Functionalized gel polymer electrolyte membrane for high performance Li metal batteries

Inorganic solid-state electrolytes have high ionic conductivity and stability, which demonstrate the promising application in building solid batteries excepting their poor interface compatibility. Hence, making the solid electrolytes flexible, such as the combination with polymer is an important strategy in mitigating such problem. In this context, a robust membrane is fabricated with nanosized Li6.4La3Zr1.4Ta0.6O12 particles being filled into the porous PVDF-HFP as gel polymer electrolyte (GPE). This membrane displays a high ionic conductivity of 3.57 × 10−4 S cm−1, a large Li-ion transference number of 0.62, as well as the good mechanical strength and thermal stability. The as prepared Li/GPE/Li symmetric cell demonstrates an underlying electrochemical activation in stabilizing the membrane-electrode interface, which seems to be balancing the trade-off between the Li diffusion and side reactions at the interface. The fabricated LiFePO4|GPE|Li coin cell delivers a high Coulombic efficiency of 98%, a good rate capability at 2C (about 120 mAh g−1) and capacity retention of 92% after 110 cycles (150 mAh g−1, 0.4C) at room temperature. This important design provides a rewarding avenue to address the interface compatibility and develop composite electrolytes for high performance Li metal batteries.