LiF‐Induced Stable Solid Electrolyte Interphase for a Wide Temperature SnO2‐Based Anode Extensible to −50 °C

Abstract

AbstractLithium‐ion batteries (LIBs) suffer dramatic energy reduction, and are even unable to safely charge below ‐10 °C, due to sluggish Li+ transport kinetics in the anode, electrolyte and solid electrolyte interphase (SEI), as well as large overpotential which causes Li plating on the anode surface. Herein, a SnO2‐LiF‐graphite (SLG) composite anode is developed for wide temperature application. The SLG with a propylene carbonate electrolyte delivers a stable capacity of more than 900 mA h g−1 at 60 °C with 100 mA g−1, maintaining 823.9 mA h g−1 at ‐10 °C. When matched with a tetrahydrofuran‐based electrolyte, the SLG delivers stable capacities of 780.4 mA h g−1 at ‐40 °C and 637.2 mA h g−1 at ‐50 °C, respectively. It is demonstrated that the LiF‐induced inorganic‐rich SEI maintains the nanostructure of the active Sn, and that their interfaces with the electrolyte are highly stable. Furthermore, the formation of α‐Sn with higher Li+ diffusion kinetics results in a very small overpotential (≈0.18 V) of lithiation for SLG from 30 °C to ‐50 °C. This work shows that LiF‐modified SnO2 anodes matched with suitable electrolytes can qualify the LIBs for a safe and long‐life at wide temperature, which is helpful to further promote these batteries for low‐temperature applications.