Effect of Ni-B-C on Electrochemical Properties of La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20 Hydrogen Storage Alloy

Ni-B-C powder prepared by ball milling was introduced to improve the electrochemical properties of new AB(3)-type hydrogen storage alloy La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20. The phase structure and surface morphology of the alloy were investigated by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results show that the alloy remains the original LaNi5 and La2Ni7 phases and some little particles appear on the surface of alloy after adding Ni-B-C. The addition of Ni-B-C improves the maximum discharge capacity and capacity retention rate. After adding a mass fraction of 10% Ni-B-C, the maximum discharge capacity increases from 346 mAh/g to 363 mAh/g, and the capacity retention rate after 50 cycles increases from 70% to 77%. The exchange current density I-0 and the limiting current density I-L reach 106 and 987 mA/g, respectively. Potentiodynamic polarization indicates that the corrosion resistance of the electrodes is enhanced. The Ni-B-C powder can improve the comprehensive electrochemical properties of the hydrogen storage alloy.