“…In 2012, triboelectric nanogenerators (TENGs) were first proposed as an effective energy harvester of various mechanical motions, including mechanical vibration, human movement, raindrops, and air/water flow [24,25,26,27,28,29,30]. TENGs are new types of energy harvesters that are lightweight and flexible with high output performance [31,32,33,34,35]. They are also referred to as green batteries, as they generate less pollution than traditional batteries, such as lead–acid and Ni–Cd batteries [36,37].…”