Synthesis of a cubane-like anion [Re4As2S2(CN)12]6− for coordinate regulation of Na+ ion transport

Abstract

A cyanometallate cluster compound Na₆[Re₄As₂S₂(CN)₁₂] (NRASCN) as a Na⁺ ionic conductor, has been synthesized by a simple solid-state synthetic route. The X-ray structural analysis shows that the structure contains a typical rhenium tetrahedron that is surrounded by the mixed ligands of μ₃-As and μ₃-S to form cubane-like cluster cores. The Na⁺ ions are well-distributed around cyanide groups and form a disordered sublattice spanning three and four Na crystallographic sites. The Na⁺ ionic conductor NRASCN exhibits a high ionic conductivity of 1.05 × 10⁻⁵ S cm⁻¹ at 25 °C. Using the PEO–NaTFSI–NRASCN composite electrolyte, an all-solid-state battery with a Na metal anode and a NaVPO₄ (NVP) cathode, shows a high specific capacity (109.4 mA h g⁻¹) and stable long-term cycling performance (1000 cycles) at a rate of 0.3 C.