PVDF-HFP/LiF Composite Interfacial Film to Enhance the Stability of Li-Metal Anodes

Lithium metal is considered to be the “holy grail” electrode due to its high theoretical energy density and low potential. However, the growth of lithium dendrites and the high reactivity of Li metal to the electrolyte result in a poor Coulombic efficiency and raise safety concerns for lithium–metal batteries (LMBs). Herein we attempt to integrate an artificial solid electrolyte interphase (SEI) and regulate Li+ flow through an organic–inorganic composite interfacial film (CIF) with a LiF-rich inner side and a polymer-rich outer side. The as-prepared CIF is tightly bound to the surface of Li metal through a facile and cost-effective strategy. The LiF-rich side (near the Li metal) renders a high surface energy and exhibits a low Li+ diffusion barrier, ensuring uniform lithium growth and hindering parasitic side reactions between the Li metal and the electrolyte. The polymer-rich outer side provides excellent compatibility with the electrolyte, considerable Li+ conductivity, and mechanical support to accommodate possible mechanical stress during battery processing. The CIF regulates Li deposition and protects Li from the corrosive electrolyte, resulting in dendrite-free and highly reversible Li-metal anodes. It exhibits superior cyclic stability during 500 h of Li plating/stripping processes under a high current density of 3 mA cm–2. The CIF, as a simple and low-cost strategy for an artificial SEI, is promising for LMBs.