Abstract
Lithium-ion batteries using either liquid electrolytes or solid electrolytes have been extensively studied in recent years, but both of these encounter safety risks such as flammability of liquid electrolytes and uncontrolled dendrite growth. In this study, a sandwich gel polymer electrolyte (SGPE) with a thermal shutdown function was developed to resolve the safety issues. By adjustment of surface pore size of the SGPE, lithium dendrite growth is suppressed. Due to the sandwich structure design, the SGPE can effectively respond to an overheating environment, regulate lithium ion transport and inhibit the penetration of lithium dendrite, demonstrating a remarkably high safety of the batteries, especially at high temperature or under thermal runaway circumstances. In addition, the LiFePO4/SGPE/Li battery exhibits a high reversible capacity of 135 mA h g-1 at 1C and maintains high capacity retention (>95%) after 200 charge-discharge cycles. This study shows a great advantage to handle thermal abuse and a stable lithium anode, suggesting a promising approach to the high safety lithium metal batteries.