Fig. 6: Electrochemical window and Na plating/stripping of COF-QSSEs.

a LSV profiles of SS|TPBD-QSSE|Na and SS|TPDBD-CNa-QSSE|Na asymmetric cells. b Calculated HOMO and LUMO values of TPBD and TPDBD based on DFT calculations. c Rate performance of Na plating/stripping for Na|QSSE|Na at 25 ± 1 °C and 0.01, 0.03, 0.04, 0.1, 0.2, 0.5, 0.6, and 0.8 mA cm−2. d Na plating/stripping of Na|QSSE|Na at a current density of 0.01 mA cm−2 and 25 ± 1 °C for 900 h and 2 h per cycle (the inset shows the time-division plating/stripping curves).