Enhanced High-Rate Lithium Storage of Nanosphere Composites with In-Situ Formed Graphene Interface Bridging Ni3Sn4-based Nanoparticles and Carbon Matrix

The nanosphere composites with in-situ formed graphene interface bridging intermetallic Ni3Sn4-based nanoparticles and carbon matrix (Ni3Sn4@g-C) are successfully fabricated through a facile organic-inorganic coordination complex-derived method. In this novel composite, numerous Ni3Sn4-based nanoparticles with a size of 10 - 80 nm are homogeneously decorated in a carbon nanosphere with a diameter of 200 - 400 nm, and at the interfaces between Ni3Sn4-based nanoparticles and the carbon matrix, several layers of graphene are in-situ formed during the fabrication process due to the catalytic effect of Ni species. When used as the anode in lithium ion batteries (LIBs), intermetallic Ni3Sn4 alloy can not only effectively alleviate the severe volume variation of Sn due to the incorporation of Ni component, but also further improve the mechanical stability and enhance the electrical conductivity of the resultant product owing to the formation of the graphene interface layers. As a result, the hierarchical Ni3Sn4@g-C composite displays high reversible capacities (547.0 mAh/g after 200 cycles at 200 mA g-1, and 542.8 mAh/g after 500 cycles at 1000 mA g-1), excellent cycling stability and superior rate properties (341.3 mAh/g even at a high rate of 2 A g-1). The unique microstructures and special introduction of Ni element in the hierarchical Ni3Sn4@g-C nanospheres are responsible for the enhanced electrochemical lithium storage properties.