The novel battery uses a water-based electrolyte that allowed developer Aquion Energy Inc. (Pittsburgh, Pa.; www.aquionenergy.com) to achieve a low-cost and safe battery with long cycle life, although more suited to stationary energy-storage applications because of large size. The Aquion battery technology, now entering its commercial launch process, employs an aqueous sodium-sulfate electrolyte. The water-based electrolyte makes the battery much safer than existing batteries that use organic-solvent-based electrolytes, says Jay Whitacre, chief technology officer of Aquion and leader of the research team at Carnegie Mellon University (Pittsburgh, Pa.; www.cmu.edu) that first developed the technology.
Sodium ions are used as the charge-carrying agent in the battery, and the electrodes are made from manganese oxide (cathode) with a cubic spinel structure, and a carbon composite material (anode). The anode hosts pseudocapacitive reactions of three different ions, Whitacre explains, namely Na+, Li+ and H+. A simple non-woven cotton fiber material separates the electrodes in the battery.
“While these batteries are excellent for long cycle life, low-cost and safety, we sacrifice somewhat on energy density,” says Whitacre, but for stationary-storage applications, energy density is less of a concern than it is for vehicle batteries, where volume and weight are critical, he adds. The battery systems consist of one or more modular units of a battery that the company calls S10. Each unit is capable of delivering 150 watts of power, and the battery cells can be linked for increased power.
Aquion has completed construction on a manufacturing line at its facility in Pennsylvania. The company expects that the batteries can be used in stationary long-duration energy-storage applications, such as microgrids, off-grid systems, integration of wind and solar power and others.
