Effects of surface modification on surface structure and electrochemical properties of Mm(Ni,Co,Mn,Al) 5.0 alloy powder

• Published in: Journal of alloys and compounds Vol. 377; no. 1; pp. 174 - 178
• Main Authors: Yanagimoto, K., Majima, K., Sunada, S., Sawada, T.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 08-09-2004; Elsevier
• Subjects: Applied sciences; Chemical and electrochemical properties; Electrochemical reactions; Energy storage materials; Exact sciences and technology; Metals. Metallurgy; Powder metallurgy; Transmission electron microscopy; Electrochemical reactions; Energy storage materials; Transmission electron microscopy; Powder metallurgy; Electrochemical properties; Transition metal; Rare earth metal alloy; Misch metal; Atomizing; Nanocrystal; Nickel alloy; Surface structure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2003.12.039

The electrochemical properties of MmNi
5-type metal hydride powders produced by gas atomization were improved by acid surface modification. FIB specimen preparation followed by FE-TEM observation was used to analyze the surface structure before/after surface modification. The original oxide layer of the surface was removed and a nickel rich layer was formed by acid treatment. The structure of the nickel rich surface differed with the treatment conditions. For acetic acid treated powder prepared in heated solution, a nanocrystalline nickel layer was formed at the surface. In the absence of any auxiliary conductivity additives, discharge capacity of this powder was improved to 254
mAh/g versus 52
mAh/g for non-treated powder and 62
mAh/g for hydrochloric acid treated powder.