Ni-FeP @carbon core–shell structure as advanced anode materials for superior lithium storage

Highlights: • Ni-FeP@C core–shell structure has been designed as the anode of Li ion batteries. • Ni doping affected the morphology of FeP and improved electrical conductivity. • The Ni-FeP@C exhibited capacity of 488 mAh g⁻¹ after 1000 cycles at 2.0 A g⁻¹. Iron phosphide (FeP) with high theoretical capacity (926 mAh g⁻¹) and low voltage window for lithium-ion batteries (LIBs) arouses extensive concern. However, inferior electron conductivity and FeP aggregation limit its applications. To settle these drawbacks, with the Ni doping, Ni-FeP@carbon (Ni-FeP@C) core–shell structure prepared by solvothermal method and phosphating process has been designed as the anode material for LIBs. Ni doping not only affected the morphology of FeP, but also improved electrical conductivity and excellent structural stability, accelerating the migration of lithium ions. Carbon shell coating promoted electron transfer and suppressed the volume fluctuation of FeP during discharge and charge process. As a consequence, the Ni-FeP@C composite delivered outstanding specific capacity (855.7 mAh g⁻¹ at 0.1 A g⁻¹) and long-cyclic performance (488 mAh g⁻¹ after 1000 cycles at 2.0 A g⁻¹). For the assembled full cell, the battery exhibited the promising cycling performance (50.4 mAh g⁻¹ after 70 cycles at 0.1 A g⁻¹). As expected, cation doping strategy in this work is of great significance for the further application of FeP materials in advanced lithium ion batteries.