Gaseous Phase and Electrochemical Hydrogen Storage Properties of Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) for Nickel Metal Hydride Battery Applications
Structural, gaseous phase hydrogen storage, and electrochemical properties of a series of the Ti50Zr1Ni44X5 (X = Ni, Cr, Mn, Fe, Co, or Cu) metal hydride alloys were studied. X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed the multi-phase nature of all alloys, which were composed of a stoichiometric TiNi matrix, a hyperstoichiometric TiNi minor phase, and a Ti2Ni secondary phase. Improvement in synergetic effects between the main TiNi and secondary Ti2Ni phases, determined by the amount of distorted lattice region in TiNi near Ti2Ni, was accomplished by the substitution of an element with a higher work function, which consequently causes a dramatic increase in gaseous phase hydrogen storage capacity compared to the Ti50Zr1Ni49 base alloy. Capacity performance is further enhanced in the electrochemical environment, especially in the cases of the Ti50Zr1Ni49 base alloy and Ti50Zr1Ni44Co5 alloy. Although the TiNi-based alloys in the current study show poorer high-rate performances compared to the commonly used AB5, AB2, and A2B7 alloys, they have adequate capacity performances and also excel in terms of cost and cycle stability. Among the alloys investigated, the Ti50Zr1Ni44Fe5 alloy demonstrated the best balance among capacity (394 mAh·g−1), high-rate performance, activation, and cycle stability and is recommended for follow-up full-cell testing and as the base composition for future formula optimization. A review of previous research works regarding the TiNi metal hydride alloys is also included.
Electrochemical properties of titanium-based hydrogen storage alloy prepared by solid phase sintering
Abstract The structure and electrochemical properties of titanium-based hydrogen storage alloy prepared by solid phase sintering at 1123 K were investigated. The result of X-ray diffraction (XRD) showed that the sintered alloy mainly consists of Ti 2 Ni phase coexisting with TiNi, TiNi 3 and Ni phases. The alloy had a maximum discharge capacity of 205 mAh/g at a discharge current density of 60 mA/g and showed a discharge capacity of 146 mAh/g at 150 mA/g. The results of linear polarization (LP) and potential-step measurement presented that the exchange current density and hydrogen diffusion efficient of the alloy were 100 mA/g and 4.2 × 10 −9  cm 2 /s, respectively. The electrochemical performance of the alloy could be effectively improved by using solid phase sintering.
Modern Lexicography: An Introduction
Chapter 1: Dictionaries and the Dictionary Chapter 2: The Lexicographical Scene of English-Speaking Countries Chapter 3: The Historical Origins of the General-Purpose Dictionary Chapter 4: General-Purpose Dictionaries and Society Chapter 5: What are General-Purpose Dictionaries Really For? Chapter 6: The Linguistic Traditions ofr Lexicography Chapter 7: Whither Lexicography? Conclusion