Effect of vapor pressure on performance of sulfurized polyacrylonitrile cathodes for Li/S batteries

Abstract

Sulfurized polyacrylonitrile (S@pPAN) composites have been synthesized in a high pressure reactor under certain vapor pressure. According to elemental analysis, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS), the hydrogen content and the degree of graphitization in S@pPAN composites decreases with increasing synthesis vapor pressure, indicating that a suitably high vapor pressure is helpful in promoting the reaction between polyacrylonitrile and elemental sulfur and finally making the conductive molecular structure of sulfurized polyacrylonitrile more complete. The results show that the sulfurized polyacrylonitrile composite prepared under 5 MPa vapor pressure (S@pPAN-5) delivers a high initial discharge specific capacity of 1821 mA h g⁻¹ and the capacity remains at 1357 mA h g⁻¹ (616.8 mA h g_composite⁻¹) after 100 cycles with a retention rate of 88% calculated from the 2^nd discharge capacity.