High\nLi⁺ and Mg²⁺ Conductivity\nin a Cu-Azolate Metal–Organic Framework

Abstract

A Cu-azolate metal–organic\nframework (MOF) uptakes stoichiometric\nloadings of Groups 1 and 2 metal halides, demonstrating efficient\nreversible release and reincorporation of immobilized anions within\nthe framework. Ion-pairing interactions lead to anion-dependent Li⁺ and Mg²⁺ transport in Cu₄(ttpm)₂·0.6CuCl₂, whose high surface area affords\na high density of uniformly distributed mobile metal cations and halide\nbinding sites. The ability to systematically tune the ionic conductivity\nyields a solid electrolyte with a Mg²⁺ ion conductivity\nrivaling the best materials reported to date. This MOF is one of the\nfirst in a promising class of frameworks that introduces the opportunity\nto control the identity, geometry, and distribution of the cation\nhopping sites, offering a versatile template for application-directed\ndesign of solid electrolytes.