A sulfur-multi walled carbon nanotubes (MWCNTs) composite is prepared by the direct precipitation method as a cathode material for lithium sulfur batteries. The microstructure and morphology of the sulfur-MWCNTs composite are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS) mapping and thermogravimetric analysis (TGA). From these results, it is found that the synthesized sulfur has an orthorhombic phase and the MWCNTs are chemically well-dispersed over the whole surface of the synthesized sulfur. Electrochemical charge-discharge tests demonstrated that the sulfur-MWCNTs composite exhibits better capacity retention (63%) than that (16%) of the precipitated sulfur, which is also prepared by the direct precipitation method without MWCNTs. The enhanced cycle performance of the sulfur-MWCNTs is mainly attributed to the formation of highly conductive electron path due to the uniformly dispersed MWCNTs. Furthermore, in order to investigate the electrochemical reaction mechanism for the Li-S cell during the discharge process, the ac-impedance spectra as a function of the state of discharge are measured and analyzed.
Bibliographical noteFunding Information:
This work was supported by the Next Generation Military Battery Research Center program of The Defense Acquisition Program Administration and Agency for Defense Development .
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Energy Engineering and Power Technology
- Physical and Theoretical Chemistry
- Electrical and Electronic Engineering