Usually, modern batteries aren’t constrained by capacity woes, but rather their overall life span. After a few years of heavy use, the lithium-ion pack can easily lose its potency. It is this fact that is often troublesome for long-term energy storage systems.
Researchers from Harvard have recently developed a flow battery that could potentially alleviate this issue. According to Harvard, the new flow battery stores energy in “organic molecules dissolved in neutral pH water.”
Simply put, flow batteries save energy in external tanks in liquid solutions. As logic would suggest, the larger the external tank, the more energy it can store. This combination creates a non-corrosive and non-toxic battery with an incredibly long lifetime, reaching up to 10 years of consistent use without failure.
Flow batteries have been a promising energy storage solution, especially in the renewable energy market, but suffered from one considerable drawback. The flow batteries would often lose energy storage capacity after going through many charge-discharge cycles. Engineers would need to perform periodic maintenance in order to restore the device to proper capacity levels.
To remedy this, the Harvard team modified the structures of molecules that are used in the positive and negative electrolyte solutions. This made the molecules water soluble, which in turn created a battery that loses only one percent of its capacity per 1,000 cycles.
“This work on aqueous soluble organic electrolytes is of high significance in pointing the way towards future batteries with vastly improved cycle life and considerably lower cost,” says the Director of Energy Storage Research at the Office of Electricity of the Department of Energy (DOE) Imre Gyuk. “I expect that efficient, long duration flow batteries will become standard as part of the infrastructure of the electric grid.”
The neutral pH chemistry helps drastically lower the cost, since it drops the price of the ion-selective membrane that separates the two sides of the battery. Expensive polymers, which are used in most flow batteries, can account for almost one-third of the total cost of the entire device. By implementing this new method, these expensive polymers can be replaced with cheap, hydrocarbon alternatives.
The researchers are currently working with several companies to implement this technology for industrial use, as well as optimize the membrane and electrolyte interactions.