High temperature phase transformation and low temperature electrochemical properties of La1.9Y4.1Ni20.8Mn0.2Al H2-storage alloy

Metal hydrides can theoretically store H-2 at extremely low temperatures in anodic nickel metal hydride batteries (Ni-MHBs). However, the evolution kinetics of H-2 was retarded at low temperatures and the H-2-storing capacity of the battery was reduced. Annealing temperature was hypothesized to be the key to regulate the phase composition and therefore, improve the electrochemical kinetics and performance in cold operating conditions. A new-type of La1.9Y4.1Ni20.8Mn0.2Al H-2-storage alloy was prepared and annealed at 1098, 1148, 1223 and 1323 K. At the annealing temperature of 1148 K, the alloy exhibited various crystalline structures and H-2 channel modifications, a high H-2 desorption plateau, resistance to oxidation/corrosion and favourable kinetic characteristics. All the measurements was performed at a temperature of 243 K, resulting in a maximum discharge specific capacity of 298.6 mAh g(-1), low-temperature discharge rate of 80.5%, and high-rate dischargeability of 62.8% at a current density of up to 300 mA g(-1). (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A new-type La1.9Y4.1Ni20.8Mn0.2Al H-2-storage alloy was prepared and annealed at 1148 K, showing improved electrochemical kinetics and high discharge performance in cold operating conditions.