A research team at Stanford University has combined a range of materials to develop a rechargeable battery that can store large amounts of renewable energy from solar or wind sources. Experts say that this technology will enable a fast and cost-effective power supply at a balanced ambient temperature in the future.
Until now, flow batteries have been considered an alternative for storing renewable energy, but the types of fluids that could be produced by electricity have been limited by the amount of energy they could provide, or even required very high temperatures or used very toxic or expensive chemicals.
However, the Stanford research team led by Professor William Chueh decided to try a mixture of sodium and potassium to produce a liquid metal at room temperature that theoretically has up to ten times more energy per gram than other materials for the liquid on the negative side of a flow battery.
By using the negative liquid metal side of the battery, the researchers found a ceramic membrane of potassium oxide and aluminum oxide to keep the negative and positive materials separate and allow the current to flow.
In this sense, they were able to double the maximum voltage of conventional flow batteries and the prototype remained stable for thousands of operating hours. This higher voltage means that the battery can store more energy regardless of its size, which in turn reduces the production costs of the battery.
The researchers also experimented with four different liquids for the positive side of the battery. In this case, the water-based fluids quonly degraded the membrane, but they claim that a non-water-based alternative could improve the performance of the battery.
Reference: High voltage, room temperature liquid metal flow battery with Na-K|K-β″-alumina stability. Joule Volume 2, Issue 7, S. 1287-1296, July 18, 2018 DOI: https://doi.org/10.1016/j.joule.2018.04.008.