Electrochemical and spectroscopic investigations of the K2SO4-V2O5 molten electrolyte

A 60 mol % K(2)SO(4)J/40 mol % V2O5 molten salt mixture was tested for elec trochemical activity to determine its propensity for sulfate transport. Res ults of cyclic voltammetry showed a high electrochemical activity due likel y to the reduction and oxidation of bulk, as opposed to minor, species. Mos t reductions and oxidations did not conform to diffusion-limited theory, an d indicated the presence of shipping reactions. By Raman spectroscopy V(V) polymers were identified in the melt consisting predominantly of VO2(SO4)(3 )(2-) and VO3- units, while VO2SO4- units were also detected. By reduction of the eutectic mixture with SO2 a V(IV) and a V(III) compound, most probab ly K-4(VO)(3)(SO4)(5) and K3V(SO4)(3) were isolated, as evidenced from infr ared and electron spin resonance spectroscopy. These compounds might be inv olved in the electrochemically observed plating and stripping reactions. (C ) 1999 The Electrochemical Society. S0013-4651(98)01-004-0. All rights rese rved.