A nanorod FeP@phosphorus-doped carbon composite for high-performance lithium-ion batteries

An iron phosphide (FeP) nanorods and phosphorus-doped carbon (P-C) composite (nanorod-FeP@P-C) has been successfully fabricated through a two-step strategy, that is, initial synthesis of Fe₂P₄O₁₂@P-C precursor by polymerization and carbonization under argon atmosphere, followed by formation of FeP nanorods by reducing the Fe₂P₄O₁₂ precursor with H₂. The nanorod-FeP@P-C material shows high specific surface area (255.21 m² g⁻¹) and the pore size distribution covers a broad range centered at 10 nm, indicating mesoporosity. Due to the synergistic effect of the nanorod structure improving the kinetics of Li⁺ insertion/extraction and the phosphorus-doped carbon enhancing material conductivity and alleviating volume change of the active material during charge–discharge, nanorod-FeP@P-C shows excellent electrochemical performance as an anode in Li-ion batteries for both half- and full cells. For the half-cell, the nanorod-FeP@P-C composite delivers a Li-ion storage capacity of 714 mA h g⁻¹ at a current density of 100 mA g⁻¹. After cycling at 2 A g⁻¹ for 800 cycles, a capacity of 625 mA h g⁻¹ is remained. When the current density increases to 5 A g⁻¹, a capacity of 420 mA h g⁻¹ is retained, indicating superior rate capability. For the full cell, a nanorod-FeP||LiMnCoNiO₂ battery exhibits stable reversible capacities of 367 mA h g⁻¹ (after 100 cycles) and 326 mA h g⁻¹ (after 300 cycles) at current densities of 200 and 500 mA g⁻¹, respectively. The work described here provides a promising anode material for Li-ion batteries, and the preparation route can be viewed as a reference for the synthesis of transition metal phosphides.