Highly reversible aqueous zinc-ion battery using the chelating agent triethanolamine as an electrolyte additive

Abstract

Aqueous zinc-ion batteries (AZIBs) have received great attention owing to the increasing demand for safe and inexpensive batteries. However, their poor cycling issue hinders their commercialization and further application, resulting from the zinc dendrite growth, corrosion, and passivation that occur on the Zn anode, as well as the dissolution and cracking issue of active materials on the cathode. Herein, we introduce the use of a chelating agent triethanolamine (TEA) as an additive in the electrolyte to enhance the cycling stability of AZIBs. TEA molecules preferentially coordinate with Zn²⁺, replacing water molecules in the solvation sheath of Zn²⁺, thereby reducing the solvation effect in the electrolyte. Moreover the adsorbed interface layer on the anode Zn surface forms a stable solid–electrolyte interphase (SEI) while the cathode forms a cathode–electrolyte interphase (CEI), suppressing the side reactions and dendrite growth of metallic Zn and protecting the cathode from dissolution while increasing the diffusion rate of Zn²⁺. The Zn‖MnO₂@CNT cell showed reversible and durable performance with 78% retention after 2000 cycles at 0.5 A g⁻¹.