A functional hyperbranched binder enabling ultra-stable sulfur cathode for high-performance lithium-sulfur battery

• 作者: Chunyang Yu Dawei Su Guoxiu Wang Lifeng Cui Xianbo Lu Xiang Luo Xiaodong Chen Ya Chen
• 来源期刊: 能源化学
• 年，卷（期）: 2020,（11）
• 页码范围: 63-72
• 页数: 10页
• 语种: 英文

摘要

Binders are of vital importance in stabilizing the cathodes to enhance the cycling stability of lithiumsulfur (Li-S) batteries.However,conventional binders are typically confronted with the drawback of inability for adsorbing lithium polysulfide (LipS),thus resulting in severe active material losing and rapid capacity fading.Herein,a novel water-soluble hyperbranched poly(amidoamine) (HPAA) binder with controllable hyperbranched molecular structure and abundant amino end groups for Li-S battery is designed and fabricated,which can improve efficient adsorption for LiPS and stability of the sulfur cathodes.Besides,the strong intermolecular hydrogen bonds in HPAA binder can contribute to the structural stability of S cathode and integration of the conductive paths.Therefore,the Li-S battery with this functional binder exhibits excellent cycle performance with a capacity retention of 91％ after 200 cycles at 0.1 C.Even at a high sulfur loading of 53 mg cm-2,a specific capacity of 601 mA h g-1 can also be achieved.Density functional theory (DFT) calculation further demonstrates that the enhanced electrochemical stability derives from the high binding energy between amino groups and LiPS and the wide electrochemical window (6.87 eV) of HPAA molecule.Based on the above all,this functional polymer will lighten a new species of binders for eco-friendly sulfur cathodes and significantly promote the practical applications of high-performance Li-S batteries.