High-performance solid composite polymer electrolyte for all solid-state lithium battery through facile microstructure regulation

Solid composite polymer electrolytes are the optimal candidate for all solid-state lithium batteries, because of their enhanced ionic conductivities, long-life cycle ability and compatibility to lithium anode. Herein, we reported a kind of solid composite polymer electrolyte comprised of poly(ethylene oxide), graphitic-like carbon nitride and lithium perchlorate, which was prepared by a facile solution blending method. Microstructure of the solid composite polymer electrolyte was regulated by thermal annealing and interaction among components and was characterized by XRD, DSC, FTIR-ATR, and ROM. The obtained solid composite polymer electrolyte achieved an ionic conductivity as high as 1.76 × 10^-5 S cm^-1 at 25°C. And the electrochemical stable window and the lithium ion transference number, t₊, were also obviously enhanced. LiFePO₄/Li solid-state batteries with the annealed PEO-LiClO₄-g-C₃N₄ solid polymer electrolyte presented a high initial discharge capacity of 161.2 mAh g^-1 and superior cycle stability with a capacity retention ratio of 81% after 200 cycles at 1C at 80°C. The above results indicates that the thermal annealing treatment and g-C₃N₄ as a novel structure modifier is crucial for obtaining the high-performance solid composite polymer electrolytes used in the all solid-state lithium battery.