Boosting Graphite Anode Performance in Potassium‐Ion Batteries With Synergistic Six‐Membered Cyclic Ether Electrolytes

Graphite anode offers high theoretical capacity and low potassium storage potential, making it attractive for practical potassium‐ion batteries (PIBs). Ether‐based electrolytes have been widely explored in graphite anodes because of their capability in robust solid‐electrolyte interphases (SEIs) formation, yet several challenges remain, including solvent co‐intercalation and poor oxidation stability. Compared to widely studied five‐membered cyclic ethers, the six‐membered counterparts possess advantages in improving the physical properties of electrolytes and formulating weak solvating structures that are beneficial for building stable interfaces. By hybridizing two six‐membered cyclic ethers, 1,3,5‐trioxane and 1,3‐dioxane, a thin, uniform, and inorganic‐rich SEI has been constructed. Consequently, the graphite anode delivers exceptional rate capability, realizing over 230 mAh g −1 at 2 C and 150 mAh g −1 at 6 C with outstanding cycling stability. Meanwhile, the formulated electrolyte demonstrates decent stability with 3.83 V‐class Prussian blue analogue cathodes, allowing the fabrication of high‐voltage full cells. This work enriches ether‐based electrolyte chemistry for advanced PIB development.