Researchers from the Institute of Energy and Environmental Chemistry (IQUEMA) of the University of Cordoba have developed a battery that uses hemoglobin to promote electrochemical reactions and can maintain its functionality for about 20 to 30 days. Hemoglobin, a protein found in red blood cells that carries oxygen from the lungs to different tissues in the body (and then carbon dioxide back again), has a very high affinity for oxygen and is an essential element of life, but what if it is also a key element in an electrochemical device, such as a zinc-air battery, in which oxygen also plays a role?
This is exactly what the Physical Chemistry (FQM-204) and Inorganic Chemistry (FQM-175) groups at the University of Cordoba (UCO) hope to validate and develop together with a group from the Polytechnic University of Cartagena. Previous research at the University of Oxford and a final degree project at the University of Cordoba (UCO) showed that hemoglobin has favorable properties during reduction and oxidation (redox) processes, the system in which energy is produced.
Therefore, the research team developed the first biocompatible battery (harmless to humans) through a proof-of-concept project that uses hemoglobin to convert chemical energy into electrical energy in an electrochemical reaction.
Hemoglobin will act as a catalyst in zinc-air batteries, one of the most sustainable alternatives to the currently dominant battery on the market: lithium-ion batteries. That is, hemoglobin is a protein responsible for facilitating an electrochemical reaction, known as the oxygen reduction reaction (ORR), which allows air to enter the battery. The oxygen is reduced and converted into water in one part of the battery (the cathode or positive electrode), releasing electrons and passing them to another part of the battery (the anode or negative electrode), where the zinc oxidation occurs.
As UCO researcher Manuel Cano Luna explains: "To be a good catalyst in the oxygen reduction reaction, a catalyst must have two properties: it needs to absorb oxygen molecules quickly and form water molecules relatively easily. And hemoglobin meets these requirements." In fact, through this process, the team managed to get their biocompatible battery prototype to work for 20 to 30 days using 0.165 milligrams of hemoglobin.
In addition to its powerful performance, the battery prototype they developed also has other advantages. First, unlike other batteries that are affected by humidity and need to be manufactured in an inert atmosphere, zinc-air batteries are more sustainable and can withstand harsh atmospheric conditions.
Second, as CanoLuna notes, "Using hemoglobin as a biocompatible catalyst holds great promise for the use of such cells in devices that are integrated into the human body, such as pacemakers. The cells operate at a pH of 7.4, similar to the pH of blood. In addition, since hemoglobin is present in nearly all mammals, animal proteins can also be used."
However, the battery they developed still has some areas for improvement. The main thing is that it is a primary battery, so it can only be discharged. Additionally, it cannot be recharged. So the team is already taking the next step to find another biological protein that can convert water into oxygen to recharge the battery. Additionally, the battery only works in the presence of oxygen, so it cannot be used in space.
The research, published in the journal Energy & Fuels, opens the door to new functional alternatives to batteries, as more mobile devices are expected and demand for renewable energy increases, necessitating the use of devices that store excess electrical energy in the form of chemical energy. On top of that, lithium-ion batteries, currently the most common type, suffer from lithium scarcity and environmental impact as hazardous waste.
Compiled source: ScitechDaily