The cooperative project, ZnMobil, founded by the Federal Ministry of Economic Affairs and Energy in Germany combines the experience of industrial and academic partners (Covestro Deutschland AG; Grillo-Werke AG; VARTA Microbattery GmbH; Accurec Recycling GmbH; Technical University Freiberg, Gottfried Wilhelm Leibniz University Hannover; University of Duisburg-Essen; the fuel cell research center ZBT GmbH) to develop a high-performance and low-cost zinc-air flow battery.
Here we present strategies to improve the depth-of-discharge of zinc-air flow batteries. The battery system consists of a 100 cm² copper plate as current collector for the zinc-suspension electrode and an oxygen reduction electrode with gas-diffusion layer (supplied by Covestro). The zinc-slurry contains zinc particles (supplied by Grillo) suspended in alkaline solution (30 wt-% KOH) and stabilized with polyacrylic acid.
The battery performance and depth-of-discharge were measured for several additives added to the zinc-slurry. Furthermore, the influence of the discharge current density on the depth-of-discharge was evaluated for these setups. Depending on the current density and additive selection, it is possible to achieve depth-of-discharge up to 90 %.