【摘要】 以Si粉和Ni粉为主要原材料,通过对Si粉和Ni粉的球磨处理,结合柠檬酸碳源的高温热解,制备出一种碳包覆的Si/NiSi₂@C复合材料。采用多种技术手段研究了不同Ni添加量和原位碳的引入对复合材料结构形貌及其作为锂离子电池负极材料的电化学性能的影响。结果表明,Si粉和Ni粉在球磨过程中反应生成了NiSi₂合金相,弥散分布于复合材料中。柠檬酸高温裂解碳包覆于Si/NiSi₂复合颗粒表面,为复合材料构建了良好的导电网络。NiSi₂和高温裂解碳不仅增加材料的导电性,而且缓冲了脱嵌锂过程中Si的体积膨胀,有效地提高了材料的电化学性能。由于NiSi₂的电化学嵌锂活性低,随着Ni添加量的增加,材料的首次充放电容量降低,但材料的循环稳定性有所增加。其中当Ni的添加量为5wt%的Si/NiSi₂@C复合材料首次充放电容量分别为2754和2235mAh/g,首次库伦效率超过80%,经100次循环后的容量保持为1242mAh/g,显示出良好的电化学性能。更多还原

【Abstract】 Carbon coated Si/NiSi₂@C composites were fabricated by ball-milling of Si and Ni powder with citric acid added,followed by heating to make the citric acid pyrolyzed.The effects of Ni content and the in situintroduced carbon on the structure,morphology and the electrochemical properties of the composites as anode materials for lithium-ion batteries were studied by some conventional techniques including electrochemical measurements.The results show that Si and Ni reacted,forming NiSi₂ alloy well dispersed in the composite after the ball-milling.The pyrolyzed carbon coated on the surfaces of the Si/NiSi₂ particles,and at the same time built conductive networks for the composites.NiSi₂ and carbon not only improve the electron conductivity,but also buffer the volume expansion during lithiation.As a result,the electrochemical properties of the composite anodes are effectively improved.The initial discharge and charge capacities of the composites decrease with the increase of the Ni addition due to the low electrochemical activation of NiSi₂ for lithium ion intercalation,however,the cyclic stability increases.Among them,the Si/NiSi₂@C composite with 5 wt%Ni addition shows favorable electrochemical properties with initial discharge and charge capacities of 2754 and 2235 mAh/g,respectively,corresponding to an initial coulombic efficiency over 80%,and a retained capacity of 1242 mAh/g after 100 cycles at a current density of 300 mA/g.更多还原