Restructuring Electrolyte Solvation by a Versatile Diluent Toward Beyond 99.9% Coulombic Efficiency of Sodium Plating/Stripping at Ultralow Temperatures

Abstract The reversible and durable operation of sodium metal batteries at low temperatures (LT) is essential for cold‐climate applications but is plagued by dendritic Na plating and unstable solid‐electrolyte interphase (SEI). Current Coulombic efficiencies of sodium plating/stripping at LT fall far below 99.9%, representing a significant performance gap yet to be filled. Here, the solvation structure of the conventional 1 m NaPF 6 in diglyme electrolyte by facile cyclic ether (1,3‐dioxolane, DOL) dilution is efficiently reconfigured. DOL diluents help shield the Na + ‐PF 6 − Coulombic interaction and intermolecular forces of diglyme, leading to anomalously high Na + ‐ion conductivity. Besides, DOL…

• NS
  Natural Science Foundation of Guangdong Province

  Award: 2023A1515010020
• HK
  Hong Kong Polytechnic University

  Awards: 2019B121205001, ZZLM, YY4V, YY5K
• GS
  Guangdong Science and Technology Department

  Award: 2019B121205001
• SS
  Shenzhen Science and Technology Innovation Program

  Award: SGDX20190816230615451
• BA
  Basic and Applied Basic Research Foundation of Guangdong Province

  Awards: 2020A1515110798, 2019B121205001