A Compact Gel Membrane Based on a Blend of PEO and PVDF for Dendrite-Free Lithium Metal Anodes

A compact gel membrane (GM) with certain flexibility is facilely fabricated after a casted PEO/PVDF blend film is swelled by a LiPF₆-based liquid electrolyte. The GM exhibits a suitable lithium ionic conductivity (0.28 mS cm⁻¹ at r.t., room temperature), a remarkable lithium-ion transference number (0.52 at r.t.), and high mechanical strength (19.0 MPa) in dry or wet state. Owing to the special comprehensive performance of the GM, dendrite-free reversible lithium plating/stripping (up to 500 h) at a current density of 0.5 mA cm⁻² and a capacity of 0.25 mAh cm⁻² is achieved for Li metal anodes at r.t. The suppression of lithium dendrite of the obtained GM is further demonstrated in Li/GM/LiFePO₄ cells with a high discharge capacity (142 mAh g⁻¹ at r.t. and 160 mAh g⁻¹at 50 °C) and a superior cycling stability. This research provides a new strategy for developing lithium metal batteries with high stability and long cycle life.