Construction of polypyrrole coated hollow cobalt manganate nanocages as an effective sulfur host for lithium-sulfur batteries

Abstract

The polysulfide shuttle phenomenon in the cycling process of lithium-sulfur (Li–S) batteries restricts their practical applications. Herein, polypyrrole (PPy) coated hollow cobalt manganate (CoMn2O4) dodecahedrons were prepared via template method, which combines the advantages of manganese-based metal oxide and conductive polymer effectively. The CoMn2O4 as bimetal oxides can trap the intermediate products and inhibit the dissolution of short chain polysulfides in the organic electrolyte. Moreover, the hollow dodecahedron structure provides enough space to alleviate volume change in the cycle process. Furthermore, the conductive PPy layer can enhance the conductivity of nanocomposite and suppress the shuttle effect in the electrolyte. The initial capacity of CoMn2O4/S@PPy cathode reaches up to 1407 mA h g-1 at 0.1 A g-1. The capacity retained ca.736 mA h g-1 at 0.1 A g-1 for 150 cycles and 659 mA h g-1 at 0.5 A g-1 when cycled 500 times, respectively, along with the Coulombic efficiency was over 99%. Owing to these outstanding electrochemical performances, the as-prepared nanocomposite is promising to be a superior sulfur host in the field of Li–S batteries.