Crystal structure, synthesis, problems, and solutions for Prussian blue analogue cathodes for high-energy and low-cost sodium-ion batteries based on recent research

초록

Sodium-ion batteries (SIBs) have garnered considerable interest due to the abundant and globally available sodium resources as well as the similar electrochemical behavior, low manufacturing cost, and inherent safety of SIBs. As a result, SIBs emerge as highly promising and cost-effective options for grid-scale energy storage applications. Nevertheless, the larger ionic radius and higher atomic mass of sodium ions compared with those of lithium ions present fundamental challenges in the improvement of SIBs with high energy densities and long cycle lives. Developing suitable electrode materials, particularly high-performance cathodes, is essential for effective sodium energy storage. Among several cathode candidates, Prussian blue analogues (PBAs) have attracted wide attention for energy storage, particularly in SIBs, due to their abundant active sites, inherent open framework structure, simple synthesis, high theoretical capacity, and notable electrochemical performance. However, the practical deployment of PBAs in SIBs is constrained by their limited electron transfer, high crystalline water content, and structural vacancies, which collectively degrade the capacity density and increase safety risks. This review begins with a comprehensive examination of PBA crystal structures. Then, the primary synthesis methods for PBAs are systematically reviewed, including hydrothermal, electrodeposition, co-precipitation, template, and mechanical ball-milling approaches. Then, this review examines the key challenges faced by PBAs and their corresponding optimization strategies, including surface modification, elemental substitution, nano-structured architectures, high-entropy design, and novel synthetic approaches. Finally, the current research advances and future directions for PBA cathodes in SIBs are critically analyzed to accelerate commercialization and guide further scientific exploration.

키워드