Fig. 5: Electrochemical energy storage performances of the Na–S@Fe₃N-NMCN cell.

a First three CV curves at a scan rate of 0.2 mV s⁻¹. b First three voltage-capacity curves at a specific current of 167.5 mA g⁻¹. c Rate capability at specific currents of 167.5, 335, 837.5, 1675, 3350, 8375, 10050, 13400, 16750 mA g⁻¹. d Comparison of EIS spectra between BC-Ar, BC-NH₃, and Fe₃N-NMCN before the rate test. e Long-term cycling performance at a specific current of 8375 mA g⁻¹. f Comparison of electrochemical performance and sulfur content with previous literature. g In situ Raman spectra at a specific current of 167.5 mA g⁻¹.