Working Towards Green Batteries
While much of the public interest is on green energy sources such as solar and wind power, many researchers recognize that green storage solutions are needed as well. Lithium-ion batteries, though rechargeable, require large amounts of energy to make and to recycle, making their current inorganic design a problem for those trying to reduce harm to the environment. Among those are researchers at Rice University and the City College of New York who have recently discovered that plant matter can be used as a cathode, instead of cobalt.
Purpurin is a material from the root of the madder plant and is typically used as a dye. When testing the electrochemical reactiveness of a multitude of organic molecules, it jumped out as it readily bounded with lithium ions. By adding carbon the researchers were able to increase conductivity which allowed the half-battery they built for testing to store 90 milliamp hours per gram after 50 cycles. This organic cathode was also built at room temperature, instead of the high temperatures needed for a cobalt cathode.
The researchers are now looking for other organic materials that can be used in batteries to eventually construct a fully organic battery. Such a battery may not end up using purpurin though, but the science they have already learned from that material is what will allow them to identify others.