Crystal chemistry and electronic structure of the metallic lithium ion conductor, LiNiN

Abstract

The layered ternary nitride LiNiN shows an interesting combination of fast Li+ ion diffusion and metallic behavior, properties which suggest potential applications as an electrode material in lithium ion batteries. A detailed investigation of the structure and properties of LiNiN using powder neutron diffraction, ab initio calculations, SQUID magnetometry, and solid-state NMR is described. Variable-temperature neutron diffraction demonstrates that LiNiN forms a variant of the parent Li3N structure in which Li + ion vacancies are ordered within the [LiN] planes and with Ni exclusively occupying interlayer positions (at 280 K: hexagonal space group P6m2, a = 3.74304(5) Å, c = 3.52542(6) Å, Z = 1). Calculations suggest that LiNiN is a one-dimensional metal, as a result of the mixed π- and σ-bonding interactions between Ni and N along the c-axis. Solid-state 7Li NMR spectra are consistent with both fast Li+ motion and metallic behavior. © 2007 American Chemical Society.