The carbon brush/collector ring device of the hydro-generator unit often encounter problems such as overheating and sparking due to the contact problem of the friction interface.Ionic liquids have excellent lubricating properties under current-carrying conditions without destroying the electrical continuity between the contact surfaces,it can improve the safety and reliability of the unit’s operation.To further explore the adaptability,reliability and related mechanism of ionic liquids as lubricants for carbon brush/collector ring assemblies,three types of ionic liquids,including imidazoles,quaternary phosphines,and functionalized ionic liquids,were selected in the experiment,and the tribological performance under current-carrying friction conditions were evaluated.The results show that functionalized ionic liquids have the best lubricating performance among the three types of ionic liquids,which can reduce the friction coefficient and contact resistance to the greatest extent,making the interface contact more stable.The length of the alkyl side chain of imidazole ionic liquids strongly affects the lubricity of the current-carrying interface,and imidazole ionic liquids with longer alkyl side chains have better tribological properties.The current-carrying and lubricating properties of ionic liquids under current-carrying friction conditions are related to the properties of the lubricant and the double-layer protective composite film formed on the wear surface,and the functionalized ionic liquids with special functionalities are more easily adsorbed on the surface of carbon brushes to form strong lubricating film.