Chelating Dicarboxylic Acid as a Multi-Functional Electrolyte Additive for Advanced Zn Anode in Aqueous Zn-Ion Batteries

Abstract

Aqueous zinc-ion batteries possess great potential as they offer high safety, low cost, high specific capacity, and long cycle life. However, critical challenges, including dendrite growth, hydrogen evolution, and corrosion, impede their commercialization viability. To address these issues, we propose a solution by introducing succinic acid (SA) to the conventional ZnSO4 electrolyte. The carboxyl groups in SA exhibit excellent coordination capabilities with Zn2+ ions, displacing some active water molecules in the Zn2+ inner solvation shell. This disruption of the hydrogen-bond network, modifies the solvation structure of Zn2+ ions, effectively suppressing hydrogen evolution. Moreover, the carboxyl group forms a strong bond with Zn metal, leading to the preferential adsorption and reaction of Zn2+ to create a Zn-SA composite film on the Zn anode’s surface. This feature reduces by-products, promotes uniform zinc ion deposition, resulting in a symmetric cell assembled with SA additive that can cycle stably for over 4000 hours at 1mA cm-2 and 1mAh cm-2, with an average Coulombic Efficiency of 99.7% during plating/stripping processes. The cell also demonstrates stable cycling for 500 hours at high current densities of up to 10mA cm-2. Zn-V2O5 full cell incorporating SA additive exhibits remarkable rate performance and specific capacity retention over 1000 cycles.

Keywords: Zinc anode, electrolyte additive, Succinic acid, Protective layer, Dendrite-free, Oriented growth