Recent understanding of solid-liquid friction in ionic liquids

Ionic liquids (ILs)-solid interfacial phenomenon is undoubtedly one of the topic issues in energy related fields, especially bringing great challenges in the development of chemical engineering. Solid-ILs friction under microscale shows outstanding properties such as widely studied electro-controllability by surface potential or electric field, and promising performance of superlubricity. Vast applications, such as boundary lubrication and supercapacitors, have been benefiting from these studies. In this review, we summarized the recent advances of the measurements of solid-ILs friction, and focused on the microscale and fascinating findings. A brief tutorial for this topic, containing both experimental and theoretical methods, was also provided. It was anticipated that this review would help researchers grasp the emerging field and stimulate the advance of new ideas and methods in ILs on solids.