Nickel-Based Anode Materials in Potassium-Ion Batteries: A Review and Perspectives

Potassium-ion batteries (PIBs) have emerged as one of the most promising alternatives to lithium-ion batteries (LIBs) for energy storage, owing to their advantages such as abundant potassium resources and low cost. The design and optimization of anode materials are paramount, as they largely determine the overall electrochemical performance of PIBs. In recent years, nickel-based compounds have attracted growing interest because of their high theoretical capacities and potentially favorable rate capability. However, the practical application of these materials as anode materials for PIBs faces major obstacles, stemming from pronounced volume expansion during the potassiation/depotassiation process and insufficient electronic conductivity during the cycling process. The latest progress of nickel-based anode materials for PIBs (nickel oxides, nickel sulfides, nickel selenides, bimetallic selenides, nickel tellurides, nickel nitrides, and nickel phosphides) was systematically reviewed in this paper. The methods of enhancing the electrochemical performance of nickel-based materials were summarized, with a focus on strategies such as compositing with carbon materials, designing nanostructures, and designing microstructures. Then, the application of these materials as anode materials in PIBs was discussed. Finally, the key challenges and future research directions for nickel-based anode materials were presented.