Heterogeneous interface of Ni-Mn composite Prussian blue analog-coated structure modulates the adsorption and conversion of polysulfides in lithium-sulfur batteries

Capacity reduction mainly caused by the shuttle effect and low conductivity restricts the commercial application of lithium-sulfur batteries (LSBs). In this work, a nickel-compound manganese Prussian blue analog-coated polypyrrole composite sulfur electrode material (3-MnNi-PBA@S@PPy) was synthesized. The composite 3-MnNi-PBA@S@PPy has strong chemisorptions to polysulfides (LiPSs) and excellent catalytic activity, which can anchor LiPSs and accelerate their conversion. The surface 3-MnNi-PBA in the 3-MnNi-PBA@S@PPy structure spontaneously reacts with polysulfides to form heterogeneous intermediate phase thiosulfate salts, which can accelerate the conversion of polysulfides. On the basis of the above advantages, 3-MnNi-PBA@S@PPy com-posites were used as cathodes for LSBs. A high initial capacity of 1285 mAh/g and excellent cycling stability were harvested at a current density of 0.1 C, and the decay rate was only 0.07% per cycle at a high current density of 0.5 C and 500 cycles. The MnNi-PBA material possesses a unique heterogeneous interface catalytic mechanism and effectively suppresses the shuttle effect of LSBs, which has a huge potential application prospect.