Enhanced Li–S Batteries Using Amine-Functionalized Carbon Nanotubes in the Cathode

详细信息    查看全文

• 作者：Lin Ma ; Houlong L. Zhuang ; Shuya Wei ; Kenville E. Hendrickson ; Mun Sek Kim ; Gil Cohn ; Richard G. Hennig ; Lynden A. Archer
• 刊名：ACS Nano
• 出版年：2016
• 出版时间：January 26, 2016
• 年：2016
• 卷：10
• 期：1
• 页码：1050-1059
• 全文大小：676K
• ISSN：1936-086X

文摘

The rechargeable lithium–sulfur (Li–S) battery is an attractive platform for high-energy, low-cost electrochemical energy storage. Practical Li–S cells are limited by several fundamental issues, including the low conductivity of sulfur and its reduction compounds with Li and the dissolution of long-chain lithium polysulfides (LiPS) into the electrolyte. We report on an approach that allows high-performance sulfur–carbon cathodes to be designed based on tethering polyethylenimine (PEI) polymers bearing large numbers of amine groups in every molecular unit to hydroxyl- and carboxyl-functionalized multiwall carbon nanotubes. Significantly, for the first time we show by means of direct dissolution kinetics measurements that the incorporation of CNT-PEI hybrids in a sulfur cathode stabilizes the cathode by both kinetic and thermodynamic processes. Composite sulfur cathodes based the CNT-PEI hybrids display high capacity at both low and high current rates, with capacity retention rates exceeding 90%. The attractive electrochemical performance of the materials is shown by means of DFT calculations and physical analysis to originate from three principal sources: (i) specific and strong interaction between sulfur species and amine groups in PEI; (ii) an interconnected conductive CNT substrate; and (iii) the combination of physical and thermal sequestration of LiPS provided by the CNT=PEI composite.