyte and a polymer coating layer coated on a surface of the pyrochlore-type oxide solid electrolyte, the polymer coating layer and the pyrochlore-type oxide solid electrolyte being connected by covalent bonds, the polymer coating layer being formed by in situ polymerization of a polymer monomer selected from a monomer having a trifluoroacetamide functional group and/or a monomer having a urethane functional group on the surface of the pyrochlore-type oxide solid electrolyte. The polymer coating layer and the polymer matrix in the modified pyrochlore oxide solid electrolyte have better compatibility, and the existence of the modified pyrochlore oxide solid electrolyte is beneficial to improving the dispersion degree of an inorganic phase in an organic phase and facilitating the transmission of lithium ions between organic/inorganic phase interfaces. In addition, the presence of the trifluoroacetamide functional group and the carbamate functional group in the polymer coating layer enhances the solubility and stability of the lithium salt, and can form a stable complex with lithium ions, thereby contributing to the improvement of lithium ion conductivity. Further, the mass content of the modified pyrochlore oxide solid electrolyte in the composite solid electrolyte membrane is 15-60%. The mass content of the modified pyrochlore oxide solid electrolyte in the composite solid electrolyte membrane is controlled within the above range, which is helpful for controlling the mechanical properties of the composite solid electrolyte membrane within a proper range while improving the lithium ion conductivity of the composite solid electrolyte membrane. Further, the mass ratio of the pyrochlore-type oxide solid electrolyte to the polymer coating layer is 1 (0.4-10), and/or the average particle diameter of the pyrochlore-type oxide solid electrolyte is 100-5000 nm, and/or the weight average molecular weight of the polymer in the polymer coating layer is 2000-50000 g/mol, and/or the weight average molecular we