Effect of relative humidity on the reaction kinetics in rubidium silver iodide based all-solid-state battery
By Akin, Mert; Wang, Yuchen; Qiao, Xiaoyao; Yan, Zhiwei; Zhou, Xiangyang
Published in Electrochimica Acta
Electrochimica Acta
2020
Abstract
Our previous study on a rechargeable rubidium silver iodide (RbAg4I5) based all-solid-state battery showed an exponential increase of the performance with increasing relative humidity (RH). Here, we investigated the effect of humidity on the electrochemical reaction kinetics at the Ag/RbAg4I5 anode and graphite/RbAg4I5 cathode using three-electrode cells. Four-electrode electrochemical impedance (EIS) measurements were conducted to evaluate the ionic conductivity of the solid electrolyte. The results unveiled that the ionic conductivity varied 4% between 35% and 100% RH in consistence with the variation of series cell resistances of the half cells. On the other hand, linear sweep voltammetry measurements of the anode and cathode half cells showed that increasing the RH from 35% to 100% increased the exchange current density by three orders of magnitude. The relationship between the water vapor adsorption and reaction kinetics was established by introducing water vapor adsorption isotherms. A proportionality was observed between the exchange current density and the number of water layers adsorbed at the electrolyte/electrode interface and a model was proposed to explain the impact of water adsorption on the electrochemical kinetics. These results suggest that the all-solid-state battery operates effectively when exposed to a high humidity environment and can be used for the applications requiring high reliability.