Weak Cation–Solvent Interactions in Ether‐Based Electrolytes Stabilizing Potassium‐ion Batteries

Abstract Conventional ether‐based electrolytes exhibited a low polarization voltage in potassium‐ion batteries, yet suffered from ion–solvent co‐intercalation phenomena in a graphite anode, inferior potassium‐metal performance, and limited oxidation stability. Here, we reveal that weakening the cation–solvent interactions could suppress the co‐intercalation behaviour, enhance the potassium‐metal performance, and improve the oxidation stability. Consequently, the graphite anode exhibits K + intercalation behaviour (K||graphite cell operates 200 cycles with 86.6 % capacity retention), the potassium metal shows highly stable plating/stripping (K||Cu cell delivers 550 cycles with average Coulombic efficiency of 98.9 %) and dendrite‐free (symmetric K||K cell operates over 1400 hours) properties, and the electrolyte exhibits high oxidation stability up to 4.4 V. The ion–solvent interaction tuning strategy provides a promising method to develop high‐performance electrolytes and beyond.