Sliding electrical contacts are commonly applied in electrical connectors, such as conductive slip rings, pantographs, switches, and commutators. However, they suffer from several unavoidable problems caused by friction and wear, including high energy consumption, intermittent failures, limited life, and even failure disasters. In this study, we realized an ultralow-friction and long-distance wear-free state, defined as structural superlubricity (SSL), between sliding electrical interfaces under ambient conditions. A conductive SSL can be implemented in experiments with single-crystal graphite flakes on flattened metals, such as Au and Ni films. Furthermore, we found that depositing a 2 to 3-nm-thick diamond-like carbon (DLC) film on a nickel alloy can lead to an even lower resistivity than that of metals alone. In addition, we revealed the mechanism by which DLC films can improve the conductivity between graphite and metals through density functional-theory simulations. In addition, we prepared a prototype of the SSL slip ring and proved that it possessed ultralow friction, was wear-free, and had no intermittent failures. Consequently, our results demonstrate a unique type of electrical-contact interface for applications requiring conduction while sliding. Thus, we opened the door for SSL electromechanical coupling. Sliding electrical contacts which are used to transfer electrical power and/or signals play an important role in many fields ( 1– 8), such as in conductive slip rings, generator and motor brushes, pantographs of electrified railways, and commutators in generators. Sliding electrical contacts are generally expected to experience as little friction and wear as possible ( 7– 11). Their friction and wear, both mechanical and electrical, are much more complex and severe than nonelectrical contacts, and may cause intermittent failures, limited lifespan, and even short-circuit disasters resulting from wear debris. Additionally, sliding electrical contacts require a stable transmitted current and low contact resistance. They are vital for providing a stable power supply or electrical signal and for avoiding extra energy consumption. Consequently, noble metals ( 9, 12– 16), such as Au, Ag, Pt, and their alloys, are widely used on both sides of the contacts for better electrical conductivity and wear resistivity. Nevertheless, these sliding electrical contacts still suffer from wear, leading to limited life and unstable current transmissions, such as intermittent failure.
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