One big part of sustainable energy that is often overlooked, is that we also need sustainable ways to store said energy. Current batteries contain significant amounts of cobalt, which is often mined using child labor in dangerous working environments. Additionally, only a very small percentage of li-ion batteries are recycled, increasing the demand for cobalt and other strategic elements.

In our last blog post about rare earths, we also mentioned that renewable technologies will need 400% more lithium, according to Jordy M. Lee, Program Manager from the Colorado School of Mines. Estimates of the U.S. Geological Survey in January 2020 state that 65% of the worldwide lithium production is used for lithium-ion (li-ion) and other rechargeable batteries.

Scientists have been working on organic batteries since 2005, when the first organic radical battery (ORB) was developed. An organic molecular radical is a molecular entity possessing one unpaired electron. Traditional li-ion Batteries work by shuffling li-ions around internally and for every li-ion that moves an electron moves. This electron is what generates the current. ORBs have the potential to be more environmentally friendly than conventional metal-based batteries, because they use organic radical polymers (flexible plastics) to provide electrical power instead of metals. Unfortunately, those batteries are still not available for consumers, but Tan Nguyen, Dr. Karen Wooley and Dr. Jodie Lutkenhaus from the Texas A&M University released a research paper in May 2021 showing how they developed a recyclable polypeptide battery that degrades on demand.

Today’s li-ion batteries consist of a metal-oxide cathode, a graphite anode and a liquid electrolyte that contains a lithium salt. The researchers replaced every component of a metal-based battery with a material that is metal free and organic. The cathode contains a polypeptide that contains functional groups (a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions) which can undergo reduction and oxidation. The anode contains a similar molecule that has a slightly different group that can also undergo reduction and oxidation. The scientists replaced the lithium-containing electrolyte with an electrolyte that contains organic salts, in that way they store energy by changing organic anions instead of lithium-cations. For every organic anion that moves, an electron is also moving and therefore powering your device.

Dr. Jodie Lutkenhaus also says that her dream would be a battery where you can collect all the materials and reconstitute them into their starting materials to make another battery for a truly circular economy. But the biggest challenge is separation. Once the battery is degraded, every little chemical species would have to be separated. The problem is that if it takes more energy to recycle the batteries than they supply, they are still useless. Another challenge is making a battery that can degrade on command while still being robust enough to be used.

Even though there are still some hurdles to overcome, and the batteries are not yet available for the public, this concept is another step towards sustainable, recyclable batteries and minimizing global dependence on strategic metals. According to Dr. Lutkenhaus polymer-based batteries could be seen next to traditional batteries in five years, but for them to be biodegradable it will most likely take additional five years.

If you want to read the full research paper, you can do it online here.