In the quiet of a lab, a team has coaxed a protein-based foam into the heart of a lithium-sulfur cathode, watching it swell into a network of microscopic channels. Those tiny passages, like a delicate scaffold, guide ions while the surrounding foam cushions the material, allowing it to endure the crushing pressure of calendering without losing its structure. The result is a cathode that remains porous and conductive even after being pressed into thin sheets, a feat that brings the promise of ultra-slim energy packs a step closer. If this approach translates to commercial cells, the bulky housings that now dominate portable gadgets could give way to sleek designs, letting future devices tap the high energy density of sulfur without the weight and volume that have long held them back.