Aqueous zinc-ion batteries are regarded as one of the new promising rechargeable batteries. However, serious Zn dendrite growth causes short-circuit issues in the batteries. Herein, we report that arginine (Arg), a cationic surfactant electrolyte additive, can inhibit irregular and nonplanar dendrite growth and induce uniform Zn deposition. It shows a long cycle life (515 h) of Zn/Zn cells in the electrolyte containing Arg, which is ∼10 times longer than that of the electrolyte with no additive. The hydrolysis of Arg produces arginine cations (Arg + ), which will be preferentially adsorbed on Zn dendrites due to the tip charge accumulation effect during the Zn plating process. Arg + increases the overpotential for the nucleation of Zn dendrites and results in uniform Zn deposition. After about 350 cycles, the MnO 2 /Zn cell shows 84.59% capacity retention and 99.85% average Coulomb efficiency in the electrolyte with the additive. The low-cost and nontoxic electrolyte additive identified in this work provides a new pathway toward inducing regular Zn deposition morphology.

Uncontrollable growth of zinc dendrites and byproducts has become the main factor which limits the life of zinc-ion batteries. Herein, we reported a nonionic surfactant, coconut diethanolamide (CDA), which can be applied as an electrolyte additive. It not only effectively suppresses zinc graft growth and promotes uniform growth of zinc dendrites but also efficiently inhibits the generation of side reactions and byproducts. When CDA is added to the electrolyte, the life of the battery has been significantly improved (1580 h). Compared with an electrolyte without CDA (100 h), its life has grown more than 10 times. CDA can adsorb on the surface of the zinc electrode to form a protective layer by its special molecular structure. Therefore, zinc ions will have a higher barrier for deposition, and there should be induced uniform deposition. Moreover, the Cu/Zn cell shows 98% average Coulomb efficiency in the electrolyte with CDA after about 620 h. In addition, after long-term cycles, the addition of CDA enables the MnO2/Zn cell to show 85% capacity retention and 98% average Coulomb efficiency. The electrolyte additives reported in this study will provide a more convenient and environmentally friendly way to effectively solve the problem of zinc branches.

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