High‐Voltage Zinc‐Ion Batteries: Design Strategies and Challenges

Rechargeable zinc-ion batteries (ZIBs) have recently attracted attention for applications in energy storage systems owing to their intrinsic safety, low cost, environmental compatibility, and competitive gravimetric energy density. To enable the practical applications of ZIBs, their energy density must be equivalent to the existing commercial lithium-ion batteries. To acquire high-energy density, increasing the operating voltage of the battery is undoubtedly an effective method, which demands cathode material to exhibit a high voltage versus Zn2+/Zn, while matching a highly reversible anode and an electrolyte with a sufficiently wide electrochemical stability window. This review focuses on the design strategies and challenges towards high-voltage ZIBs. First, the basic electrochemistry of ZIBs and the recent progress in various high-voltage cathode materials for ZIBs, including Prussian blue analogs, polyanionic compounds, and metal-based oxides are introduced. The challenges and corresponding countermeasures of these materials are discussed, while strategies to further improve the cathode operating voltage, influence factors of voltage in the redox reaction, and energy storage mechanism are also illustrated. The following section describes the strategies towards high-performance Zn anode, and summarizes the electrolytes that can help increase the battery voltage. The final section outlines the potential development in ZIBs.