文摘
The mechanism of the sulfur cathode in Li–S batteries has been proposed. It was revealed by the real-time quantitative determination of polysulfide species and elemental sulfur by means of high-performance liquid chromatography in the course of the discharge and recharge of a Li–S battery. A three-step reduction mechanism including two chemical equilibrium reactions was proposed for the sulfur cathode discharge. The typical two-plateau discharge curve for the sulfur cathode can be explained. A two-step oxidation mechanism for Lib>2b>S and Lib>2b>Sb>2b> with a single chemical equilibrium among soluble polysulfide ions was proposed. The chemical equilibrium among Sb>5b>2–, Sb>6b>2–, Sb>7b>2–, and Sb>8b>2– throughout the entire oxidation process resulted for a single flat recharge curve in Li–S batteries.