Electrochemical lithiation and delithiation performance of SnSb–Ag/carbon nanonube composites for lithium-ion batteries

Abstract

SnSb–Ag/Carbon nanonube (CNT) composites materials are synthesised using chemical reduction methods. The microstructure, morphologies and electrochemical properties of these materials are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), constant current charge/discharge tests and cyclic voltammetry tests. The results indicate that Ag promotes the entire charge–discharge process during the complex multi-step reaction process and, to some extent, prevent the reunion of nanoparticles. At the same time, CNTs, with a large space volume and form a network structure, prevent particles aggregation and increase the buffer space between the alloy particles, which greatly reduce the diffusion distance of lithium ions and the occurrence of lithium trapping in the active electrode materials. CNTs also have excellent mechanical properties and toughness, they effectively buffer enormous stresses during the volume expansion of alloy particles, weakening the forces between the particles and reducing the rate of formation of powder particles. All these factors cause the SnSbAg0.1/6% CNT composites exhibit excellent cycle life by controlling the lithiation of the anode material; the reversible capacity for the 50th cycle is 639.6 mAh g−1 between 0.05 and 1.5 V.