Designing hierarchical MnO/polypyrrole heterostructures to couple polysulfides adsorption and electrocatalysis in lithium-sulfur batteries

Efficiency of entrapping and conversion toward lithium polysulfides (LiPSs) plays a key role in promoting the utilization of sulfur and regulating LiPSs redox in lithium-sulfur (Li-S) batteries. However, a well-designed electrocatalyst with abundant active centers to facilitate conversion of LiPSs and prolong the lifespan of Li-S batteries is still required. Herein, a novel heterostructure of polypyrrole (PPy) nanotubes composite with hierarchical MnO (MnO/PPy-2) was designed as a host. N-containing functional groups and p-conjugated structures in PPy and polar MnO supply proper trapping ability toward LiPSs. More polar (=C-N+) and Mn-OH bonds are beneficial for electron transfer on conductive PPy substrate, which guarantee the uniform deposition of Li2S. Moreover, the hierarchical structure provides abundant surface and active sites for LiPSs entrapping and catalyzing, avoiding the electric contact loss. The synergetic merits of proper adsorption and conversion make MnO/PPy-2 composite a competitive host in the Li-S field. The cathode (S-MnO/PPy-2) exhibits a superior rate performance and cycling stability enabling 1000 cycles at 1 C with 0.032% capacity loss per cycle. This work paves a way to fabricate and utilize conductive polymer/metal oxides heterostructures as catalyst in Li-S batteries and provides a new sight to understand catalyst design in energy storage devices.

Automated summary

A novel heterostructure composed of polypyrrole nanotubes and hierarchical MnO was designed as a host for lithium-sulfur batteries, demonstrating enhanced efficiency in trapping and converting lithium polysulfides. The unique design provides abundant active sites for catalyzing LiPSs, resulting in superior rate performance and cycling stability in the cathode. This work sheds light on the potential of conductive polymer/metal oxides heterostructures as catalysts in energy storage devices.