Fig. 4

Sodium storage performance. a The first charge/discharge curves of S1–S4 electrodes. b CV curves of S1–S4 electrodes at a scan rate of 0.1 mV s⁻¹. c Rate capabilities of S1–S4 electrodes. d CV curve of the S4 electrode between 2.0 and 4.0 V with shadowed area representing the surface capacitive contribution at a scan rate of 0.1 mV s⁻¹. e EIS spectra of S1–S4 electrodes. f Cycle performances of S1–S4 electrodes. g Typical charge/discharge curves of the S4 cathode, the NGS anode, and the S4//NGS full cell. h Charge/discharge curves of the S4//NGS full cell at different C rates. The reversible capacity of the full cell at the high rate of 50 C is mainly limited by the NGS anode. i Cycle performance of the S4//NGS full cell at 10 C. Inset in (i) is the optical image of the punch cell device powering a LED