Enhancing the durability of Prussian white based sodium batteries through the lithium salt-mediated electrode interface

Abstract

Prussian white (PW) shows potential as a cathode material for high-energy sodium-ion batteries (SIBs) due to its advantages such as high operating voltage, high specific capacity, and cost-effectiveness. However, their practical applications are hampered by insufficient cyclic stability challenges resulting from structural collapse due to electrolyte erosion and irreversible phase transitions. Compared to the cumbersome PW modification and coating processes, we have found that the introduction of lithium salt (LiDFOB) can efficiently mediate the electrode interface. Theoretical simulations and experimental analysis results indicate that LiDFOB can not only alleviate dendritic growth issues in sodium metal anodes but also generate a low impedance interface layer rich in LiF and B–O at the cathode, mitigating problems such as electrolyte erosion, metal ion dissolution, and irreversible phase transitions. The addition of this additive significantly improves the cycle retention rate of PW from 44.92% to 71.33% over 200 cycles, while also enhancing its rate capability. These exceptional electrochemical characteristics demonstrate the potential benefits of incorporating lithium salt additives into the electrolytes of SIBs, which will greatly advance the development and application of Mn-based Prussian blue analog (PBA) materials.