Route to sustainable lithium-sulfur batteries with high practical capacity through a fluorine free polysulfide catholyte and self-standing Carbon Nanofiber membranes

We report on a new strategy to improve the capacity, reduce the manufacturing costs and increase the sustainability of Lithium-Sulfur (LiS) batteries. It is based on a semi-liquid cathode composed of a Li(2)S(8) polysulphide catholyte and a binder-free carbon nanofiber membrane with tailored morphology. The polysulphides in the catholyte have the dual role of active material and providing Li(+)-conduction, i.e. no traditional Li-salt is used in this cell. The cell is able to deliver an areal capacity as high as 7 mAh cm(−2), twice than that of commercial Lithium-ion batteries (LiBs) and 2–4 times higher than that of state-of-the-art LiS cells. In addition, the battery concept has an improved sustainability from a material point of view by being mainly based on sulfur and carbon and being completely fluorine-free, no fluorinated salt or binders are used, and has potential for upscaling and competitive price. The combination of these properties makes the semi-liquid LiS cell here reported a very promising new concept for practical large-scale energy storage applications.