碳化钼改性二氧化硅的制备及其电化学性能  

Preparation and Electrochemical Properties of Molybdenum Carbide Modified Silica

作　　者：王玉乐 杨柯利[1] 高艳芳[1] WANG Yu-Le;YANG Ke-Li;GAO Yan-Fang(School of Chemical Engineering,Inner Mongolia University of Technology,Hohhot 010051,China)

机构地区：[1]内蒙古工业大学化工学院,呼和浩特010051

出　　处：《应用化学》2022年第11期1716-1725,共10页Chinese Journal of Applied Chemistry

摘　　要：采用硅酸四乙酯、钼酸铵和蔗糖分别作为硅源、钼源和碳源,通过溶胶-凝胶法制备了碳包覆二氧化硅(SiO_(2))和碳化钼(Mo_(2)C)颗粒的SiO_(2)/Mo_(2)C/C复合物,并借助X射线衍射仪、透射电子显微镜等仪器对复合物的物相组成、形貌结构等进行了表征测试,同时研究了复合物作为锂离子电池负极材料的电化学性能。结果表明,当硅酸四乙酯、钼酸铵和蔗糖的质量比为3∶1∶2(记为SiO_(2)/Mo_(2)C/C 2)用作锂离子电池的负极材料时具有较好的电化学性能。在电流密度为100 mA/g,首次充电和放电比容量分别为662和896 mA·h/g,经过200次循环后,可逆容量仍可达625 mA·h/g。即使在2 A/g的大电流密度下,可逆容量仍可达272 mA·h/g。该复合材料表现出良好的倍率性能和循环稳定性,这主要归因于Mo_(2)C具有良好的稳定性和较高的导电性,提高了SiO_(2)的导电性,同时碳包覆层可以保护核心材料直接与电解液反应生成副产物,还可以作为缓冲层减缓SiO_(2)的体积膨胀,因此在进行充放电的过程中,材料的电化学性能得到显著的提升。在此提出利用过渡金属碳化物改善SiO_(2)导电性和循环性能的新思想,可以为其它负极材料的改性提供新的研究思路并扩宽研究方向。Carbon-coated silica(SiO_(2))and molybdenum carbide(Mo_(2)C)particles are prepared by sol-gel method using tetraethyl silicate,ammonium molybdate and sucrose as silicon,molybdenum and carbon sources,respectively.The phase composition,morphology and structure of the composite are characterized by means of X-ray diffractometer,transmission electron microscope and other instruments,and the electrochemical performance of the composite as a negative electrode material for lithium ion batteries is also studied.The results show that when the mass ratio of tetraethyl silicate,ammonium molybdate and sucrose is 3∶1∶2(denoted as SiO_(2)/Mo_(2)C/C 2),it has good electrochemical performance when it is used as the negative electrode material of lithium ion battery.At the current density of 100 mA/g,the first charge and discharge specific capacities are 662 mA·h/g and 896 mA·h/g,respectively,and the reversible capacity can still reach 625 mA·h/g after 200 cycles.Even at a larger current density of 2 A/g,the reversible capacity can still reach 272 mA·h/g.The composite exhibits good rate performance and cycling stability,which is mainly attributed to the good stability and high electrical conductivity of Mo_(2)C which can effectively improve the poor conductivity of SiO_(2) itself.The core material directly reacts with the electrolyte to generate by-products,and in addition,it can be used as a buffer layer to slow down the volume expansion of SiO_(2),so the electrochemical performance of the material is significantly improved during the charging and discharging process.The new idea of using transition metal carbides to modify the poor conductivity and cycle performance of SiO_(2) proposed here can provide new research ideas and broaden the research direction for the modification of other anode materials.

关 键 词：二氧化硅 碳化钼 碳包覆 锂离子电池 

分 类 号：O646[理学—物理化学]