Energy Storage Science and Technology ›› 2017, Vol. 6 ›› Issue (3): 411-417.doi: 10.12028/j.issn.2095-4239.2016.0047

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Preparation and properties of manganese dioxide coated carbon nanotubes-sulfur composite cathode material

SHANG Yongliang1, WANG Chengwen1, LIU Bin1, LIU Jun1,2, KE Xi1,2, LIU Liying1,2, SHI Zhicong1,2   

  1. 1School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong, China; 2 Guangdong Research Centre for New Energy Materials and Devices Engineering Technology, Guangzhou 510006, Guangdong, China
  • Received:2016-12-19 Revised:2017-01-23 Online:2017-05-01 Published:2017-05-01

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Abstract:

The development of lithium-sulfur batteries has been hindered by the poor conductivity of sulfur and the dissolution of intermediate species (lithium polysulfides) into the electrolyte. In this study, MnO2@MWCNT-S was synthesized by impregnating multi-walled carbon nanotubes (MWCNT) with sulfur, followed by the coating of manganese dioxide (MnO2) on the surface. MWCNT can provide electronic conductive path to improve the conductivity of electrode material, while MnO2 has strong chemical adsorption to the polysulfide, thereby inhibiting the dissolution of polysulfide and enhancing the utilization of active materials. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization show that sulfur is uniformLy distributed across the carbon nanotubes and their surface is covered by a layer of manganese dioxide. The content of sulfur in MnO2 @MWCNT-S composites is 58.4% by thermogravimetric analysis (TGA). Electrochemical testing indicated that MnO2 coating has improved the initial capacity of MWCNT-S composite and effectively retarded the dissolution of polysulfides. The MnO2@MWCNT-S composite showed a high initial discharge capacity of 1148.98 mA·h·g-1 and maintained 560.04 mA·h·g-1 after 100 cycles at 0.1 C rate.