Enhanced electrochemical properties of LaFeO3 with Ni modification for MH–Ni batteries

Abstract

In this work, we synthesized LaFeO3–xwt%Ni (x = 0, 5, 10, 15) composites via a solid-state reaction method by adding Ni to the reactants, La2O3 and Fe2O3. Field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS) results revealed that Ni powders evenly dispersed among the LaFeO3 particles and apparently reduced their aggregation, which imparted the composites with a loose structure. Moreover, the Ni formed a conductive network, thus improving the conductivity of the composites. The maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 266.8 mAh·g–1 (x = 0) to 339.7 mAh·g–1 (x = 10). In particular, the high-rate dischargeability of the LaFeO3–10wt%Ni electrode at a discharge current density of 1500 mA·g−1 reached 54.6%, which was approximately 1.5 times higher than that of the pure LaFeO3. Such a Ni-modified loose structure not only increased the charge transfer rate on the surface of the LaFeO3 particles but also enhanced the hydrogen diffusion rate in the bulk LaFeO3.