Electrochemical and kinetic performance of amorphous/nanostructured TiNi-based intermetallic compound with Nb substituti
- PDF / 565,899 Bytes
- 11 Pages / 584.957 x 782.986 pts Page_size
- 57 Downloads / 187 Views
ARTICLE Electrochemical and kinetic performance of amorphous/ nanostructured TiNi-based intermetallic compound with Nb substitution synthesized by mechanical alloying Roozbeh Abbasi and Seyed Farshid Kashani-Bozorga) Center of Excellence for Surface Engineering and Corrosion Protection of Industries, School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran 1417466191, Iran (Received 28 April 2018; accepted 22 June 2018)
The electrochemical behavior of TiNi(1x)Nbx (x 5 0, 0.05, 0.1, 0.2) ternary intermetallic compounds synthesized by mechanical alloying was investigated and compared to that of binary TiNi. The structure of 20-h milled product with initial stoichiometric composition of TiNi0.95Nb0.05 was found to be amorphous/nanostructured. Upon cycling, this ternary milled product exhibited the highest discharge capacity (166.1 mA h/g) after 10 cycles and best cycle stability (;91%) while those of the binary TiNi were 147 mA h/g and ;83%, respectively; i.e., slight amount of Nb substitution (0.05 mol) for Ni in the TiNi not only increased discharge capacity and cycle stability but also enhanced the kinetics of hydrogen absorption/desorption through increasing the exchange current density and hydrogen diffusion coefficient. However, additional Nb content was found to have negative effect on electrochemical properties; this was related to the existence of Nb element in addition to the ternary amorphous/nanocrystalline structures.
I. INTRODUCTION
Considered as a promising rechargeable battery, nickel metal hydride (Ni–MH) batteries have been used in portable electronics and high power applications in the past decades.1 With the advent of Li-ion batteries, however, Ni–MH batteries have faced serious challenges mostly due to the higher energy density, no memory, and lower self-discharge offered by the newer battery technology. Nevertheless, Ni–MH batteries continue to develop and be utilized especially in high power application industries such as hybrid electric vehicles thanks to their higher safety and energy efficiency under high current rates, superior environmental friendliness, greater applicability in a broad temperature range, and lower production costs.1 The hydrogen-absorbing negative electrode of Ni–MH batteries has been the subject of numerous studies over the years intending to improve the performance in terms of discharge capacity, high rate discharge ability (HRD), cycle life, and nonambient temperature performance. Among the hydrogen storage alloys (HSAs), the well-known shape memory TiNi intermetallic compound shares unique hydrogen storage properties in close-to-ambient conditions of pressure and temperature making it a promising candidate as an AB-type HSA to be used as the negative electrode of a)
Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2018.231 J. Mater. Res., 2018
Ni–MH batteries.2 It typically crystallizes in a high temperature (austenite) cubic CsCl-type structure (Pm3m) and has the gaseous hydrogen stor
Data Loading...
