SnCo1-xYx/C纳米晶复合材料的制备及电性能

Synthesis and Electrochemical Properties of SnCo1-xYx/C Nano-crystalline Composite

摘要:

采用先烧结后球磨的方法制备SnCo1-xYx/C (x=0，0.03，0.1，0.3，0.5)纳米晶负极材料，考察了Y添加量对材料结构和电化学性能的影响。结构分析表明，SnCo/C是由CoSn相和炭黑组成，对于SnCo1-xYx/C，当x=0.03时，出现了CoSn2相，当Y含量较高时，出现了Sn和Y2O3，CoSn与CoSn2相以纳米晶尺度均匀分布在颗粒中。少量Y固溶于CoSn和CoSn2相以及存在于它们的晶界或相界，其余大部分Y与O形成Y2O3分布在颗粒边缘。电化学分析表明，随着Y含量的增加，SnCo1-xYx/C的首次放电容量和循环性能都呈现先增加后减小的趋势。当x=0.1时，放电容量接近最大值，为378 mA·h/g，循环性能达到最大值，50次循环后容量保持率为87.6%。

Abstract:

The SnCo1-xYx/C (x=0, 0.03, 0.1, 0.3, 0.5) anode materials for Li-ion batteries were synthesized by solid-state sintering followed by ball milling. The influences of Y contents on structures and electrochemical properties of the materials were investigated. Structure analyses reveal that SnCo/C consists of CoSn phase and carbon black. For SnCo1-xYx/C samples, CoSn2 phase appears when x is 0.03. When Y content is higher, a little amount of Sn and Y2O3 forms. Nano-crystalline CoSn and CoSn2 phase co-exist homogeneously in internal particles. A small amount of Y dissolve into CoSn and CoSn2 phase and exist in their grain boundaries and phase boundaries, and most of other Y reacts with O to form Y2O3 distributing at edges of particles. Electrochemical analysis shows that with Y content increasing, the discharge capacity and cycle performance of SnCo1-xYx/C both increase firstly and then decrease. As x is 0.1, the discharge capacity is 378 mA·h/g, close to the maximum, and the cycle performance reaches to the maximum that the capacity retention is above 87.6% after 50 cycles.