SnLi4.4 nanoparticles encapsulated in carbon matrix as high performance anode material for lithium-ion batteries

Induction melting associated with simple ball-milling is utilized to synthesize a SnLi4.4@C core-shell hierarchical composite in which nanometer-sized SnLi4.4 particles are uniformly dispersed and encapsulated by carbon matrix. When evaluated as anode materials for lithium ion batteries, the composite exhibits a reversible capacity of 680 mA h g(-1) after 200 cycles at 200 mA g(-1). A capacity of 310 mA h g(-1) is obtained even at a high rate of 5000 mA g(-1). The superior electrochemical performance is ascribed to the fact that the prelithiated SnLi4.4 will not exert any expansion stress on the carbon matrix during the subsequent delithiation and lithiation processes, therefore guarantee the sustainable integrity of the composite in the prolonged cycling. The carbon matrix offers continuous transport paths for Li+ ions and electrons inside the composite. Meanwhile the carbon can sufficiently prevent the disintegration and aggregation of Sn nanoparticles upon prolonged cycling. The present study effectively circumvents the low initial Coulombic efficiency of the Sn-related nanocomposites and provides a protocol for pairing lithium-free cathodes to make the next-generation high energy lithium ion batteries. (C) 2014 Elsevier Ltd. All rights reserved.