Phosphorization-Introduced Defect-Rich Phosphorus-Doped Co3O4 with Propelling Adsorption–Catalysis Transformation of Polysulfide

Abstract

Cathodic polysulfide electrocatalysts are introduced to confidently accelerate the polysulfide conversion to propel the increased practical density of lithium–sulfur (Li–S) batteries. Defect engineering as an advanced functional strategy has been confirmed to have the competent capability of optimizing the electrocatalytic kinetics. In this work, the conventional phosphorization process is used to process Co₃O₄ anchored on nitrogen-doped carbon nanotubes. Unexpectedly, there is no phase change, only phosphorus doping with rich lattice dislocation on Co₃O₄. With the combined characterization of X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy, it is found that phosphorus doping transfers part of the oxygen vacancies to the lattice oxygen of Co₃O₄, which can induce the catalytic active species Co–O–P. The concomitant lattice dislocations can strengthen the chemical adsorption of phosphorus-doped Co₃O₄ for polysulfides and even elevate more catalytically active sites. With the use of defect-rich phosphorus-doped Co₃O₄ embedded in a nitrogen-doped carbon nanotube (P-Co₃O₄/NCNT) as an electrocatalyst, Li–S batteries showcase enhanced oxidation and reduction kinetics and an improved rate performance. This work provides new insight into the rational design of the electrocatalyst of heteroatom-doped metal compounds for high-performance Li–S batteries.