Kinetics of chemical decomposition of the solid electrolyte RbCu 4Cl 3I 2 by iodine

Abstract

In the solid electrolyte cell, copper–RbCu 4Cl 3I 2–I 2, glassy carbon, the EMF values at open circuit were measured as a function of time. Iodine was generated through anodic electrochemical decomposition of the electrolyte RbCu 4Cl 3I 2 and this iodine then further reacted with the fresh electrolyte. An equation was deduced which relates the EMF values to the iodine concentration at the glassy carbon surface. It was shown that slow diffusion of the iodine in the reaction product layer is a limiting step in the chemical interaction of iodine with RbCu 4Cl 3I 2. For the compressed RbCu 4Cl 3I 2 sample investigated, the iodine diffusion coefficient was calculated to be 6.2×10 −7 cm 2/s. Iodine loss from the glassy carbon surface was about 1.1×10 −4 g/cm 2 s. The thickness of the RbCu 4Cl 3I 2 sample was equal to 2 mm.