Melamine assisted liquid exfoliation approach for the synthesis of nitrogen doped graphene-like carbon nano sheets from bio-waste bagasse material and its application towards high areal density Li-S batteries

Li-S battery has received considerable attention as futuristic technology, however, solutions for challenging problems such as polysulfide shuttle and low sulfur loadings, etc. still remain elusive. Here we report design of efficient polysulfide trap by preparing graphene like nitrogen doped carbon (NBC) sheets from bagasse (sugarcane waste). Further, we prepared S@NBC composites by chemical absorption of S onto NBC matrix and studied their beneficial aspects as cathode for Li-S battery. The S@NBC displays extraordinarily good performance with a reversible capacity of 1169 mAh g−1 at 0.2 C with 77% capacity retention after 200 cycles which also exhibits remarkable 85% retention of higher order polysulfide even after 200 cycles. Moreover, by placing a second cathode layer the cyclability will be increased beyond 500 cycles. The remarkable cycling performance is attributed to the effective chemisorption of sulfur and polysulfides by the nitrogen doped carbon. Further, sulfur loading is increased to 12 mg cm−2 by stacking four cathode layers and we could achieve high areal capacity of 12 mAh cm−2 which is three times higher than the present day lithium ion battery. [Display omitted]