Porous Graphitic Carbon Derived from Biomass for Advanced Lithium Sulfur Batteries

Abstract

Porous graphitic carbon (PGC) with a hollow core and graphitic shell structure was prepared via a facile catalytic graphitization approach using sawdust as the raw material and Fe(NO3)(3) as the graphitization catalyst. Sawdust reacted with Fe(NO3)(3) at low temperatures to form a transition metal carbide (Fe3C) core and a graphitic carbon (GC) shell. With the dissolution of Fe3C, PGC with a hollow core and GC shell was formed. This PGC was employed as the sulfur reservoir for lithium sulfur (Li-S) batteries. The PGC/S composite showed excellent capacity retention and cycling performance. The initial discharge capacity of PGC/S cell was 1235 mAh g(-1) and the capacity retention was 800 mAh g(-1) after 20 cycles at 0.1 C. The cell also delivered a capacity retention of 405 mAh g(-1) at 1 C after 150 cycles. The outstanding electrochemical performance of the PGC/S composite can be attributed to its unique porous structure. The hollow structure provided sufficient space to accommodate sulfur and confine polysulfides, and the graphitic shell improved the conductivity of the electrode and facilitated rapid electron transfer in it. Therefore, the PGC/S composite was found to be a promising cathode material for Li-S batteries with excellent electrochemical performance. Moreover, the low-cost, green, and facile preparation process used in this study for the PGC matrix can be used for fabricating high-performance Li-S batteries.