Modifying Specific Li-Sites of LiNH2 by Na: Study of Multication Hydride Li3Na(NH2)4 in Electrochemical Applications

Abstract

Optimizing the electrochemical properties of a solid-state electrolyte, for an all-solid-state Li-ion secondary battery, requires understanding the impact of structural modification on the relevant electrochemical properties of the electrolyte. By replacing Li+, with Na+, from the specific lattice site (2c) of tetragonal LiNH2, a crystalline multication ionic hydride Li3Na(NH2)4 is formed which is ordered-variant of LiNH2 with modified anion and cation dynamics. In comparison to LiNH2, the modified structure shows improved ionic conductivity (∼10–5 S/cm at 373 K), and a wide electrochemical operation window (−2 to +5 V) using a Li electrode. The presence of Na+, on the specific lattice site of LiNH2, alters the stability of Li+ cations and increases the number of the carrier ions in the multicationic structure of Li3Na(NH2)4. The study demonstrates the possibility of structural engineering by tuning the site-specific activity in multicationic, stable, lightweight, amide-based hydrides for electrochemical ...