Sulfur vacancies in Co9S8−x/N-doped graphene enhancing the electrochemical kinetics for high-performance lithium–sulfur batteries

论文题目：Sulfur vacancies in Co9S8−x/N-doped graphene enhancing the electrochemical kinetics for high-performance lithium–sulfur batteries

论文作者：Haojie Li, Yihua Song, Kai Xi, Wei Wang, Sheng Liu, Guoran Li* , Xueping Gao

发表期刊：Journal of Materials Chemistry A, 9(17), 10704-10713, 2021    

Abstract： 

A sufficient areal capacity is necessary for achieving high-energy lithium-sulfur batteries, which require sufficiently high sulfur loading in  the cathode materials. Therefore, the kinetically fast catalytic  conversion of polysulfide intermediates is especially important for the  full utilization of sulfur. Herein, Co9S8-x/N-dopedgraphene (Co9S8-x/N-G) is used as a sulfur host material and electrocatalyst in a high-sulfur-loading cathode, in which sulfurvacancies are generated via the hydrogen reduction of stoichiometric Co9S8. The produced sulfurvacanciesinCo9S8-x/N-G effectively improve the adsorption ability for polysulfide anions, and theoretical calculations indicate that Co9S8-x has lower adsorption energy for polysulfides than Co9S8.  Furthermore, electrochemical experiments reveal that the electrode  process kinetics for the catalytic conversion of polysulfides are  enhanced by sulfurvacancies. As a result, the S/Co9S8-x/N-G cathode with a high sulfur  loading of 14.6 mg cm(-2) delivers a high areal capacity of 12.9 mA h  cm(-2), and long-term cycling stability with a slow decay rate of 0.035%  per cycle during 1000 cycles at 1C. Additionally, the pouch cell shows  foldable flexibility and a stable areal capacity of 5.9 mA h cm(-2) at a  sulfur loading of 7.1 mg cm(-2). The results show that enhancing the polysulfide conversion process kinetics using sulfurvacancies could be an effective approach for obtaining high-performance lithium-sulfur batteries.