Manipulating the redox kinetics of Li-S chemistry by porous hollow cobalt-B, N codoped-graphitic carbon polyhedrons for high performance lithium-sulfur batteries

Lithium-sulfur batteries have attracted tremendous attention due to their inherently high theoretical energy density of sulfur cathode for next-generation energy storage systems. However, shuttle of soluble polysulfides and sluggish redox kinetics in sulfur cathode still limit its practical application. Herein, a hollow porous B, N-codoped graphitic carbon-Co composite (h-Co-BN-GC) is synthesized, combining the advantages of synergetic structural and chemical bonding confinement to reserve the soluble polysulfides. A serial of further electrochemical redox kinetic studies confirm that the ultrafine Co nanoparticles and B, N-codoped species serve as dual electrocatalysts, substantially promote the redox of polysulfides reaction kinetics. Benefiting from the above merits, the as-obtained 80S@h-Co-BN-GC composite demonstrates an improved electrochemical performance. It delivers a high first discharge capacity of 1089 mAh g(-1) and remarkable capacity retention of 877 mAh g(-1) after 500 cycles at 0.5C rate, with nearly 100% Coulombic efficiency maintenance. These results suggest that the 80S@h-Co-BN-GC composite provides possibility of practical applications in high performance Li-S batteries. (C) 2019 Elsevier Ltd. All rights reserved.