Surface Electric Field Shielding for Passivation-Free Zinc Anode Dissolution in Alkaline Batteries

Zinc anodes in alkaline electrolytes undergo spontaneous passivation, severely reducing their capacity utilization and battery performance. Strategies such as fabricating zinc powder or sponge structures improve zinc utilization by increasing reaction surface areas but often exacerbate hydrogen evolution. Here an alternative approach is reported: shielding the zinc reaction surface with miniature Faraday cages to reduce undesirable current crowding and mitigate passivation. This is demonstrates with an interwoven layer structure of bismuth dendrites on zinc plate anodes (Bi@Zn), achieving near-complete zinc dissolution and over 100 mAh cm^-2 discharge capacity, even in low alkaline or lean electrolytes where bare zinc fails rapidly. Multi-scale characterizations and simulations reveal that bismuth (Bi) Faraday cages delay passivation by dissipating localized electric fields, thereby suppressing Zn(OH)₄²⁻ accumulation and resultant ZnO precipitation near the reaction surface. As a result, a primary zinc-air battery using Bi@Zn achieves full discharge, whereas bare zinc fails at one-tenth of the discharge depth. Moreover, the Bi shielding layer enhances zinc anode reversibility, shown by a fivefold improvement in cycling stability of a nickel-zinc rechargeable battery with 10 mAh cm⁻² at 20 mA cm⁻². Importantly, the similar high zinc utilization achieved with copper shielding layers underscores the effectiveness of surface electric field shielding strategy.