Enhancing structural integrity and cycle life of sulfur electrodes for Li-S batteries through an eco-friendly water-soluble binder

Abstract

The utilization of lithium-sulfur (Li-S) batteries is limited by their high volume expansion, low ionic conductivity, and the dissolution of lithium polysulfides in the sulfur electrode when conventional binders are used. This study introduces a cross-linked multifunctional binder designed to ensure strong contact with polysulfides and excellent mechanical properties through a polymerization process between polyvinyl alcohol (PVA) and succinimide (SUM). The abundant polar groups in PVA/SUM interact with polysulfides, reducing their mobility. The amide groups facilitate rapid ion transfer by interacting with Li-ions. Consequently, the sulfur electrode with the cross-linked PVA/SUM binder (PVA-10 wt% SUM) exhibits outstanding rate performance and impressive capacity retention of 616 mAh/g after 200 cycles at a 1.0C-rate, even with a sulfur loading over 4 mg/cm2. This work provides a cost-effective and efficient solution for water-soluble cross-linked binders in high-performance Li-S batteries, addressing the problem of polysulfide dissolution effectively.