Recent progress in organic Polymers-Composited sulfur materials as cathodes for Lithium-Sulfur battery

With a theoretical specific capacity of 1675 mAh g−1 and an energy density of 2600 W h g−1, environmentally friendly lithium-sulfur batteries (LSBs) have been considered to be one of the most promising candidates for the next generation of high energy density storage devices, which are expected to meet the requirements of transportation vehicles and power grid energy storage. However, LSBs still have several technical challenges hindering their practical applications. One of the challenges is the dissolution of the cathode sulfur and polysulfides caused shuttle effect which can significantly reduce their cycle-life. To mitigate the challenges, conductive organic polymers have been explored for holders to encapsulate sulfur and inhibit the dissolution of polysulfides into the electrolyte, as well as increase both the electric and ionic conductivities of the corresponding cathodes. This paper reviews the recent progress in conductive organic polymers-composited sulfur materials as cathodes for LSBs in terms of their synthesis, characterization, functional mechanisms and performance validation/optimization. The reviewed polymers include polyacrylonitrile (PAN), polyaniline (PANI), polythiophene (PTh), polypyrrole (PPy), pypercrosslinked polymers (HCPs), etc. Several technical challenges of these organic polymers-based materials are analyzed with respect to their LSB performance, and several possible further research directions for overcoming the challenges are also proposed for further development toward practical applications.