The next generation of batteries that’s environmentally friendly could be developed using a molecule that transports oxygen in blood.
Although lithium-ion batteries are currently the standard for consumer electronics, lithium-oxygen (Li-O2) batteries hold a charge for much longer and could therefore eventually replace lithium-ion batteries. Electric cars could travel four to five times longer than they currently can and electronic devices would only need to be charged every few weeks.
Li-O2 batteries are however not yet efficient enough for commercial application and form lithium peroxide, a solid precipitate that coats the surface of the batteries’ oxygen electrodes. These problems will have to be addressed before Li-O2 batteries can become the new standard. One challenge is to find a catalyst that facilitates a process known as oxygen evolution reaction efficiently. This reaction is where lithium oxide products decompose back into oxygen gas and lithium ions.
Andre Taylor, associate professor of chemical and environmental engineering at Yale, has identified a molecule that could function as a better catalyst. The molecule is known as heme and a team at Taylor’s lab showed that it lowers the amount of energy needed to improve the battery’s charge and discharge cycle times, thereby improving the Li-O2 cell function.
Hemoglobin is made up of two parts of which heme is the molecule that carries oxygen in the blood of animals. The molecule dissolves into the battery’s electrolytes when used in a Li-O2 battery and acts as what is known as a redox mediator. This decreases the energy barrier required so that the electrochemical reaction can take place.
Taylor notes that when animals breathe in air, the heme molecule absorbs oxygen from the air and transports it to the lungs. It also transports carbon dioxide back out during the exhale cycle. As heme has a good binding with oxygen, the team identified this as a way to enhance lithium-air batteries.
The discovery could help reduce the amount of animal waste disposal as the process uses a biomolecule that is traditionally wasted. In the animal products industry, the disposal of blood is a problem. Taylor notes that they can take the heme molecules from these waste products and use it for renewable energy storage. By using recyclable biowaste as a catalyst material, the effectiveness of the technology is improved. At the same time, it could be preferential in developing green energy applications.
The results were published in the Nature Communications journal.