Carbon nanotube-modified separator for lithium–sulfur batteries: Effects of mass loading and adding polyvinylpyrrolidone on electrochemical performance. (November 2019)

• Record Type: Journal Article
• Authors: Li, Nuo; Ma, Xiaojuan; Ye, Hongqi; Wang, Shuai; Han, Kai
• Is Part Of: Journal of physics and chemistry of solids. Volume 134(2019)
• Page Start: 69
• Page End: 76
• Publication Date: 2019-11
• Subjects: Carbon nanotube -- Lithium-sulfur battery -- Mass loading -- Polyvinylpyrrolidone -- Separator modification; Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2019.05.045
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: Lithium-sulfur (Li–S) batteries are considered among the most promising systems for next-generation energy storage because of their high theoretical energy density, inexpensiveness, and the environmentally friendliness of the sulfur cathode material. Carbon nanotube (CNT) has been used widely for separator modification to overcome the shuttle effect of polysulfides. This strategy based on CNT can improve the performance of Li–S batteries in terms of their cycling stability and rate capability. However, the performance improvement has not been assessed under various mass loadings of CNT, which would significantly affect the entire battery energy density and manufacturing cost. In this study, we prepared CNT-modified polypropylene (CNT-PP) separators and explored the effects of different CNT mass loadings on the performance of Li–S batteries. We also developed an approach to reduce the amount of CNTs required while maintaining high performance. The results showed that the CNT-PP separator significantly improved the electrochemical performance of the pure sulfur cathode compared with the PP separator, and a CNT mass loading of 0.6 mg cm −2 obtained the optimal battery performance. Moreover, polyvinylpyrrolidone (PVP) was added to reduce the CNT mass loading, which promoted the dispersion of the CNT in aqueous solution and also enabled the chemical interaction between the CNT and polysulfides to inhibit the shuttling effect. When CNT/PVP was applied to modify the PP separator, the mass loading could be reduced by about 33% compared with the pure CNT while maintaining the optimal battery performance. At a CNT/PVP mass loading of 0.4 mg cm −2, the cells had a much higher initial capacity (1226 mAh g −1 at 0.1 C and 936 mA h g −1 at 2 C) and cycling stability (617 mAh g −1 after 300 cycles at 1 C) than the cells containing pure CNT-modified separators with a CNT mass loading of 0.6 mg cm −2 . These findings could facilitate the development of a facile approach for the practical application of Li–S batteries. Graphical abstract: Image 1 Highlights: CNT and CNT/PVP-modified PP separators were fabricated via vacuum filtration. CNT mass loading of 0.6 mg cm −2 obtains optimal lithium sulfur battery performance. Mass loading reduced by about 33% when CNT/PVP was applied.