Fast Ionic Storage in Aqueous Rechargeable Batteries: From Fundamentals to Applications

Abstract The highly dynamic nature of grid‐scale energy systems necessitates fast kinetics in energy storage and conversion systems. Rechargeable aqueous batteries are a promising energy‐storage solution for renewable‐energy grids as the ionic diffusivity in aqueous electrolytes can be up to 1–2 orders of magnitude higher than in organic systems, in addition to being highly safe and low cost. Recent research in this regard has focussed on developing suitable electrode materials for fast ionic storage in aqueous electrolytes. In this review, breakthroughs in the field of fast ionic storage in aqueous battery materials, and 1D/2D/3D and over‐3D‐tunnel materials are summarized, and tunnels in over‐3D materials are not oriented in any direction in particular. Various materials with different tunnel sizes are developed to be suitable for the different ionic radii of Li + , Na + , K + , H + , NH 4 + , and Zn 2+ , which show significant differences in the reaction kinetics of ionic storage. New topochemical paths for ion insertion/extraction, which provide superfast ionic storage, are also discussed.