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The maximum current(based on how long you want your electrolyzer to last) is based on the electrode size according to my minimal research. The larger the electrode the more current is allowed. So why not make the electrodes as big as possible using the design in the illustration below (that I made in the camera app on my phone). Why don’t people do this?

Something I note is that comparatively to a dry cell since there are multiple electrodes you can share the voltage between many of them instead of sharing current. This concept can’t do that, but it doesn’t need to because it doesn’t need to share current either. Do what is the problem with this design? Why don’t people use it?

enter image description here

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The geometrical arrangement for galvanic cells and electrolytic cells is usually very different. The spiral arrangement is routinely used for the former, but not the latter.

For the electrolytic cells, there are preferred interleaved comb structures, with alternating plates A B A B.

This arrangement is easier to assemble and maintain. It is also easier to control the inter-electrode distance, preventing short circuits, and it is less blocking electrolyte motion.

In the case when products being formed on the cathode and anode are not to be mixed up, the electrodes are not even interleaved, but are kept in separate compartments.

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    $\begingroup$ I also suppose it has something to do with mechanical strength, where something like a spiral wound membrane element is fine. Since membranes are typically flexible, but electrodes are not as flexible and any mechanical failure will destroy the cell. $\endgroup$
    – Noah
    Commented Mar 1 at 10:00
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I found another reason it isn’t used, for anyone who may view this question in the future. Energy efficiency goes way down. Electrolysis only requires 2 volts to work. Anything more than that is really just an inefficiency. In a dry cell, it powers every nth plate and not power the ones in between, which causes the voltage to be shared between the plates. They do this because as the current goes up, so does the voltage based on resistance which means you have unnecessary voltage. However, in the spiral wound you can’t share the voltage which means you will be drawing unnecessary voltage and therefore unnecessary power for the electrolysis. The trade off is that you can go to much higher currents and have much more gas output.

Also a quick other reason is that is hard to compress the spiral wound uniformly to make sure there are no shorts, and it requires a lot of calculation to find the correct size for the container of the spiral wound for compression.

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