Water-Soluble Trifunctional Binder for Sulfur Cathodes for Lithium–Sulfur Battery
Yajun Yang, Juncheng Qiu, Lei Cai, Canbin Liu, Shuxing Wu, Xiujuan Wei, Dong Luo, Bingkai Zhang, Xulai Yang, Kwun Nam Hui, Jing Liu, Zhan Lin
Abstract
Conventional polymer binder in a lithium–sulfur (Li–S) battery, poly(vinylidene fluoride) (PVDF), suffers from insufficient ion conductivity, poor polysulfide-trapping ability, weak mechanical property, and requirement of organic solvents, which significantly encumber the industrial application of Li–S battery. Herein, a water-soluble binder with trifunctions, covalently cross-linked quaternary ammonium cationic starch (c-QACS), is developed to confront these issues. Similar to the poly(ethylene oxide) solid electrolytes, the c-QACS binder remarkably improves Li+ ion transfer capacity. The abundant O actives endow the c-QACS binder with admirable lithium polysulfide-trapping capability to retard the shuttle effect. In addition, the formed 3D network effectively maintains the electrode integrity during cycling. Benefiting from the above merits, the sulfur cathode with the c-QACS binder demonstrates a performance improvement of 300 and 150% compared with sulfur cathode with PVDF and bulk QACS binder after 100 cycles at 0.2C.