Stannaborates: tuning the ion conductivity of dodecaborate salts with tin substitution

Abstract

Metal substituted dodecaborate anions can be coupled with alkali metal cations to have great potential as solid-state ion conductors for battery applications. A tin atom can replace a B–H unit within an unsubstituted dodecaborate cage to produce a stable, polar divalent anion. The chemical and structural change in forming a stannaborate results in a modified crystal structure of respective group 1 metal salts, and as a result, improves the material's ion conductivity. Li₂B₁₁H₁₁Sn shows high ion conductivity of ∼8 mS cm⁻¹ at 130 °C, similar to the state-of-the-art LiCB₁₁H₁₂ at these temperatures, however, obtaining high ion conductivity at room temperature is not possible with pristine alkali metal stannaborates.