Lithium-ion-conducting glass-ceramics of a boron-containing alkali sodalite Li₈B₆Si₆O₂₄Cl₂

Alkali sodalites containing boron (B) as the main framework cation are scarce. A cubic lithium sodalite containing B in the sodalite framework, Li8B6Si6O24Cl2, whose lattice parameter [7.8856(1) Å] is the smallest of the known alkali sodalites, has been discovered, and Li8B6Si6O24Cl2-based glass-ceramics have been prepared from the Li2O–B2O3–SiO2–LiCl quaternary system. The relative density of the resulting glass-ceramics and weight fraction of Li8B6Si6O24Cl2 in their crystalline part reached ∼0.98 and ≳0.9, respectively. The dc conductivity recorded at 60 °C with non-blocking Li–Au electrodes was ∼1.5 × 10−6 and ∼2.3 × 10−7 S cm−1 in partially and highly crystallized samples, respectively, and the activation energy of conductivity was ∼0.5–0.6 eV. The glass-ceramics were stable in contact with Li metal and the transport number of Li+ ion was ∼0.95.