Accelerating interfacial desolvation kinetics using NaF-rich composite sodium for high-performance all-climate sodium–metal batteries

Abstract

Sodium–metal batteries (SMBs) are considered the ideal candidates for the next-generation large-scale energy storage batteries. However, achieving all-climate SMBs operating in a wide temperature range remains a huge challenge because of the instability of the Na/electrolyte interphases and sluggish reaction kinetics, particularly at ultra-low temperatures (−40 °C). Herein, we develop a novel NaF-rich composite sodium anode by impregnating NaF into metallic Na (NaF@Na) for the first time. Through this design, an NaF-rich SEI can be embedded into the anode homogeneously, which can endow the Na/electrolyte interface with a good thermal stability at 60 °C and accelerate the desolvation of Na⁺-solvent molecular clusters at −40 °C. In light of these collective advancements, the NaF@Na‖NVP full cell realized stable all-climate operation from −40 to 60 °C with a commercial ester-based electrolyte, displaying a high-capacity retention of 90% after 400 cycles (0.2C) even at −40 °C together with an outstanding electrochemical performance at 60 °C (106.1 mA h g⁻¹ and 76% capacity retention over 2400 cycles at 10C), which has rarely been achieved in previous studies. This unique composite Na anode design offers new insights and prospects for all-climate operation and lays the basis for practical SMBs.