Effect of catalysts La2O3/Carbon on the electrochemical and kinetic properties of AB5-type hydrogen storage alloy

•LaNi5 + x wt. % La2O3/C (x = 0, 2, 4, 6, 8) alloy prepared by ball milling.•LaNi5-La2O3/C has excellent electrochemical kinetic properties.•LaNi5 + 6 wt% La2O3/C alloy has excellent HRD capability and discharge capacity.•La2O3/C improves more active sites and H diffusion channels for LaNi5 alloys.•La2O3/C can reduce the surface charge transfer resistance of LaNi5 alloy. In this investigation, LaNi5 + x wt.% La2O3/C (x = 0, 2, 4, 6, 8) composites were synthesized using ball milling technology, with La2O3/C produced via a modified blow molding carbonization method employed as an additive. Characterization of the composite samples phase composition and microstructure was conducted using XRD and SEM techniques, revealing that the incorporation of La2O3/C catalyst mitigated agglomeration phenomena during milling, thereby enhancing grinding efficiency. Electrochemical assessments demonstrated improved kinetic performance in the LaNi5-La2O3/C alloys compared to the pure milled counterparts, nevertheless, cycling stability of the alloy samples declined with increasing La2O3/C ratio. Notably, the LaNi5 + 6 wt% La2O3/C composite exhibited superior electrochemical kinetics, displaying accelerated activation kinetics and achieving the discharge capacity of 289.15 mAh/g after the second cycle, alongside excellent HRD performance. Simultaneously, with the increase in La2O3/C content, the hydrogen diffusion coefficient (D) of the alloy increased from 1.95 × 10−10 cm2/s (x = 0) to 2.16 × 10−10 cm2/s (x = 6), and the limiting current density reached a maximum value of 507.1 mA/g. This is due to La2O3/C providing more active sites and hydrogen transfer channels for the alloy due to its unique mesoporous structure and high specific surface area, thereby enhancing the electrochemical activity of the alloy surface. Additionally, the incorporation of La2O3/C reduced the apparent activation enthalpy (ΔrH*) for charge transfer on the alloy surface, enhancing the conductivity of the alloy. Therefore, La2O3/C demonstrates that carbon-supported rare earth oxide composites have broad prospects for achieving high energy density nickel-hydrogen batteries.