Dual-Functional LiCl Additive for Highly Reversible Zinc Metal Anode

Zinc metal has emerged as a promising candidate for high-capacity and low-cost anodes in aqueous zinc-ion batteries; nevertheless, it encounters serious obstacles, including low cycling stability and poor reversibility, caused by parasitic reactions and the formation of zinc dendrites. Herein, the study proposes a novel nonprotonic dimethylacetamide (DMAC)/ZnCl₂/LiCl electrolyte that enables both solvation structural modulation of [ZnCl_x]^2-x and the cationic electrostatic shielding effect of [Li(DMAC)]⁺ by controlling the concentration of LiCl. The optimal concentration of LiCl electrolyte (0.28 m), which results in the highest ratio of [ZnCl₃]⁻, strikes a balance between low desolvation energy and a high mass transfer rate while promoting homoepitaxial deposition of Zn (002). Moreover, inert [Li(DMAC)]⁺ ions, which possess a lower reduction potential, preferentially adsorb onto zinc protrusions, mitigating the tip effect. Leveraging electrolyte engineering, the zinc deposition/stripping process results in impressive long-term stability, surpassing 2,800 cycles, and the Zn||MnO₂ cell also achieves a stable lifespan extending beyond 1400 cycles. The research highlights the potential of LiCl as an additive in the modulation of water-free electrolytes.