Weakly Coordinating Diluent Modulated Solvation Chemistry for High‐Performance Sodium Metal Batteries

Abstract Diluents have been extensively employed to overcome the disadvantages of high viscosity and sluggish kinetics of high‐concentration electrolytes, but generally do not change the pristine solvation structure. Herein, a weakly coordinating diluent, hexafluoroisopropyl methyl ether (HFME), is applied to regulate the coordination of Na + with diglyme and anion and form a diluent‐participated solvate. This unique solvation structure promotes the accelerated decomposition of anions and diluents, with the construction of robust inorganic‐rich electrode‐electrolyte interphases. In addition, the introduction of HFME reduces the desolvation energy of Na + , improves ionic conductivity, strengthens the antioxidant, and enhances the safety of the electrolyte. As a result, the assembled Na||Na symmetric cell achieves a stable cycle of over 1800 h. The cell of Na||P’2‐Na 0.67 MnO 2 delivers a high capacity retention of 87.3 % with a high average Coulombic efficiency of 99.7 % after 350 cycles. This work provides valuable insights into solvation chemistry for advanced electrolyte engineering.