Anode properties of Al2O3-added MgH2 for all-solid-state lithium-ion batteries

Abstract

All-solid-state lithium-ion batteries (LIBs) with aluminum oxide (Al2O3)-added magnesium hydride (MgH2), (100 − y)MgH2-yAl2O3 (y = 1, 5, 25 mol%) were fabricated, and their anode properties were investigated. Coulombic efficiency is increased by adding Al2O3. In addition, cycle properties are improved by adding Al2O3 as well. 27Al-magic angle spinning (MAS) nuclear magnetic resonance (NMR) and some other analyses were carried out to approach the mechanism of this additive, by which the coulombic efficiency and the cycle properties were improved. Although the niobium oxide (Nb2O5)-added MgH2 also showed the better kinetic properties compared with pristine MgH2 in our previous report, Nb2O5 should be well known as the best catalyst for hydrogen ab/desorption properties of MgH2. However, it is revealed that the hydrogen desorption temperature does not depend on Al2O3 contents. According to some detailed analyses, pentahedral-coordinated aluminum atom was successfully observed after Li insertion reaction by 27Al MAS NMR measurement. From the other experimental results, it is concluded that this pentahedral-coordinated aluminum atom could play an important role on the increasing coulombic efficiency and cycle properties.