Facile Synthesis of Iron Phosphide Nanoparticles in 3D Porous Carbon Framework as Superior Anodes for Sodium-Ion Batteries

Iron phosphide (FeP) represents a promising anode material for sodium-ion batteries, attributed to its significant theoretical capacity, moderate operating potential, and natural abundance. However, due to the low conductivity and significant volume expansion of FeP electrodes, their specific capacity and cycle life decrease rapidly during charging and discharging. In this study, we synthesized FeP nanoparticles supported on a three-dimensional porous carbon framework composite (FeP@PCF) using a straightforward colloidal blow molding method, employing iron nitrate nonahydrate and polyvinylpyrrolidone as raw materials. The nanoscale size of the FeP particles, along with the abundant mesopores and high specific surface area of the 3D porous carbon framework, contribute to the impressive sodium storage performance of FeP@PCF. It is revealed that FeP@PCF achieves a remarkable capacity of 196.6 mA h g−1 at a current density of 1.0 A g−1. Furthermore, after 800 cycles at this current density, it retains a capacity of 172.4 mA h g−1, demonstrating excellent cycling performance. Kinetic and dynamic studies indicate that this exceptional performance is largely attributed to the well-designed FeP@PCF, which exhibits a high capacitive contribution of 88.3% at a scan rate of 1 mV s−1.