Sulfur Cathodes with Self-Organized Cellulose Nanofibers in Stable Ah-Level, >300 Wh kg-1 Lithium-Sulfur Cells

The realization of lithium-sulfur (Li-S) batteries as an energy storage technology depends on unlocking practical performance at commercially relevant pouch cell scales. Typically, the heterogeneous and porous nature of large scale, high sulfur loading Li-S batteries require increased electrolyte levels and impede electronic conductivity. Improved cathode structures offer a pathway to strong performance at large battery scales. Here, the successful development of a new cathode using highly-carboxylated and negatively surface charged cellulose nanofibers as a backbone that addresses these issues and delivers an ordered, dense architecture whilst maintaining long term cycle life, is reported. Taken together this leads to an Ah-level pouch cell with a peak capacity above 1200 mAh g(-1) and an areal capacity of around 15 mAh cm(-2), which achieves a high gravimetric energy density of up to 330 Wh kg(-1) and volumetric energy density of 480 Wh L-1. The cell is used to power a drone for 10 min, demonstrating the ability of this discovery to be translated at practical scales.