Poly(3,4-ethylenedioxythiophene)-coated sulfur for flexible and binder-free cathodes of lithium-sulfur batteries

Flexible energy storage devices are becoming increasingly important for next-generation flexible electronic devices. However, the low energy density of conventional lithium-ion batteries cannot fulfill their high capacity requirement. Therefore, lithium-sulfur (Li-S) batteries with high theoretical capacity and energy density have attracted attention as new-generation energy storage devices. In this work, we designed a freestanding poly(3,4-ethylenedioxythiophene) (PEDOT)-coated diamond-shaped sulfur (D-sulfur)/single-walled carbon nanotube (SWCNT) composite cathode. The conductive PEDOT and SWCNTs effectively confined the dissolution of lithium polysulfides, and a flexible network was successfully fabricated. The D-sulfur/SWCNT composite cathode exhibited a high capacity and stable cycling performance. The initial discharge capacity reached 1520 mA h g^-1 at 0.1C, and the capacity retention was 76% after 250 cycles at 0.5C. Furthermore, the D-sulfur/SWCNT was used as a flexible cathode to fabricate a prototype of a flexible Li-S battery, which shows its potential application in flexible integrated systems.