Study on the high-temperature electrochemical performance of perovskite-type oxide LaFeO3 with carbon modification

Abstract

To further improve the high-temperature electrochemical performance of perovskite-type oxides, the LaFeO3 carbon-coated composites used as the negative materials for MH-Ni batteries were obtained using the polyaniline (PANI) pyrolysis method. Transmission electron microscopy (TEM) results revealed that LaFeO3 particles were evenly coated with carbon layers, forming a core–shell structure. The carbon layers could enhance the conductivity and electrocatalytic activity, speeding up hydrogen protons transferring from electrolyte to electrode interface. Furthermore, the carbon coatings hindered the LaFeO3 particles from aggregating into stacks and reduced the corrosion of the LaFeO3 electrodes. At an elevated temperature (60 °C), owing to the carbon coatings, the maximum discharge capacity of the LaFeO3 electrodes remarkably increased from 211 mAh g−1 to 358 mAh g−1, and charge retention (CR) increased from 85.4% to 94.6%. Also, the high rate dischargeability at a discharge current density of 1500 mA g−1 (HRD1500) increased from 21.0% to 37.6%, and the capacity retention rate after 100 cycles (S100) increased from 63.0% to 70.9%.