By Julián Villarreal, The University of Texas at Austin, Korgel Research Group and MRS Student Chapter
It often takes decades to go from benchtop discoveries to off-the-shelf products, and many times manufacturing solutions that are low-cost and environmentally benign are needed to translate lab-scale innovations to technological solutions.
In the case of, Jay Whitacre, a materials science professor at Carnegie-Mellon University (who also holds a joint appointment in energy policy), the timescale was much abbreviated. Recently profiled by Kevin Bullis in MIT’s Technology Review magazine, Whitacre was able to spin off his work on aqueous-electrolyte sodium-ion batteries at Carnegie-Mellon and found Aquion Energy in a matter of a few short years between 2007 and 2009. The battery concept, based on manganese oxide intercalation cathodes and activated carbon anodes, originated with a materials selection strategy that evaluated candidate materials based on performance criteria and the costs of raw materials and precursors. This strategy lead them to target materials compatible with stationary storage solutions costing less than $5-$10 per kg that could deliver 20-50 Wh per kg for thousands of cycles. The best candidate turned out to be the cubic spinel γ-MnO2, implemented in a Na2SO4 solution of neutral pH. This material system was also amenable to low-cost manufacturing. So, having spun off this research in 2009, Aquion begun pilot-scale production of the battery system in 2011. Whiteacre and co-workers reported a description of their protoype system in 2012, and Bullis reports that Aquion will commence full-scale production operations this spring in a Pennsylvania factory. The company has even managed to make use of repurposed equipment--their hydraulic presses used to make the cathode wafers pressed out aspirin pills in a past life.
While the technology is not well-suited to high-energy-density applications or those that requiring fast charging and discharging, it might be feasible in off-grid applications (perhaps in the developing world) and for energy management as an uninterruptible power source. For instance, two of Aquion’s battery pallets, each containing 84 individual batteries, could power the average U.S. home for one day, writes Bullis.