A Bistable Triboelectric Nanogenerator for Low‐Grade Thermal Energy Harvesting and Solar Thermal Energy Conversion

Abstract Converting ubiquitous ambient low‐grade thermal energy into electricity is of great significance for tackling the fossil energy shortage and environmental crisis but poses a considerable challenge. Here, a novel thermal‐driven triboelectric nanogenerator (TD‐TENG) is developed, which utilizes a bimetallic beam with a bi‐stable dynamic feature to induce continuous mechanical oscillations, and the mechanical motion is then converted into electric power using a contact‐separation TENG. The thermal process inside the device is systematically investigated and effective thermal management is conducted accordingly. After optimization, the TD‐TENG can produce a power density of 323.9 mW m −2 at 59.5 °C, obtaining the highest record of TENG‐based thermal energy harvesters. Besides, the first prototype of TENG‐based solar thermal harvester is successfully demonstrated, with a power density of 364.4 mW m −2 . Moreover, the TD‐TENG can harvest and dissipate the heat at the same time, exhibiting great potential in over‐heated electronics protection as well as architectural energy conservation. Most importantly, the operation temperature range of the TD‐TENG is tunable by adjusting the bimetal parameters, allowing the device a wide and flexible working thermal gradient. These unique properties validate the TD‐TENG is a simple, feasible, cost‐effective, and high‐efficient low‐grade thermal energy harvester.