Though there are huge lithium-ion battery installations from the likes of Tesla that can store energy harvested from renewables like wind and solar, they're not exactly cheap. The USC researchers looked to an existing design that stores energy in liquid form.
In the so-called redox flow battery, a positive chemical and a negative chemical are stored in separate tanks. The chemicals are pumped in and out of a chamber where they exchange ions across a membrane – flowing one way to charge and the other to discharge.
Though such systems have previously used expensive, dangerous and toxic vanadium and bromine dissolved in acid for their electrolytes in the past, we have seen recent designs that replace those with organic or more environment-friendly alternatives.
For its design, the USC team used a waste product of the mining industry and an organic material that can be made from carbon-based feedstocks, including carbon dioxide, and is already used in other redox flow batteries.