Aqueous potassium-ion battery cathodes: Current status and prospects

In the post-lithium-ion battery era, potassium-ion batteries (PIBs) show great potential due to their high energy density and economic competitiveness from abundant potassium resources. In comparison with traditional organic electrolytes, aqueous electrolytes bring lower costs, higher safety, and more environmentally friendly preparation processes for PIBs. Against this background, aqueous PIBs (APIBs) have gradually become a research hotspot in the past few years. Cathodes, a critical component of APIBs, directly affect energy density, safety, and stability. Herein, this review systematically summarizes the research progress of typical APIB cathode materials, some breakthrough investigations of which are highlighted. Meanwhile, material synthesis methods, electrolyte design strategies, electrochemical performance optimization pathways, and electrochemical reaction mechanisms are introduced briefly. Finally, the current challenges and corresponding improvement strategies are proposed to provide a reference for further development.