Superlubricating electrical contact between graphite layers

Abstract

High-conductivity sliding electrical contact with low friction plays a significant role in the long life and high reliability of electromechanical systems. Reducing friction needs weak interfacial electronic coupling; in contrast, enhancing conductivity requires strong coupling; thus it is a serious challenge to achieve high conductivity with low friction. Here, using our self-developed thermally assisted mechanical exfoliation and transfer (TAMET) method, we experimentally achieved superlubricating electrical contact by establishing a sliding electrical system between graphite layers (Gr); the friction coefficient was as low as 0.0004, and the electric current density was as high as 510 A/cm². Compared with the commercial Ir atomic force microscopy (AFM) tip–Gr contact, the friction force of incommensurate graphene layer friction is an order of magnitude lower, yet it has a similar high electrical conductivity. On the basis of the electronic property fluctuation (EPF) model and first principles calculations, we revealed that the sliding energy barrier remains almost unchanged under an applied current because of the negligible electron transfer variation during the sliding process. We offer a method for achieving superlubricating electrical contact with high conductivity and low friction, shedding light on improving the service life and reliability of sliding electrical contacts in a wide range of electromechanical systems.