So ok, now we see that we can indeed influence the level of internal resistance in an electrolysis cell, just as we can in a primary or secondary cell battery. The next step seemed to be to identify all of the sources of resistance within such a cell and to devise ways to modify each so that their effect on the operation of the cell could be minimized or increased as the requirements of a particular setup demanded.
Once I reached this point in the research I felt like I had arrived. My experiments were bearing out my initial theories. Unfortunately that feeling didn't last for long. I felt that I had made quite a bit of progress along the road to a better understanding of the electrolysis process, but it wasn't enough. Too many questions still remained hanging, without answers, and that annoys me.
With the realization that just as many electrons must exit the
cell at the Anode as enter it at the Cathode (to maintain chemical equilibrium)
there came the understanding that the only real obstacle that remained
was to find a way to reduce or eliminate the voltage drop across the cell.
Ok , fine. I thought. So therefore, by identifying ALL of the sources of
such resistance within the cell and then eliminating them, or modifying
them in order to reduce their negative impact, it should be possible to
drastically improve the efficiency of the system. Once that was done you
could pass a charge through a very long series of cells with little waste
of energy and thereby exponentially increase the amount of energy delivered
back to you as H2 gas.I know I mentioned this a few paragraphs ago but
it's importance cannot be stressed enough. Understanding all of the sources
of resistance within the cell and being able to modify them is the key
to the whole process of producing H2 from water more effeciently.
In the first part of this paper I looked at electrode size and the
number of ions available in the solution. These are two of the biggest
contributors to cell resistance and, as I have demonstrated, both of these
sources can be manipulated through a very wide set of paramaters.
Not yet satisfied I started to experiment with some new ideas. One thing that differentiates between electrolysis cells and wet cell batteries is that batteries use the potential difference created between two electrodes of different metals to provide the "push" needed to get a current flowing between them. Electrolysis cells, on the other hand, use electrodes of the same, chemically inert, metal and consequently no potential difference is thought to be developed between them.
Much of what determines the "potential" of a given type of metal is the number of free electrons which are thought to exist within the metal. Those metals which have more free electrons have more potential to give some off or to more easily move a charge through them and so are good conductors. Metals with fewer free electrons, conversely, have a lower tendency to give any off, better ability to accept more of them and are worse conductors. So with two identical pieces of metal one wouldn't tend to expect any difference in potential between them.
Is that "written in stone" though, I wondered? It would be SO useful to be able to create some type of potential difference (voltage) in the electrolysis cell itself, to further offset the losses created by the various sources of internal resistance. It would do this by adding to the voltage supplied by your power source much as each battery in a series adds it's owm voltage to that of the others which precede it in the series.
Footnotes: There are several other factors which contribute to or otherwise influence the internal resistance of a cell which I am not going to address here. Such as; distance between the electrodes, mixed electrolytes which don't share a common ion, temperature of the solution, polarization of the electrodes,etc.