锂离子电池Mo2C/N-C复合材料的制备及性能研究

Preparation and property of Mo2C/N-C composite material for lithium-ion battery

以三氧化钼、草酸、盐酸多巴胺为原料,通过水热和高温煅烧的方法制备了碳化钼与氮掺杂碳纳米管(Mo2C/N-C)复合材料。采用X射线衍射仪、热重分析仪、扫描电子显微镜、透射电子显微镜、拉曼光谱等表征手段研究了Mo2C/N-C复合材料的化学组成、结构与形貌,并使用电池测试系统对材料进行了电化学性能测试。结果表明:Mo2C/N-C复合材料具有棒状碳纳米管结构,长径比较大,Mo2C纳米微晶均匀分布在氮掺杂的碳基质中。Mo2C的纳米微晶缩短了Li+离子的扩散路径,纵横比较大的棒状结构缩短了电解质中离子迁移路径,且氮掺杂的碳基质加速了电子转移并在放电/充电循环期间缓冲了Mo2C的体积变化。用Mo2C/N-C作为锂离子电池的负极材料,电流密度为100mA/g时,复合材料初始放电比容量为1146.5mAh/g,充电比容量为855.2mAh/g,库伦效率为74.59%。经过100次充放电循环后,复合材料放电比容量为574.2mAh/g,库仑效率为98.08%,表现出优异的电化学性能。

Mo2C/N-C(molybdenum carbide and nitrogen doped carbon)nanotube composite cathode materials were prepared by simple hydrothermal and high temperature pyrolysis using molybdenum trioxide,oxalic acid and dopamine hydrochloride as raw materials.XRD,TG,SEM,TEM,Raman and other characterization methods were used to study the chemical composition,structure and morphology of Mo2C/N-C samples,and the electrochemical performance of the samples was tested by the battery test system.The results shown that the material had a rod-like carbon nanotube structure with larger aspect ratio,and the Mo2C nanocrystallite was uniformly distributed in the nitrogen-doped carbon matrix.The nanocrystallites of Mo2C shortened the diffusion path of Li+,the rod-like structure with larger aspect ratio shortened the ion migration path in the electrolyte,and the nitrogen-doped carbon matrix accelerated electron transfer and buffered the volume change of Mo2C during the discharge/charge cycle.Therefore,the prepared cathode exhibited excellent electrochemical performance:when the charge and discharge were performed at the current density of 100mA/g,the discharge specific capacity of the first cycle was 1146.5mAh/g,the charge specific capacity was 855.2mAh/g,and coulomb efficiency reached 74.59%.After 100cycles,the discharge specific capacity was 574.2mAh/g,and the coulombic efficiency reached 98.08%.