Gas Evolution Characterization of NiZn Batteries with Residual Gas Analysis

Abstract

As humanity strives to reduce its impact on the environment, the need for safe, recyclable, and efficient batteries increases. Nickel-Zinc batteries offer a solution to some of the world’s needs with its materials being abundant and recyclable, its ability to discharge at high currents, and its safe and nontoxic materials providing low risk with applications. Nickel-Zinc batteries are rechargeable, have a ZnO anode, a NiOOH cathode, and an aqueous KOH solution as the electrolyte. During cycling, Ni-Zn cells produce and consume H2 and O2 gas. This gassing behavior has not previously been characterized. The goal of this research was to analyze this gassing behavior by measuring the partial pressure vs. time of a cell’s headspace gas during cycling. The headspace gas was leaked into a vacuum chamber and analyzed with an RGA quadrupole mass spectrometer. The primary trend of the H2 gassing was that the cell produced hydrogen during charging and was rapidly consumed at the end of charging, which indicated recombination with oxygen at an internal catalyst coil. The consumption stopped about midway through discharging and began to produce the H2 gas again. The O2 gassing peaked as H2 was consumed and slowly tapered off during the rest of the discharge and charge. The curvature of these partial pressure plots was dependent of the cycle number and charge rate. The eventual goal of this research is to use the gassing data to indicate the different phases of the electrode materials present throughout cycling. Figure 1