Preparation And Modification Of TIN-Based Alloy Anode Materials For Lithiumion Batteries

Lithium ion batteries have attracted numerous researchers and been widely used in portable electric products and powered transport due to the advantages of high capacity, high working voltage, low self-dischargment, no memory effect, safety and environmentally friendly. However, as a traditional anode material, graphite is of low specific capacity (372mAh/g) and poor high-rate performance. Much attention has been paid to find a kind of anode material with higher capacity, better high-rate performance and lower cost. The specific capacity of tin (990mAh/g) is about2.7times higher than graphite and tin has attracted wide attention by its good electronic transmission performance and high tap density. In this paper, tin-based alloy anode material was synthesized using ball-milling method and chemical reduction method. XRD, SEM, EDS and FTIR were used to characterize the composition, structure and morphology. Galvanostatic charge-discharge, CV and EIS were used to systemically analyze the electrochemical performance of the material.(1) FexCu6-xSn5(x=0,0.5,1,2) alloy was synthesized by mechanical ball-milling method. The results showed that the cycling performance of the material improved while the increase of iron content with the structure of hexagonal Cu6Sn5remain unchanged. However, when the iron content continued to increase, the cycling performance declined. Thus appropriate amount of Fe doping is benifical to improve the cycling performance. On this basis, we coated the FeCu5Sn5alloy with different carbon contents, it showed that with the increase of carbon content, the cycling performance was greatly improved. The initial discharge capacity of the material with carbon content of20%is682mAh/g, while the discharge capacity of which remained376mAh/g after50cycles.(2) Surface treatment of Cu6Sn5alloy was done using AgNO3solution. The result showed that Ag particles deposited on the surface and formed Cu6Sn5-Ag composite. The specific capacity of the material had a significant improvement and the cycling performance enhanced meanwhile. When the concentration of AgNO3solution was0.3mol/L, the material had an initial discharge capacity of623mAh/g, which remained359mAh/g after50cycles.(3) FeSn2/CNTs composites were synthesized by chemical reduction method, we compared the lithium storage properties of FeSn2、CNTs and FeSn2/CNTs composites. The results showed that the FeSn2/CNTs composites had better electrochemical properties with initial discharge capacity of642mAh/g, and remained400mAh/g after20cycles.