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

• Published in: Carbon (New York) Vol. 149; pp. 564 - 571
• Main Authors: Li, Na, Chen, Kanghua, Chen, Songyi, Wang, Fei, Wang, Dudan, Gan, Fangyu, He, Xuan, Huang, Yuanchun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.08.2019
• Subjects: Dual electrocatalysts; Lithium-sulfur batteries; Shuttle effect; Sulfur cathode; Dual electrocatalysts; Shuttle effect; Sulfur cathode; Lithium-sulfur batteries
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2019.04.022

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-CoBN-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-CoBN-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-CoBN-GC composite provides possibility of practical applications in high performance LiS batteries. To solve the two big problems (the shuttle effect of LiPSs and sluggish reaction kinetics), which hindered the commercialization of LiS batteries, a porous hollow cobalt-B, N codoped-graphitic carbon polyhedrons has been designed as a novel S host material for the first time to achieve excellent cycling stability and rate capability simultaneously. The h-CoBN-GC is consisted of homogeneously inlaid ultrafine Co nanoparticles in nitrogen-doped carbon shell. As a result of this fascinating structure, the h-CoBN-GC based sulfur cathode with 6.5 mg cm−2 sulfur delivers a high initial capacity of 520 mAh g−1 and remarkable capacity retention of 79% after 100 cycles at 0.5C. [Display omitted]