Etch-evaporation enabled defect engineering to prepare high-loading Mn single atom catalyst for Li-S battery applications

Abstract

Excellent specific discharge capacity and cycling stability are essential for high-performance lithium-sulfur (Li-S) batteries, but hard to achieve simultaneously due to the shuttle effect and sluggish reaction kinetics of polysulfides. Herein, we report an etch-evaporation enabled defect engineering strategy to fabricate atomically dispersed, manganese-nitrogen doped porous carbon (Mn-N-C) for separator modification. With Zinc atoms evaporation and NH3 etch, abundant spatial confinement sites and N dopants are created in Mn-N-C, and the final Mn loading can reach as high as 2.31 wt%. Density function theory (DFT) calculations reveal that Mn atoms in Mn-N-C play a crucial role in polysulfides adsorption and electrical conductivity enhancement. Therefore, the Mn-N-C modified separator can exhibit high conductivity, strong immobilization and excellent catalytic activity, thus favoring polysulfides conversion and Li2S nucleation/dissolution. The Li-S battery equipped with the modified separator exhibits an initial discharge capacity of 1596 mAh g−1 at 0.1C (S loading mass was 1.2 mg cm−2), which decays 0.045 % per cycle after 1000 cycles at 1C. Our work demonstrates that the etch-evaporation enabled defect engineering strategy is effective for fabrication of high-performance Li-S battery catalyst; it also shows an attractive prospect to synthesize other high loading metal ion dispersed, nitrogen doped carbon materials for electrochemical applications.