Fabrication of polypyrrole coated cobalt manganate porous nanocubes by a facile template precipitation and annealing method for lithium–sulfur batteries

Abstract Lithium–sulfur (Li–S) batteries suffer from the poor conductivity originated from sulfur and shuttle effect arisen from the polysulfides dissolution. Herein, cobalt manganate (CoMn2O4) porous nanocubes coated with polypyrrole (PPy) as sulfur carrier are prepared using MnCO3 nanocube template through a precipitation method and a subsequent annealing process. The unique approach can obtain porous CoMn2O4 nanocubes with uniform morphology and abundant exposed active sites. The plentiful mesopores among the porous nanocubes are beneficial to accommodation of sulfur. In addition, the porous CoMn2O4 nanocubes can trap polysulfides in the cycling process owing to the chemical bonds between CoMn2O4 and polysulfides. Moreover, PPy coating severed as conductive layer not only enhances electrical conductivity of the cathode, but also confines polysulfides via the formation of N–Li–S bonds during cycling process. Therefore, the porous CoMn2O4/S@PPy nanocubes with 66.9% sulfur mass content delivered a capacity of 533 mAh g−1 over 500 cycles at 1 A g−1 with a capacity decay rate of 0.064% each cycle, and a Coulombic efficiency of 98%, suggesting the enhanced cycling performance of cathode. The facile template precipitation method combined with an annealing process contribute a new approach to synthesize unique porous CoMn2O4 structure as sulfur carrier for Li–S batteries