Formulation and characterization of zinc slurries for zinc slurry - Air redox flow battery: A rheological approach

This study presents rheometry as an optimization tool to increase discharge performance of a zinc slurry - air redox flow battery (RFB). Incorporation of electrode suspension slurry to metal-air batteries, in which dense metal solid microparticles are suspended in a conductive fluid with the aid of gelling agents, was investigated. Electrochemical performance of zinc anode slurries was characterized in a single redox flow battery cell in discharge mode. Rheological behavior of each of the slurries is investigated and the key parameters underlying the cell performance were determined. Combined rheological and electrochemical effects were examined and an optimal PAA concentration of 0.40 wt % was found for the zinc slurry system, in which slurry stability is not compromised and conductivity is satisfactory. Furthermore, at the reported gelling agent optimal concentration, a maximum peak power density of 24 mW/cm2 is obtained from polarization curves, improving previous reported performances using the same cell configuration by a factor of 2.4. These results bring more understanding in the development of slurry-based RFBs with a rheometric approach.