A team of scientists and engineers from Harvard’s School of Engineering and Applied Sciences has demonstrated a rechargeable battery that, it claims, could make storage of electricity from intermittent energy sources safe and cost-effective for residential and commercial use.
The work builds on the earlier development of a flow battery, in which rechargeability is provided by chemical components dissolved in liquids contained within the system.
According to the researchers, the active components in most flow battery designs are metal ions dissolved in acid. However, the team said, these metals can be expensive, corrosive, tricky to handle and kinetically sluggish.
Previously Professor Michael Aziz and his team demonstrated a flow battery that replaced metals with quinones, organic molecules featuring in biological processes like photosynthesis and cellular respiration. While quinones formed the negative side of the battery, the positive side relied on a bromine bearing electrolyte. Looking to replace this, the team has used ferrocyanide ions.
“This is chemistry I’d be happy to put in my basement,” said Prof Aziz. “The non toxicity and cheap, abundant materials placed in water solution mean that it’s safe – it can’t catch on fire – and that’s huge when you’re storing large amounts of electrical energy anywhere near people.”
Ferrocyanide, which is soluble and stable in alkaline solutions, is paired with a quinone compound that is also soluble and stable under alkaline conditions. Because it is non-corrosive, the flow battery system components can be constructed of simpler, less expensive, materials such as plastics.
Graham Pitcher and Tom Austin-Morgan