Refining the inner Helmholtz plane adsorption for achieving a stable solid-electrolyte interphase in reversible aqueous Zn-ion pouch cells

Abstract

The reversibility and stability of aqueous Zn ion batteries (AZIBs) is extremely dependent on inner Helmholtz plane (IHP) structure and properties at the zinc anode/aqueous electrolyte interface. The hydrogen evolution reaction, corrosion, passivation, and uncontrolled growth of Zn dendrites all stem from the abundant presence of active H2O and irregular deposition of Zn within the IHP. In this study, we propose a strategy by using N, N'-Methylenebisacrylamide (MBA) as a bis-zincophilic site additive to effectively regulate molecular distribution within the IHP. This approach can prevent active H2O molecules from decomposing and suppress side reactions, while also can homogenize ion flux to obtain the uniform Zn deposition and stripping. Moreover, the adsorption of MBA onto IHP promotes the formation of a compact and homogeneous solid-electrolyte interphase (SEI). As a result, the utilization of an MBA/ZnSO4 electrolyte resulted in exceptional Coulombic efficiency of 99.7 % for up to 1300 cycles. The Zn//Zn symmetric pouch cell demonstrated an impressively high accumulated capacity exceeding 15,000 mA h. Furthermore, the Zn//NH4V4O10 zinc-ion pouch cell exhibited a capacity retention rate of 85 % after undergoing 1000 cycles at a current density of 1 A g−1. These results highlight the significant potential of incorporating MBA additive into practical applications.