Layered nanocomposite separators enabling dendrite-free lithium metal anodes at ultrahigh current density and cycling capacity

Non-uniform and dendritic lithium (Li) deposition in Li metal batteries largely compromises battery performance including cycle life, capacity and safety. Various innovative approaches have been proposed to solve these issues, but stable cycling of Li metal anode at high current density and cycling capacity remains challenging. Here, we report design of layered nanocomposite separators with nacre-like microstructure by considering both the electrochemical deposition behavior and spatial distribution of Li+ ions. The separators are prepared by flow-induced alignment of Laponite@RD nanosheets along the Celgard separator surface and in situ crosslinking of the nanosheets with polyvinylalcohol. The separators enable dendrite-free lithium metal anodes at ultrahigh current density and cycling capacity simultaneously. Remarkably, stable Li metal anode with low overpotential and a long cycle life of over 2000 h is achieved by the separator even at a current density of 30 mA cm−2 and a cycling capacity of 15.0 mA h cm−2. The Li-sulfur (5.4 mg cm−2 S loading) and Li-NCM523 (8.8 mg cm−2 NCM523 loading) batteries show excellent rate performance and cycling stability. This study demonstrates the potential of polymer/clay layered nanocomposite separators for stable cycling of Li metal anodes at high current density and cycling capacity.