December 12, 2012
Researchers Make Greener Batteries From Plants
Brett Smith for redOrbit.com - Your Universe Online
We use batteries for almost every electronic device under the sun. But every point in the lifespan of these energy cells, from production to disposal, is fraught with environmental hazards.As a result, the race to develop a ℠greener´ battery is currently surging ahead and chemists from The City College of New York (CCNY), in collaboration with researchers from Rice University and the U.S. Army Research Laboratory, have developed a component for a promising new lithium-ion battery powered by purpurin, a dye derived from the roots of the madder plant.
“Green batteries are the need of the hour, yet this topic hasn´t really been addressed properly,” said lead author Arava Leela Mohana Reddy, an engineer at Rice. “This is an area that needs immediate attention and sustained thrust, but you cannot discover sustainable technology overnight.”
“The current focus of the research community is still on conventional batteries, meeting challenges like improving capacity,” he added. “While those issues are important, so are issues like sustainability and recyclability.”
Purpurin has been used for centuries in textile production to make vivid red, orange, and pink dyes, but the research team has found that it can also be used as the basis for a sustainable and eco-friendly alternative to conventional lithium-ion (Li-ion) batteries, according to their report in the open-access journal, Scientific Reports.
Li-ion batteries, which are not sustainable, are made using finite supplies of metal ores, such as cobalt. Both the production and recycling of these batteries is a high energy affair. The production and recycling processes also result in the pumping of about 72 kilograms of carbon dioxide into the atmosphere for every kilowatt-hour of energy in a Li-ion battery, according to Reddy.
To make the sustainable alternative, the engineering team began by dissolving the purpurin in an alcohol solvent and adding lithium salt. After the removal of the solvent and the addition of 20 percent carbon to increase conductivity, the purpurin electrode is ready for use.
“The chemistry is quite simple,” coauthor and City College researcher Subbiah Nagarajan said in a statement.
“In the literature there are one or two other natural organic molecules in development for batteries, but the process to make them is much more tedious and complicated,” added study co-author George John, a chemistry professor at City College.
As an added benefit, the industrial growing of madder for battery production would increase biomass, resulting in more carbon dioxide absorption.
The result of the team´s effort is a blueprint for a green battery cathode, and Reddy has said he hopes to formulate a complete green battery. His team is now testing organic molecules suitable for anodes and electrolytes. He added that a working prototype of a completely organic battery should happen within a few years.
“We can say it is definitely going to happen, and sometime soon, because in this case we are fully aware of the mechanism,” said John. “When you can generate something new or unheard of, you think of chemistry in a different way,” he added. “That a natural material or dye can be used for a battery, that is exciting, even for me.”