Fe–P alloys with high phosphorous content have been targeted as promising anode materials because of their high theoretical capacity. However, the synthesis and cycling performance remain great challenges. Hereby FeP y (3 ≤ y ≤ 4) nanoparticles are facilely synthesized through a dry mechanochemical method by reacting iron and red phosphorus powders in an inert atmosphere. The morphology and crystal structure of this material are characterized by SEM and XRD, respectively, while the electrochemical performance is evaluated by a number of different techniques. The 1st and 2nd discharge capacity of FeP y reaches 1984 mAh g−1 and 1486 mAh g−1, respectively, and after 10 cycles at 0.03 mA cm−2 (20 mA g−1, 0.03C), the capacity remains 1089 mAh g−1 with a coulombic efficiency of 97%, much higher than the reported results to date. The cyclability of this material becomes fairly better at a higher current density, but the specific capacity is lower compared to that of the smaller current density. By adding fluoroethylene carbonate (FEC) to the electrolyte, the cycling performance of this material was improved. The EIS analysis has also been performed in order to better understand the capacity fade mechanism of FeP y .