Molybdenum disulfide/polyaniline interlayer for lithium polysulphide trapping in lithium-sulphur batteries

Lithium-sulphur battery technology promises much higher energy storage capacity compared to common Li-ion commercial batteries. Li–S batteries have high theoretical capacity of 1672 mAh g−1, thanks to conversion reaction from solid sulphur to lithium polysulfides (LiPSs). Unfortunately, few issues are still hindering their commercialization. The main problem afflicting lithium sulphur batteries is the shuttle phenomenon, due to soluble long chain LiPSs generated at the cathode. In the last years, many interlayer separators have been based on materials showing physical blocking of LiPSs. In particular, MoS2 and PANI separately showed strong adsorption capability, preventing polysulfides dissolution and accelerating the redox reaction kinetics. In the present work we rationally design, for the first time, composite materials based on PANI and MoS2, with the aim to evaluate the specific role of each component and their synergy as LiPSs blocking-agents, by implementation of a second layer containing the MoS2/PANI composite directly on the top of the standard S/C electrode. The systematic study confirms that double-layer containing the composite remarkably improves the performance of the sulphur cathode, showing specific capacity close to 600 mAh g−1, which is 42% higher than the standard sulphur cathode, after 500 cycles.