Effect of Mechanical Milling on the Structure and Electrochemical Properties of Ti₂Ni Alloy in an Alkaline Battery

Abstract

Mechanical milling (MM) has been used to treat the crystalline Ti 2 Ni alloy prepared by solid-state sintering. Changes of the structure, morphology, and electrochemical properties were investigated. The particle size of the alloy decreases first and then increases after the milling. Moreover, MM contributes to a decrease in grain size and the formation and increase of the amorphous phase by increasing the milling time, resulting in improvements of the antipulverization ability and cycle life after the milling. The result of linear polarization indicates that the exchange current density, determined by the competition between the specific surface area and amorphous phase, increases first and then decreases. The amorphous phase is beneficial to hydrogen diffusion according to the result of potential-step measurement. The electrochemical properties of Ti 2 Ni alloy are significantly improved by the non-equilibrium processing technology.

The Current Status of Hydrogen Storage Alloy Development for Electrochemical Applications

“…Recently, a study on substituting Ni in TiNi with various modifiers revealed that Fe, Co, and Cr increase the electrochemical capacity up to 400 mAh·g −1 with good activation performance [ 165 ]. Zhao et al fabricated amorphous Ti 2 Ni alloy by solid-state sintering and ball milling [ 166 ], and the resulting material shows improved cycle stability but also lower capacity compared to crystalline Ti 2 Ni. Annealing treatment was then proposed in addition to sintering and ball milling, which results in a thicker oxide layer on the surface of amorphous Ti 2 Ni and improves both capacity and charge retention of the alloy [ 167 ].…”

Structural evolution and electrochemical hydrogenation behavior of Ti2Ni alloy

“…The increase in the temperature facilitates the hydrogen diffusion within the bulk alloy. The hydrogen diffusion coefficient, 3.8 Â 10 À12 cm 2 /s, of the alloy prepared by the induction melting is lower than that, 6.2 Â 10 À12 cm 2 /s, of the alloy prepared by solid sintering using raw materials of TiH 2 and Ni [14], which is probably ascribed to that the solid sintering contributes to the formation of a micro-porous structure, facilitating the hydrogen diffusion. Fig.…”

“…The hydrogen diffusion coefficient calculated by Eq. (2) is also listed in Table 1 by considering an average particle radius of 6 mm [14]. The increase in the temperature facilitates the hydrogen diffusion within the bulk alloy.…”

“…Elemental substitution for Ti 2 Ni alloy showed slight improvements in the electrochemical hydrogenation properties [11e13]. Zhao et al [14] claimed that the amorphous structure of Ti 2 Ni alloy was beneficial to restrain that capacity loss. In this work, we systematically investigated the structure and hydrogen storage properties of a crystalline Ti 2 Ni alloy in order to achieve a better understanding of the mechanism of its electrochemical hydrogen absorption/ desorption, which showed significant discrepancies from that reported by Luan et al [10].…”

Mechanical Milling: a Top Down Approach for the Synthesis of Nanomaterials and Nanocomposites

“…A TiN-TiB 2 composite was fabricated by ball milling of the mixture for 70 h and then sintering at 5 GPa, 1300℃. X. Zhao et al [94] used mechanical milling to treat the crystalline Ti 2 Ni alloy prepared by solid-state sintering. The particle size of the alloy decreased first and then increased after the milling.…”