Fast Li-ion transport and uniform Li-ion flux enabled by a double-layered polymer electrolyte for high performance Li metal battery

Polymer-based lithium metal batteries are considered to be one of the most promising Li-based energy storage systems for portable devices and flexible technologies. However, low ionic conductivity of polymer electrolytes and poor compatibility in electrode-electrolyte interfaces restrict the wide applications of polymer-based lithium metal batteries. Here we report a novel polycarbonate-polyethylene oxide based polymer electrolyte with a double layered structure to achieve fast Li-ion conduction and uniform Li-ion flux. Comprehensive experiments and simulations show the ion-dipolar pair of [C=O center dot center dot center dot Li+] is the main reason for Li+ conduction, and the balances of coupling/decoupling in Li+center dot center dot center dot TESI- and Li+center dot center dot center dot PAN/PVEC synergistically facilitate a fast Li+ transport on the cathode side, which results in high Li+ transference number (0.602) and high ionic conductivity (1.56 x 10(-4) S cm(-1), 20 degrees C) of DLPE. Besides, uniform Li+ flux in PEGDMA-SiO2-Pyr(14)TSFI achieves stable Li/electrolyte interface rich in LiF and Li3N on the anode side. Benefit from this design, the DLPE-based LiFePO4 and LiNi0.8Co0.1Mn0.1O2 battery deliver high safety and high stable performances under various extreme conditions.