Effects of electroless composite plating Ni–Cu–P on the electrochemical properties of La–Mg–Ni-based hydrogen storage alloy

• Published in: Applied surface science 2013-04, Vol.271, p.210-215
• Main Authors: Yang, Shuqin, Liu, Hongping, Han, Shumin, Li, Yuan, Shen, Wenzhuo
• Format: Article
• Language: English
• Subjects: Composite plating; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electrochemical kinetic characteristics; Exact sciences and technology; La–Mg–Ni-based alloys; Ni–Cu–P; Physics
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2013.01.161

► Electroless composite plating Ni–Cu–P treatment was applied to La–Mg–Ni-based alloys. ► Ni–Cu–P particles deposited on the alloy surface uniformly and compactly. ► Ni–Cu–P coatings enhanced the catalytic activity of the alloy and acted as a protective layer. ► Electrochemical characteristics have been improved effectively by the Ni–Cu–P metallic layers. In order to improve the overall electrochemical performances of La–Mg–Ni-based hydrogen storage alloy, electroless composite plating Ni–Cu–P treatment was applied to La0.88Mg0.12Ni2.95Mn0.10Co0.55Al0.10 alloy powders. SEM observation showed that the composite treatment resulted in spherical particles more densely depositing on the alloy surface, and subsequently EDS analysis indicated that the particles should be Ni–Cu-P compounds. These particle coatings enhanced the conductivity and the catalytic activity, besides acting as a protective layer, thereby improving the electrochemical properties of the alloy. The discharge capacity of the alloy electrode noticeably increased from 338mA/g to 361mA/g. The capacity retention after 200 charge/discharge cycles and the high rate dischargeability (HRD) at 1500mA/g discharge current density of the alloy electrode increased from 76.0% and 27.7% to 84.8% and 37.0%, respectively. The superior HRD value is believed to be ascribed to the improved kinetics from the compact metallic layers on the surface.