A novel binder-sulfonated polystyrene for the sulfur cathode of Li-S batteries

In order to suppress the capacity fading of lithium-sulfur batteries, sulfonated polystyrene (SPS) which was prepared via homogeneous reaction has been applied as a functional binder for the sulfur cathode of lithium sulfur batteries in this study. The SPS and its application for lithium sulfur batteries were characterized by Fourier transformation infrared spectroscopy (FT-IR), thermogravimetry (TG), X-ray diffraction (XRD), scanning electron microscopy (SEM), and charge-discharge test. The traditional binder poly vinylidene fluoride (PVDF) was used for comparison. Results show that for the sulfur cathode with PVDF as binder, the capacity retention after 100 cycles at 200 mA g(-1) is 46.9% and sever voltage fading performance from 10th to 100th cycle can be observed. While for SPS binder, the capacity retention after 100 cycles is 74.4% and there is almost no change of the first plateau at around 2.3 V in the discharge curve from 10th to 100th cycle, indicating obvious electrochemical performance improvement of lithium sulfur battery.