Nanopile Interlocking Separator Coating toward Uniform Li Deposition of the Li Metal Anodes

Abstract

Uncontrollable growth of Lithium (Li) dendrite has severely hindered the development of Li metal anodes, while separator modification is regarded as a simple and effective way to mitigate the growth of Li dendrite. However, the “drop-dregs” phenomenon of coating layer desquamated from polyolefin separator due to their different Young’s modulus would induce non-uniform Li ionic flux, finally resulting in deteriorative electrochemical performance and even thermal runaway of the battery. Herein, we introduce a novel nanopile mechanical interlocking strategy to create delamination-free separator modification, that could stably generate homogeneous Li ionic flux to guide long-term uniform Li deposition. Both experimental and simulation results demonstrate strong bonding strength between coating layer and membrane matrix based on this physical interlocking mechanism. Consequently, with nearly dendrite-free Li deposition and largely reduced interface impedance, 1000 h stable cycling of Li//Li half cells enrolled this modified separator is successfully achieved. And a significantly improvement of Li/LiFePO4 full cells in long-term cycling stability to 500 cycles further indicates its promising practical potential. Moreover, this presented approach without any binding agents or surface activation procedures could be facilely scaled up, providing an applicable and durable separator modification solution towards stable Li metal anodes.