Unlocking the structure and cation synergistic modulation of Prussian blue analogues with double redox mechanism for improved aqueous nonmetallic ion storage.

Prussian blue analogs (PBAs) exhibit high energy density and a good electrochemical stability window in aqueous non-metallic ion batteries, which is conducive to achieving high energy output and stable operation. Additionally, their synthesis process is simple and environmentally friendly, meeting the demands of sustainable development. However, the poor conductivity, structural stability issues, and inadequate ion diffusion pathways limit their application in batteries. To overcome these challenges, researchers have adopted various optimization strategies: enhancing the conductivity of PBAs by compositing with high-conductivity carbon materials such as graphite, carbon nanotubes, or graphene; optimizing synthesis conditions such as temperature and reaction time to improve the defect and structural water content of PBAs, thereby enhancing their stability and electrochemical performance; employing surface modification techniques, such as conductive polymer encapsulation and acid etching, to improve their electrochemical stability and ion transport performance; and optimizing ion diffusion efficiency and battery kinetics by selecting suitable electrolytes and additives. These comprehensive measures contribute to improving the electrochemical performance of PBAs and promoting the development of their commercial applications. Based on prior research advancements, we introduce a novel synergistic regulation strategy: the creation of multi-redox-active centers to augment the transport capability of non-metallic ions and the optimization of defect structures through the establishment of a metal ion concentration gradient, thereby enhancing both electrochemical stability and performance.