Solvation Structure Dual‐Regulator Enabled Multidimensional Improvement for Low‐Temperature Potassium Ion Batteries

Abstract The operation of graphite‐based potassium ion batteries (Gr‐PIBs) remains challenging at low temperatures, limited by slow dynamic behavior. Herein, the solvation structure dual‐regulator strategy of electrolyte is proposed for multidimensional improvement of K + transfer process including ion transfer at both bulk and interface. The designed electrolyte (an amide solvent, 2,2,2‐Trifluoro‐N, N‐dimethylacetamide) with low freezing point and low viscosity as the primary regulator, and a fluorinated solvent (1,1,2,2‐Tetrafluoroethyl‐2,2,3,3‐tetrafluoropropylether) as the secondary regulator provides a flowing environment and low resistive interface for fast ion transfer. As a result, the regulated electrolyte has a low freezing point of −51.9 °C and exhibits a high ionic conductivity of 3.2 mS cm −1 at −20 °C. Based on the solvation structure dual‐regulator, the graphite anode delivered a high capacity of 252 mAh g −1 which is over 85% of room‐temperature capacity, and the capacity retention rate of a full cell at −20 °C is over 80%. These results demonstrate that the solvation structure dual‐regulator can improve the performances of Gr‐PIBs, promoting the development of low‐temperature PIBs and beyond.