Effective Solution toward the Issues of Zn-Based Anodes for Advanced Alkaline Ni–Zn Batteries
Alkaline nickel–zinc (Ni–Zn) batteries, as traditional rechargeable aqueous batteries, possess an obvious advantage in terms of energy density, but their development has been hindered by the anode-concerned problems, Zn dendrites, self-corrosion, passivation, deformation, and hydrogen evolution reaction (HER). Herein, to solve these problems, a dual protective strategy is proposed toward the anode using ZnO as an initial active material, including a C coating on ZnO (ZnO@C) and a thin poly(vinyl alcohol) (PVA) layer coating on the electrode (ZnO@C-PVA). In a three-electrode configuration, the reversible capacity can reach 600 mAh g–1 for the ZnO@C-PVA. Using excessive commercial Ni(OH)2 as the cathode, the alkaline Ni–Zn cells exhibit good electrochemical performance: Discharge capacity can be as high as 640–650 mAh g–1 at 4 A g–1 with a Coulomb efficiency (CE) as high as 97–99% after activity, suggesting low self-corrosion and HER. Capacity retention is 97% after 1200 cycles, indicating rather good durability. The discharge capacity is even slightly increased with the increase of charge/discharge current density (≤8 A g–1), implying good rate performance. Additionally, the discharge voltage can reach 1.8 V (midpoint value) at various current densities, reflecting the fast reaction kinetics of the anode. Most importantly, no Zn dendrites and passivation are observed after long-term cycling. The strategy proposed here can solve the anode-concerned problems effectively, exhibiting a high application prospect.
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