Surface Coating on a Separator with a Reductive Solid Li-Ion Conductor for Dendrite-Free Li-Metal Batteries

The poor mechanical strength of the polymer separator and the uneven deposition of Li ions during the stripping/plating process in the lithium-metal batteries have severely deteriorated the electrochemical performance and safety of lithium batteries. Herein, a polydopamine-modified polypropylene (PP) separator with a coating layer of 1.5 μm thickness of polydopamine-modified perovskite Li-ion solid electrolyte Li3/8Sr3/8Ta3/4Zr1/4O3 (LSTZ) nanopowders is proposed, which can effectively promote the Li+/electron transfer and physical performance during the discharge/charge process in lithium-metal batteries. The LSTZ-decorated PP separators provide an improved wettability of the liquid electrolyte and excellent Li+/electron balance at the separator/lithium-metal interfaces, leading to higher Coulombic efficiencies and enhanced cycling stabilities in both Li/LSTZ-coated PP/Cu and Li/ LSTZ-coated PP/Li cells. As a result, the Li/LSTZ-coated PP/LiFePO4 cells have a capacity retention rate of 90% after 600 cycles and a Coulombic efficiency of 93.3%.