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.