Noncollapsible, Meringue‐Structured Cathodes for a Volumetrically Efficient Li–S Battery

Lithium–sulfur (Li–S) batteries promise exceptional gravimetric energy densities but are hindered by their poor volumetric performance. This is further exacerbated when taking into account the considerable volume expansion of sulfur during cycling. Intrinsically ion‐diffusion‐limited sulfur cathodes make electrode densification and therefore volumetric energy density a critical challenge. In this work, we introduce a protein‐foamed binder (PFB) that, upon drying, templates cylindrical pores within the cathode. Strategically engineered with high density physical cross‐links, PFB forms a mechanically robust and adhesive binder matrix capable of withstanding significant electrode densification (from 0.51 to 1.62 g cm −3 ), while fully preserving its templated structure. These noncollapsible pores form a network of ion transport channels, enabling excellent sulfur utilization and rate capability despite its high density, delivering 1,361 mAh g −1 at 0.05C and 625 mAh g −1 at 4C. This translates to a volumetric capacity of 1,550 mAh cm −3 and volumetric energy density ( E V ) of 3,285 Wh L −1 , rivaling state‐of‐the‐art Li–S batteries and surpassing lithium‐ion battery benchmarks even when considering sulfur volume changes. Moreover, we demonstrate high areal loadings of up to 16 mg cm −2 , delivering 16.6 mAh cm −2 . This work introduces an electrode design philosophy which reconciles high cathode density with efficient ion transport for volumetrically efficient Li–S batteries.