Origin of shuttle-free sulfurized polyacrylonitrile in lithium-sulfur batteries

Sulfurized polyacrylonitrile (S-cPAN) shows an intrinsic shuttle-free capability during cycling with high reversible capacity, making it a promising material for lithium-sulfur (Li–S) battery. However, the lithiation/delithiation mechanism of S-cPAN is still debatable and unclear. In this work, the fundamental reaction mechanism of S-cPAN cathode material is unveiled by in-situ Raman and in-situ X-ray absorption (XAS) spectroscopies. Together with density functional theory calculation, the formation of -N-Sx-N- (x