Abstract
Vanadium Redox Flow batteries (VRFBs) have been gaining commercial ground as a possible storage solution to the intermittent nature of some forms of renewable energy. Their relatively simple and flexible design makes them technically and economically capable of scale-up to grid level. Energy is stored electrochemically, using the multiple oxidation states of vanadium. A key component of the VRFB is the Ion Exchange Membrane. Nafion, a perfluorinated sulfonic acid polymer, is a typical material used for this purpose with many advantages – including material compatibility and physical strength. However, its low ion selectivity means that vanadium ions can also cross the material in addition to the desired protons. This unwanted crossover of species can lead to electrolyte imbalance and therefore, a reduction in capacity and efficiency over time and charge-discharge cycling.
This investigation attempts to reduce vanadium crossover, and that of other unwanted species, by incorporating a graphene nanocomposite layer onto the Nafion ion exchange membrane. Graphene is a single atom layer of graphite that has been proven to be a complete material barrier with the exception of protons. Working with the Manchester Graphene Engineering Innovation Centre, various loadings of graphene nanoparticles were incorporated into Nafion. These were then assessed at Thornton with respect to their ability to reduce vanadium crossover whilst maintaining battery cell performance.
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Speaker's Bio
Lewis is an MRes student in the Faculty of Science and Engineering, University of Chester, conducting research under the supervision of Dr David Ward.