Engineering active sites for advanced room-temperature Na-S batteries

Room temperature sodium-sulfur (RT Na-S) batteries attract many attentions since they endow many overwhelming merits, for instances, resources abundances of S and Na, high theoretical capacity of S (1672 mAh g-1), non-toxicity, and cost-efficiency. Nevertheless, the Na-S batteries are often restrained for their poor cycling performance and inferior Coulombic efficiency, which result from the sodium polysulfide (NaPSs) dissolution and the sluggish kinetics reactions. These issues always result in fast active materials loss and rapid cycling decay. To overcome these challenges, preventing the reactions between NaPSs species on the cathode, long-chain NaPSs dissolution and improving the kinetics reaction are extremely important. Therefore, it is very important to prepare the novel hosts with proper pore structure and enough surface area to embed the active materials and provide enough volume for S expansion during the cell working. Moreover, by decoration of abundant electrocatalytic active sites, the hosts can efficiently trap and catalyze NaPSs intermediates, which is in favour of construction of RT Na-S batteries with excellent performance. In this doctoral work, three different works are investigated, including single atomic Fe grown on nanospheres (S@Fe-SA-PNC), a general strategy to fabricate single atomic sites decorated on carbon nanospheres (S@Metal-SA-PNC, Metal= Mn, Co, Ni, Cu, Sn, Pb), as well as FeS nanoparticles decorated carbon nanotubes (S@FeS-CNT).