碳包覆二氧化钛制备高倍率Li4Ti5O12/C负极材料  

Preparation of Li4Ti5O12/C as high-rate anode material by carbon-coated TiO2

作　　者：李达禄 张祥昕 苗小飞 陈素晶[1] 张易宁[1,2] LI Dalu;ZHANG Xiangxin;MIAO Xiaofei;CHEN Sujing;ZHANG Yining(Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences,Fuzhou 350002,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院福建物质结构研究所,福建福州350002 [2]中国科学院大学,北京100049

出　　处：《电子元件与材料》2019年第7期19-24,31,共7页Electronic Components And Materials

基　　金：国家自然科学基金-青年科学基金(51602310);福建省科技厅引导性项目(2018H0041,2018H0042);福建省STS极化配套项目(2016T3022,2018T3010);中国科学院洁净能源创新研究院合作基金(DNL180308)

摘　　要：通过预先碳包覆二氧化钛方式成功制备了高倍率钛酸锂负极材料(LTO/C)。使用XRD、SEM、TG和TEM技术表征材料的组成、结构和形貌特征。结果表明二氧化钛表面的碳层能有效抑制钛酸锂晶粒的生长和团聚,钛酸锂晶粒尺寸维持在200 nm左右,其中晶粒表面均匀包覆着一层厚度约为10 nm的碳层,碳含量为质量分数4.5%,提高了晶粒表面的电子导电率。通过循环伏安法和交流阻抗谱分析得出晶粒的减小和电子导电率的提高使得LTO/C电极具有更大的锂离子扩散系数和更小的电荷传导阻抗,这能更好地抑制电极在高倍率充放电过程中出现的极化,提高材料的倍率性能和循环稳定性。在0 5C,1C,2C,5C,10C和20C电流密度下,LTO/C电极可逆放电比容量分别为175,170,167,160,151和135mAh·g^-1;在20C高倍率下循环500圈容量保持率为93%,仅9mAh·g^-1容量损失。The high-rate lithium titanate(LTO/C) anode material was prepared by the way of carbon-coated TiO2.The composition,structure and morphology of the samples were characterized with XRD,SEM,TGA and TEM.The results show that the introduction of the carbon layer on the surface of TiO2 could effectively inhibit the growth and agglomeration of lithium titanate grains,and the size of the grain is maintained at about 200 nm.The electronic conductivity of the grain surface is enhanced in which the surface of the grains is coated by 4.5%(mass fraction) carbon layer with the thickness of about 10 nm.The cyclic voltammetry and impedance spectroscopy results indicate that due to the decrease of grain size and the increase of electronic conductivity,LTO/C electrode has larger lithium ion diffusion coefficient and smaller charge transfer resistance to inhibit the polarization during the process of discharge-charge at high rate,leading to excellent rate performance and cycle stability of the LTO/C electrode.This LTO/C electrode demonstrates a high reversible discharge capacity of 175,170,167,160,151 and 135 mAh·g^-1 at the current density of 0.5 C,1 C,2 C,5 C,10 C and 20 C,respectively.Moreover,the capacity retention still maintains 93% after 500 cycles at the high rate current density of 20 C,and the loss of capacity is only 9 mAh·g^-1.

关 键 词：钛酸锂 锂离子电池 碳包覆 负极材料 高倍率 

分 类 号：TM912.9[电气工程—电力电子与电力传动]