A droplet‐based electricity generator incorporating Kelvin water dropper with ultrahigh instantaneous power density

• Published in: Droplet (Print) Vol. 3; no. 1
• Main Authors: Li, Yang, Qin, Xuezhi, Feng, Yawei, Song, Yuxin, Yi, Zhiran, Zheng, Huanxi, Zhou, Peiyang, Wu, Chenyang, Yang, Siyan, Wang, Lili, Zhu, Pingan, Xu, Wanghuai, Wang, Zuankai
• Format: Journal Article
• Language: English
• Published: Changchun John Wiley & Sons, Inc 01.01.2024; Wiley
• Subjects: Alternative energy sources; Carbon; Electricity generation; Electrodes; Energy resources; Renewable resources; Transistors; Water
• ISSN: 2731-4375; 2769-2159; 2731-4375
• DOI: 10.1002/dro2.91

Harvesting renewable water energy in various formats such as raindrops, waves, and evaporation is one of the key strategies for achieving global carbon neutrality. The recent decade has witnessed rapid advancement of the droplet‐based electricity generator (DEG) with a continuous leap in the instantaneous output power density from 50 W/m2 to several kW/m2. Despite this, further pushing the upper limit of the output performance of DEG is still constrained by low surface charge density and long precharging time. Here, we report a DEG incorporating the Kelvin water dropper (K‐DEG) that can generate an ultrahigh instantaneous power density of 105 W/m2 upon one droplet impinging. In this design, the Kelvin water dropper continuously replenishes the high density of surface charges on DEG, while DEG fully releases these surface charges into electric output. K‐DEG with such a high output can directly light five 6‐W commercial lamps and even charge a cellphone by using falling droplets. Water, as a widely accessible and renewable energy source, holds an immense amount of energy estimated at 60 petawatts (1015 W) per year, several orders of magnitude greater than the global electricity consumption. Although significant progress has been made in harvesting high‐frequency and centralized hydrodynamic energy using electromagnetic generators, efficiently harvesting low‐frequency and decentralized water energy in various forms such as raindrops, river/ocean waves, tides, and even moisture remains a challenge. Here, we develop a droplet‐based electricity generator incorporating the Kelvin water dropper (K‐DEG), in which the Kelvin water dropper can instantly inject abundant charges on the surface of the dielectric layer of DEG as a result of corona discharge, while DEG can fully release these surface charges into electricity generation upon droplet impinging. With this elegant integration of DEG with Kelvin water dropper, K‐DEG can generate an enormously boosted transferred charge of 201 nC and output voltage up to 2000 V from one droplet impinging (100 μL).