Vapor-grown carbon fibers enhanced sulfur-multi walled carbon nanotubes composite cathode for lithium/sulfur batteries
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. Engineering Research Center of High Performance Battery Materials and Devices,
Research Institute of Central South University in Shenzhen, Shenzhen 518057, China)
2. Engineering Research Center of High Performance Battery Materials and Devices,
Research Institute of Central South University in Shenzhen, Shenzhen 518057, China)
Abstract: Vapor-grown carbon fibers (VGCFs) were introduced as conductive additives for sulfur-multiwalled carbon nanotubes (S-MWCNTs) composite cathode of lithium-sulfur batteries. The performance of S-MWCNTs composite cathodes with carbon black and VGCFs as sole conductive additives was investigated using scanning electron microscopy (SEM), galvanostatic charge-discharge tests and electrochemical impedance spectroscopy (EIS). The results show that the S-MWCNTs composite cathode with VGCFs displays a network-like morphology and exhibits higher activity and better cycle durability compared with the composite cathode with carbon black, delivering an initial discharge capacity of 1254 mA·h/g and a capacity of 716 mA·h/g after 40 cycles at 335 mA/g. The interconnected VGCFs can provide a stable conductive network, suppress the aggregation of cathode materials and residual lithium sulfide and maintain the porosity of cathode, and therefore the electrochemical performance of S-MWCNTs composite cathode is enhanced.
Key words: lithium-sulfur batteries; carbon fiber; composite cathode; multiwalled carbon nanotube