Highly reversible zinc anode enabled by a trace-amount additive with pH buffering capability†

Both high reversibility and cycle stability for zinc anode are desirable for practical applications. However, it is a challenge to obtain both due to severe hydrogen evolution, corrosion and pH fluctuation. Here, a trace-amount additive (0.1 wt%), ammonium succinate, is proposed to effectively suppress the above issues. The additive with high zinc absorbability not only participates in the Zn²⁺ solvation shell, reducing H₂O activity in the solvation shell but also forms an adsorption layer to inhibit corrosion and regulate ion flux for uniform deposition. More importantly, the strong pH buffering ability enabled by NH₄⁺ endows batteries with high cycle stability. Therefore, an unprecedentedly high average coulombic efficiency of 99.91% at 1 mA cm⁻² was obtained, and the symmetrical cell could stably cycle with a high cumulative capacity of 6150 mA h cm⁻² at 10 mA cm⁻², demonstrating the feasibility for both high reversibility and cycle stability for zinc anode.