Superstretchable, thermostable and ultrahigh-loading lithium–sulfur batteries based on nanostructural gel cathodes and gel electrolytes

Lithium–sulfur batteries are desirable for portable and wearable electronic devices because of their high energy density, low cost and environmental friendliness. Herein, the fabrication of superstretchable Li−S batteries based on highly elastic gel cathodes (fracture strain: 1671%), gel electrolytes (fracture strain: 1223%), zigzag Cu wire-interconnected Li anode pieces and soft packages, is demonstrated. A phase inversion approach is developed to prepare gel cathodes composed of a homogeneously distributed 3D porous fluorinated copolymer skeleton, interlaced electron-conductive networks and sulfur-encapsulated hierarchical polar nanocomposites. The highly elastic gel cathodes possess tri-continuous structures with interpenetrated macropores favourable for high sulfur loading, electrolyte permeation and ion transport. The gel electrolytes with an amorphous phase copolymer matrix and tethered anions exhibit high ionic conductivity, thermal stability, flexibility and effective suppression of Li dendrite growth. The soft-packed Li‒S batteries can be stretched up to 420% of their original length, function normally at 80 °C and deliver an ultrahigh areal capacity of 11.0 mAh cm−2 at a sulfur loading of 14 mg cm−2.