Influence Of Fe On Structure And Electrochemical Performance Of Sn_xCo_y/C Anode Material

A novel investigate the influence of Fe on structures and electrochemical performance of Sn,Co and C anode composite material. Using solid-phase sintering and then ball milling, SnxCoy/C composite material,are prepared and then SnxCoyFe0.2/C composite material are prepared. In the optimal system, SnCoFex/C composite material are prepared.The results of X-ray diffraction indicated that in SnxCoy/C composite material, Sn2Co/C consists of CoSn2,CoSn phase and a small amount of elementary substance of Sn; SnCo/C contains SnCo phase; Sn2Co3/C contains Sn2Co3 phase. In SnxCoyFe0.2/C samples, Sn2CoFe0.2/C consists of CoSn2,CoSn phase and a small amount of elementary substance of Sn; SnCoFe0.2/C contains SnCo phase and a small amount of Sn2Co3 phase. Sn2Co3Fe0.2/C contains Sn2Co3 phase. Fe exist with the form of solid solution, and contributes to grain refinement. In SnCoFey/C samples, with increasing content of Fe, Co3Sn2 is formed firstly on the matrix of CoSn phase Then a little amounts of FeSn2,Co and Sn are formed. And with increasing content of Fe, grain sizes reduce. Besides, grain of sintered samples using milling could be further refined.Electrical performance test showed that in SnxCoy/C composite material, initial discharge capacity and initial charge-discharge efficiency are both improved with increasing content of Sn, ,while the cycle performance is decreasing. In SnxCoyFe0.2/C samples, initial discharge capacity and initial charge-discharge efficiency are also improved with increasing content of Sn,, while the cycle performance is decreasing; Compared with SnxCoy/C, initial discharge capacity,initial charge-discharge efficiency and the cycle performance are improved. In SnCoFey/C samples, with increasing content of Fe, the initial discharge capacity and initial charge-discharge efficiency are both improved first and then are decreasing, and the cycle performance is improved first and then tended to be stable;The initial discharge capacity and initial charge-discharge efficiency of SnCoFe0.3/C are the largest, and they are respectively 359mAh/g and 74%,and the reversible capacity remains above 91.4% of the initial discharge capacity after 25 charge-discharge cycles.