Electric power is increasingly replacing the gasoline engine in everything from cars to yard tools and even airplanes. But while there are a number of benefits to this greener alternative, batteries have some problems of their own. Many types of batteries are made with toxic materials, and lithium-ion cells have a nasty habit of bursting into flames. An up-and-coming technology called the organic flow battery could eventually address many of these concerns; however, it’s not quite ready for most real-world applications yet.
Even so, it’s a very interesting concept that is well worth digging into. That is just what YouTuber Marb’s lab did. After reading through a research paper on the topic, Marb’s lab decided to build his own organic flow battery. This one is particularly interesting for the electrolyte that powers it. You won’t find a long list of toxic chemicals — just some matcha tea.
The front panel (📷: Marb’s lab)
Unlike conventional batteries that store energy inside sealed cells, flow batteries keep their active chemicals in liquid form. These liquids can be stored in separate reservoirs and circulated through the battery as needed. In this case, the main ingredient is epigallocatechin gallate (EGCG), a naturally occurring compound found in green tea. When mixed into an alkaline solution, the compound becomes part of the electrochemical reaction that generates electricity.
To explore the concept, Marb’s lab built an elaborate test rig. The main structure is assembled from 2020 aluminum extrusions mounted to a thick aluminum base plate. The sturdy frame supports a collection of custom-fabricated electrodes, measurement instruments, and fluid containers. A retro-inspired front panel cut from acrylic houses an analog voltmeter, analog ammeter, and a small motor-driven propeller that serves as a visual indicator of the battery’s output.
One of the system’s key components is the oxygen-consuming carbon electrode. Built from a brass tube, carbon rod, and a perforated plastic sleeve, the electrode is packed with activated carbon granules to dramatically increase its surface area. This provides a much larger reactive interface than the carbon rod alone could provide. Marb’s lab also fabricated platinum reference electrodes housed inside PVC tubing and sealed with degassed epoxy resin.
An overview of the system (📷: Marb’s lab)
The battery consists of two separate chambers divided by a porous ceramic cylinder. The ceramic barrier allows ions to move between the chambers while preventing the solutions from mixing directly. For experimenters on a budget, Marb notes that a standard terracotta flower pot can serve a similar purpose.
Inside the central chamber, the carbon electrode sits in sulfuric acid along with sodium peroxodisulfate, which decomposes to form oxygen-rich compounds that improve the electrode’s performance. The outer chamber contains the matcha tea suspension mixed with sodium hydroxide. Once both solutions are in place, the system immediately begins producing electricity.
While this homemade battery is more laboratory experiment than practical power source, it demonstrates that electrical energy can be generated from some very ordinary materials. Perhaps with further development, safer and more environmentally friendly batteries can power all of our electric vehicles and gadgets in the future.
