Electrical Conductivity in Tetra- <i>n</i> -butylammonium Formate, Acetate, and Oxalate Semiclathrate Hydrates

Semiclathrate hydrate (SCH) is a crystalline inclusion compound promising for use as an electroconductive and energy-storage material. In this study, the electrochemical properties of three single-crystalline tetra-n-butylammonium (TBA) carboxylate SCHs, namely, TBA-formate, TBA-acetate, and (TBA)2-oxalate SCHs, were investigated. All three SCHs exhibit Arrhenius-type conductivity, with TBA-formate SCH demonstrating the highest electrical conductivity. Electrochemical impedance analyses correlated the differences in carrier concentration among the SCHs with variations in electrical conductivity. These findings suggest that defect generation within the hydrogen-bonding network plays a significant role in enhancing the electrical conductivity, potentially serving as a key conduction mechanism in these materials. These results contribute to a deeper understanding of the potential uses of SCHs as advanced materials.