Redox-flow batteries were made more environmentally friendly by replacing their core element, the liquid electrolyte — which is mostly made up of ecologically harmful heavy metals or rare earths — with vanillin, a commonly used flavor compound obtained from lignin. Lignin is potentially suitable as a starting material for the production of electrolytes.
Researchers refined lignin into vanillin to use as a redox-active material using mild and green chemistry without the use of toxic and expensive metal catalysts. The process works at room temperature and can be implemented with common household chemicals. Vanillin is also available in large quantities — even from supermarkets.
The separation and refining process is highly scalable and suitable for continuous production. The researchers’ plant can be paired with a pulp mill to isolate the vanillin from the lignin that is left over as waste. Whatever is not needed can subsequently flow back into the regular cycle and be used energetically as usual.
Redox flow technology is an important piece of the puzzle for the expansion of renewable energies such as wind and solar power, as it is characterized by the storage of large amounts of energy and can therefore cushion voltage peaks in the power grid. The batteries are also suitable as backup storage for stationary applications such as power plants, hospitals, mobile phone systems, or e-fueling stations. Redox flow batteries are more easily scalable, less toxic, more recyclable, and more fireproof than lithium-ion batteries. Other major advantages are their high life expectancy and low self-discharge.