High performance sulfur/nitrogen-doped graphene cathode for lithium/sulfur batteries
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A sulfur/nitrogen-doped graphene (S/N-G) composite was synthesized by simple sonicated mixing of nanosized sulfur suspension and nitrogen-doped graphene suspension followed by heat treatment. Scanning electron microscopy and energy dispersive spectroscopy mapping showed the formation of a porous structure with uniform distribution of sulfur and nitrogen-doped graphene. Electrochemical performance reveals that the resultant S/N-G composite exhibits a high reversible capacity of 1355 mAh g−1 at the initial cycle, with 823 mAh g−1 remaining after 80 cycles at 0.1 C. Moreover, a reversible capacity of 475 mAh g−1 could still be obtained at 2.5 C. Such an electrochemical performance of S/N-G composite is superior to the graphene counterpart. The enhanced electrochemical performance can be attributed to the introduction of nitrogen-doped graphene with the N functionalization, which provides both a more effective electron conduction path and a stronger physical and chemical confinement setting for elemental sulfur and resident polysulfides.
KeywordsLithium/sulfur battery Sulfur/nitrogen-doped graphene (S/N-G) composite Cathode material Simple sonicated mixing
This research was supported by the Research Grant from the Ministry of Education and Science of Kazakhstan and by a Subproject supported under the Technology Commercialization Project by the World Bank and the Government of Kazakhstan (Group 157). The authors acknowledge the administrative support from the Institute of Batteries LLC (Director Dr. I. Kurmanbayeva) for this work. Y. Zhao and Y. Zhang are grateful of financial support by the National Natural Science Foundation of China (Grant No. 21406052) and financial support by Program for the Outstanding Young Talents of Hebei Province (Grant No. BJ2014010).
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