摘要:
以酸处理的中间相碳微球(MCMB)为载体,用化学还原法在碳球表面沉积SnSb合金,合成SnSb包覆碳球的核壳结构负极材料.采用XRD, SEM技术对材料的结构和形貌进行了表征,用恒电流充放电(CC)、循环伏安(CV)和交流阻抗(EIS)测试了材料的电化学性能.实验结果表明:SnSb/MCMB样品呈现纳米晶与非晶态的混合组织;单一SnSb合金的容量衰减较快,而对于SnSb/MCMB复合材料,细小的合金颗粒均匀钉扎在MCMB表面,不仅改善了颗粒的团聚现象,而且增强了材料的导电能力,使材料的循环稳定性得到改善,复合材料具有936.161 mAh/g的首次放电比容量,首次库仑效率80.3%,50次循环后容量维持在498.221 mAh/g.
Abstract:
SnSb/MCMB composite material was prepared by multi-step synthesis methods. Mesocarbon Microbeads (MCMB) powders were modified by acid treatment firstly, and then SnSb nano particles were deposited on the surface of MCMB through chemical reduction method forming a core-shell composite structure. To characterize the phase and morphology of the composites material, X-ray diffraction (XRD), scanning electron microscope (SEM) were used. The constant current charge and discharge (CD) and cyclic volt ampere (CV) methods were also used to test the electrochemical performance of SnSb/MCMB. The results demonstrated that SnSb/MCMB presents a multiphase system of nanocrystalline and amorphous structure. The capacity attenuation of SnSb alloy is faster than that of SnSb/MCMB. For the SnSb/MCMB composite, the tiny alloy particles were dispersed on the surface of MCMB powders, preventing from the serious agglomeration of nano particles. At the same time, the inner core MCMB can also buffering the volume effect of the alloy compoites to improve the elecrtochemical cycling stability. The composite material was a first discharge specific capacity of 936.161 mAh/g and the first Coulomb efficiency 80.3%. The specific capacity was still up to 498.221 mAh/g after 50 cycles.
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