N-Butyl Pyridinium Diiodido Argentate(I): A One-Dimensional Ag-I Network with Superior Solid-State Ionic Conductivity at Room Temperature

Abstract

A new solid-state material, N-butyl pyridinium diiodido argentate(I), is synthesized using a simple and effective one-pot approach. In the solid state, the compound exhibits 1D ([AgI2]−)n chains that are stabilized by the N-butyl pyridinium cation. The 1D structure is further manifested by the formation of long, needle-like crystals, as revealed from electron microscopy. As the general composition is derived from metal halide-based ionic liquids, the compound has a low melting point of 100–101 °C, as confirmed by differential scanning calorimetry. Most importantly, the compound has a conductivity of 10−6 S cm−1 at room temperature. At higher temperatures the conductivity increases and reaches to 10−4S cm−1 at 70 °C. In contrast to AgI, however, the current material has a highly anisotropic 1D arrangement of the ionic domains. This provides direct and tuneable access to fast and anisotropic ionic conduction. The material is thus a significant step forward beyond current ion conductors and a highly promising prototype for the rational design of highly conductive ionic solid-state conductors for battery or solar cell applications.