Research On Some Sb Or Bi-Based Intermetallic Compounds As Anode Material Of Li-ion Batteries

Image that novel lithium-ion batteries have higher capacities and lower output voltages in comparison with the tranditional lithium-ion batteries based on carbonaceous anode material to fit in with the technical development of portable electrical devices.Some new intermetallic compounds have been prepared and stuided as anode materials for lithium ion betteries in the present work.The electrochemical properties of CoSb3 alloys with different structures have been investigated. It was found that the reversible capacity exceeded 570mAhg-1 in the first cycle and remainde 400 mAhg-1 in the first 10 cycles for the annealed CoSb3, which were significantly better than those of the as-melted CoSb3. The mechanism of the insertion of lithium ions into CoSb3 electrode was analyzed by ex-situ XRD. It was found that an irreversible decomposition of CoSb3 was involved in the first cycle, and the reversible extraction-insertion of lithium ions from-into the electrode took place with the formation and decomposition of lithium antimonides such as LiaSb and Li3Sb in the succeeding cycles. It was also found that the particel sizes or charge/discharge cut-off voltages could affect the electrochemical properties of CoSb3. As an important electrochemical parameter, the Li+ diffusion coefficient of DLi=10-12 cm2s-1 was measured with the method of GITT.Two kinds of CoSb3/C hybrids, CoSb3-MCMB and CoSb3-CNT have been prepared and studied. It was found that the reversible capacities and cycle life of the CoSb3 electrode can be significantly improved by using MCMB additives, with the reversible capacity of 715 mAhg-1 in the first cycle and 529 mAhg-1 after 10 cycles. However, the effect of CNT additives is not obvious.Comparing the cycle properties of CoFe3Sb12 with those of FeSb2, we found that the latter with the fractional capacity RIO/I of 72% was much higher than that the former with RIO/I of 50%. From the ex-situ XRD analyses, it was found that there were two different types of the insertion reactions in the first cycle. One type is topotactic reaction and the other is reconstitution reaction. The chemical diffusion coefficient DLi Versus lithium content x in CoFe3Sb12 has been examined by EIS for the first discharge.Bi2Te3/polyaniline composites were prepared by mechanical blending. A reversible capacity of about 476mAhg-1 has been obtained in the first cycle. The reversible capacity keeps about 280 mAhg-1 in the first 10 cycles.C-Si composite material have been obtained by CVD method. The electrochemical properties were better than those of natural graphite.