摘要
Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur （Li-S） batteries. The ability to engineer the porosity, wall thickness, and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries, such as fast capacity decay and poor high-rate performance. In this work, highly ordered, ultrathin mesoporous graphitic-carbon frameworks （MGFs） having unique cage-like mesoporosity, derived from self-assembled Fe304 nanoparticle superlattices, are demonstrated to be an excellent host for encapsulating sulfur. The resulting S@MGFs exhibit high specific capacity （1,446 mAh.g-1 at 0.15 C）, good rate capability （430 mAh.g-1 at 6 C）, and exceptional cycling stability （-0.049% capacity decay per cycle at 1 C） when used as Li-S cathodes. The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs. In addition to the interconnected, ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport, the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides, leading to improved capacity retention even at high current densities.
Mesoporous carbons have been widely utilized as the sulfur host for lithium-sulfur （Li-S） batteries. The ability to engineer the porosity, wall thickness, and graphitization degree of the carbon host is essential for addressing issues that hamper commercialization of Li-S batteries, such as fast capacity decay and poor high-rate performance. In this work, highly ordered, ultrathin mesoporous graphitic-carbon frameworks （MGFs） having unique cage-like mesoporosity, derived from self-assembled Fe304 nanoparticle superlattices, are demonstrated to be an excellent host for encapsulating sulfur. The resulting S@MGFs exhibit high specific capacity （1,446 mAh.g-1 at 0.15 C）, good rate capability （430 mAh.g-1 at 6 C）, and exceptional cycling stability （-0.049% capacity decay per cycle at 1 C） when used as Li-S cathodes. The superior electrochemical performance of the S@MGFs is attributed to the many unique and advantageous structural features of MGFs. In addition to the interconnected, ultrathin graphitic-carbon framework that ensures rapid electron and lithium-ion transport, the microporous openings between adjacent mesopores efficiently suppress the diffusion of polysulfides, leading to improved capacity retention even at high current densities.
基金
A. G. D. acknowledges the financial support from the National Basic Research Program of China （No. 2014CB845602）, Natural National Science Foundation of China （No. 21373052）, and Shanghai International Science and Technology Cooperation Project （No. 15520720100）. D. Y. is grateful for financial support from Natural National Science Foundation of China （Nos. 51373035, 51373040, 51573030, and 51573028）, and International Science and Technology Cooperation Program of China （No. 2014DFE40130）.
