An Effective Activation Method for Industrially Produced TiFeMn Powder for Hydrogen Storage

This work proposes an effective thermal activation method with low technical effort for industrially produced titanium-iron-manganese powders (TiFeMn) for hydrogen storage. In this context, the influence of temperature and particle size of TiFeMn on the activation process is systematically studied. The results obtained from this investigation suggest that the activation of the TiFeMn material at temperatures as low as 50 {\deg}C is already possible and that an increase to 90 {\deg}C strongly reduces the incubation time for activation, i.e. the incubation time of the 90 {\deg}C/90 {\deg}C sample is about 0.84 h while ~ 277 h is required for the 50 {\deg}C/50 {\deg}C sample. Selecting TiFeMn particles of larger size also leads to significant improvements in the activation performance of the investigated material. The proposed activation routine makes it possible to overcome the oxide layer existing on the compound surface, which acts as a diffusion barrier for the hydrogen atoms. This activation method induces further cracks and defects in the powder granules, generating new surfaces for hydrogen absorption with greater frequency, and thus leading to faster sorption kinetics in the subsequent absorption-desorption cycles.