Prussian blue analogues for advanced non-aqueous sodium ion batteries: Redox mechanisms, key challenges and modification strategies

Abstract

The increasing demand for sustainable energy storage solutions has driven significant advancements in sodium-ion batteries (SIBs), which offer a cost-effective and resource-abundant alternative to lithium-ion batteries. Among various cathode materials, Prussian Blue Analogues (PBAs) have emerged as promising candidates due to their unique open-framework structures, high theoretical capacities, and eco-friendly synthesis methods. This review provides a comprehensive analysis of recent advancements in PBAs for SIBs, focusing on the intricate relationships between their crystal structures, sodium-ion storage mechanisms, and electrochemical performance. Key challenges, such as structural defects, crystalline water content, low reaction kinetics, and the Jahn-Teller effect, are critically examined alongside failure mechanisms that impact long-term cycling stability. Advanced modification strategies, including vacancy control, water content optimization, surface/interface engineering, and compositional tuning, are discussed to address these issues. Furthermore, this paper highlights innovative approaches such as high-entropy strategies, heterostructure design, and electrolyte optimization to enhance the stability, conductivity, and rate capability of PBAs. By providing up-to-date insights and proposing future research directions, this review aims to advance the practical implementation of PBAs in next-generation SIBs with improved performance and commercial viability.