Structure and Electrochemical Behavior of ZnLaFeO4 Alloy as a Negative Electrode in Ni-MH Batteries

This study investigates the structure and electrochemical performance of the ZnLaFeO4 alloy as a negative electrode material in Ni-MH batteries. The alloy powder was prepared using the sol–gel hydrothermal method. The results demonstrate how the incorporation of La ions influences both the crystal structure and the electrochemical performance of the material. Structural analysis of the ZnLaFeO4 sample reveals a dominant perovskite-type phase, LaFeO3, along with two minor phases: spinel ZnFe2O4 and lanthanum (III) oxide (La2O3). The electrochemical performance of the negative electrodes was evaluated at room temperature and a C/10 rate using various techniques, including chronopotentiometry and cyclic voltammetry. The experimental results indicate that incorporating La cations into the ZnFe2O4 alloy structure, along with the emergence of the LaFeO3 phase at grain boundaries, significantly slowed down the alloy's activation process, resulting in a maximum discharge capacity of 106 mAhg⁻¹. Over extended cycling, a correlation between discharge capacity, polarization behavior, and current density evolution was observed.