Redox flow batteries (RFBs) are a promising electrochemical technology for energy-intensive grid storage, but further cost reductions are needed for widespread adoption spurring research efforts into new redox chemistries and reactor designs. Notably the recent emergence of redox active organic molecules offers intriguing new pathways to low cost energy storage through tunable molecular structure and inexpensive synthesis routes. While the rapid and continued advancement of these redox couples is exciting, iterative design-test-improve cycles are slowed as molecules become increasingly robust and failure modes become more nuanced. Consequently, there is a growing need more advanced diagnostic techniques to evaluate materials performance, particularly stability.<br/><br/>Typical methods for characterizing the decay of RFB materials include extensive cycling in an electrochemical cell to correlate capacity fade to overall species decay or monitoring decay of a single reporter constituent (e.g., charged material) via different spectroscopy techniques (e.g., NMR, EPR, or UV-Vis). These methods are challenged by, in the case of cell cycling, disambiguation of the sources of capacity fade, and, in the case of spectroscopies, issues operating under RFB relevant conditions (e.g., concentrated electrolytes and active species). Here, I will present a new technique to quantitatively probe active species stability in RFB-type electrolytes using a microelectrode. The talk will include discussion of underlying theory, systematic evaluation of sources of error, method validation using model compounds, and, finally, demonstration with several redox couples.

Decay characterization of redox-flow battery materials utilizing a microelectrode

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.