Regulation of anion-Na + coordination chemistry in electrolyte solvates for low-temperature sodium-ion batteries

• Published in: Proceedings of the National Academy of Sciences - PNAS 2024-01, Vol.121 (5), p.e2316914121
• Main Authors: Zhou, Xunzhu, Huang, Yaohui, Wen, Bo, Yang, Zhuo, Hao, Zhiqiang, Li, Lin, Chou, Shu-Lei, Li, Fujun
• Format: Article
• Language: English
• Subjects: Anions; Energy storage; Low temperature; Physical Sciences; Room temperature; Sheaths; Sodium; Sodium-ion batteries; Solvation; Storage systems
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.2316914121

High-performance sodium storage at low temperature is urgent with the increasingly stringent demand for energy storage systems. However, the aggravated capacity loss is induced by the sluggish interfacial kinetics, which originates from the interfacial Na desolvation. Herein, all-fluorinated anions with ultrahigh electron donicity, trifluoroacetate (TFA ), are introduced into the diglyme (G2)-based electrolyte for the anion-reinforced solvates in a wide temperature range. The unique solvation structure with TFA anions and decreased G2 molecules occupying the inner sheath accelerates desolvation of Na to exhibit decreased desolvation energy from 4.16 to 3.49 kJ mol and 24.74 to 16.55 kJ mol beyond and below -20 °C, respectively, compared with that in 1.0 M NaPF -G2. These enable the cell of Na||Na V (PO ) to deliver 60.2% of its room-temperature capacity and high capacity retention of 99.2% after 100 cycles at -40 °C. This work highlights regulation of solvation chemistry for highly stable sodium-ion batteries at low temperature.