Need a battery? Just check the garden

Money doesn’t grow on trees, but batteries could. Sort of.

In one more step of a global effort to develop greener battery technology, researchers at Rice University say they have found a way to replace a costly metallic component in lithium-ion batteries with material from a common plant.

While many of today’s lithium-ion batteries incorporate cobalt, which has to be mined and then altered at high temperature for use in batteries, Rice researchers say they can accomplish the same function using a dye extracted from a plant.

Reaching into an oxygen-free box to combine and assemble materials, researchers have shown that in altered form the plant-based substance can be incorporated into a lithium-ion battery that is almost as effective as today’s versions, said Leela Mohana Reddy, the lead researcher in the effort.

The chemically altered dye can hold and move the energy-carrying lithium ion in the same way as lithium compounds involving cobalt or other substances. The material was derived from a small flowering plant called a madder, native to southern Europe and the Mediterranean region. Scientists are testing other dyes that could prove even more effective, Reddy said. His group’s findings appeared last month in Nature’s online journal Scientific Reports.

Although the science behind the green battery component is in its early stages, if developed further it could lead to a change in one of three main battery parts: the cathode. Simply changing that component would increase the sustainability of battery production, Reddy said.

“You don’t have to do any mining,” he said. “You just plant and then you can turn it into a dye and then into a battery material with simple chemistry at room temperature.”
Scientists worldwide are trying to find ways to make energy storage devices out of more environmentally friendly materials, said Daniel Abraham, a materials scientist focusing on lithium-ion batteries at Argonne National Laboratory.

Progress in various laboratories has resulted in a steady stream of discoveries by researchers hoping to make batteries easier to produce and recycle, he said.

That has left battery makers and lithium producers with a lot of developing technology to consider, said James Calaway, the chairman and largest shareholder of Orocobre, an Australia-based lithium producer that is developing a $250 million lithium carbonate facility in Argentina.

“There are so many ideas at every major university, it’s hard to know at this early stage whether one idea is significant or not,” Calaway said. “The way you’ll know it is, over time, what ideas get taken up by the big battery makers, because in the end they are the guys who will determine what gets made.”

That could happen sooner than later, with advancements in battery research seemingly building on each other in recent years, Abraham said.

The science that led to Reddy’s experimentation with plant materials grew out of another researcher’s efforts in France, he said. And growing enthusiasm from researchers around the world has led to visions of an all-organic battery, Abraham said.

“If you want to come up with a truly organic sustainable battery made up of plant material, every component of the cell should be made from these organic components and that will make it truly eco-friendly and sustainable,” Abraham said. “That’s the ultimate goal.”

Abraham predicted that efforts behind organic batteries will bring commercially available products to the market in five years and perhaps lead to their wide availability in a decade.
Still, the technology has a long way to go, he said. First, while lab research has shown promise, most tests have not developed to a stage that would appeal to consumers.

Rice’s plant-based cathodes, for example, would, at their current stage, be able to work in lithium-ion batteries to generate the same amount of energy as today’s versions, but at twice the physical size, Abraham said.

That would not make them feasible for products like iPhones and computers, which have shrunk as lithium-ion batteries have become more compact and energy dense, he said.
Researchers in Rice’s labs hope continued development with plant-based cathodes and other battery components will lead to better batteries for producers and consumers, said Pulickel Ajayan, a professor of material science and mechanical engineering who oversees the laboratory that housed Reddy’s research.

“It might still take a few years to find the right molecule but I think it’s very possible that we will find it,” Ajayan said, referring to the possibility of making a better plant-based cathode.
He said the group is looking for corporate partners to assist in pushing the research further. Reddy said cutting metals out of batteries would make them cheaper to produce and could reduce the need for mining of materials like cobalt.

As he handled coin-sized batteries he had made using the plant-based cathodes, Reddy was optimistic that Rice would find a powerful battery solution.

“There is a lot of room here in this direction and we can definitely get higher capacity than what we have now,” he said.