Electrochemical Role of Multifunctional Bismuth-Containing Cuprate Ceramic Additive in ZnO Electrodes for Alkaline Ni-Zn Batteries

The multifunctional bismuth-containing cuprate ceramic—Bi1.7Pb0.3Sr2CaCu2Ox (B(Pb)SCCO 2212)—has been employed as a functional additive at 5 wt.% for the zinc electrode in alkaline Ni-Zn batteries in order to improve electrochemical performance and cycling stability. Our study focuses on the electrochemical role of this additive in a 7 M KOH electrolyte, simulating the battery environment. Cyclic Voltammetry (CV) and Chronopotentiometry (CP) were used to investigate the electrochemical processes occurring during electrode operation. The obtained results reveal that an additional cathodic response associated with the B(Pb)SCCO 2212-containing electrode occurs at potentials preceding the main ZnO/Zn reduction process. The CV curves have shown broad cathodic a broad cathodic response consistent with the electrochemical reduction of Bi- and Cu-containing species originating from the ceramic additive. Since these processes occur before the main ZnO/Zn reduction, the formation of reduced Bi/Cu-containing phases may contribute to charge transport within the active mass and to the reduced polarization observed for the modified electrode. These findings provide a possible electrochemical explanation for the improved behavior of zinc electrodes containing 5 wt.% B(Pb)SCCO 2212.