The structural change of the negative electrode of a Ni-MH battery has been studied using a special sample holder for in-situ X-ray diffraction. The special sample holder consists of a reaction cell for charge or discharge, i.e. hydrogen absorption or hydrogen desorption, respectively, and a pressurizer to exclude an electrolyte. Useful X-ray diffraction spectra are required for this study.

By pressing the polymer thin film between the reaction cell and the pressurizer to the negative electrode, the pressure in the pressurizer was increased and the electrolyte between the negative electrode and the polymer thin film was then excluded. As a result, this new holder was found to be a very useful and unique attachment for the in-situ X-ray measurement of the structural change with charging and discharging processes of the negative electrode.