Engineering checkerboard-like heterostructured sulfur electrocatalyst towards high-performance lithium sulfur batteries

Lithium-sulfur (Li-S) batteries are showing a huge potentiality in the energy storage market owing to its high theoretical energy density and cost-effectiveness. However, there are still some thorny issues needed to be tackled before realizing their practical applications, including underperformed rate capability and unsatisfactory cycling stability. Herein, we have constructed the checkerboard-like heterostructured CoS₂/Co nanoparticle inside porous carbon by the electrochemically-sulfonated reaction of lithium polysulfides (LiPS) and used them as sulfur electrocatalyst. Benefiting from this structure advantage, the catalyst can not only promote the chemical adsorption of LiPS, but also acts as promoter to provide coupled electrons to accelerate its redox reaction. Through synergistic enhancement, the checkerboard-like CoS₂/Co heterostructure provides a boosted chemical adsorption and accelerated catalytic conversion of LiPS, rendering suppressed shuttle effect and enhanced Li-S kinetics. In addition, the porous carbon carriers offer abundant nanoscale pores to effectively immobilize sulfur and accommodate its volume expansion. Therefore, the CoS₂/Co sulfur composites exhibit decent rate capability up to 5C and long-term cycling performance over 500 cycles at 1C with a capacity fading rate below 0.059% per cycle. Moreover, an admirable cyclic stability can also be achieved under raised sulfur loading of 7.13 mg∙cm⁻² and low E/S ratio of 4.5 mL∙g⁻¹.