Safety-reinforced rechargeable Li-CO2 battery based on a composite solid state electrolyte

The rechargeable Li-CO2 battery has been receiving significant attention owing to its merits of high energy density and the efficient utilization of CO2. However, the widely application is plagued by severe security risks, such as leakage, flammability and lithium dendrites growth due to the use of liquid organic electrolytes. Here, a composite solid state electrolyte consisting of polyethylene oxide (PEO) and 20 wt.% Li7La3Zr1.4Ta0.6O12 (LLZTO) was prepared and first introduced into Li-CO2 battery to solve the problems. The composite solid state electrolyte exhibited high ionic conductivity (1.03 × 10−1 S·cm−1 at 70 °C), wide electrochemical window (5 V vs. Li+/Li), good mechanical properties and excellent flexibility. Ultimately, the Li symmetric cell with PEO/LLZTO composite solid state electrolyte can operate 1,500 h at a current density of 0.1 mA·cm−2. The assembled all-solid-state Li-CO2 battery behaved a long cycle life of 70 cycles at a current density of 100 mA·g−1 with fixed capacity of 1,000 mAh·g−1. Our work provides new perspective to develop rechargeable all-solid-state Li-CO2 batteries.