Most batteries — whether they’re embedded in your iPhone or they’re plugged into the power grid somewhere — use some kind of metal to create the chemical reaction that stores the energy. In laptops and Teslas, that metal is lithium; in traditional cars it’s lead. But researchers at University of Southern California are developing an all-organic, water-based battery that can be entirely synthesized (not using materials mined from the earth) and uses no metals or toxic chemicals.
USC chemistry professor Sri Narayan told me he thinks that in the future, when batteries are scaled up to the point where they’re commonly used on the power grid at large sizes, then using metals and toxic chemicals in them will be a big problem. He thinks the notion of “clean storage” — batteries made using more sustainable methods — will be important down the road.
Batteries that use naturally occurring water and organic molecules could also be less expensive than comparable batteries that use rare or expensive metals. As the demand for grid batteries grows, metals under any type of supply constraint could increase in price.
Narayan’s battery uses water and organic compounds called quinones (oxidized organic compounds) for its electroactive part. Quinones are naturally occurring, energy-storing compounds found in plants, animals and bacteria and are used in photosynthesis and cellular respiration. The battery specifically uses an adapted version of benzoquinone that can be dissolved in water.
The USC battery isn’t designed like the closed ones used in your phone and laptop. It’s a redox flow battery. Fow batteries store energy like lithium ion batteries but have their electrolyte (the substance that acts as the medium for the charging and discharging of the battery) separated out of the battery cell in liquid-filled tanks. Flow batteries are used for stationary applications like the power grid — you won’t find them in moving cars or mobile gadgets.
While it might sound like an awkward set-up, the benefit of a flow battery is that it can be cheaper than traditional metal-based closed batteries, it can be more flexible (you can add more tanks and electroactive material to that type of open system), it can last many more years (the electrolyte doesn’t degrade as fast) and it can provide a longer burst of sustained power. Dozens of companies and researchers are trying to innovate around flow batteries, from startup EnerVault to startup Primus Power, to lab work like that at Harvard.
But the USC group is one of the only projects using organic compounds and no metal
. Many redox-flow batteries use vanadium. EnerVault’s uses iron-chromium.
Narayan says the goal is for his battery to cost $100 per kilowatt hour and last for 15 years. Lead acid batteries cost about that today, but they last only about a year.
The battery is still in the lab phase, and USC is funding its research in part with a grant, awarded last year, from the Department of Energy’s early-stage high-risk ARPA-E. program. If the battery moves through the lab stage with flying colors and proves to be promising for commercialization, Narayan says USC might work with a company in Colorado to produce a commercial battery.