多壁碳纳米管纸作正极集流体的锂硫电池性能

Performance of lithium sulfur batteries using multiwalled carbon nanotube paper as cathode current collector

为了改善锂硫电池的循环性能,以纸纤维为基体,多壁碳纳米管(MWCNTs)为导电剂,采用真空抽滤法制得MWCNTs导电纸,并将MWCNTs导电纸作为正极集流体代替铝箔应用于锂硫电池。对MWCNTs导电纸进行了形貌结构表征和电化学性能测试,并对循环后的MWCNTs导电纸电极进行EDS检测。结果显示,MWCNTs均匀地附着在纸纤维基体上,多空隙的MWCNTs导电纸三维结构明显。采用MWCNTs导电纸作集流体的锂硫电池在0.05C和1C倍率充放电下循环30次,比容量分别保持615mAh/g、496mAh/g,库伦效率达97.5%以上,且电荷转移电阻在循环后降低。EDS元素分析结果证实MWCNTs导电纸对多硫化锂有吸附作用,从而一定程度抑制了锂硫电池的穿梭效应。因此,以MWCNTs导电纸作为集流体能有效增加活性物质硫的负载量和接触面积,使锂硫电池具有良好的循环稳定性和库伦效率性能。

In order to improve the cycle performance of lithium sulfur battery,the multiwalled carbon nanotubes（MWCNTs）paper were prepared by vacuum filtration method using paper fibers as the matrix and MWCNTs as the conductive additive.The MWCNTs paper was applied as the cathode current collector for lithium sulfur battery instead of aluminum foil.The morphology structure were characterized by SEM and the electrochemical properties were tested by the cell tester,and the EDS element analysis for the MWCNTs paper and sulfur composite cathode after cycles were also performed.The results show that MWCNTs are uniformly adhered to the paper fiber,and the porous MWCNTs paper has obviously 3D structure.The electrochemical tests indicate that the lithium sulfur battery with MWCNTs paper as current collector hold a specific capacity of 615 mAh/g and 496 mAh/g after 30 cycles in the current rate of 0.05 Cand 1C,respectively.The Coulombic efficiency maintains as high as 97.5%,and the charge transfer resistance decrease after cycles.The EDS element analysis verifies that the MWCNTs paper has adsorption role for the lithium polysulfides.The shuttle effect is restrained in some degree by the MWCNTs paper.As a result,MWCNTs paper used as the current collector can increase the sulfur loading capacity and contact area significantly,and improve the cycle stability and the Coulombic efficiency of lithium-sulfur battery.