6.25.2020

How a Acid Base Flow Battery Actually works

A flow battery is simply a battery where the electrodes are liquids.  You still need current collectors but these can be the same metals instead of being different, also the benefit is these electrodes do not dissolve and you simple recharge the battery by replacing the liquid.

So how does an acid base battery work?  This isn't something I could figure out before.  With the proactive help of Johan Nygren (twitter) I think I have a pretty good model now.  He had me watch the video below about EZ water


What this video shows is that water will separate positive and negative ions because of a nearby charge (the hydrophilic surface in the case of the video).  A couple things can be predicted which is that you can create EZ water by charging the water with a negative and a positive electrode as well.  Energy can be extracted by this zone not only from setting up a battery using the EZ zone but also from using this  coupled with water evaporation .

Anyway here is my current model on how an acid-base battery works.


So notice the acid is on the right and base on the left.  The acid can be anything but preferably a strong acid.  Also Oxoacids or other oxidizers on the acid side might be best since the acid side seems to be receiving electrons, so it is being reduced.  On the left side since the two halves are connected by a semipermeable membrane, the protons on the right are causing the potassium ions on the left to move farther away.  This causes the EZ zone to build which Johan calls the "Alkaline Gel"  He also supposes that this zone may be "metallic" in nature with decentralized electrons (which if true could only help our battery).  On the left side the negatively charged OH- groups congregate from the attraction of the H+ ions and repulsion of the K+ ions from the H+ ions.  Urea or other reducing agents (including light especially infrared) on the base side may help donate electrons to improve voltage.

What this EZ zone does for us is make it much easier for us to harvest electrons since all the negatively charged aspect of the alkaline electrolyte are concentrated for us.  So According the Johan these OH- groups collapse into H2O2 which then dissociate into O2 gas and H2O.  What this means is we will loose the alkalinity of our EZ zone so the battery will need to be recharged, preferably by replacing the electrolyte.

These electrons are pulled out through the circuit due to electrical connection to the Acid side via the current collectors and wires.  This act of pulling electrons from the OH- zone into the H+ zone creates a current flow and allows us to do electrical work.  The electrons are falling down a concentration gradient.  When the electrons reach the H+ acid side they are absorbed by the H+ ions and form H2 gas.  Again this decreases the Proton concentration in the acid side and eventually we will run out of protons and our voltage will decrease and we will need to recharge the liquid.

Another observation I have made is that in an acid base battery like this getting the positive and negative current collector as close to the membrane as possible increases current.  So this would make sense because our model shows that the most electrically active areas will be right on either side of the membrane.

Other things to enhance the battery acide from oxidizers (like hydrogen peroxide or others), reducing agents (like urea or others), and light could also be catalysts like fenton reagents (including chelate iron or cobalt or others) and sparging gasses (like hydrogen and/or oxygen and/or nitrous oxide).

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