Can garden herbs improve your car battery?

The last place you'd expect to find garden herbs is in your car battery. But at least one, Rubia, can make car batteries more energy efficient, studies find. 

Joanne Ciccarello/Staff/File
Trey Leavenworth harvests some herbs in Cape Cod, Mass. in this 2011 file photo. Herbs are great for cooking, but studies suggest that Rubia may make car batteries run more efficiently.

However you choose to enjoy herbal products, the last place you'd expect to find them is in your electric car battery.

Thanks to a new discovery though, the Madder plant, also known as Rubia, could prove useful as a natural cathode in batteries.

Madder has long been used as a source of purpurin, an organic dye used since ancient times to color fabrics.

As ScienceBlog reports, scientists at Rice University and the City College of New York have discovered that purpurin also makes a good natural cathode for lithium ion batteries.

Unlike many other future battery technologies, this one isn't aimed at improving charging time, increasing capacity or reducing weight--it's simply tasked with making batteries greener.

While the battery toxicity and rare earth metal arguments from electric car naysayers are often exaggerated, finding a renewable alternative to lithium and cobalt cathodes certainly couldn't hurt.

Green batteries are the need of the hour, yet this topic hasn’t really been addressed properly,” suggests Arava Leela Mohana Reddy, author of the study.

"[Lithium-ion batteries aren't] environmentally friendly. They use cathodes of lithium cobalt oxide, which are very expensive. You have to mine the cobalt metal and manufacture the cathodes in a high-temperature environment. There are a lot of costs."

While current lithium-ion batteries are recycled and reused in huge numbers (and lead-acid batteries are the world's most recycled product), Reddy also explains that extracting the cobalt from batteries, during the recycling process, is quite energy-intensive.

The discovery that purpurin was a suitable alternative came during testing different organic molecules for their ability to interact with lithium ions.

Purpurin turned out to be most suitable. 20 percent carbon is added to increase conductivity, and the cathodes can even be made at room temperature. Better still, some of the purpurin used in future could be harvested from agricultural waste.

In addition to the organic cathodes, the team is working on finding organic materials suitable for anodes, and an electrolyte that doesn't break the molecules down. A working prototype of a completely organic battery could be completed in only a few years.

As with other battery technologies, we await the team's results with interest. It's good to see that, in addition to improving a battery's performance, work is still being done to make them greener, too.

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