High-Energy-Density Aqueous Zinc-Ion Batteries: Recent Progress, Design Strategies, Challenges, and Perspectives.

Aqueous zinc-ion batteries (AZIBs) are emerging as a promising energy storage technique supplementary to Li-ion batteries, attracting much research attention owing to their intrinsic safety, cost economy, and environmental friendliness. However, energy densities for AZIBs still do not fulfill practical requirements because of the low specific and areal capacity, limited working potential, and excessive negative-to-positive electrode capacity (N/P) ratio. In this review, a comprehensive overview of basic requirements and major challenges for achieving high-energy-density AZIBs is provided. Following that, recent progress in the optimization of each component and the overall configuration is summarized, and crucial design principles are discussed. Apart from conventional emphasis on each part, especially cathode materials, separately, the comprehensive discussion about the synergistic interactions among all components is conducted. Finally, the outlook and research direction are given to provide valuable guidance for the further holistic development of high-energy-density aqueous zinc-ion batteries.