Unveiling the Electrostatic Potential Assist Weakly Solvating Electrolytes Design Toward High Performance Sodium Metal Batteries

ABSTRACT Sodium metal batteries (SMBs), which employ sodium metal as the anode material, have appeared as a potential option for future energy storage technology. However, several issues, such as ongoing side reactions, hinder the development and application. To address the above issues, the weakly solvating electrolytes (WSEs) are introduced, but unified design principles are still lacking. Thus, proposing a design principle for WSEs is of great significance for the further development of SMBs. In this work, a rational strategy for constructing WSEs is proposed, which is based on screening suitable solvents via molecular electrostatic potential and binding energy between solvents and Na + . Theoretical investigations reveal that the complementary effect between weakly solvating solvents and moderately polar solvents is conducive to the formation of high‐performance WSEs. The anion‐rich weak solvation structure formed by this electrolyte effectively facilitates the formation of a dense solid electrolyte interphase (SEI), which is further confirmed by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The Na||Na 3 V 2 (PO 4 ) 3 battery assembled with this electrolyte demonstrates a remarkable capacity retention of 82.7% after 2500 cycles at 5 C. This study provides valuable theoretical insights for the fundamental understanding of WSEs, which is conducive to the development of high‐performance SMBs.