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 potassiummetal 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 j j graphite cell operates 200 cycles with 86.6 % capacity retention), the potassium metal shows highly stable plating/stripping (K j j Cu cell delivers 550 cycles with average Coulombic efficiency of 98.9 %) and dendritefree (symmetric K j j 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 highperformance electrolytes and beyond.

Electrolytes are critical for the safety and long-term cyclability of potassium ion batteries. Here, a low-concentration, non-flammable, and weakly solvating electrolyte enables the cycling stability of K||graphite cell for over 2 years.

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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 potassiummetal 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 j j graphite cell operates 200 cycles with 86.6 % capacity retention), the potassium metal shows highly stable plating/stripping (K j j Cu cell delivers 550 cycles with average Coulombic efficiency of 98.9 %) and dendritefree (symmetric K j j 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 highperformance electrolytes and beyond.