Molecular-confinement of polysulfides within mesoscale electrodes for the practical application of lithium sulfur batteries

Nitrogen-doped porous carbon (NPC) and multi-wall carbon nanotubes (MWCNT) have been frequently studied to immobilize sulfur in lithium sulfur (Li-S) batteries. However, neither NPC nor MWCNT itself can effectively confine the soluble polysufides if cathode thickness e.g. sulfur loading is increased. In this work, NPC was combined with MWCNTs to construct an integrated host structure to immobilize sulfur at a relevant scale. The function of doped nitrogen atoms was revisited and found to effectively attract sulfur radicals generated during the electrochemical process. The addition of MWCNT facilitated the uniform coating of sulfur nanocomposites to a practically thickness and homogenized the distribution of sulfur particles in the pristine electrodes, while NPC provided sufficient pore volume to trap the dissolved polysulfides species. More importantly, the difficulty of electrode wetting, a critical challenge for thick sulfur cathodes, is also mitigated after the adoption of MWCNT, leading to a high areal capacity of ca. 2.5 mA h/cm(2) with a capacity retention of 81.6% over 100 cycles. (C) 2015 Elsevier Ltd. All rights reserved.