Influence of electrolyte composition and temperature on behaviour of AB5 hydrogen storage alloy used as negative electrode in Ni–MH batteries

• Published in: Journal of power sources 2014-10, Vol.263, p.304-309
• Main Authors: Karwowska, Malgorzata, Jaron, Tomasz, Fijalkowski, Karol J., Leszczynski, Piotr J., Rogulski, Zbigniew, Czerwinski, Andrzej
• Format: Article
• Language: English
• Subjects: AB5 alloy; Alternative fuels. Production and utilization; Applied sciences; Diffusion coefficient; Direct energy conversion and energy accumulation; Electrical engineering. Electrical power engineering; Electrical power engineering; Electrochemical conversion: primary and secondary batteries, fuel cells; Energy; Exact sciences and technology; Fuels; Hydrogen; Hydrogen sorption; Limited volume electrode (LVE); Materials; Ni–MH battery
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2014.04.050

The AB5-type metal alloy (Mm–Ni4.1Al0.2Mn0.4Co0.45) has been investigated in different electrolytes (LiOH, NaOH, KOH, RbOH, CsOH). All of the electrochemical measurements have been performed using limited volume electrode technique (LVE). Thickness of the working electrode is nearly equal to the diameter of the grain (ca. 50 μm). Hydrogen diffusion coefficient has been determined using chronoamperometry. Hydrogen diffusion coefficient calculated for 100% state of charge reaches maximum value in KOH (DH = 4.65·10−10 cm2 s−1). We have obtained the highest value of capacity for the electrode in KOH and the lowest – in CsOH. The temperature influence on alloy capacity has been also tested. The alloy has been also characterised with SEM coupled with EDS, TGA/DSC and powder XRD. The unit cell of MmNi4.1Al0.2Mn0.4Co0.45 have been refined in the Cu5.4Yb0.8 structure type (a modified LaNi5 structure); the structure is unaffected by the electrochemical treatment. •The AB5-type metal alloy (Mm–Ni4.1Al0.2Mn0.4Co0.45) has been investigated in alkali metals hydroxides solutions.•Hydrogen diffusion coefficient has been determined using limited volume electrode (LVE) containing no binder additives.•The unit cell of LaMmNi4.1Al0.2Mn0.4Co0.45 have been refined in the Cu5.4Yb0.8 structure type.