High capacity and rate capability of S/3D ordered bimodal mesoporous carbon cathode for lithium/sulfur batteries
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High capacity and rate capability of S/3D ordered bimodal mesoporous carbon cathode for lithium/sulfur batteries Yan Song1, Jun Ren1, Guoyan Wu1, Wulin Zhang1, Chengwei Zhang1,a), Fuxing Yin1,b) 1
School of Materials Science & Engineering, Hebei University of Technology, Tianjin 300130, China; and Tianjin Key Laboratory of Materials Laminating Fabrication and Interface Control Technology, Hebei University of Technology, Tianjin 300130, China a) Address all correspondence to these authors. e-mail: [email protected] b) e-mail: [email protected] Received: 9 October 2018; accepted: 13 November 2018
3D ordered bimodal mesoporous carbon (OBMC) with a high specific surface area of 1368.7 m2/g, ordered large mesopores, and small mesopores on the walls is prepared by a surfactant-free rapid method using SiO2 nanosphere arrays as templates. The resulting OBMC is then composited with sulfur to prepare S/OBMC hybrids via a simple solution infiltration method followed by a heat treatment process. In S/OBMC composite, sulfur is uniformly infiltrated inside the 3D hierarchical pores of OBMC. On the basis of this systematic design, the obtained S/OBMC cathode shows a large discharge capacity value of 1590 mA h/g at first cycle and maintains 989 mA h/g after 100 cycles at 0.2 C. Furthermore, at 1 C charge–discharge rate, a reversible discharge capacity of 733 mA h/g after 100 cycles is reached. The extraordinary electrochemical property of S/OBMC derives from the unique bimodal mesoporous structure with large mesopores and small mesopores that can facilitate the mass transfer and strict dissolution of polysulfide species into the electrolyte.
Introduction Thanks to the high theoretical energy density (2576 W h/kg), lithium/sulfur (Li/S) batteries have been considered as one of the desirable energy storage systems [1, 2, 3]. Nevertheless, the practical applications of Li/S batteries still have several obstacles for practical use, such as low utilization of S caused by the insulation of S and the poor stability because of the dissolution and detachment of the soluble lithium polysulfides from the electrode during the reaction processes [4, 5, 6]. Many ways have been attempted to circumvent the above-mentioned problems. Among them, one of the effective ways is to introduce carbon materials to form the sulfur/carbon cathodes as a result of the obvious superior properties of carbon materials, including high surface areas, good electrical conductivity, excellent chemical stability, and superior affinity for sulfur within their porous bodies [7, 8]. Thus, various nanostructured carbons, such as porous carbon [9], carbon nanotubes [10], graphene sheets [11], and graphene oxide sheets [12], are applied to composite with sulfur to obtain advanced composite cathode with good cycling performance. In our previous study, sulfur was supported on a kind of hierarchically porous carbon with ordered macropores and
ª Materials Research Society 2019
mesopores as a cathode, and it delivers 703 mA h/g at 0.2 C after 100 cycles. However, it has poo
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