Anion‐Reinforced Solvation Structure Enables Stable Operation of Ether‐Based Electrolyte in High‐Voltage Potassium Metal Batteries

Abstract Electrolytes with anion‐dominated solvation are promising candidates to achieve dendrite‐free and high‐voltage potassium metal batteries. However, it's challenging to form anion‐reinforced solvates at low salt concentrations. Herein, we construct an anion‐reinforced solvation structure at a moderate concentration of 1.5 M with weakly coordinated cosolvent ethylene glycol dibutyl ether. The unique solvation structure accelerates the desolvation of K + , strengthens the oxidative stability to 4.94 V and facilitates the formation of inorganic‐rich and stable electrode‐electrolyte interface. These enable stable plating/stripping of K metal anode over 2200 h, high capacity retention of 83.0 % after 150 cycles with a high cut‐off voltage of 4.5 V in K 0.67 MnO 2 //K cells, and even 91.5 % after 30 cycles under 4.7 V. This work provides insight into weakly coordinated cosolvent and opens new avenues for designing ether‐based high‐voltage electrolytes.