One-Step Synthesis of Hollow Prussian Blue Sodium-Ion Battery Cathode Material for Activating Deep Inert Iron

Prussian blue and its analogs have attracted significant attention as cathode materials for sodium-ion batteries due to their excellent performance and low cost. However, in typical Prussian blue materials, the process of sodium ion insertion and extraction usually initiates at the surface. Sodium ions struggle to diffuse into the center of the material, resulting in a relatively low overall specific capacity. To address this issue, we synthesized a Prussian material with a hollow structure in one step using a hydrothermal method. Under the action of ethanol and acetic acid, the material surface undergoes etching, exposing the central portion of the material and activating the previously inert iron that was difficult to react. The prepared Prussian blue improved the material’s specific capacity by increasing the specific surface area, activating deep-seated inert iron, and enhancing electrochemical activity. The material exhibits a specific capacity of 132.8 mAh g–1 at 0.1 C (1 C = 100 mA g–1), 109 mAh g–1 at 10 C, and a capacity retention of 83.5% after 300 cycles at 1 C, demonstrating good rate performance and excellent cycling stability. This simple synthesis strategy offers an excellent approach for preparing high-performance hollow-structured Prussian blue materials.