One-Step Pre-Sodiation and Dehydration of Prussian Blue Analog Nanostructures via Sodium Benzophenone for Sodium-Ion Batteries

Prussian blue analogs (PBAs) face two major challenges in sodium-ion batteries: sodium content that falls below the theoretical value and the difficulty of dehydrating the crystal water in their applications. This study proposes a one-step presodiation and dehydration strategy for PBA nanostructures, resulting in a PBA electrode (H-PB) with both low water content and high sodium content through the use of sodium benzophenone. This strategy minimizes water reabsorption during electrode preparation and eliminates the need for secondary drying. The H-PB half-cell achieves an initial Coulombic efficiency of 98.4% at a current density of 0.2 C, a significant improvement over the 30.0% efficiency observed for the high water and low sodium content PBA electrode (L-PB). Additionally, when paired with commercial hard carbon, the H-PB electrode demonstrated a capacity retention of 70.0% after 100 cycles at 1 C. This study provides a straightforward method for one-step presodiation and dehydration of PBAs as positive electrodes.