Mechanochemical synthesis of InP nanoparticles embedded in hybrid conductive matrix for high-performance lithium-ion batteries

Abstract InP nanoparticles distributed in a TiO2-C hybrid matrix (InP@TiO2-C) are proposed as a promising anode material for Li-ion batteries. A primary mechanochemical process on the precursor materials (In2O3, Ti, and P) leads to the formation of InP and TiO2 nanocrystal particles. The introduction of carbon during secondary ball milling results in the formation of InP nanoparticles that are embedded in the TiO2-C hybrid conductive matrix (InP@TiO2-C); this is confirmed by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray characterizations. As an anode material, InP@TiO2-C exhibits impressive electrochemical performance in both half- and full-cell batteries. Various ex situ analyses including XRD, high-resolution TEM (HRTEM), and XPS were synergistically used to demonstrate the mechanism of lithium-ion storage for the InP@TiO2-C electrode during the electrochemical reaction, and to elucidate the roles of active InP particles and the TiO2-C buffering hybrid matrix. Consequently, as an anode for half-cell batteries, the InP@TiO2-C delivers a high reversible capacity (∼850 mAh g-1 after 120 cycles at 0.1 mA g-1), excellent life span at 0.5 A g-1 (∼750 mAh g-1 after 800 cycles), and high rate capability (85% capacity retention at 10 A g-1 compared with that at 0.1 A g-1). Moreover, as an anode for practical full-cell batteries with LiFePO4@graphite cathodes, it delivers a promising initial energy density of 214 Wh kg-1 (based on the total mass of the anode and cathode) and a good stability (retention of 61%) over 150 cycles.