A saccharide-based binder for efficient polysulfide regulations in Li-S batteries

Abstract

The viability of lithium-sulfur batteries as an energy storage technology depends on unlocking long-term cycle stability. Most instability stems from the release and transport of polysulfides from the cathode, which causes mossy growth on the lithium anode, leading to continuous consumption of electrolyte. Therefore, development of a durable cathode with minimal polysulfide escape is critical. Here, we present a saccharide-based binder system that has a capacity for the regulation of polysulfides due to its reducing properties. Furthermore, the binder promotes the formation of viscoelastic filaments during casting which endows the sulfur cathode with a desirable web-like microstructure. Taken together this leads to 97% sulfur utilisation with a cycle life of 1000 cycles (9 months) and capacity retention (around 700 mAh g⁻¹ after 1000 cycles). A pouch cell prototype with a specific energy of up to 206 Wh kg⁻¹ is produced, demonstrating the promising potential for practical applications.

The long-term cycling of Li-S batteries depends on the polysulfides shuttling regulation. Here, the authors present a saccharide-based binder system to control the polysulfides migration and improve the cycle life of a Li-S pouch cell.