Highly Elastic and Polar Block Polymer Binder Enabling Accommodation of Volume Change and Confinement of Polysulfide for High-Performance Lithium–Sulfur Batteries
Dongli Chen, Mingming Song, Ming Zhu, Tao Zhu, Peibin Kang, Xiaoping Yang, Gang Sui
Abstract
Lithium polysulfide (LiPS) shuttling and sulfur volume change causing degradation of electrodes have hindered the practical application of lithium–sulfur batteries. Here, a highly elastic and polar block polymer binder, poly(acrylic acid)-b-((poly(n-butyl acrylate)-co-poly(2,2,3,4,4,4-hexafluorobutyl acrylate))-b-poly(acrylic acid) (PAA-b-(PnBA-co-PHFBA)-b-PAA), was designed and synthesized to both accommodate sulfur volume change and confine LiPSs. The rigid–soft modulated triblock polymer combined the traditional polar binder PAA, low glass-temperature PnBA, and high-polarity PHFBA. The resultant binder can not only adjust the striking volume expansion and inhibit disintegration of a pure sulfur cathode but also strongly anchor LiPSs. The cycle stability and rate performance of lithium–sulfur batteries were significantly improved after being incorporated with the multifunctional binder. Besides, abundant F atoms can enhance ionic conductivity to improve electrochemical reaction of the sulfur cathode. This work offers a feasible and effective strategy for designing an efficient multifunctional binder toward building next-generation high energy density lithium–sulfur batteries.