Long-Lasting Lithium-Ion Batteries Enabled by Advanced Anode Design of a Hydrangea-like FeP/SnP@C Heterostructure

Transition metal phosphide (TMP)-based anode materials for lithium-ion batteries (LIBs) have garnered significant attention due to their high theoretical specific capacity and cost-effectiveness, yet they suffer from volume changes and pulverization during cycling. Herein, an advanced heterostructural FeP/SnP@C material was synthesized and applied as the anode material for tackling the key issues. The FeP/SnP@C composite comprises ultrathin nanosheets arranged in a hydrangea-like morphology, boasting a substantial specific surface area toward electrolyte penetration. Moreover, the heterogeneous interface between FeP and SnP creates a self-generated electric field, thereby improving electrochemical reaction kinetics and furnishing additional active sites for lithium storage performance. Electrochemical measurements reveal an initial discharge specific capacity of 1140.7 mAh g^-1 at a current density of 0.2 A g^-1, which remains at 756.1 mAh g^-1 after 200 cycles. Even at a high current density of 2 A g^-1, the electrode material exhibits a reversible specific capacity of 284.2 mAh g^-1 after 1000 cycles, showcasing its excellent long-life cyclic stability. When assembled into full cells with commercial LiFePO₄, FeP/SnP@C shows high discharge capacity and exceptional cyclic stability with a high value of 101.2 mAh g^-1 after 100 cycles. This work provides new insights for rational design of TMP-based anodes for advanced LIBs.