Fig. 4: Characterization of ZABs.

a Schematic diagram of a ZAB. b Charge‒discharge polarization curves. c Polarization curves and power densities of ZABs loaded with N₁S₁@CF and commercial Pt/C. d Constant current discharge curves at different current densities for ZABs with N₁S₁@CF as the cathode catalyst. e Mass-to-capacity curves. f Constant current discharge‒charge cycle curves at 10 mA cm⁻² for rechargeable ZABs with N₁S₁@CF and commercial Pt/C as catalysts. g Constant current discharge‒charge cycle curves at different current densities for ZABs. h Constant current discharge‒charge cycle curves at 10 mA cm⁻² for ZABs with N₁S₁@CF as the catalyst, with the inset showing a homemade ZAB with a multimeter (left) and a white LED (∼3 V) powered by two integrated ZABs (right).