Engineering Spin State in Spinel Co₃O₄ nanosheets by V-Doping for Bidirectional Catalysis of Polysulfides in Lithium-Sulfur Batteries

The slow bidirectional conversion and fast shuttling of lithium polysulfides (LiPSs) remain the main obstacles that inhibit the practical application of lithium sulfur batteries (LSBs). Here, by engineering the in-spin state of spinel oxides, V doping-induced hexagonal nanosheets (V-Co3O4 NS) with intermediate spin state (IS, t(2g)(5) e(g)(1)) can form stable bond order toward LiS* based on the ligand field theory and molecular orbital theory, thus effectively accelerating the sulfur conversion kinetics. Owing to these merits, the V-Co3O4 NS modified separator base battery achieves a high areal capacity of 15.37 mAh cm(-2) with sulfur loading of 15.4 mg cm(-2), and it displays a low-capacity attenuation of 0.015% each cycle at 3.0 C for 1900 cycles.