王瑜东, 杨凯, 张明杰, 李建玲, 高飞, 刘皓, 耿萌萌. 静电纺丝法制备空心钛酸锂材料[J]. 工程科学学报, 2019, 41(1): 111-116. DOI: 10.13374/j.issn2095-9389.2019.01.012
引用本文: 王瑜东, 杨凯, 张明杰, 李建玲, 高飞, 刘皓, 耿萌萌. 静电纺丝法制备空心钛酸锂材料[J]. 工程科学学报, 2019, 41(1): 111-116. DOI: 10.13374/j.issn2095-9389.2019.01.012
WANG Yu-dong, YANG Kai, ZHANG Ming-jie, LI Jian-ling, GAO Fei, LIU Hao, GENG Meng-meng. Fabrication of hollow lithium titanate material by electrospinning[J]. Chinese Journal of Engineering, 2019, 41(1): 111-116. DOI: 10.13374/j.issn2095-9389.2019.01.012
Citation: WANG Yu-dong, YANG Kai, ZHANG Ming-jie, LI Jian-ling, GAO Fei, LIU Hao, GENG Meng-meng. Fabrication of hollow lithium titanate material by electrospinning[J]. Chinese Journal of Engineering, 2019, 41(1): 111-116. DOI: 10.13374/j.issn2095-9389.2019.01.012

静电纺丝法制备空心钛酸锂材料

Fabrication of hollow lithium titanate material by electrospinning

  • 摘要: 为进一步提升钛酸锂材料的性能, 本文在传统静电纺丝技术的基础上, 将纺丝喷头改进成内外嵌套的同轴喷头, 以两种溶液的形式进行同轴共纺, 得到了具有空心结构的钛酸锂纤维丝.将其与传统静电纺丝法制备的实心结构钛酸锂纤维丝进行对比, 结果表明: 空心钛酸锂材料粒度均一、无团聚现象, 材料具有明显的空心结构, 结晶性能良好, 比表面积是实心结构的1.3倍.形貌结构的改善极大地提高了空心钛酸锂材料的电化学性能, 表现为小倍率下二者的放电比容量接近理论比容量, 但在20C倍率下空心结构的钛酸锂材料优于实心钛酸锂, 仍可达到130 mA·h·g-1, 循环200周后容量保持率仍达98%, 具有良好的稳定性; 循环伏安和交流阻抗曲线也表明: 空心结构使得钛酸锂材料的极化程度减少, 电化学反应阻抗降低, 更有利于电化学反应的进行.

     

    Abstract: Lithium titanate (Li4Ti5O12, LTO) is an important material to be used as an anode for LIBs (Li+ ion battery). LTO is a zero-strain material (i.e., no structural change occurs during Li insertion/extraction). Although LTO is a very safe material that can be used as an anode material in high and low temperature environment, its rate capability is compromised by its low electronic conductivity and poor Li+ diffusion coefficient. In the recent years, considerable research around the world has focused on improving LTO rate performance. Efforts to achieve better electrical conduction between LTO particles have included LTO particle size control, conductive-material surface coatings, and alien ion doping. However, in this study electrochemical properties were improved by changing the morphology of LTO. Based on traditional electrospinning technology, LTO fibers with a hollow structure were produced using a nested coaxial nozzle modified from the conventional spinning nozzle and coaxial cospinning with two different solutions. A comparison of this results with those of solid LTO prepared by traditional electrospinning technology demonstrates that hollow LTO is characterized by uniform particle size and no agglomeration, along with an obvious hollow structure, clear crystal lattice stripes, and good crystallization property. The specific surface of this hollow LTO is 1.3 times than its solid counterpart. This morphological change greatly improves the electrochemical performance of the material. Although the discharge specific capacities of both the solid and hollow LTO are close to the theoretical value for small ratios, the hollow LTO is superior to its solid counterpart at 20C. The discharge specific capacity of the hollow LTO can reach 130 mA·h·g-1 at 20C, and after 200 cycles, its capacity retention ratio remains at 98%, which suggests good stability. Cyclic voltammetry and AC impedance curves also show that the hollow structure reduces the degree of polarization and the electrochemical reaction impedance of LTO, which makes LTO more conducive to electrochemical reaction.

     

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