V4P7@C nanocomposite as a high performance anode material for lithium-ion batteries

The V4P7 phase is synthesized by a facile high energy mechanical milling (HEMM) using vanadium (V) and red phosphorus (P), and its electrochemical properties and reaction mechanism as an anode for lithium ion batteries (LIBs) are investigated. As-synthesized 100 nm-sized V4P7 nanopowder electrode shows the insertion reaction during lithiation/delithiation by forming the amorphous Li-V-P ternary phase and delivers the high discharge and charge capacities of 1035 and 882 mA h g(-1), respectively, with a high Coulombic efficiency of 85% at the current density of 100 mA g(-1). In addition, V4P7 nanopowder is encapsulated with the conformal carbon layer, which is achieved through polymerization of dopamine and subsequent carbonization. As-fabricated core-shell V4P7@C nanocomposite electrode exhibits the much improved high rate capability and long cycle stability, delivering a high capacity of 388 mA h g(-1) after 200 cycles at a high current density of 1 A g(-1), which is attributed to high electrical conductivity, high Li+ ion mobility, and structural stability to restrict the aggregation and pulverization of active materials.