Sodium‐Ion Battery with a Wide Operation‐Temperature Range from −70 to 100 °C

Sodium‐ion batteries (SIBs), as one of the potential candidates for grid‐scale energy storage systems, are required to tackle extreme weather conditions. However, the all‐weather SIBs with a wide operation‐temperature range are rarely reported. Herein, we propose a wide‐temperature range SIB, which involves a carbon‐coated Na4Fe3(PO4)2P2O7 (NFPP@C) cathode, a bismuth (Bi) anode, and a diglyme‐based electrolyte. We demonstrate that solvated Na+ can be directly stored by the Bi anode via an alloying reaction without the de‐solvent process. Furthermore, the NFPP@C cathode exhibits a high Na+ diffusion coefficient at low temperature. As a result, the Bi//NFPP@C battery exhibits perfect low‐temperature behavior. Even at −70 °C, this battery still delivers 70.19 % of the room‐temperature capacity. Furthermore, benefitting from the high boiling point of the electrolyte, this battery also works well at a high temperature of up to 100 °C. These results are encouraging for the further exploration of wide‐temperature range SIBs.