Interfacial energy storage in aqueous zinc-ion batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are attractive for large-scale energy storage due to their intrinsic safety, low cost, and environmental compatibility. However, the high charge-to-radius (q/r) ratio of Zn2+ leads to strong solvation and sluggish solid-state diffusion, which hinder efficient charge transport across solid–solid and solid–liquid interfaces. These limitations reduce both cycling stability and rate performances. In this review, we summarize interfacial transport regulation strategies, including solid–solid interfacial modulation via electrostatic fields, interfacial bonding, and ion–electron decoupling to enhance solid-state Zn2+ mobility. We further discuss solid–liquid interfacial desolvation regulation including water activity control, solvation structure tuning, and selective ion channels to mitigate desolvation barriers. We also describe emerging mechanisms involving water dissociation at interfaces, where protons and hydroxide ions act as alternative charge carriers. These unconventional pathways can complement or even outperform traditional Zn2+ intercalation. Collectively, these interfacial strategies not only accelerate Zn2+ transport but also introduce new electrochemical phenomena that boost capacity and rate performances of AZIBs. Advancing the deliberate design and mechanistic understanding of such interfacial processes will be essential to unlocking the full potential of next-generation AZIBs.