Scientists have created new, water-based organic batteries that are long-lasting and built from cheap, eco-friendly components. They built the new battery, which uses no metals or toxic materials, for use in power plants, where it could make the energy grid more resilient and efficient by creating a large-scale way to store energy for use as needed.
“The batteries last for about 5,000 recharge cycles, giving them an estimated 15-year life span,” says Sri Narayan, professor of chemistry at the University of Southern California and corresponding author of the paper published online in the Journal of the Electrochemical Society.
“Lithium ion batteries degrade after around 1,000 cycles and cost 10 times more to manufacture.”
Narayan collaborated with G.K. Surya Prakash, professor of chemistry and director of the Loker Hydrocarbon Research Institute. “Such organic flow batteries will be game-changers for grid electrical energy storage in terms of simplicity, cost, reliability, and sustainability,” Prakash says.
The batteries could pave the way for renewable energy sources to make up a greater share of the nation’s energy generation. Solar panels can only generate power when the sun’s shining, and wind turbines can only generate power when the wind blows. That inherent unreliability makes it difficult for power companies to rely on them to meet customer demand.
With batteries to store surplus energy, which can be doled out as needed, that sporadic unreliability could cease to be an issue. “‘Mega-scale’ energy storage is a critical problem in the future of renewable energy,” Narayan says. The new battery is based on a redox flow design—similar in design to a fuel cell, with two tanks of electroactive materials dissolved in water.
The solutions are pumped into a cell containing a membrane between the two fluids with electrodes on either side releasing energy. The design has the advantage of decoupling power from energy. The tanks of electroactive materials can be made as large as needed—increasing the total amount of energy the system can store—or the central cell can be tweaked to release that energy faster or slower, altering the amount of power (energy released over time) that the system can generate.
Nature’s energy transfer
The team’s breakthrough centered on the electroactive materials. While previous battery designs have used metals or toxic chemicals, Narayan and Prakash wanted to find an organic compound that could be dissolved in water. Such a system would create a minimal impact on the environment and would likely be cheap, they figured.
Through a combination of molecule design and trial-and-error, the scientists found that certain naturally occurring quinones—oxidized organic compounds—fit the bill. Quinones are found in plants, fungi, bacteria, and some animals, and are involved in photosynthesis and cellular respiration. “These are the types of molecules that nature uses for energy transfer,” Narayan says.
Currently, the quinones needed for the batteries are manufactured from naturally occurring hydrocarbons. In the future, the potential exists to derive them from carbon dioxide, Narayan says.
The team has filed several patents in regard to the design of the battery and next plans to build a larger-scale version.
The Advanced Research Projects Agency-Energy’s Open-Funding Opportunity Announcement program, USC, and the Loker Hydrocarbon Research Institute supported the research.