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Ti4O7-Filled Nitrogen-Doped Carbon/Ti4O7 Double-Layer Spheres As Sulfur Host for Advanced Lithium Sulfur Batteries

Thursday, 23 June 2016
Riverside Center (Hyatt Regency)
H. Xu (Guangzhou HKUST Fok Ying Tung Research Institute), Y. Yang, J. Su, and G. Chen (The Hong Kong University of Science and Technology)
Holding the largest market share, Li-ion batteries have been optimized for the post two decades, although their capacity is limited by the energy density of intercalation materials to ~300 mA h g-1. New chemistries are being sought as the next-generation energy storage device with higher energy density and reduced cost. Lithium-sulfur batteries, with their environmental benignity, competitive cost and high theoretical energy density (~2600 Wh kg-1), were intensively investigated in recent years as a promising candidate to replace the current lithium ion batteries. In this study, nitrogen-doped hollow carbon spheres (NC) with conducting Magnéli-phase Ti4O7 as the filling agent were designed delicately by employing one-step approach to reduce TiO2 and carbonize polydopamine on pre-synthesized SiO2 spheres as the sacrificial template, followed by the infiltration of sulfur at 155oC. The properties and performance of the composite (NC/Ti4O7/S) were examined and evaluated as the cathode material for lithium sulfur (Li-S) batteries. It was demonstrated that the sulfur particles could be well contained in the NC/Ti4O7 shells with the sulfur content being ~70%, while the particle size and thickness of the carbon shell can be easily tuned by controlling the reactant concentration and reaction time. The assembled battery exhibited an initial capacity of ~938 mAh g-1 at 0.5 C with a high retention rate of 94.8% after 100 cycles, which corresponds to a capacity decay of 0.052% per cycle. The NC/Ti4O7/S composite provides a promising cathode material for future lithium sulfur batteries.