The performances of lithium-sulfur (Li-S) batteries have been markedly impaired by intricate multi-electron sulfur chemistry involving reversible conversion of polysulfides (LiPSs) to Li2S upon discharge and back to S8 upon charge. Herein, graphene in situ coated TiO2 nanotubes are realized via a direct chemical vapor deposition (CVD) technique, leading to the design of a graphene-TiO2 (G-TiO2) promotor for Li-S chemistry. With the aid of detailed experimental and theoretical characterization, we reveal that the direct CVD-derived G-TiO2 realizes not only the coupling of Li+-ion diffusion and electron transfer but also efficient regulation of LiPSs, thereby producing a synergistic catalyzing effect on both LiPS conversion and Li2S decomposition. As a result, S/graphene-TiO2 (S/G-TiO2) presents a remarkable rate capability and an ultralow capacity decay rate of 0.052% over 1000 cycles at 2.0C. Even at a high sulfur loading of 9.4 mg cm-2, such a cathode still delivers a superior areal capacity of 8.7 mA h cm-2. This work would motivate the deep-seated revisiting of the sulfur reaction mechanism and offer a rational strategy to construct high-energy and long-life Li-S batteries.
|Original language||English (US)|
|Number of pages||10|
|Journal||Journal of Materials Chemistry A|
|State||Published - 2019|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by the National Natural Science Foundation of China (51702225), the National Key Research and
Development Program (2016YFA0200103), and Jiangsu Youth Science Foundation (BK20170336). The authors acknowledge
the support from Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies, Suzhou, China.