Professors Genki Kobayashi (Genki Kobayashi) and Ryoji Kanno (Ryoji Kanno) of Tokyo Institute of Technology and from the Institute of Molecular Science (ISM), Japan Agency for the Advancement of Science and Technology (JST), Kyoto University (Kyoto University) and the High Energy Accelerator Research Institute (KEK) The researchers inferred that hydride ions (H-) are expected to be used in high-energy-density storage devices. Using oxygen hydride solid-state batteries, researchers demonstrated for the first time that pure hydride ions (H-) can conduct in oxides.
The crystal lattice of metal hydrides is often not flexible enough to make hydride ions (H-) difficult to transmit, which is why researchers turn to oxygen hydrides—oxygen and hydrogen share the same lattice position. Another challenge is the high electron-donating properties of hydrogen, which means that the electrons will dissociate from the hydride ion (H-) and protons and electrons will appear, causing electrons (not hydride ions) to migrate. Therefore, the research team had to find another system that contained cations in which more electrons were donated than hydrogen.
The crystal structure of La2-x-ySrx+yLiH1-x+yO3-y(x=0, y=0, 1, 2)
The researchers examined how the structure of the oxyhydrogen compound changes with the composition and synthesis conditions, and at the same time studied the characteristics of the electronic structure, and found that the ionic Li-H bond in the compound, that is, the presence of hydride ions (H –).
All solid-state hydride ion (H–) battery: the discharge curve of a solid-state battery with Ti/o-La2LiHO3/TiH2 structure.
The middle illustration is a schematic diagram of the battery and the electrochemical reaction that it may cause
Next, the researchers used La2LiHO3 in the orthogonal structure phase (o-La2LiHO3) as the electrolyte of the battery (with titanium anode and hydride cathode). Because the electrode phase change caused by the discharge is consistent with the Ti-H phase, it shows the migration of hydride ions. The researchers concluded: "The successful construction of an all-solid-state electrochemical cell with hydride ion (H–) diffusion not only demonstrates the ability of oxygen hydride to be used as a hydride ion (H–) solid electrode, but also contributes to the development of An electrochemical solid-state element that conducts hydride ions (H–)."