by Julie Marcus
December 11, 2012
Scientists from The City College of New York and Rice University used purpurin, a dye extracted from the rose madder root, to power an environmentally friendly battery. The goal is to develop a non-toxic and sustainable lithium-ion battery. On December 11, 2012, the researchers reported their results in Nature’s online and open access publication, Scientific Reports.
The madder plant roots have been used as a natural fabric dye for over 3,500 years in Asia and in the Middle East. The plant dye was used to color fabrics a bright orange, red, and pink.
Lithium-ion batteries are in high demand. They are used in mobile phones and now in electric cars. The problem with traditional lithium-ion (Li-ion) batteries is that they put the environment at risk when making them, when they are recycled, and when they are disposed of. These problems have prompted scientists to develop a battery that would be less expensive to make, safer for the environment, and to come from a sustainable resource.
Currently, Li-ion batteries require the mining of metal ores – such as cobalt – that must be transformed, explained the lead author, Dr. Leela Reddy, a research scientist in Professor Ajayan’s lab in the Department of Mechanical Engineering and Material Science at Rice University. Dr. Reddy explained that 30 percent of cobalt is used to make batteries and the supply of the metal ore is limited.
Currently, Li-ion batteries use extra energy when they are made or recycled. The traditional Li-ion battery is made up of cobalt salt and lithium which are merged together at high temperatures. The manufacturing or recycling of the Li-ion batteries adds around 72 kilograms of carbon dioxide to the atmosphere for every kilowatt-hour of energy that the Li-ion battery provides, Dr. Reddy added.
This led the scientist to investigate purpurin and its relatives as an alternative to using metal ores. The molecules in purpurin are fashioned similarly to electrodes and they are a good match for combining with lithium. The scientist point out that growing madder or another plant source for Li-ion batteries would help absorb carbon dioxide. Another benefit is that the batteries would not contain toxic waste and they would be safe to throw away.
Purpurin would not need to be heated up to combine with the lithium salt. Instead, the room-temperature purpurin is dissolved in an alcohol-based solvent and then it is combined with lithium salt. The scientists say that there is a change in color from reddish yellow to pink once the lithium ion binds with the purpurin.
They are confident that a commercially available environmentally friendly Li-ion battery will be a reality in just a few years. Dr. Reddy hopes to have a working prototype of a complete organic battery within a few years.
Originally published by BestSyndication.com