Carbon-coated Fe2O3 nanocrystals with enhanced lithium storage capability

Homogeneous and highly crystalline Fe2O3 nanocrystals (∼8 nm) embedded in interconnected carbon nanospheres (∼50 nm) (Fe2O3@C) have been fabricated by one-step hydrothermal reaction followed by annealing with Ar. When used as the anode materials for lithium-ion batteries, the Fe2O3@C nanospheres with 55.24 wt% Fe2O3 deliver high reversible lithium storage capacity (826 mAh/g at 0.1 A/g after 20 cycles), high Coulombic efficiency (∼99%) and good cycling stability, which are much better than that of commercial Fe2O3 nanoparticles. These excellent electrochemical performances could be attributed to the robust and high-conducting interconnected carbon nanospheres embedded with a mass of small Fe2O3 nanocrystals, which not only can offer large quantity of accessible active sites for lithium-ion reaction as well as good conductivity and short diffusion length for electron and ion transport, but also can effectively suppress the aggregation and buffer the volume expansion of Fe2O3 nanocrystals during the repeated lithiation and delithiation processes.