锂硫电池载硫材料碳纳米管修饰V_(2)O_(5)纳米球的制备及其性能研究

Preparation and Properties of Carbon Nanotube-modified V_(2)O_(5)Nanospheres for Lithium-sulfur Batteries

锂硫电池因具有优异的理论容量、能量密度和可持续发展特性而受到越来越广泛的关注。决定锂硫电池性能的最主要因素之一是其正极材料。本文分别通过自组装法和模板法,制备了两种V_(2)O_(5)纳米球,并在制备过程中添加了碳纳米管。以所得到的材料作为正极改性材料,组装了扣式锂硫电池。通过对所制备材料的结构以及电化学性能研究,并与商用V_(2)O_(5)进行对比,发现V_(2)O_(5)纳米球具有良好电化学性能,其电池性能显著优于商用V_(2)O_(5)。这可归因于所合成的V_(2)O_(5)纳米球一方面具有较高的比表面积,有利于活性物种硫的负载,另一方面表面连接有碳纳米管,有利于提高电子传输性能。基于自组装法(1号样品)和模板法(2号样品)所得V_(2)O_(5)纳米球的锂硫电池,在0.1C的倍率下首次充放电比容量分别可达到1049mAh/g和1035mAh/g;经过200次循环后,其放电比容量分别为702 mAh/g和767mA/g。

Lithium-sulfur batteries are receiving increasing attention due to their excellent theoretical capacity,energy density and sustainability properties.One of the most important factors determining the performance of lithium-sulfur batteries is their cathode material.In this paper,two types of V_(2)O_(5) nanospheres were prepared by the self-assembly method and the template method,respectively,and carbon nanotubes were added in the preparation process.The obtained materials were used as the cathode modification materials to assemble the button lithium-sulphur batteries.This can be attributed to the high specific surface area of the synthesized V_(2)O_(5) nanospheres on the one hand,which facilitates the loading of the active species sulphur,and the carbon nanotubes attached to the surface on the other hand,which facilitates the improvement of the electron transport properties.The lithium-sulphur batteries based on the V_(2)O_(5) nanospheres obtained by the self-assembly method(sample 1)and the template method(sample 2)can reach a first charge/discharge specific capacity of 1049 mAh/g and 1035 mAh/g at a multiplication rate of 0.1C,respectively;after 200 cycles,their discharge specific capacities are 702 mAh/g and 767 mA/g,respectively.