Hu Linyu, Dai Chunlong, Lim Jin-Myoung, Chen Yuming, Lian Xin, Wang Minqiang, Li Yi, Xiao Penghao, Henkelman Graeme, Xu Maowen
Faculty of Materials and Energy , Southwest University , Chongqing 400715 , P. R. China . Email:
Texas Materials Institute , Department of Chemistry , The Institute for Computational Engineering and Sciences , University of Texas at Austin , Austin , Texas 78712 , USA . Email:
Chem Sci. 2017 Nov 6;9(3):666-675. doi: 10.1039/c7sc03960c. eCollection 2018 Jan 21.
Li-S batteries have attracted enormous interest due to their potentially high energy density, non-toxicity and the low cost of sulfur. The main challenges of sulfur cathodes are the short cycling life and limited power density caused by the low conductivity of sulfur and dissolution of Li polysulfides. Here we design a new double-hierarchical sulfur host to address these problems. Hierarchical carbon spheres (HCSs), constructed from building blocks of hollow carbon nanobubbles for loading sulfur, are sealed within a thin, polar MoS coating composed of ultrathin nanosheets. Experimental and theoretical studies show a strong absorption of the MoS nanoshell to polysulfides, and the excellent stability of the MoS nanosheets after the adsorption of polysulfides. Moreover, MoS promotes the electrochemical redox kinetics in Li-S batteries. Benefiting from the unique hierarchical, hollow and compositional characteristics of the host, the S/MoS@HCS composite electrode shows a high capacity of 1048 mA h g at 0.2C, good rate capacity and long cycling life with a slow capacity decay of 0.06% per cycle.
锂硫电池因其潜在的高能量密度、无毒以及硫的低成本而备受关注。硫阴极的主要挑战在于硫的低导电性和多硫化锂的溶解导致的循环寿命短和功率密度有限。在此，我们设计了一种新型的双分级硫主体来解决这些问题。由用于负载硫的中空碳纳米气泡构建块构成的分级碳球（HCSs）被密封在由超薄纳米片组成的薄极性MoS涂层内。实验和理论研究表明，MoS纳米壳对多硫化物有很强的吸收作用，且多硫化物吸附后MoS纳米片具有优异的稳定性。此外，MoS促进了锂硫电池中的电化学氧化还原动力学。受益于主体独特的分级、中空和组成特性，S/MoS@HCS复合电极在0.2C时显示出1048 mA h g的高容量、良好的倍率性能和长循环寿命，容量衰减缓慢，每循环0.06%。
