Unusual Mesoporous Carbonaceous Matrix Loading with Sulfur as the Cathode of Lithium Sulfur Battery with Exceptionally Stable High Rate Performance.
Unusual three-dimensional mesoporous carbon/reduced graphene oxide (MP-C/rGO) matrix possessing graphene nanolayer pore walls built up by three to five graphene monosheets and some carbon particles with the sizes of about 5 nm located between the graphene nanolayers was prepared by facile freeze-drying and then carbonization of the poly(vinyl alcohol) and graphene oxide mixture. The mesoporous carbonaceous MP-C/rGO sample has a high specific surface area of 661.6 m2 g-1, large specific pore volume of 1.54 m3 g-1, and focused pore size distribution of 2-10 nm. About 64 wt % sulfur could be held in the pores of the MP-C/rGO matrix. As the cathode of a Li-S battery, the MP-C/rGO/S composite showed excellent electrochemical property including a high initial specific capacity of 919 mA h g-1 at 1 C with the capacity retention ratio of 63.3% and the Coulombic efficiency above 90% after 500 cycles. Meanwhile, the initial specific capacity of 602 mA h g-1 at 5 C and remaining capacity of 391 mA h g-1 after 500 cycles with an outstanding Coulombic efficiency of 97% indicate its exceptionally stable rate performance.