The ternary conductive polymer coated S/BDPC composite cathode for enhancing the electrochemical prospects in Li-S batteries

Lithium-sulfur (Li-S) battery processes high theoretical capacity (1675 mA h g(-1)) and energy density (2600 Wh kg(-1)), which was widely accepted as one of the most promising candidates for energy storage devices. In this presented study, bamboo-derived hierarchical porous carbon (BDPC) was adopted as a conducting substrate for containing S. Soft polystyrene (PS) and polyaniline (PANI), were prepared as coating layers. The main purpose is to figure out the specific roles that the polymer shells and the heteroatoms doped on polymer backbone play during cycles. The ternary products were characterized by structural analysis and electrochemical testing. The results indicate that, as compared to BDPC/S, the PS@BDPC/S electrode displays higher capacity retention during long-term cycles, especially at the high current rate. It is attributed to the integrated coating shell, which provides physical confinement and reserves spaces for restraining volume expansion. It is noted that the PANI@BDPC/S electrode presents a higher initial capacity, remarkable long-life performance, and excellent rate property. The outstanding performances are closely related to the nitrogen atom doped on PANI backbone, they provide not just abundant polar conducting sites for fast electron/Li-ion transport but strong chemical anchoring for restricting the migration of polysulfides. Therefore, our study poses a clearer understanding of the functionalized polymers used in Li-S battery.