Enhancing capacity and transport kinetics of C@TiOcore-shell composite anode by phase interface engineering.

In nanocomposite electrodes, besides the synergistic effect that takes advantage of the merits of each component, phase interfaces between the components would contribute significantly to the overall electrochemical properties. However, the knowledge of such effects is far from being well developed up to now. The present work aims at a mechanistic understanding of the phase interface effect in C@TiOcore-shell nanocomposite anode which is both scientifically and industrially important. Firstly, amorphous C, anatase TiOand C@anatse-TiOelectrodes are compared. The C@anatase-TiOshows an obvious higher specific capacity (316.5 mAh gat a current density of 37 mA gafter 100 cycles) and Li-ion diffusion coefficient (4.0 × 10cms) than the amorphous C (178 mAh gand 2.9 × 10cms) and anatase TiO(120 mAh gand 1.6 × 10cms) owing to the C/TiOphase interface effect. Then, C@anatase/rutile-TiOis obtained by a heat treatment of the C@anatase-TiO. Due to an anatase-to-rutile phase transformation and diffusion of C along the anatase/rutile phase interface, additional abundant C/TiOphase interfaces are created. This endows the C@anatase/rutile-TiOwith further boosted specific capacity (409.4 mAh gat 37 mA gafter 100 cycles) and Li-ion diffusion coefficient (3.2 × 10cms), and excellent rate capability (368.6 mAh gat 444 mA g). These greatly enhanced electrochemical properties explicitly reveal phase interface engineering as a feasible way to boost the electrochemical performance of nanocomposite anodes for Li-ion batteries.