As simple of a concept flow batteries are, the used chemicals can still be somewhat problematic in the context of a school experiment. To this end [Markus Bindhammer] decided to implement a flow battery version that uses compounds from green tea for its electrolyte, based on a German research paper from 2016.
These organic flow batteries can use gallic acid, pyrogallol as well as the polyphenols in green tea, making them rather safe even in the hands of more careless students. The demonstrated flow battery uses a carbon electrode with activated carbon around it to increase surface area, a platinum wire electrode, and a graphite foil as third electrode.
In the paper a silver electrode is also used, along with the additional electrodes, and a terracotta flower pot as the barrier between the carbon and graphite electrodes, with [Markus] further explaining that there are fortunately cheaper options than what he is using, especially with the flower pot instead of a special ceramic vessel.
The electrolyte solution has epigallocatechin gallate (EGCG) dissolved in it, which here comes in the form of finely ground green tea powder (commonly known as matcha), which so happens to be pretty rich in this substance. In the below graphic by [Markus] you can see the complete set of solutions and other relevant details.
Of course, the performance of this type of flow cell isn’t amazing, with a cell voltage of less than a volt and a few mA of current, but it’s enough to spin a small fan, and to light up a few LEDs. This would be more than enough to demonstrate the reaction and flow cells in general, as long as you don’t mind donating some tasty matcha to science.
Continue reading “Building An Organic Flow Battery Based On Green Tea”
of a pair of electrolytes. These are held externally to the cell and connected with a pair of pumps. The capacity of a flow battery depends not upon the electrodes but instead the volume and concentration of the electrolyte, which means, for stationary installations, to increase storage, you need a bigger pair of tanks. There are even 4 MWh containerised flow batteries installed in various locations where the storage of renewable-derived energy needs a buffer to smooth out the power flow. The neat thing about vanadium flow batteries is centred around the versatility of vanadium itself. It can exist in four stable oxidation states so that a flow battery can utilise it for both sides of the reaction cell.
