Electrochemical reduction of La(Ni3.6Co0.7Al0.4Mn0.3) (LaMM) deuterides investigated by in situ neutron powder diffraction: Following the metal-hydride phase transition under technical operating conditions in a KOD electrolyte

We investigated the first charge cycle of LaNi3.6Co0.7Al0.4Mn0.3 (LaMM) during electrochemical reduction in a 6N KOD (potassium deuteroxide) electrolyte, corresponding to conditions of commercially used batteries by means of in situ neutron powder diffraction. Our measurement allowed to directly analyze the phase range of the α and β phases and the related volume change as a function of the charge transfer. The intercalation of hydrogen was followed in a home-made electrochemical cell, installed on the high intensity neutron powder diffractometer (DMC) at the Swiss continuous spallation neutron source. Compared to previous investigations following mostly in situ charging under pressure (following pressure–composition–temperature isotherms, PCT), our experimental conditions reflect closely the process as used in technical battery applications. ► In-situ study of the phases and volume expansion in a commercial LaNi5- type hydride. ► In-situ chemical reduction and neutron diffraction of La(Ni6Co0.7Al0.4Mn0.3) (LaMM). ► Neutron diffraction under operating conditions as in commercial button cells. ► Hydride volume expansion clearly quantified by alpha/beta phases contributions.