Type Of Triboelectric Nanogenerators Research Articles

Schottky model for triboelectric temperature dependence

The triboelectric effect, charging by contact, is the working principle in a device called a triboelectric nanogenerator. They are used as efficient energy transducers in energy harvesting. In such generators the charging of surfaces at contact is followed by a separation of the surfaces increasing the electrical energy which can subsequently be used. Different materials have different triboelectric potentials leading to charging at contact. The temperature dependence of the charging has just recently been studied: the triboelectric effect is decreasing with temperature for a generator of Al-PTFE-Cu. Here, we suggest a mechanism to explain this effect assuming ion transfer using a two-level Schottky model where the two levels corresponds to the two surfaces. The difference in binding energy for ions on the two surfaces then enters the formula for charging. We fit the triboelectric power density as a function of temperature obtained from a two-level Schottky model to measured data for nanogenerators made of Al-PTFE-Cu found in three references. We obtain an average separation energy corresponding to a temperature of 365 K which is of the right magnitude for physically adsorbed atoms. We anticipate that this model could be used for many types of triboelectric nanogenerators.

Hybrid operation of triboelectric nanogenerator for electricity generation by a low-temperature differential heat engine

Summary There are many types of triboelectric nanogenerators (TENGs) which differ in their operational modes (contact mode, sliding mode, etc.), converting mechanical energy into electrical energy. This paper introduces electricity generation from a small low-temperature differential heat engine capable of utilizing low-grade thermal energy. The engine is similar to the Gamma-type Stirling engine and could run on temperature differentials ranging from 90 down to a few degrees Celsius. The work presented here gives technical details of how a small low-temperature differential heat engine could be integrated with a TENG for electricity generation. Two different schemes were tested for the operation of TENG: one in non-contact sliding mode and the other in vertical contact-separation mode. For the temperature difference of 74.4 °C, the former delivered a maximum output voltage of 70 V whereas the latter resulted in 35 V. A maximum combined output voltage of 105 V was obtained capable of charging a 4.7 μF capacitor and discharged through LED lighting. Copyright © 2017 John Wiley & Sons, Ltd.

Comb-shaped electrode-based triboelectric nanogenerators for bi-directional mechanical energy harvesting

Triboelectric nanogenerators (TENGs), which utilize coupling of contact electrification and electric induction to effectively harvest the mechanical energy around us, have attracted much attention due to their advantages such as simple design and high accessibility. Herein, we report new types of TENGs containing comb-shaped electrode, which are fabricated with a simple thermal nanoimprinting process where a commercially-available metal mesh was used as a stamp to simply impart microtopography on the TENGs to increase electrical output performance. The fabricated TENG with the comb-shaped electrode enables to harvest bi-directional mechanical energy (including both lateral and vertical contact/separation), which can be a new strategy to efficiently harvest the energy from complex real mechanical motions. The TENG with the comb-shaped electrode generates a short circuit current (Isc) of 85nA and an open circuit voltage (Voc) of 6.4V under the lateral contact/separation, which are increased up to 850% and 1600%, respectively, compared to the TENGs with the conventional rectangular electrode. The TENG with comb-shaped electrode is also found to harvest energy of Isc of 339nA and Voc of 31V at a pressing frequency of 0.5Hz and force of 58.8N under the vertical contact/separation without significant loss of electrical output performance compared with the TENG with the conventional rectangular electrode. The results indicate that the comb-shaped electrode would be a powerful (potential) candidate of electrode shape of the TENG to harvest the energy from real mechanical motions.