Potassium ions stabilized hollow Mn-based prussian blue analogue nanocubes as cathode for high performance sodium ions battery

Mn-based Prussian blue analogue is regarded as one of the promising cathodes for sodium ions battery owing to its high theoretical capacity and low cost. However, the unstable structure during charging/discharging process and the poor cycle life hinder its commercial application. In this work, potassium ions stabilized hollow Mn-based Prussian blue analogue is synthesized through a simple sodium citrate assisted method using for cathode of sodium-ions batteries. Although unique hollow structure could suffer volume variation during charging/discharging process, the K+ is introduced to further stabilize its structure. The PBAs cathode exhibits a high reversible specific capacity of 128 mA h g−1 at 50 mA and superior rate performance of 72 mA h g−1 at a high current density of 3200 mA g−1, which is attributed to its stable structure and enhanced sodium ions transport kinetics. Ex-situ XRD/Raman tests and electrochemical measurements further prove the synergistic effect of various alkali ions (K+/Na+) and unique hollow structure. They work together to improve the structural stability and promote sodium ions diffusion rate of Mn-based PBAs.