Mica-based triboelectric nanogenerators for energy harvesting

Abstract

Mica, an abundant raw clay mineral, has negatively charged silicate layers owing to the replacement of Si atoms with Al atoms; hence, it easily loses electrons during the friction contact with other materials. Mica is reported as the most positive inorganic non-metal triboelectric material. However, the triboelectric performance characteristics of mica and its influencing factors have not been sufficiently studied. Herein, a triboelectric nanogenerator (TENG) was fabricated using a raw mica layer and a polytetrafluoroethylene film as the positive and negative friction materials, respectively. The effects of the mica layer thickness, air-bubble defect in mica, applied force, and working frequency on the TENG performance were investigated. Mainly owing to the excellent positive triboelectric property and extremely flat and smooth surface of mica, the mica-based TENG achieved the maximum output power density of 62.82 mW/m2. A multi-layer sandwich mica-based TENG generated −147 V under the force of 1 N. Moreover, the mica layers attached to a shoe sole could harvest mechanical energy when walking on a plastic floor, thereby directly lighting four LEDs. This study reveals that mica exhibits excellent triboelectric performance and is a promising positive friction layer candidate for environmentally friendly TENGs.