关键词: 锂离子电池, 负极材料, Si-Mn/C复合材料, 机械球磨

Abstract: Si-Mn/C composite was obtained by sequentially ball-milling the mixture of the silicon and manganese powders (atomic ratio of 3:5), followed by the addition of 20wt% graphite. The phase structure and morphology of the composite were analyzed by X-ray diffraction (XRD) and scanning electronmicroscope (SEM). The results of XRD showed that there was no new alloy phase in the composite obtained by ball milling. SEM micrographs confirmed that particle size was about 0.5～2.0μm and the addition of the carbon restrained the morphological change of active center (Si) during cycling. The Si-Mn particles were dispersed among the carbon matrix homogeneously, which ensured a good electric contact. Electrochemical tests showed that the material obtained by adding carbon achieved better reversible capacity and cycleability. The Si-Mn/C composite had a reversible capacity of 347mAh·g^-1 and a coulombic efficiency of 70%, and the Si-Mn/C composite electrode annealed at 200℃ revealed a reversible capacity of 463mAh·g^-1 and a charge-discharge efficiency of 70%. Moreover, the reversible capacity retained 426mAh·g^-1 after 30 cycles with a charge-discharge efficiency of over 97

Key words: lithium ion battery, anode material, Si-Mn/C composite, mechanical ball milling