Achieving high contact-electrification charge density on inorganic materials

Triboelectric nanogenerator has been considered as a potential choice for the booming Internet of Things as distributed energy supply unit. However, the widely used organic materials are restricted by weak aging/temperature resistance in severe conditions. In comparison, inorganic materials possess better aging/temperature resistance, but they have been overshadowed by their inferior charge density. To address this issue, inorganic single crystals have been used as a friction layer to improve the contact electrification effect of inorganic materials. This approach enhances the charge density to 170 μC m−2 and 335 μC m−2, reaching its theoretical value in air and under vacuum, respectively. Meanwhile, a quantitative understanding of the charge transfer mechanism between single crystal and metal is established, which is strongly influenced by the work function and atom species at the interface. This work provides theoretical guidance for the contact electrification process of inorganic material, and breaks its shackle of inferior charge density, greatly expanding the triboelectric series and laying a foundation for the application of triboelectric nanogenerator in extreme environments.