摘要
以氧化石墨烯(GO)为基底,钛酸四丁酯、一水合氢氧化锂、六水合硝酸钇为原料,十六烷基三甲基溴化铵为表面活性剂,采用溶剂热法合成前驱体,在N2气氛保护下高温煅烧合成了钇掺杂钛酸锂/氧化石墨烯纳米复合材料。采用SEM、XRD、EDS、Raman对复合材料进行了形貌、结构和成分表征。将复合材料用作锂离子电池负极材料,采用循环伏安法、恒流充放电循环法研究了其电化学性能。结果表明,片状钛酸锂包覆在氧化石墨烯片上形成了钇掺杂钛酸锂/氧化石墨烯纳米复合材料。在100 mA/g的电流密度下,钇掺杂量为8%(以钛酸锂的物质的量为基准,下同)的纳米复合材料的首次放电比容量为145.5mA·h/g,经过100圈充放电循环后容量衰减几乎为0,经过200圈循环后容量衰减1.59%,经过300圈循环后容量衰减3.24%,与目前容量保持率只有80%左右的石墨负极相比有明显的改进。钇元素的掺杂和钛酸锂包覆氧化石墨烯形式的复合材料可以减小钛酸锂电极在充放电循环中的极化程度,从而改善了材料的循环性能。
Yttrium-doped lithium titanate/graphene oxide nanocomposites were synthesized by calcination of nanocomposite precursor, which was prepared by solvothermal method using graphene as base,tetrabutyl titanate, lithium hydroxide monohydrate and yttrium nitrate hexahydrate as raw materials, and hexadecyl trimethyl ammonium bromide as surfactant, at high temperature under the protection of N2atmosphere. The morphology, structure and composition of the nanocomposites obtained were then characterized by SEM, XRD, EDS, Raman spectroscopy. The nanocomposites were further used in lithiumion battery as anode material, and their electrochemical properties were evaluated by cyclic voltammetry and constant current charge-discharge cycle method. The results showed that yttrium-doped lithium titanate/graphene nanocomposites had a morphology of graphene sheets coated with flake lithium titanate.Under a current density of 100 mA/g, the nanocomposites with a yttrium dopping amount 8%(based on the amount of substance of lithium titanate, the same below) exhitbited an initial discharge capacity of 145.5 mA·h/g,and its capacity fading was 0 after 100 charge-discharge cycles, 1.59% after 200 cycles, and 3.24% after 300 cycles, which was significantly improved compared with the graphite anode whose capacity retention rate was only about 80%. The doping of yttrium and graphene coated with lithium titanate reduced the polarization degree of lithium titanate electrode in the charge and discharge cycle and improved the cycle performance of the material.
作者
闫共芹
袭沂东
祝玉婷
YAN Gongqin;XI Yidong;ZHU Yuting(School of Mechanical and Automotive Engineering,Guangxi University of Science and Technology,Liuzhou 545616,Guangxi,China)
出处
《精细化工》
EI
CAS
CSCD
北大核心
2023年第2期280-289,共10页
Fine Chemicals
基金
广西自然科学基金(2020GXNSFAA159024)
柳州市科技计划项目(2018DH10507)
广西科技大学2022年硕士研究生创新项目(GKYC202216)。
关键词
钇掺杂钛酸锂/氧化石墨烯纳米复合材料
溶剂热-煅烧合成
锂离子电池
负极材料
电化学性能
功能材料
yttrium-doped lithium titanate/graphene oxide nanocomposites
solvothermal-calcination synthesis
lithium-ion batteries
anode materials
electrochemical properties
functional materials
