Targeted leveling of the undercoordinated high field density sites renders effective zinc dendrite inhibition

Suppressing morphological instability during electrodeposition of zinc has lately been the subject of intense research owing to its significance for aqueous zinc-ion batteries with tremendous potential for renewable and grid storage applications. A variety of surface coating and electrolyte optimization approaches have been explored, but controlled leveling of undercoordinated zinc sites that are responsible for uneven dendritic deposition have never been considered. Here, the unique and targeted leveling action of two additives on two crystallographically distinct active Zn sites - on the corrugated {100}hexagonal facets of growing zinc crystallites and around surface irregularities, respectively - is unraveled through both theory and experiments, which enables compact and smooth deposition morphology conducive for stable cycling. An optimized ratio of the additives endows over 1200 h of Zn plating/stripping at 2 mA - 2 mAh cm−2, a 40-fold enhancement over the additive-free zinc sulfate electrolyte. Most importantly, the stability of the Zn cycling translates to the long-term full cell cyclability for a high cathode loading without affecting the obtainable capacity and rate performance. Fundamentally, this work reveals the unique mechanistic vantage of the additive functionality relative to the nature of the undercoordinated zinc site, critical to achieving comprehensive control over the zinc deposition morphology for durable cycling.