Yolk–shell structured sulfur composite cathode for high performance lithium–sulfur battery

Lithium–sulfur batteries (LSBs) suffer from the unavoidable ‘shuttle effects’ of lithium polysulfides (LPSs) and the infinite volume change of the sulfur. Herein, the authors prepared a yolk–shell structured N-doped carbon nanotubes/sulfur/poly(3,4-ethylenedioxythiophene) nanotube (N-CNTs/S@PEDOT) composite as a cathode for LSBs. The yolk–shell structure with void spaces can effectively buffer the volume expansion of sulfur, while the outer ‘shell’ can act as a physical barrier to minimise the ‘shuttle effects’ of LPSs. Moreover, the N-CNTs with high conductivity and superior structural stability are able to improve the electron transfer efficiency and cycling performance. Therefore, the specially designed yolk–shell structured N-CNTs/S@PEDOT composite cathode exhibits an extraordinary rate performance and enhanced cycling stability (602 mAh g⁻¹ after 200 cycles at 0.1 C).