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 10⁻⁴ S 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.