Single-atom tailoring of Li₂S to Form Li₂S₂ for building better lithium-sulfur batteries

The Li₂S-based cathodes to couple with Li-free anodes are regarded as a commercially available approach to overcome the safety risk of lithium metal anodes. However, the passivated Li₂S instinct leads to a high activation potential in the initial charging process, and the notorious shuttle effect of polysulfide is inevitable upon cell cycling. Here we create a single atom tailoring strategy by comproportionation reactions (Li₂S + 1/8S₈ = Li₂S₂) to form the Li₂S₂ materials without any complex manufacturing process or additives, where the Li₂S₂ cell enables a lower potential barrier and allows for the 3.0 V activation voltage without any other material modification. Meanwhile, the polar conducting material TaB₂ is introduced to restrain the migration of polysulfides, and provide fast redox reaction kinetics. With those ingenious tailoring of cell designs, the Li₂S₂-TaB₂ cell (Li₂S₂: 88 wt%) exhibits high areal capacity (4.6 mAh/cm² at 6.0 mg/cm² Li₂S₂ loading), excellent cycling stability (500 cycles at 1.6 mA/cm²).