Progress in development of H– conductors
2021 Volume 46 Issue 1 Pages 12-17
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2021 Volume 46 Issue 1 Pages 12-17
The conduction of hydride ions (H–) is particularly attractive because these ions are similar in size to oxide and fluoride ions that are suitable for fast ionic conduction, while they also exhibit strong reducing properties through the standard H−/H2 redox potential (−2.3 V), which is comparable to that of Mg/Mg2+ (−2.4 V). Hydride ion conductors may therefore be applied in energy storage/conversion devices with high energy densities. Recently, we have developed a series of K2NiF4-type oxyhydrides, La2−x−ySrx+yLiH1−x+yO3−y, which are equipped with anion sub-lattices that exhibit flexibility in the storage of H−, O2−, and vacancies. More specifically, the all-solid-state Ti/La2−x−ySrx+yLiH1−x+yO3−y/TiH2 cell exhibited a redox reaction with hydrogen storage/desorption on the electrodes. The present success in the construction of this all-solid-state electrochemical cell exhibiting H− diffusion confirms not only the capability of the oxyhydride system to act as a solid hydride electrolyte, but also the possibility of developing electrochemical solid devices based on H− conduction for the first time.
