My goal is to increase the efficiency of a nickel-iron battery. One of the options to reach this goal is:suppressing the hydrogen production. Due to electrolysis, the electrolyt will start discomposing at a certain potential (when charging, about 1.6 Volt). I expect that the electrochemical stability/window of the solution increases when the water activity decreases.

Recently, i read an article about molecular crowding electrolytes, a proces in which the water activity is lowered due to the presence of other molecules. I would like to know if it is possible to decrease the water activity, due to molecular crowding, by increasing the concentration of KOH in the elektrolyt.


I have some doubts about the outcome.

Optimal setting for all major commercial cells is well optimized during the years of development. Without bringing a new technology in chemistry or materials of cells, the improvement is not much probable.

Increasing of hydroxide concentration would decrease water activity. But it may have also adverse effects, like partial dehydration and deactivation of active electrode components (hydroxides/hydrated oxides), leading to worse cell performance and lifetime, or it may affect conductivity. Highly concentrated solutions are quite viscous and affecting the proper procedure of the cell assemmly.


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