Carbonaceous and Polymer Materials for Li–S Batteries with an Emphasis on Flexible Devices

Flexible energy storage devices have received tremendous attention with the rapid development of wearable electronics. Commercial lithium-ion batteries are gradually reaching their theoretical capacity, which is still unable to meet the requirements of flexible electronics for high energy density. Lithium–sulfur batteries with a high theoretical capacity of 1675 mA h g⁻¹ are regarded as the most promising next-generation high-energy-density power source. Herein, the various recent efforts in the development of lithium–sulfur batteries based on carbonaceous and polymer materials are summarized, with an emphasis on flexible systems. Flexible lithium–sulfur batteries based on carbonaceous materials such as carbon nanotubes, graphene, and carbonized polymer or biomass, polymers, and solid-state electrolytes are reviewed. Finally, the challenges and further improvements of lithium–sulfur batteries are summarized and prospected.