Recent Progress in Triboelectric Nanogenerators as a Renewable and Sustainable Power Source

The newly developed triboelectric nanogenerators (TENGs) provide an excellent approach to convert mechanical energy into electricity, which are mainly based on the coupling between triboelectrification and electrostatic induction. The TENG has the potential of harvesting many kinds of mechanical energies such as vibration, rotation, wind, human motion, and even water wave energy, which could be a new paradigm for scavenging large scale energy. It also demonstrates a possible route towards practical applications for powering electronic devices. This paper presents a comprehensive review of the four modes of TENGs: vertical contact-separation mode, in-plane sliding mode, single-electrode mode, and free-standing triboelectric-layer mode. The performance enhancements of TENGs for harvesting energy as a sustainable power source are also discussed. In addition, recent reports on the hybridized nanogenerator are introduced, which may enable fully self-powered electronic devices. Finally, the practical applications of TENGs for energy harvesting are presented.