Clean energy is the leading solution to climate change. However, solar and wind power are inconsistent in producing enough energy for a reliable power grid. Lithium-ion batteries, on the other hand, can store energy, but are a limited resource.
Nian Liu, Associate Professor at Georgia Tech, said: “Variable power sources, such as clean energy, are difficult to manage, so how can we use an energy storage device or system to smooth out these fluctuations?”
Flow batteries offer the solution. Electrolyte flows from the storage tank of this rechargeable battery through an electrochemical cell. Existing flow battery technologies cost him more than $200 per kilowatt-hour, too expensive for practical use, but Liu’s lab at the School of Chemistry and Biomolecular Engineering (ChBE) has developed a more compact flow battery cell configuration. developed. Reduces overall flow battery size and cost. This work has the potential to revolutionize how everything from major commercial buildings to residential buildings is powered.
The all-Georgia Tech research team published their findings in the Proceedings of the National Academy of Sciences paper, “Submillimeter-wave bundled microtubular flow battery cells with ultra-high volumetric power densities.”
Flow batteries offer the solution. This work has the potential to revolutionize how everything from major commercial buildings to residential buildings is powered.
find the flow
Flow batteries are named after the flow cell in which electronic exchange takes place. Their traditional design, the planar cell, requires bulky flow distributors and gaskets, increasing size and cost, but reducing overall performance. The cell itself is also expensive. To reduce footprint and cost, researchers focused on improving the flow cell’s volumetric power density (W/L-of-cell).
They turned to submillimeter bundle microtubule (SBMT) membranes, a configuration commonly used in chemical separations: made of fibrous filter membranes known as hollow fibers. This innovation features a space-saving design that can relieve pressure across the membrane through which ions pass without the need for additional supporting infrastructure.
ChBE Professor Ryan Lively said: “We recognized the benefits that hollow fibers have for separators and set out to achieve the same benefits in the battery field.”
Applying this concept, researchers have developed an SMBT that reduces the intermembrane distance by a factor of nearly 100. The microtubule membrane of this design does not require a large support material and simultaneously acts as an electrolyte distributor. Bundled microtubes shorten the distance between the electrode and membrane and increase the volumetric power density. This binding design is an important discovery for maximizing the potential of flow batteries.
Powering the battery
To validate the new battery composition, researchers used four different chemicals: vanadium, zinc bromide, quinone bromide, and zinc iodide. All chemicals work, but two were the most promising. Vanadium was the most mature chemical, but it is difficult to obtain and the reduced form is unstable in air. They found zinc iodide to be the most energy dense option and most effective for residential units. Zinc iodide offered many advantages even compared to lithium. It has fewer supply chain issues, becomes zinc oxide, and is soluble in acids, making it much easier to recycle.
This electrochemical solution for this uniquely shaped flow battery has proven to be more powerful than conventional planar cells.
“The superior performance of SMBT was also demonstrated by finite element analysis,” said Xing Xie, assistant professor in the Department of Civil and Environmental Engineering. “This simulation method will also be applied to future studies on cell performance optimization and scale-up.”
Using zinc iodide chemistry, the battery can operate for over 220 hours or over 2,500 cycles in off-peak conditions. Using recycled electrolyte also has the potential to reduce costs from $800 to less than $200 per kilowatt-hour.
Building the future of energy
Researchers are already working on commercialization, focusing on developing and increasing the size of batteries using different chemistries such as vanadium. Scaling requires coming up with an automated process for manufacturing hollow fiber modules, which is currently done manually for each fiber. They hope to eventually deploy the battery to his 1.4-megawatt microgrid at Georgia Tech in Tech Square. This project will test the integration of microgrids into the power grid and provide a living laboratory for professors and students.
SBMT cells can also be applied in various energy storage systems such as electrolysis and fuel cells. This technology can also be enhanced with advanced materials and different chemicals for different applications.
“This innovation is very application driven,” says Liu. “We need to achieve carbon neutrality by increasing the share of renewable energy in energy generation. Currently, he is less than 15% in the US, but our research could change this.”
Original: Researchers create smaller, cheaper flow batteries for clean energy
Than: Georgia Tech
