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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.

The role of amphiphilicity in polysaccharide-based superabsorbent polymers is paramount in determining material properties. While the performance of freeze-dried polymers is improved by maximizing hydrophilicity, this may not be the case for evaporative-dried polymers. In this study, four diglycidyl ether crosslinkers, with varying chain lengths and amphiphilicities, were used to synthesize a series of evaporative-dried carboxymethyl cellulose-based superabsorbent films. Through structural and physiochemical characterization, the effect of amphiphilicity on swelling and mechanical properties was established. Contrary to freeze-dried polymers, it was found that the addition of hydrophobic moieties by crosslinking with novel poly(propylene glycol) diglycidyl ether crosslinkers increased the swelling performance of evaporative-dried polymers. By adding hydrophobic functional groups, a reduction in inter-chain hydrogen bonding occurs during evaporative-drying, reducing the degree of hornification and decreasing the entropy requirement for water uptake. By optimizing the amphiphilic ratio, a poly(propylene glycol)-carboxymethyl cellulose polymer achieved a swelling capacity of 182 g/g which is competitive with freeze-dried cellulose-based hydrogels. The mechanical properties of these films improved with the addition of the crosslinkers, with glycerol-carboxymethyl cellulose polymers achieving a tensile strength of 39 MPa and a Young’s Modulus of 4.0 GPa, indicating their potential application as low-cost, swellable films.