Constructing a catalytic reservoir using cobalt nanoparticles-MoS2@nitrogen doped carbon nanotubes on the separator to immobilize polysulfides and accelerate their conversion for lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are considered as one of the most promising electrochemical energy storage systems because of their high theoretical specific capacity and energy density. However, the shuttle effect of polysulfides and the slow redox kinetics significantly hinder their practical application. This study demonstrates a separator modification strategy that is expected to address these issues. The material for the modification is a functional carbon nanotube containing nitrogen heteroatoms and encapsulating cobalt nanoparticles. The external surface of the carbon nanotube was covered with a layer of molybdenum disulfide nanosheets (Co-MoS2@NC). The electrochemical measurements showed that the Co-MoS2@NC modified separator can inhibit the shuttle effect and promote the kinetics of the redox reaction. Both experimental investigation and the theoretical study confirmed the capability of MoS2 for the chemical adsorption and the catalytic conversion of the polysulfides. The electrochemical insight studies showed that the Li-S battery assembled with the Co-MoS2@NC modified separator has an excellent Li+ diffusion rate, enhanced rate performance (610.1 mAh g(-1) at 4 C), and stable cycle life (only 0.053% capacity decay per cycle at 1 C after 1000 cycles). It is expected that this modification strategy will find its promising application for high-performance and long-life Li-S batteries.