Extended Data Fig. 6: Characterizations of Na anode immersed and cycled in 4 M AlCl3 in SOCl2 with and without 2 wt% NaFSI/NaTFSI, and charge–discharge curves of the normal battery versus decayed battery.
a, Atomic percentage of different elements on the Na metal when immersed in 4 M AlCl3 in SOCl2 with and without 2 wt% NaFSI/NaTFSI as additives. b, F 1s spectrum of Na immersed in 4 M AlCl3 in SOCl2 with/without additives. c, S 2p spectrum of Na immersed in 4 M AlCl3 in SOCl2 with/without additives. d, Cl 2p spectrum of Na immersed in 4 M AlCl3 in SOCl2 with/without additives. e, Atomic percentage of different elements on the Na metal after cycling for 21 cycles in Na/Cl2 battery when 4 M AlCl3 in SOCl2 with and without 2 wt% NaFSI/NaTFSI as additives were used as the electrolyte. f, F 1s spectrum of Na cycled in Na/Cl2 battery when 4 M AlCl3 in SOCl2 with/without additives were used as the electrolyte. g, SEM images of Na anode from actual Na/Cl2 battery in charged state (top images) and when lost cycling capability (bottom images). Note that in the case of battery without fluoride additive, the Na anode surface was coated by more densely packed NaCl particles, eventually leading to the loss of re-chargeability. h, Charge–discharge curves of the battery at normal state and after the battery started to decay.
