Development of Lithium Sulfur Batteries with Improved Cycle Life and High-Power Properties

Tremendous effort has been applied to developing viable lithium sulfur batteries and significant progress has been reported. However, lithium sulfur batteries still exhibit significant capacity decay over cycling, probably due to the detachment or dissolution of Li_xS from the carbon surface during the discharge process. Here, we report the development of a new type of lithium sulfur batteries using functionalized multiwall carbon nanotube (MWCNT). We assembled an electrode consisting of densely packed MWCNT composites, which enabled strong interactions between the nonpolar carbon and the polar Li_xS clusters. We characterized the electrodes using Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS) and Fourier Transform Infrared spectroscopy (FTIR). We found that the electrodes had high cycling performance with specific capacities of 1250 mAh/g and 990 mAh/g at the C/5 and C/2 current rates, respectively. Up to 80% capacity was retained over 300 cycles at C/5 and 200 cycles at C/2. The developed battery may be promising for applications in hybrid vehicles and renewable energy.