2014 Volume 82 Issue 11 Pages 985-991
To well understand the mechanism of acid stratification in vented lead-acid batteries, the distributions of sulfuric acid in the vertical direction were measured by a refractive index meter. Also, the measurement of the electrochemical potential distributions in the vertical direction was tried using four dynamic hydrogen electrodes (DHEs). The acid stratification and its relaxation were confirmed by the measurement of sulfuric acid distributions during the charge/discharge and the rest state. There was a difference of four times in the time constant of the acid stratification relaxation between the upper part (top) and the lower part (bottom). This suggests that the acid diffusion is not a dominant reaction of the acid stratification relaxation. The local charge and discharge simultaneously must be occurred on the positive and negative electrode individually due to the electrochemical potential difference. In other words, the electrochemical potential difference probably is the dominant driving force of the acid stratification relaxation. The electrochemical potential distributions in the vertical direction were actually measured using the four DHEs.
