Entropy‐Repaired Solvation Structure Strategy for High‐Efficiency Phosphate‐Based Localized High‐Concentration Electrolytes in Potassium Batteries

Abstract The safety and cycling stability of potassium‐ion batteries (PIBs) are deeply associated with potassium‐ion electrolytes. However, due to the weak Lewis acidity of potassium ions, localized high‐concentration electrolytes in PIBs are prone to excessive weak solvation. Herein, we propose an entropy repair strategy for the solvation structure of potassium ions and systematically design a moderately weakly solvated high‐entropy localized high‐concentration electrolyte. The repaired electrolyte can achieve an average stable Coulombic efficiency of 99.4 % on the Cu collector surface. The potassium symmetric battery can be stably cycled for over 10000 h under a high current density of 0.5 mA cm −2 and a large deposition capacity of 1 mAh cm −2 . The potassium metal pouch cell, using K 1.92 Fe[Fe(CN) 6 ] 0.94 ⋅0.5H 2 O as the cathode, maintains a capacity retention of 87.5 % after 2000 cycles at a current density of 0.5 A g −1 . Even when the current density is increased tenfold from 0.1 A g −1 , the battery still retains 67.1 % of its capacity. Additionally, due to the introduction of multiple solvents, the potassium metal battery with perylene‐3,4,9,10‐tetracarboxylic dianhydride as the cathode can maintain reversible capacities of 94.0 and 77.3 mAh g −1 and operate stably at ambient temperatures of −20 and −40 °C, respectively.