Fully Enclosed Triboelectric Nanogenerators for Applications in Water and Harsh Environments

Abstract

With the growing threat of energy crises, new technologies for harvesting wasted ambient mechanical energy are becoming one of the most important fi elds of research. [ 1 ] Currently, there are three physical effects used for harvesting small scale mechanical energy: electromagnetic, [ 2,3 ] piezoelectric, [ 4,5 ] and triboelectric effects. [ 6,7 ] In parallel to the development of micro-/nanopower sources, it is necessary to explore the possibility of harvesting large-scale ambient mechanical energy, such as ocean waves and natural wind. [ 8 ] Such energy is abundant and has much less dependence on season, day or night, and the weather than solar energy does. Moreover, the mechanical energy generated by human motion, such as walking or shaking, is usually wasted. [ 9 ] Harvesting this kind of energy has potential for powering portable electronic devices.Triboelectric nanogenerators (TENGs) fabricated using the polymer-polymer or polymer-metal fi lm materials have been extensively developed to power some small electronic devices (such as liquid crystal displays (LCDs) and light-emitting diodes (LEDs)). [ 10,11 ] The mechanism is based on the triboelectric effect, [ 12 ] in which cycled contact-separation between two different triboelectric materials can induce a voltage drop for driving electrons to fl ow in the external circuit. Although many kinds of TENGs have been fabricated, [ 13,14 ] they are based on a working process with the acting surfaces being exposed to ambient atmosphere, which can limit their applications in some cases. It has been reported that the ambient environment such as humidity can largely weaken the triboelectric effect, [ 15 ] so that the fabricated TENGs cannot work under harsh conditions with the presence of water. To solve this problem, it is necessary to develop fully enclosed or packaged TENGs that can tolerate the environment in which they will be employed.Here, we have demonstrated the fi rst fully enclosed TENGs, which can be used to harvest the wave and biomechanical energies. A TENG was fabricated by using the polytetrafl uoroethylene (PTFE)-polyamide (PA) fi lm materials in an enclosed sphere, which can be used to harvest the wave energy from water for driving electronic devices. Two TENGs in an enclosed cylinder can be used to directly light up 60 green LEDs by moving the mass rod at the center of the cylinder; this has potential applications for harvesting the wave and biomechanical energies. The energies produced by the TENGs can be stored in a Li-ion battery for driving an ascorbic acid (AA) biosensor. Figure 1 a shows a schematic diagram of a conventional TENG, which consists of a Cu fi lm as the top electrode, a PTFE fi lm, a PA fi lm, and a Cu fi lm as the bottom electrode. The TENG was driven by a homemade force loading system with the working frequency of 1 Hz. Figure 1 b shows the output performance of the fabricated TENG in air, where the open-circuit voltage ( V oc ) and the short-circuit current ( I sc ) were about 50 V and 14 μ A under the forward connection to th...

Triboelectric nanogenerators as new energy technology and self-powered sensors – Principles, problems and perspectives

“…Looking in to the future, by constructing a three-dimensional network of the TENGs, such as a 3D fishing net, as schematically shown in Fig. 3, if the output of each unit is 1 mW on average, 39,40 our calculation shows that 1 MW power can be generated using 1 km square of surface area in ocean, possibly provides a feasible blue energy for large-scale energy needs of the world in near future.…”

Triboelectric Nanogenerator: A Foundation of the Energy for the New Era

“…The application of TENGs in harvesting natural mechanical energy, such as wind energy, [114][115][116][117] raindrop energy, [118][119][120] ultrasonic energy, [121] and water wave energy, [122][123][124] has attracted numerous research interests. Among them, the concept of using a TENG to harvest the kinetic energy of water waves in the vast oceans, that is, blue energy, [15,125] is particularly important, since recent studies suggest that a TENG is Adv.…”

Triboelectric Nanogenerator Based on Fully Enclosed Rolling Spherical Structure for Harvesting Low‐Frequency Water Wave Energy

“…Widely distributed water kinetic energy is an abundant source for large-scale applications, and the energy provided by water is much less dependent on seasonality, daylight, weather, and/or temperature. Although some TENGs used for harvesting wave energy have been fabricated and sealed in enclosed casings based on rolling structures, [18][19][20][21] they all utilized single-electrode and attachedelectrode modes. Although some TENGs used for harvesting wave energy have been fabricated and sealed in enclosed casings based on rolling structures, [18][19][20][21] they all utilized single-electrode and attachedelectrode modes.…”

“…Although some TENGs used for harvesting wave energy have been fabricated and sealed in enclosed casings based on rolling structures, [18][19][20][21] they all utilized single-electrode and attachedelectrode modes. [ 22 ] For attached-electrode mode designs, [ 18 ] it requires that the two triboelectric materials must be fully contacted; even an air gap with tens of microns will largely degrade their performance. [ 22 ] For attached-electrode mode designs, [ 18 ] it requires that the two triboelectric materials must be fully contacted; even an air gap with tens of microns will largely degrade their performance.…”