Bifunctional Interphase Promotes Li⁺ De‐Solvation and Transportation Enabling Fast‐Charging Graphite Anode at Low Temperature

Abstract

The most successful lithium-ion batteries (LIBs) based on ethylene carbonate electrolytes and graphite anodes still suffer from severe energy and power loss at temperatures below -20 °C, which is because of high viscosity or even solidification of electrolytes, sluggish de-solvation of Li⁺ at the electrode surface, and slow Li⁺ transportation in solid electrolyte interphase (SEI). Here, a coherent lithium phosphide (Li₃P) coating firmly bonding to the graphite surface to effectively address these challenges is engineered. The dense, continuous, and robust Li₃P interphase with high ionic conductivity enhances Li⁺ transportation across the SEI. Plus, it promotes Li⁺ de-solvation through an electron transfer mechanism, which simultaneously accelerates the charge transport kinetics and stands against the co-intercalation of low-melting-point solvent molecules, such as propylene carbonate (PC), 1,3-dioxolane, and 1,2-dimethoxyethane. Consequently, an unprecedented combination of high-capacity retention and fast-charging ability for LIBs at low temperatures is achieved. In full-cells encompassing the Li₃P-coated graphite anode and PC electrolytes, an impressive 70% of their room-temperature capacity is attained at -20 °C with a 4 C charging rate and a 65% capacity retention is achieved at -40 °C with a 0.05 C charging rate. This research pioneers a transformative trajectory in fortifying LIB performance in cryogenic environments.