Fig. 4: Electrochemical performance of symmetric batteries of Zn or Zn-Al alloy electrodes.

a Comparison of voltage profiles for monometallic Zn, hypoeutectic Zn₅₀Al₅₀ and eutectic Zn₈₈Al₁₂ (λ = ∼450 nm) symmetric batteries during Zn stripping/plating at various current densities from 1 to 5 C in aqueous ZnSO₄ electrolyte with the absence of O₂, where 1 C = 0.5 mA cm⁻². b Long-term Zn stripping/plating cycling of symmetric batteries of monometallic Zn, hypoeutectic Zn₅₀Al₅₀ or eutectic Zn₈₈Al₁₂ alloys (λ = ∼450 nm) at the current density of 0.5 mA cm⁻² in aqueous ZnSO₄ electrolyte with the absence of O₂. c–e Comparisons of EIS spectra for eutectic Zn₈₈Al₁₂ (λ = ∼450 nm) (c), hypoeutectic Zn₅₀Al₅₀ (d) monometallic Zn (e) symmetric batteries after the 1^st and 100^th cycles in aqueous ZnSO₄ electrolyte in the absence of O₂. Inset: Expanded view for EIS of Zn₈₈Al₁₂. f–h SEM images of eutectic Zn₈₈Al₁₂ (λ = ∼450 nm) (f), hypoeutectic Zn₅₀Al₅₀ (g) monometallic Zn (h), electrodes after long-term Zn stripping/plating cycling measurements for 2000, 520, and 42 h in aqueous ZnSO₄ electrolyte with the absence of O₂, respectively. Scale bare, 5 μm (f–h).