Triboelectric nanogenerators (TENGs) have shown promising potential for large-scale blue energy harvesting. However, the lack of reasonable designs has largely hindered TENG from harvesting energy from both rough and tranquil seas. Herein, a fully symmetrical triboelectric nanogenerator based on an elliptical cylindrical structure (EC-TENG) is proposed for all-weather blue energy harvesting. The novel elliptical cylindrical shell provides a unique self-stability, high sensitivity to wave triggering, and most importantly, an anti-overturning capability for the EC-TENG. Moreover, benefiting from its internal symmetrical design, the EC-TENG can produce energy normally, even if it was overturned under a rude oscillation in the rough seas, which distinguishes this work from previous reported TENGs. The working mechanism and output performance are systematically studied. The as-fabricated EC-TENG is capable of lighting 400 light-emitting diodes and driving small electronics. More than that, an automatic monitoring system powered by the EC-TENG can also monitor the water level in real-time and provide an alarm if necessary. This work presents an innovative and reliable approach toward all-weather wave energy harvesting in actual marine environments.

Traditional alternating current (AC) and direct current (DC) triboelectric nanogenerators (TENGs), which are implemented via the pairwise coupling of triboelectrification, electrostatic induction, and electrostatic discharge, have been widely explored in various fields. In this work, the comprehensive integration and synergetic utilization of triboelectrification, electrostatic induction, and electrostatic discharge in a single device for the first time is realized, achieving a dual‐functional TENG (DF‐TENG) to produce an AC/DC convertible output. Distinguishing from the conventional TENGs, the coupling of triboelectrification and electrostatic discharge enables charge circulation between the dielectric tribo‐layers, while electrostatic induction realizes charge transfer in the external circuit. This novel energy conversion mechanism has been proven to be applicable to a variety of materials, including polymers, fabrics, and semiconductors. The output mode of the DF‐TENG can be tuned by adjusting the slider motion state, and its constant output current and power density can reach 1.51 mA m−2 Hz−1 and 398 mW m−2 Hz−1, respectively, which are the highest records reported for constant DC‐TENGs to date. This work not only provides a paradigm shift to achieve AC/DC convertible output, but it also exhibits high potential for extending the TENG design philosophy.

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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.

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