A Single‐Droplet Electricity Generator Achieves an Ultrahigh Output Over 100 V Without Pre‐Charging

Abstract

various scattered and irregular energy sources in the natural environment. [10] Although this type of energy is small, it is distributed extremely widely. If utilized reasonably, it will certainly make a significant contribution to human energy strategy.Coupled with contact electrification and electrostatic induction, Prof. Wang's group first invented the triboelectric nanogenerator (TENG) in 2012. [11] Presently, as the mainstream technology for energy harvesting, TENG has shown great application prospects in the fields of micro-nano energy, self-powered system, and blue energy due to its environmental friendliness, high efficiency, and accessibility. [12][13][14][15] After decades of research, the theory and output of TENG based on solid-solid interface has been deeply explored and improved. [16][17][18] However, in addition to the mechanical energy-electricity conversion between the solidsolid interface, the triboelectricity at solid-liquid interface can also be seen everywhere in the environment, such as in the falling raindrops. [19] Recently, the mechanism of solid-liquid electrification has been explored, and theories such as the electric-double-layer model and Wang's hybrid layer model have also been proposed to expand its applications. [20,21] However, these works of research are mainly concentrated on the solid-liquid electrificationThe working principle of the triboelectric nanogenerator (TENG), contact electrification and electrostatic induction, has been used to harvest raindrop energy in recent years. However, the existing research is mainly concentrated on solid-liquid electrification, and adopts traditional electrostatic induction (TEI) for output. As a result, the efficiency of droplet electricity generators (DEGs) is severely constrained. Therefore, previous studies deem that the DEG output is limited by interfacial effects. This study reveals that this view is inappropriate and, in reality, the output strategy is the key bottleneck restricting the DEG performance. Here, a switch effect based on an electricdouble-layer capacitor (EDLC) is introduced, and an equivalent circuit model is established to understand its working mechanism. Without pre-charging, a single droplet can generate high voltage over 100 V and the output is directly improved by two-orders of magnitude compared with TEI, which is precisely utilizing the interfacial effect. This work provides insightful perspective and lays solid foundation for DEG applications in large scale.

An integrally underwater self-healable droplet-based triboelectric nanogenerator

“…The output performance of the SHD-TENG is related to the maximum diffusion area of the droplet when it contacts the top electrode ( S max ) and the maximum area change rate of the diffusing droplet (d S /d t max ). 50,51 As α increased, S max reduced, which is not conducive to good output performance. On the contrary, d S /d t max got larger with α increasing which is beneficial to the improvement of the output performance (Fig.…”

Non‐Hookean Droplet Spring for Enhancing Hydropower Harvest

“…The variation in droplet-solid contact area is critical for the generated current (I) of the droplet-based triboelectric nanogenerator (D-TENG, Figure 4d): I ∼ dS/dt. [30][31][32][33][34][35] This is because when a droplet impacts on a dielectric substrate (such as PTFE), the capacitance of the formed hybrid electrical double layer changes with the droplet-solid contact area. [36][37][38][39][40][41] Therefore, the multi-droplet-spring can be utilized to optimize the performance of the droplet-based TENG.…”

A Review: Contact Electrification on Special Interfaces

“…The instantaneous power density was several orders of magnitude higher than before. Zhang et al (2021), as shown in Figure 8A, introduced an electric doublelayer capacitor at the liquid-solid contact electrification interface of DEG, and established an equivalent circuit model of DEG with a switching effect, achieving a power output of two orders of magnitude higher than the previous electrostatic induction power generation without polarizing the solid surface. As shown in In terms of liquid-solid contact electrification based triboelectric nanogenerator for water drop energy and ocean energy collection, as shown in Figure 8C, Gang et al (2021) prepared textile TENG which can collect raindrop energy and generate a voltage of 4.3 V and a current of 6 μA.…”