Mn3O4 anchored polypyrrole nanotubes as an efficient sulfur host for high performance lithium-sulfur batteries

Abstract

Lithium-sulfur batteries have attracted numerous attentions owing to their high theory discharge specific capacity and energy density. However, sulfur cathode usually suffers from poor cycle stability and slow reaction kinetics, caused by its poor conductivity, excessive volume changes during charge/discharge processes, complex sulfur species conversion reaction and the dissolution of polysulfide intermediates. Here, we present a free-standing framework of Mn₃O₄ nanoparticles combine with polypyrrole (PPy) nanotubes as host materials for lithium-sulfur batteries to overcome these issues. In this construction, PPy nanotubes serve as the excellent container of sulfur and physical barrier for the excessive volume expansion of sulfur during electrochemical reaction processes, and the nanotubes also provide an efficient conductive network for the rapid transmission of electrons and ions, while Mn₃O₄ nanoparticles facilitate trapping lithium polysulfides. The coordination of PPy nanotubes and Mn₃O₄ effectively alleviate the shuttle effect as well as enhance the utilization of sulfur. The obtained PPy@Mn₃O₄-S sample shows high capacities of 1419.9 and 925.5 mAh g^-1 at 0.1 C and 1 C rate, respectively, and exhibits a low capacity fading rate of 0.062% per cycle for 800 cycles at 1 C rate. This work provides a new and effective way for the design of lithium-sulfur batteries with both high rate performance and long cycle stability.

Keywords: Cathode materials; Lithium-sulfur batteries; Long cycle stability; Mn(3)O(4); Polypyrrole.