Dendrite-free zinc anode enabled by zinc-chelating chemistry

Rechargeable aqueous Zn-ion battery has been considered as a key complement to the existing battery technologies due to its intrinsic merits such as operational safety and cost saving. However, issues of dendrite growth and accompanied water consumption hinder its further development. In this work, we utilize a chelating agent, 2-Bis(2-hydroxyethyl) amino-2-(hydroxymethyl)-1,3-propanediol (BIS-TRIS), to regulate the solvation sheath structure of Zn2+. Benefiting from such zinc-chelating coordination, Zn2+ 2D diffusion can be restricted and the altered deposition kinetic has contributed to the inhibition of the dendrite growth. In addition, partial substitution of water in solvation shell with chelator can also greatly suppress the competitive hydrogen evolution reaction (HER). Consequently, a stable symmetric Zn cell with lifetime more than 1000 h at a current density of 1 mA cm−2 is achieved. Moreover, the aqueous Zn/MnO2 battery with BIS-TRIS as electrolyte additive delivers an 86% capacity retention after 600 cycles at 500 mA g−1. This zinc-chelating coordination based facile strategy opens a new window for the future development in dendrite-free Zn anode.