Interfacial chemistry in aqueous rechargeable batteries: critical insights into solvation control, stability limits, and design challenges

Abstract

Aqueous rechargeable batteries offer a unique combination of nonflammability, materials abundance, and manufacturing simplicity, making them attractive for stationary and large-scale energy storage. Their development, however, is fundamentally limited by the chemical activity of water, which couples charge storage with proton transfer, gas evolution, and interfacial degradation. In this review, aqueous batteries are analysed from an interfacial-centric perspective, where electrolyte solvation, local proton activity, and electric double-layer organization collectively determine electrochemical stability and device performance. Progress across aqueous lithium-, sodium-, and zinc-based batteries, metal anode systems, nickel–metal hydride cells, and aqueous redox-flow batteries reveals that controlled restructuring of solvation environments and interfaces can kinetically suppress parasitic reactions while stabilizing reversible charge storage. Strategies based on concentrated electrolytes, mixed-solvent coordination, and engineered interphases are discussed in terms of their ability to redirect water reduction toward passivating reactions rather than irreversible degradation. In parallel, unresolved challenges are identified, including the lack of predictive links between bulk electrolyte composition and interfacial behaviour, insufficient quantification of side reactions under realistic operating conditions, and the time-dependent evolution of electrolyte properties and interfacial structures during electrochemical cycling. Addressing these issues through a coordinated electrolyte, interface, and diagnostic design is essential for advancing aqueous batteries toward high-voltage, long-life, and scalable energy-storage technologies.