Scalable Synthesis of LiF-rich 3D Architected Li Metal Anode via Direct Lithium-Fluoropolymer Pyrolysis to Enable Fast Li Cycling

Abstract

Lithium metal anode holds an important position in fast-charging batteries. But lithium dendrite issues tend to exacerbate at high currents. LiF can be considered as an effective way to improve the Li metal surface electrochemical stability to achieve high power and high energy. However, most of reported work are relying on in situ formation of a 2D LiF on Li metal in liquid electrolyte, which limits the scalability and plated Li quantity. Here, we address this challenge and report a scalable synthesis of LiF-rich 3D architected Li metal anode via a direct pyrolysis of molten lithium and fluoropolymer to enable fast Li charging with high current density (20 mA cm−2) and high areal capacity (20 mAh cm−2). The 3D structure is synthesized by the pyrolysis of fluoropolymer with Li metal and results show high similarity to the pristine electrolyte-derived solid-electrolyte-interphase (SEI). This concept using pyrolysis of fluoropolymer with Li-containing active materials could be also extended to modify Li metal oxide cathode (e.g., LiNi0.5Mn1.5O4) for mixed conductive interphase and engineer Li solid ion conductors (e.g., Li garnet-type oxides) for interface stabilization and framework design.