Construction of tubular polypyrrole-wrapped biomass-derived carbon nanospheres as cathode materials for lithium-sulfur batteries

A promising hybrid material composed of tubular polypyrrole (T-PPy)-wrapped monodisperse biomass-derived carbon nanospheres (BCSs) was first synthesized successfully via a simple hydrothermal approach by using watermelon juice as the carbon source, and further used as an anchoring object for sulfur (S) of lithium-sulfur (Li-S) batteries. The use of BCSs with hydrophilic nature as a framework could provide large interface areas between the active materials and electrolyte, and improve the dispersion of T-PPy, which could help in the active material utilization. As a result, BCS@T-PPy/S as a cathode material exhibited a high capacity of 1143.6 mA h g^-1 and delivered a stable capacity up to 685.8 mA h g^-1 after 500 cycles at 0.5 C, demonstrating its promising application for rechargeable Li-S batteries.