Electrodeposited ZnNi-Alloy Anode for 2D Nucleation-Induced Dendrite Suppression in Aqueous Zinc-Ion Batteries

Aqueous zinc (Zn)-ion batteries (AZIBs) are a promising low-cost, safe, and sustainable alternative to the erstwhile nonaqueous Li-ion batteries. Despite these head-start advantages, the Zn-anode/electrolyte interface poses several formidable fundamental challenges, as its mismanagement often leads to a plethora of detrimental factors, including uncontrolled growth of zinc dendrites, resulting in poor battery cyclability. Contrary to the conventional Zn-anode, we demonstrate here an alternative zinc–nickel (ZnNi)-alloy anode obtained via the electrodeposition of Ni & Zn on a Zn-foil (denoted as ZnNi-alloy@Zn). This strategy leverages excellent corrosion resistance, mechanical durability, and zincophilicity of nickel-based alloys. The ZnNi alloy sustains uniform Zn2+ ion flux and facilitates homogeneous Zn-deposition, effectively suppressing dendrite growth. Contrary to an instantaneous Zn-nucleation growth observed in the case of the unmodified Zn-foil (as per the Scharifker–Hill analysis), Zn nucleation on the ZnNi@Zn surface occurs in an progressive manner. Due to the significant reduction in the corrosion current, the Zn–Ni alloy exhibited enhanced long-term stability in both symmetric and full-cell configurations. The ZnNi || ZnNi symmetric cell demonstrated cycling performance for over 934 h with a low voltage hysteresis of 36 mV during Zn plating/stripping. When assembled with a MnO2 cathode, the ZnNi full cell delivered a high discharge capacity of 122 mAh g–1 over 400 cycles at a current density of 2 A g–1 (capacity retention ≈ 92.56%), outperforming the full cell with the unmodified-Zn anode (≈81 mAh g–1 over 300 cycles at a current density of 2 A g–1; capacity retention ≈ 48.78%). This work highlights a practical and scalable strategy to mitigate detrimental performance factors of the Zn-anode in aqueous ZIBs, thus advancing the viability of ZIBs as a prominent sustainable energy storage solution.