Preparation And Electrochemical Properties Of The Sn, Sb-based Alloys And Their Composites Research

In this paper, CoSb,Cu2Sb,SnSb and Sn/SnSb four alloy powderswere prepared by the chemical reduction method using CoCl₂·6H₂O,CuCl₂,SnCl₂·2H₂O and SbCl₃ as the starting materials, sodium citrate asthe complexant and NaBH₄ as the reducing agent. For an example ofCoSb alloy, the effect of reducing agent kinds and temperature on thealloy's particle size and distribution were investigated. The effect ofparticle size and different charge-discharge current density on theelectrochemical performance of alloy powder were also studied. Theelectrochemical performances of Cu₂Sb,SnSb and Sn/SnSb alloypowders were compared, the test results indicate that the first charge anddischarge specific capacities of SnSb and Sn/SnSb are higher than that ofCu₂Sb. After 15 cycles, the charge specific capacities of Cu₂Sb,SnSb andSn/SnSb are fading to 184.6 mAh·g^-1, 182.7mAh·g^-1 and 337.7 mAh·g^-1,respectively. The fading rates of SnSb and Sn/SnSb are 55.33％and47.39％, respectively, but that of Cu₂Sb is only 26.16％. This is mainlyascribe to the "active/non-active" composite structure of Cu₂Sb alloy,but the cycle performance of Sn/SnSb multiphase alloy is superior to thatof SnSb alloy mainly due to the existence of excess Sn.The HCl-doped conductive polyaniline(PAn) was synthesized bytypical MacDiarmid oxidation method using ammonium persulfate.Co-Sn and Sn/SnSb alloy were prepared by chemical reduction method.The Co-Sn/PAn and Sn-SnSb/PAn composite materials were prepared bysimple mixing alloy and PAn powders with the weight ratio of alloy andPAn 9:1. The electrochemical performances test show that the initialreversible capacities of Co-Sn/PAn and Sn-SnSb/PAn compositematerials are 302 mAh·g^-1 and 542 mAh·g^-1, respectively. The cycleperformances of the two composite materials are better than that of theseparately pure alloy material. PAn can buffer the volume expansion ofalloy in some degree which has the property of good conductivity andflexible. PAn also can increase the electric contact between particles,therefore, the utilize rate of active material is enhanced. The Sn-SnSb/Graphite composite materials with different graphitecontents were prepared by ball milling. The electrochemicalperformances of Sn-SnSb/Graphite composite materials and pureSn-SnSb multiphase alloy were compared. The results show that theelement of graphite can effectively improve the cycle performance ofalloy material. The effect of graphite content on the electrochemicalperformance of the composite materials was also investigated. Theincrease of graphite content is in favor of enhancing the firstcharge-discharge efficiency and improving the cycle performance, but thereversible capacity of the composite electrode decreases with theincreasing quantities of graphite. Especially, the cycle stability ofcomposite electrode with the graphite content of 30％is excellent. After15 cycles, the fading rate of reversible capacity is only 8.6％.