Researchers have developed a low cost membrane technology that can be used for a flow battery in energy storage systems.
The team from the Berkeley Lab, UC Berkeley, the Massachusetts Institute of Technology, and Istituto Italiano di Tecnologia used a class of polymers known as AquaPIMs (aqueous-compatible polymers of intrinsic microporosity) for long-lasting and low-cost aqueous grid batteries that use materials such as zinc, iron, and water. The team also developed a simple model showing how different battery membranes impact the lifetime of the flow battery, which is expected to accelerate early stage R&D for such technologies, particularly in the search for a suitable membrane for different battery chemistries.
"Our AquaPIM membrane technology is well-positioned to accelerate the path to market for flow batteries that use scalable, low-cost, water-based chemistries," said Brett Helms, a principal investigator in the Joint Center for Energy Storage Research (JCESR) and staff scientist at Berkeley Lab's Molecular Foundry who led the study. "By using our technology and accompanying empirical models for battery performance and lifetime, other researchers will be able to quickly evaluate the readiness of each component that goes into the battery, from the membrane to the charge-storing materials. This should save time and resources for researchers and product developers alike."
Most grid battery chemistries have highly alkaline (or basic) electrodes with a positively charged cathode on one side, and a negatively charged anode on the other side. But current state-of-the-art membranes are designed for acidic chemistries, such as the fluorinated membranes found in fuel cells, but not for alkaline flow batteries. Fluorinated polymer membranes are also expensive. According to Helms, they can make up 15% to 20% of the battery's cost, which can run in the range of $300/kWh.