Cross-linking copolymers of acrylates’ gel electrolytes with high conductivity for lithium-ion batteries

Abstract

The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5 × 10−3 Scm−1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.