Harvesting energy from high‐frequency impinging water droplets by a droplet‐based electricity generator

Abstract

Harvesting energy from water, in the form of raindrops, river, and ocean waves, is of considerable importance and has potential applications in self‐powered electronic devices and large‐scale energy needs. Recently, the droplet‐based electricity generator has shown an increase by several orders of magnitude in electrical output, overcoming the drawback of traditional droplet‐based device limited by interfacial effects. Despite this exciting result, the output performance of this novel droplet‐based electricity generator is limited by relatively low frequency of impinging droplets owing to the formation of a continuous liquid film at high impact frequency, which might hinder its practical applications. To overcome this challenge, here, we report the design of a superhydrophobic surface based droplet electricity generator, referred to as SHS‐DEG, which can timely shed water droplets from the surface without the formation of liquid film at high impact frequency, and thereby generating enhanced average electrical output. Moreover, our SHS‐DEG exhibits many distinctive advantages over conventional design including robustness, long‐term durability, and power generation stability even in harsh environments. We envision that the ability to harvest electrical energy from water droplets at high impact frequency has promising applications in various energy‐harvesting systems.

A Hydrophobic Self-Repairing Power Textile for Effective Water Droplet Energy Harvesting

“…In addition, since better hydrophobic surface allows droplets to quickly slide off the surface, which can achieve high-frequency water droplet energy harvesting and the surface with preferable hydrophobicity can harvest more droplet energy at per unit time and increase the total output power. 44 As shown in Figure 3d,g and Figure S13, hydrophobic fabrics with SiO 2 /FDTS and SiO 2 /PVDF-HFP/FDTS have the preferable electric output. Although the coated fabric containing SiO 2 /FDTS possesses higher electric output than SiO 2 /PVDF-HFP/FDTS, the coated fabric of SiO 2 /FDTS has poor stability because the SiO 2 /FDTS will shed from the coating layer without the immobilization of PVDF-HFP after a short time water droplet impact and gradually becomes hydrophilic (Figure S7).…”

“…The residual water droplet on the surface will shield a part of negative charges on dielectric, which decreases the number of induced charges on bottom electrode. In addition, since better hydrophobic surface allows droplets to quickly slide off the surface, which can achieve high-frequency water droplet energy harvesting and the surface with preferable hydrophobicity can harvest more droplet energy at per unit time and increase the total output power . As shown in Figure d,g and Figure S13, hydrophobic fabrics with SiO 2 /FDTS and SiO 2 /PVDF-HFP/FDTS have the preferable electric output.…”

Droplet Bouncing: Fundamentals, Regulations, and Applications

“…To solve it, the superhydrophobic‐surface‐based device for electricity generation is further developed. [ 220 ] The super‐repellent property of the base surface (tapered post diameter from ≈80 to ≈800 nm) allows the quick removal of the impacting droplets (volume 1–6 μL, velocity ≈1.85 m s ‐1 ) without the accumulation. This largely increases the output of electrical generation.…”

A droplet‐based electricity generator with ultrahigh instantaneous output and short charging time

“…In the future, it is essential to develop ideal and scalable dielectric materials featuring high charge storage capability and propose new design architecture to further advance the output performances of DEG. [48][49][50][51][52][53][54][55] We envision that the working mechanism and circuit model we proposed in this will provide important insights for liquid energy harvesting.…”