High electrochemical stability of a 3D cross-linked network PEO@nano-SiO2 composite polymer electrolyte for lithium metal batterie

Polymer electrolytes have attracted great attention due to their promising abilities, however, only on further improving their safety and electrochemical performance can they be used as next generation electrolytes. Here, a novel composite polymer electrolyte (CPE) with nano-SiO2 acting as a cross-linking agent to form a 3D cross-linked network was synthesized to improve the electrochemical stability and mechanical ability. The novel CPE exhibited some excellent properties such as high ionic conductivity (4.65 x 10(-3) S cm(-1) at room temperature) with a broad electrochemical stability window (approximate to 5.4 V vs. Li/Li+), high ionic transfer number (0.45), high mechanical robustness and flexibility (Young's module approximate to 8.9 MPa, breaking strain 181%), and excellent interface stability. The lithium metal battery LiFePO4/CPE/Li was assembled and delivered a specific capacity of 160 mA h g(-1) with a capacity retention of above 90% after 500 cycles at 1C. Furthermore, to cooperate with high voltage cathode materials LiNi0.8Co0.1Mn0.1O2 and LiNi0.5Mn1.5O4, the novel CPE still delivered superior cycling performance compared to traditional electrolytes.