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CSCD
Sodium metal is a promising anode for sodium batteries due to its high theoretical capacity and low cost. However, the serious Na dendrite growth and low Coulombic efficiency, especially at high current densities/cycling capacities, severely limit the application of sodium metal anodes. Herein, trifluoromethylfullerene, C60(CF3)6, is designed as an electrolyte additive to enable the high-rate cycling of sodium metal anodes with high Coulombic efficiency. The CF3 groups contribute to the formation of stable NaF-rich solid electrolyte interface layer, while C60 cages induce the uniform distribution of sodium ions and promote the formation of smooth and compact morphology. Thus, Na||Cu cell with C60(CF3)6 can be cycled at 2 mA·cm−2 and 10 mAh·cm−2 over 180 cycles with an average Coulombic efficiency of 99.9%, and Na||Na cell can be cycled at 10 mA·cm−2 over 600 cycles. Furthermore, Na||NaV2(PO4)3@C full cell exhibits high capacity retention of 84% over 2,000 cycles at 20 C (~ 3 mA·cm−2).
This work was supported by the National Science Foundation of China (Nos. 21925104, 51672093, 51821005, U1966214, 51902116, and 21975087). We thank the Analytical and Testing Center of HUST for all related measurements.