Intermolecular Interaction Mediated Potassium Ion Intercalation Chemistry in Ether‐Based Electrolyte for Potassium‐Ion Batteries

Abstract Electrolyte design is indeed a highly effective strategy to improve battery performance. However, identifying the intermolecular interaction in electrolyte solvation structure is rarely reported in potassium‐ion batteries. Herein, it is discovered that a solvent‐solvent intermolecular interaction can be formed when introducing the cyclopentylmethyl ether (CPME) solvent into the commonly used 1,2‐dimethoxyethane (DME)‐based electrolytes. Such interaction is not only analyzed by 2D 1 H‐ 1 H correlation spectroscopy for the first time but also found that it can weaken the K + ‐DME interaction significantly, consequently enabling a reversible K + (de‐)intercalation within the graphite. By employing this strategy without using any fluorine‐based solvent, a new fluorine‐free and low‐concentration ether‐based electrolyte is designed, which is not only compatible with graphite but also facilitates the design of high‐energy‐density and safe potassium ion sulfur batteries. A novel molecular interfacial model is further presented to analyze the interfacial behaviors of K + ‐solvent‐anion complexes on the electrode surface that are affected by intermolecular interactions, elucidating the reasons behind the superior electrolyte compatibility and graphite electrode performance at the molecular scale. This work sheds some light on the critical role of solvent–solvent interactions in electrolyte design for potassium‐ion batteries and provides valuable insights for engineering and enhancing the performance of electrolytes and batteries.