Interfacial synergy of nanoengineered PANI/MnO2 for strong anchoring and fast conversion of polysulfides in Li-S batteries

Abstract

The shuttle of polysulfides and slow sulfur redox kinetics are the two main issues in the practical application of lithium sulfur (Li-S) batteries. The interface-induced electric fields produced in MnO2-based conductive composites are proposed to solve the above obstacles. Herein, a novel hybrid structure of birnessite-MnO2 nanosheets in situ formed inside polyaniline nanotubes (NSs-MnO2@PANI) is prepared and applied as a catalytic host in Li-S batteries. The DFT calculation combined with experiments reveal the interface-induced electric field with a direction pointing from PANI to birnessite-MnO2 is created, which would induce interface charge redistribution and result in electron-rich MnO2 region and electron-deficient PANI region, optimizing the strong anchoring of polysulfides and their fast catalytic conversions. Owing to the interfacial synergy, the NSs-MnO2@PANI/S cathode delivers higher capacity than PANI/S at rates from 0.1 C (1473.7 vs. 467.5 mAh g−1) to 5 C (513.2 vs. 38.1 mAh g−1), with a low decay rate of 0.054% during 500 cycles at 0.2 C. Further, at an extremely high sulfur loading of 15.9 mg cm−2, the areal capacity achieves a high level of 10.2 mAh cm−2 at 0.05 C, with stable cycling at 1 C. Our work provides new insights for attaining high-energy and stable Li-S batteries.