Long-life Ni-MH batteries with high-power delivery at lower temperatures: Coordination of low-temperature and high-power delivery with cycling life of low-Al AB5-type hydrogen storage alloys

Abstract

Although a low-Al or an Al-free design is an efficient way to develop low-temperature and high-rate metal hydride alloys, the cycling life of these alloys is poor. Our strategy is to employ B-side anti-corrosion elements (e.g., Fe, Si, Sn, Cu) to coordinate the low-temperature and high-power delivery with cycling life. We confirmed that excellent electrochemical kinetics (i.e., surface catalytic and bulk H-diffusion ability) is the primary condition for low-temperature and high-rate delivery, while it reverses with anti-corrosion ability. As a result, the low-temperature dischargeability (LTD), high-rate dischargeability (HRD) and peak power (Ppeak) progressively decrease with Ni, Si, Cu, Fe, Sn and Al substitution, but the cycling stability successively increases with Ni, Si, Fe, Sn, Cu and Al substitution. Based on the thermodynamics and the coordination of the LTD, the HRD and Ppeak with the cycling life, the (LaCe)1.0(NiCoMn)4.85Al0.05Cu0.1 alloy presents the best overall electrochemical properties. Notably, when using an as-designed Cu-doped anode, the assembled commercial 100 Ah prismatic Ni-MH batteries present excellent power delivery at −40 °C.