Time-Resolved In Situ Spectroelectrochemical Study on Reduction of Sulfur in N,N[sup ʹ]-Dimethylformamide

Real-time in situ spectroelectrochemical studies have been carried out in -dimethyl formamide containing lithium trifluoromethane sulfonate as an electrolyte and the results are reported. The results indicate that the primary reduction product of the cyclic form of sulfur, undergoes an equilibrium reaction to its linear chain counterpart, which then dissociates into various products. These two dianions and were produced along with a minor product, at the potential corresponding to the first electron transfer. These products were further reduced or dissociated to species including and at the second electron-transfer step as evidenced by the spectral shifts observed during electrolysis. The reduction reactions are generally chemically reversible, making it possible to use sulfur reduction as a cathode reaction for Li/S batteries.