Zinc-ion batteries: Materials, mechanisms, and applications

The increasing global demand for energy and the potential environmental impact of increased energy consumption require greener, safer, and more cost-efficient energy storage technologies. Lithium-ion batteries (LIBs) have been successful in meeting much of today's energy storage demand; however, lithium (Li) is a costly metal, is unevenly distributed around the world, and poses serious safety and environmental concerns. Alternate battery technologies should thus be developed. Zinc-ion batteries (ZIBs) have recently attracted attention due to their safety, environmental friendliness, and lower cost, compared to LIBs. They use aqueous electrolytes, which give them an advantage over multivalent ion batteries (e.g., Mg²⁺, Ca²⁺, Al³⁺) that require more complex electrolytes. However, as with every new technology, many fundamental and practical challenges must be overcome for ZIBs to become commercial products. In this manuscript, we present a timely review and offer perspectives on recent developments and future directions in ZIBs research. The review is divided into five parts: (i) cathode material development, including an understanding of their reaction mechanism; (ii) electrolyte development and characterization; (iii) zinc anode, current collector, and separator design; (iv) applications; and (v) outlook and perspective.