Regulating the Architecture of a Solid Electrolyte Interface on a Li-Metal Anode of a Li–O₂ Battery by a Dithiobiuret Additive

Different from other typical architectures of lithium-ion cells (e.g., NCM//graphite, etc.), Li-metal is indispensable to the construction of Li–O2 batteries (LOBs), since Li-metal can be consumed as a lithium source for the initial discharge process on the cathode side. However, the unstable solid electrolyte interface (SEI) film and related hazardous dendrite growth plague the stability and further development of the Li-metal anode, which would be exacerbated by an O2 atmosphere in LOBs. Herein, the dithiobiuret (DTB, C2H5N3S2) additive was introduced into a typical ether electrolyte to regulate the Li+ solvated sheath configuration, and the solvation sheath was tailored and evolved to a solvent-depleted state. Consequently, an anion-derived SEI film architecture with F-rich and O-deficient components was formed. Systematically, studies of spectroscopy and electrochemical analysis demonstrated that such specific SEI architecture can trigger grain refinement and promote dendrite-free morphology. Benefiting from the addition of DTB and under an O2 atmosphere, the electrochemical performance of both Li/Li symmetrical cells and Li–O2 cells has been significantly enhanced.