This paper will describe the development and applications of Dioxide Materials’ new brand of novel Sustanion™ polymer Anion Exchange Membranes (AEMs). The styrene backbone of these membranes is functionalized in various degrees by the imidazolium functional group and includes other additives to yield several compositions for tailoring the properties and performance of these membranes. The advantage of using the Sustanion™ membranes over any commercially available AEM technologies is demonstrated in terms of their significantly higher anionic conductivities in Figure 1. Furthermore, the membranes are stable and maintain these conductivities when exposed to 1M KOH at 60 ^oC for up to a period of at least 1500 hours.

We have corroborated these finding by testing these membranes in-situ CO₂ and water electrolyzers. Our results speak for themselves. The CO₂ electrolyzers have run under 3V at 200 mA/cm² with a voltage rise of only between 4 and 6 µV/hr for 3700 hours. Keep in mind, these currents are more than a factor of 4 higher than our closest competitor. For water electrolyzers, our Sustainion™ membranes have helped us embark on the Holy Grail of base metal catalysts using NiFe on stainless steel anodes and NiFeCo cathodes. We can maintain 1 A/cm² at 1.9V at 60^oC in 1M KOH for 200 hours with less than 5 mV voltage variation. This is unprecedented since under the same conditions, we have failed to find a single instance in literature of values surpassing the above results by including even high loadings of precious metal catalysts. The cell is still running.

As such, we are expecting to offer these membranes for beta-testing by various academic and industry groups. Based on our current findings, we envision the Sustainion™ membranes making similar breakthroughs in applications of alkaline anion exchange based fuel cells, flow batteries and even electrodiyalsis among other untapped electrochemical applications.

Acknowledgement

Parts of this work were supported by ARPA-E under contracts DE-AR0000345 and DE-AR0000684 and by 3M. The opinions here are those of the authors and may not reflect the opinions of ARPA-E or 3M. Assistance from colleagues, collaborators and friends from 3M are gratefully acknowledged.