fig5

Figure 5. Electrochemical characterizations of CrO_x/NC, MnFeCoNi/NC, CrMnFeCoNi-(CrO_x)₁/NC, and (Pt/C+RuO₂)-based ZABs: (A) discharge-charge polarization curves and (B) corresponding power density curves at current ramping rate of 1 mA s^-1; (C) ORR LSV curves, (D) OER LSV curves, and (E) potential gaps (△E₁₀ and △E₁₀₀) of CrMnFeCoNi-(CrO_x)₁/NC and (Pt/C+RuO₂)-based air electrodes in 6.0 M KOH at scan rate of 1 mV s^-1; (F) Step voltage diagrams of CrO_x/NC, MnFeCoNi/NC, CrMnFeCoNi-(CrO_x)₁/NC, and (Pt/C+RuO₂)-based ZABs working at varying charge/discharge current densities from 10 to 50 and then back to 10 mA cm^-2; (G) Specific capacities achieved by CrO_x/NC, MnFeCoNi/NC, CrMnFeCoNi-(CrO_x)₁/NC, and (Pt/C+RuO₂)-based ZABs at 50 mA cm^-2; (H) Galvanostatic cycling discharge-charge stability tests of CrMnFeCoNi-(CrO_x)₁/NC and (Pt/C+RuO₂)-based ZABs at 10 mA cm^-2 with duration of 20 min per cycle (10 min discharge + 10 min charge). ORR: Oxygen reduction reaction; LSV: linear sweep voltammetry; OER: oxygen evolution reaction; ZABs: zinc-air batteries.