Influence of SynthesisMethods on the Structure andHydrogenation Properties of TiNi

Batteries with a low amount of critical raw materials in their electrode composition are needed for a sustainable energy transition. Today, nickel–metal hydride (Ni-<i>M</i>H) commercial batteries contain strategic rare-earth elements in the negative electrode, but alternative materials exist. The synthesis efficiency and hydrogenation properties of the rare-earth-free TiNi compound are investigated here for three different routes: induction melting (IM), mechanical alloying (MA), and powder metallurgy (PM). Reaction yields of 76, 30, and 95% were obtained for IM, MA, and PM methods, respectively. IM and PM samples have similar hydrogenation capacity both by solid–gas (∼ 1.25 H/f.u. at <i>T</i> = 100 °C and <i>P</i>_H2 = 20 bar) and electrochemical (∼ 165 mAh g ^–1 at RT and C/10 regime) reactions. In contrast, the MA sample exhibits lower solid–gas (0.9 H/f.u.) and electrochemical (107 mAh g ^–1) capacities under the same hydrogenation conditions. Moreover, the PM sample outperforms both the IM and MA ones in hydrogenation kinetics. Crystallinity and diffusion lengths were found to determine the hydrogenation properties in TiNi. PM emerged as the most suitable method, offering not only the highest yield and enhanced hydrogenation properties but also easier powder processing and shorter synthesis time. These results highlight PM as an efficient method for producing high-performance TiNi electrodes for Ni-<i>M</i>H batteries.