Of all well-suited battery technologies for offsetting the intermittent delivery of renewable energy, “flow” batteries look promising because it’s relatively simple to scale their tanks, pumps and pipes to the required sizes needed to handle large capacities of energy.
Researchers from the Stanford University and Department of Energy’s SLAC National Accelerator Laboratory have come up with a new design of a low-cost, long-life flow battery that could enable solar and wind energy become a major supply mix to the electrical delivery network called “the grid”.
Adding renewable energy sources into the grid can cause serious damage to the electrical infrastructure because of the large and sudden power fluctuations of these sources caused by swings in times of day. It does us no good if we can’t save electricity for use at the times when the wind isn’t blowing and the sun refuse to shine.
The existing flow batteries have interaction chambers through which two different liquids are pumped while dissolved molecules in the liquids undergo chemical reactions that store or give up energy. Because the chamber has a membrane that only allows ions not dissolved in reaction to pass through it, the active ions are kept separately apart. This design has two setbacks:
i) The high cost of liquids containing rare elements such as vanadium – especially in the large quantities needed for grid storage
ii) The membrane, which is also expensive and requires maintenance
The state-of-the-art battery designed by Stanford University and DOE’s SLAC make use of a simplified single stream of molecules, and membrane isn’t needed. Its molecules are majorly made up of less expensive lithium and sulfur which react with a piece of lithium metal coated with a barrier that permits electrons to go through without lessening the value of the metal. At the time of discharging, molecules of the lithium compound called lithium polysulfide absorb lithium ions, and when charging, they lose them back into the compound liquid. The whole stream of the molecules is dissolved in an organic solvent.
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