SnCo_(1-x)Y_x/C纳米晶复合材料的制备及电性能

Synthesis and Electrochemical Properties of SnCo_(1-x)Y_x/C Nano-crystalline Composite

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378mA·h/g,循环性能达到最大值,50次循环后容量保持率为87.6%。

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 Y 2 O 3 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.