Recent advances in cathode materials for aqueous zinc-ion batteries: Mechanisms, materials, challenges, and opportunities

Zinc-ion batteries (ZIBs) exhibit considerable potential for future grid-scale energy storage and wearable digital electronic applications. ZIBs are promising alternatives to current Li-ion batteries owing to their environmental friendliness, cost-effectiveness, abundant resources, high safety, and sufficient gravimetric energy density. However, to date, there remain challenges in finding suitable cathode materials with high working potentials, excellent electrochemical performance, and satisfactory structural stability that severely hinder the practical applications of ZIBs. To achieve the full potential of aqueous ZIBs (AZIBs), extensive research efforts are required to design and develop high-performance cathode materials. This minireview provides a concise overview of the fundamental and recent developments and challenges in cathode materials for AZIBs. First, the fundamental chemical parameters, constraints, and techniques of metallic Zn anodes are emphasized. Subsequently, several types of cathode materials are categorized and discussed in terms of their structural and electrochemical performance, challenges, and approaches to enhance their electrochemical performance. Special emphasis is placed on two important cathodes, manganese and vanadium oxide cathodes, which are rapidly developing state-of-the-art ZIB cathodes. The authors pay special attention to the mechanistic study and structural transformation of cathode materials based on Zn intercalation and deintercalation chemistry. Finally, the current issues and future perspectives in the AZIB field are discussed. Graphical abstract