Direct Current Triboelectric Nanogenerators

Abstract

become a more serious issue. [1-3] Efficient conversion of ambient neglected energy into electricity has been a research hotspot from last decade. [4-18] In particular, the triboelectric nanogenerator (TENG) based on coupling the contact electrification (CE) and electrostatic induction possesses incomparable superiority in harvesting low frequency and micro mechanical energy. [19-21] Various environmental based mechanical energy including human motion, [22-30] rotating motion, [31,32] vibration, [33-38] water drop, [39,40] sea wave, [41-44] and wind, [45-56] can be harvested effectively with TENGs. Moreover, the self-powered systems without external power supply, [57-59] can be built based on TENG, [60-68] which can be applied to environmental surveillance, [60-62] chemical detection, [62-64] tracking system, [65,66] liquid volume monitoring, [67] electronic skin, [68] etc. In conventional TENGs, a pulsed alternating current (AC) output is obtained by changing the distance or contact area periodically between the materials with opposite electrostatic charges. [69-73] In order to obtain direct current (DC) output, some necessary rectification methods are needed, such as power management circuits, [47,74-76] rectifier bridge, [77-82] and electric brushes, [83,84] which will reduce the portability and energy utilization efficiency. [85] Moreover, the pulsed AC output leads to a high crest factor (the ratio between the peak and the root-mean square value of output), which means the output is unstable. [86,87] These inherent output characteristics of the conventional TENGs can seriously affect its widespread applications in driving electronics and charging energy storage devices where DC output is most appropriate. In this case, the novel strategies and technologies for converting mechanical energy directly into DC electric energy are essential. Lately, various types of DC triboelectric nanogenerators (DC-TENGs) with new frictional materials and different structures are introduced. [88-91] The concept of DC-TENG as illustrated in Figure 1, describes that the mechanical energy is harvested and converted into constant DC electric power, which is suitable to power electronic equipment or charge energy storage devices. In the future, this promising research field will also attract more and more scientific efforts. The progress and development of DC-TENG is summarized in this paper, which begins with the development and working mechanisms of the insulator-based DC-TENG by phase coupling and dielectric breakdown. The DC voltage output of various insulator-based DC-TENGs can reach up to kV, and its crest factor is close to 1. Thereafter, the semiconductor-based DC-TENG with lower internal impedance and higher output current density is introduced. The charge transfer process in

Recent Advances towards Ocean Energy Harvesting and Self‐Powered Applications Based on Triboelectric Nanogenerators

“…Output of TENGs is alternating current, which cannot be used directly to power micro sensors, and using full‐wave bridge rectifier arises energy loss. [ 216,217 ] Cheng et al. [ 218 ] added an inductor in the circuit so that conversion efficiency of AC to DC can reach more than 72%.…”

Wind driven semiconductor electricity generator with high direct current output based on a dynamic Schottky junction

“…[21][22][23][24] In order to store energy and consume energy, the generator also needs an external rectifying circuit to change this into direct current. In contrast, direct current generators, [25][26][27][28] like nanogenerators, [29][30][31][32][33][34][35][36] which do not need an additional rectifying circuit to convert alternating current, [37][38][39] have greater potential and will be more efficient to power sensors directly. 40,41 However, for powering the distributed sensors in the IoTs and making the wind generator more convenient, there is an urgent need to invent a novel type of generator using a simpler device.…”

Redox-induced electricity for energy scavenging and self-powered sensors

“…As reported by the European Renewable Energy Council, almost 50% of the total energy supply will be derived from renewable sources by 2040. 2 For instance, some excellent energyharvesting nanogenerators based on triboelectric, [3][4][5] piezoelectric, 6,7 pyroelectric, 8,9 thermoelectric effects, 10,11 and redoxinduced electricity 12 have become a new hope for researchers to tackle the energy demand and toxicity of batteries. Many of these energy harvesting systems have been hybridized to achieve higher outputs by harvesting more than one sustainable energy source.…”