Non-solvating additives regulate zinc deposition through anion-gated Stern-layer competition

Abstract

While additive-induced modulation of solvation structure has emerged as an effective strategy to enhance the performance of aqueous zinc-ion batteries, the electrochemical mechanisms by which non-solvation additives interact with ion species within the electric double layer and their subsequent impact on solid electrolyte interphase evolution remain poorly understood. Here, we propose an anion-released interfacial engineering strategy that leverages the competitive spatial distribution between surface-affinitive anions and cationic regulators within the Stern layer. This competition governs additive accessibility to the interface and enables the construction of a robust, inorganic–organic hybrid interface. Combined with in situ spectra and theoretical simulations, we decouple the key kinetic processes in Zn deposition, revealing that fast Zn2+ transport within the solid electrolyte interphase, coupled with moderated desolvation at the interface, underpins dendrite-free and highly reversible cycling. This study has the potential to establish a mechanistic framework for the interfacial function of non-solvating additives, thus offering refined insights into electrolyte design and interphase engineering for high-performance aqueous metal batteries. Aqueous zinc-ion batteries can benefit from electrolyte additives, but their interfacial mechanisms remain unclear. Here, authors explore tetraethylammonium-based salts as functional additives and investigate their non-solvating nature to regulate ion distributions at the interface to form a robust interphase, enabling reversible and long-lived zinc batteries.