Kinetic investigation of sulfurized polyacrylonitrile cathode material by electrochemical impedance spectroscopy

► The impact of initial lithiation depth on the performance of sulfur composite materials is crucial. ► This research reveals more characteristics of the sulfur composite, which helps to understand more about the sulfur composite prepared by sulfurized polyacrylonitrile at 300 °C. ► The sulfur composite material needs full lithiation at the initial cycle for activation to release its electrochemical property.