Bimetallic phosphide AlP/SiP₂ composite as an anode material for lithium-ion batteries with long cycle life

AlP and SiP₂ are promising alloy-type anode materials for lithium-ion batteries (LIBs), owing to their good conductivity, high storage capacity and appropriate working potential. However, they still suffer from rapid capacity decay due to the huge volume expansion and the resultant pulverization. Carbon modification can not only relieve volume changes but also provide a conducting matrix for the active material. Moreover, the charge transfer of the multi-phase composite can be accelerated owing to its electric field at the heterointerface. Hence, a bimetallic phosphide AlP/SiP₂@C composite was synthesized for the first time via a facile and scalable high energy ball milling method and applied as an anode material for LIBs. Benefitting from the above combined advantages of the heterostructure and carbon layer protection, the AlP/SiP₂@C electrode delivered a high reversible capacity (1482 mA h g^-1 at the current density of 0.3 A g^-1) and durable lifespan (516 mA h g^-1 after 4000 cycles at a current density of 3 A g^-1), which are superior to those of the binary AlP@C and SiP₂@C composites.