Coumarin as an Efficient Bifunctional Additive to Promote the Performance of Aqueous Zinc‐Ion Batteries

Aqueous zinc‐ion batteries (AZIBs) hold great promise as next‐generation energy storage systems. However, AZIBs currently face several challenges, such as hydrogen evolution reaction (HER), zinc metal corrosion, and zinc dendrite growth, which pose a serious obstacle to the practical application of AZIBs. In this study, coumarin (CMA) containing carboxylate groups (COO) was employed as a bifunctional electrolyte additive to improve the reversibility of AZIBs. Typically, the carboxylate with high nucleophilicity would coordinate with Zn 2+ to regulate the Zn 2+ solvation structure, and meanwhile, the carboxylate on CMA could also result in preferentially uniform Zn 2+ deposition on the beneficial (002) plane. Accordingly, CMA was able to effectively inhibit HER, dendrite growth, and corrosion during the deposition and stripping processes. As a result, the CMA@ZnSO 4 electrolyte enabled a symmetric Zn||Zn cell to achieve stable cycling for more than 430 h at 5 and 1 mAh cm −2 . In addition, the asymmetric Zn||Cu cell with CMA@ZnSO 4 displayed a stable cycling over 90 cycles at 1 and 1 mAh cm −2 , and it gave an average Coulombic efficiency (ACE) of 99.54%, indicating its excellent reversibility during the zinc plating/stripping process. In this study, an innovative strategy is proposed for constructing high‐performance AZIBs, which is based on natural products to promote the desolvation and to induce the oriented deposition of Zn 2+ ions on the (002) plane of the Zn anode, thereby suppressing undesirable issues such as HER, zinc corrosion, and dendrite growth.