Researchers at Massachusetts Institute of Technology (MIT) have developed a new battery made partly from carbon dioxide captured from power plants. While still based on early-stage research and far from commercial deployment, this battery could continuously convert carbon dioxide into a solid mineral carbonate as it discharges, said the study published in the journal Joule. The researchers believe that the new battery formulation could open up new avenues for tailoring electrochemical carbon dioxide conversion reactions, which may ultimately help reduce the emission of the greenhouse gas into the atmosphere. The battery is made from lithium metal, carbon, and an electrolyte that the researchers designed. Currently, power plants equipped with carbon capture systems generally use up to 30 per cent of the electricity they generate just to power the capture, release, and storage of carbon dioxide. Anything that can reduce the cost of that capture process, or that can result in an end product that has value, could significantly change the economics of such systems, the researchers said. However, "carbon dioxide is not very reactive, so trying to find new reaction pathways is important", explained Betar Gallant, Assistant Professor at MIT. While interest has grown recently in the development of lithium-carbon-dioxide batteries, which use the gas as a reactant during discharge, the low reactivity of carbon dioxide has typically required the use of metal catalysts. Not only are these expensive, but their function remains poorly understood, and reactions are difficult to control. By incorporating the gas in a liquid state, however, Gallant and her co-workers found a way to achieve electrochemical carbon dioxide conversion using only a carbon electrode. The key is to pre-activate the carbon dioxide by incorporating it into an amine solution, the study said. "What we've shown for the first time is that this technique activates the carbon dioxide for more facile electrochemistry," Gallant said. "These two chemistries - aqueous amines and non-aqueous battery electrolytes - are not normally used together, but we found that their combination imparts new and interesting behaviours that can increase the discharge voltage and allow for sustained conversion of carbon dioxide," she added. They showed through a series of experiments that this approach does work, and can produce a lithium-carbon dioxide battery with voltage and capacity that are competitive with that of state-of-the-art lithium gas batteries.