Ternary Cu2P7/CuP2/C composite: A high-performance multi-phase anode material for Li/Na-ion batteries endowed by heterointerfaces

Phosphides are promising anode candidates profiting from their relatively smaller voltage hysteresis which thus are promising to be high energy efficiency and power capabilities for secondary batteries, compared with the corresponding fluorides, oxides and sulfides. Herein we for the first time synthesized ternary Cu2P7/CuP2/graphite composite by a facile ball milling method. When initiated as anodes for Li-ion batteries, the as-synthesized ternary composite provides 1415 mA h g−1 after 100 cycles and 684 mA h g−1 at a high current density of 10 A g−1. When initiated as anodes for Na-ion batteries, the as-synthesized ternary composite provides 1254 mA h g−1 after 100 cycles and 200 mA h g−1 at a high current density of 5 A g−1. These electrochemical performances are comparable or even surpass the P/C, CuP2/C and other transition metal phosphides reported before. The enhanced performances can be attributed to the high P concentration, layered structure and small band gap of the Cu2P7 phase and the heterointerface between these phases, which not only assists electron and Li-ion transportation and but also creates more active sites endowed by interfacial coupling and positive electrochemical synergistic effect. The multiphase design strategy can further excite more research interest in the energy-storage field.