Breaking Barriers Toward Practicality: Critical Materials and Strategies for High-Energy-Density Aqueous Zinc-Ion Batteries.

Driven by the demands of grid-scale energy storage and the electrification of transport, achieving superior energy density is pivotal to establishing a more sustainable and economically resilient battery ecosystem. However, aqueous zinc-ion batteries (ZIBs), despite their cost-effectiveness, inherent safety, high theoretical capacity (820 mAh g-1), and favorable redox potential (-0.762 V vs. SHE), still suffer from insufficient energy densities that fall short of commercial requirements. In this review, the obstacles hindering energy density and fundamental pathways toward high-energy-density ZIBs are systematically elucidated. Subsequently, recent advancements in optimization strategies are critically analyzed, encompassing electrode engineering, electrolyte optimization, and separator modification. Finally, a forward-looking perspective is provided on the design principles and potential research directions for developing high-energy-density ZIBs.