Catalyzing polysulfide conversion by g-C3N4 in a graphene network for long-life lithium-sulfur batteries
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The practical application of lithium-sulfur batteries with a high energy density has been plagued by the poor cycling stability of the sulfur cathode, which is a result of the insulating nature of sulfur and the dissolution of polysulfides. Much work has been done to construct nanostructured or doped carbon as a porous or polar host for promising sulfur cathodes, although restricting the polysulfide shuttle effect by improving the redox reaction kinetics is more attractive. Herein, we present a well-designed strategy by introducing graphitic carbon nitride (g-C3N4) into a three-dimensional hierarchical porous graphene assembly to achieve a synergistic combination of confinement and catalyzation of polysulfides. The porous g-C3N4 nanosheets in situ formed inside the graphene network afford a highly accessible surface to catalyze the transformation of polysulfides, and the hierarchical porous graphene-assembled carbon can function as a conductive network and provide appropriate space for g-C3N4 catalysis in the sulfur cathode. Thus, this hybrid can effectively improve sulfur utilization and block the dissolution of polysulfides, achieving excellent cycling performance for sulfur cathodes in lithium-sulfur batteries.
Keywordslithium-sulfur batteries lithium polysulfide graphitic carbon nitride (g-C3N4) graphene catalytic conversion
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This work was supported by the National Basic Research Program of China (No. 2014CB932400). Q.-H. Y. is grateful for the support of the National Natural Science Foundation of China (No. 51525204) and Y. T. acknowledges support from the National Natural Science Foundation of China (No. 51702229).
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