A start of the renaissance for nickel metal hydride batteries: a hydrogen storage alloy series with an ultra-long cycle life

Abstract

Nickel metal hydride (Ni-MH) batteries have demonstrated key technology advantages for applications in new-energy vehicles, while the main challenge derives from the insufficient cycle lives (about 500 cycles) of their negative electrode materials—hydrogen storage alloys. As a result, progress in their development has been very limited over the past decades. Here we propose a theoretical framework to design a series of long-life and low-cost hydrogen storage alloys, by considering the electronegativities of the elements to enhance the alloys' corrosion resistance. Two novel candidate alloys, La_0.6Ce_0.3Y_0.1Ni_3.7Co_0.75Mn_0.3Al_0.35 and La_0.55Ce_0.3Y_0.15Ni_3.7Co_0.75Mn_0.3Al_0.35, show ultra-long cycle lives of 1325 and 1407 cycles, respectively, which are almost triple that of the commercial alloy (MmNi_3.55Co_0.75Mn_0.4Al_0.3) that is used in Ni-MH batteries. The usage costs of Ni-MH batteries based on these two alloys are only 1/4 of that of the lithium-ion battery, showing better market prospects for large-scale applications.