锂离子电池负极用多孔碳包覆Li_(4)Ti_(5)O_(12)复合材料的制备及电化学性能  

Preparation and Electrochemical Properties of Li_(4)Ti_(5)O_(12)@Porous-C Composite as Anode of Lithium Ion Battery

作　　者：王鸣[1] 方鹏飞 都亮 齐鹏涛 沈丁[1] WANG Ming;FANG Pengfei;DU Liang;QI Pengtao;SHEN Ding(School of Materials Science and Engineering,Liaoning Technical University,Fuxin 123000,Liaoning,China)

机构地区：[1]辽宁工程技术大学材料科学与工程学院,辽宁阜新123000

出　　处：《硅酸盐学报》2022年第2期364-371,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金项目(51874167,51774175);辽宁省教育厅科学研究面上项目(LJKZ0363);辽宁工程技术大学学科创新团队项目(LNTU20TD-09,LNTU20TD-16)。

摘　　要：利用水热合成和高温活化处理对Li_(4)Ti_(5)O_(12)进行多孔碳包覆复合改性实验,制备了Li_(4)Ti_(5)O_(12)@porous-C复合材料,研究了复合材料微观结构和电化学性能。结果表明:Li_(4)Ti_(5)O_(12)完全被包覆在多孔碳层中,同时,Li_(4)Ti_(5)O_(12)@porous-C复合材料表面碳层孔洞分布均匀,碳层厚度约为(8.5±3.6)nm。其首次放电比容量为363 mAh/g,约为纯Li_(4)Ti_(5)O_(12)放电比容量的2倍;交流阻抗值降低,仅为纯Li_(4)Ti_(5)O_(12)的阻抗值的一半;Li_(4)Ti_(5)O_(12)@porous-C复合材料在循环200周后的放电比容量为251 mAh/g,容量保持率为97.7%(纯LTO的比容量为143 mAh/g,保持率为94.7%),放电比容量提高了近1倍,而且特别是在不同放电速率下进行倍率测试时,其可逆容量比Li_(4)Ti_(5)O_(12)提高超1.5倍。对Li_(4)Ti_(5)O_(12)表面进行多孔碳包覆改性,可以同时提高其比表面积和电子传输速率,这也是其电化学性能也显著提高的主要原因。A composite of porous carbon coated Li_(4)Ti_(5)O_(12)was prepared by a hydrothermal synthesis and high-temperature activation method.The microstructure and electrochemical properties of the composite were investigated.The results show that Li_(4)Ti_(5)O_(12)is completely coated on the porous carbon layer.Meanwhile,the surface pores of Li_(4)Ti_(5)O_(12)@porous C composite are evenly distributed,and the carbon layer thickness is approximately(8.5±3.6)nm.The discharge capacity at first cycle is 363 mAh/g,which is approximately twice greater than that of pure Li_(4)Ti_(5)O_(12).The AC impedance value of Li_(4)Ti_(5)O_(12)@porous C composite decreases,which is only the half of that of pure Li_(4)Ti_(5)O_(12).The discharge specific capacity of Li_(4)Ti_(5)O_(12)@porous-C composite is 251 mAh/g and the retention rate is 97.7%after 200 cycles(i.e.,the specific capacity of pure Li_(4)Ti_(5)O_(12)is 143 mAh/g and the retention rate is 94.7%),the discharge specific capacity is nearly doubled,especially when the rate test is carried out at different discharge rates.The reversible capacity is twice greater than that of Li_(4)Ti_(5)O_(12).The porous carbon coated modification of Li_(4)Ti_(5)O_(12)can increase the specific surface area and the electron transfer rate for the higher electrochemical properties.

关 键 词：钛酸锂 多孔碳包覆 电化学性能 锂离子电池 

分 类 号：TB332[一般工业技术—材料科学与工程]