Sulfurized Polyacrylonitrile Cathodes for Advanced Lithium–Sulfur Batteries

The emerging lithium–sulfur (Li–S) batteries are attracting significant interest in both academic and industrial fields owing to their top-ranked capacity and energy density. The sulfur cathode dominates the energy contribution to such a promising energy storage device; nevertheless, it suffers the severe polysulfide shuttling effect resulting from the unavoidable dissolution of polysulfides in the ether-based electrolyte. The low electric conductivity of both sulfur and its reduction products Li2S further degrades the utilization of active mass, leading to the unsatisfactory specific capacity and retarded redox reaction kinetics. In such circumstances, an organosulfur cathode with short-chain sulfur species bonded in a polymeric matrix is reported to have an efficient sulfur conversion with stabilized cycle performance, among which sulfurized polyacrylonitrile (SPAN) is a promising organosulfur cathode with extremely high specific capacity and long-term lifespan. To improve the sulfur conversion, numerous porous carbon materials, polar metal compound additives such as metal sulfides, oxides, and phosphides, as well as heteroatom doping were intensively applied for promoting SPAN-based cells with outstanding electrochemical performance. In this chapter, the chemical structure and redox reaction mechanisms of SPAN are discussed, followed by a general review of the strategies applied in this field in terms of SPAN cathode, expecting to render the readers an overview of the development and prospects of such promising material.