How do you store renewable energy so it's there when you need it, even when the sun isn't shining or the wind isn't blowing? Giant batteries designed for the electrical grid -- called flow batteries, which store electricity in tanks of liquid electrolyte -- could be the answer, but so far utilities have yet to find a cost-effective battery that can reliably power thousands of homes throughout a lifecycle of 10 to 20 years.

Now, a battery membrane technology developed by researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) may point to a solution.

As reported in the journal of Joule, the researchers developed a versatile yet affordable battery membrane -- from a class of polymers known as AquaPIMs. This class of polymers makes long-lasting and low-cost grid batteries possible based solely on readily available materials such as zinc, iron, and water. The team also developed a simple model showing how different battery membranes impact the lifetime of the battery, which is expected to accelerate early stage R&D for flow-battery technologies, particularly in the search for a suitable membrane for different battery chemistries.