On the Spontaneous Build-Up of Voltage between Dissimilar Metals Under High Relative Humidity Conditions

J Y Lax,H Saaroni,C Price

doi:10.1038/s41598-020-64409-2

Abstract

Certain metals can surprisingly build-up charge spontaneously, when exposed to high relative humidity (RH), although they need to be isolated from the ground. We have explored this phenomenon, building on former experimental knowledge and carrying out additional experiments, to identify the parameters that could enhance this charging. We used many types of metals with different characteristics under different RH and temperature conditions. While some metals were unaffected by high RH, others, like zinc and stainless steel, did acquire charge, when RH was >60%, and charged a capacitor to a voltage of 1 V. For the first time, we also performed outdoors experiments, showing this phenomenon is also valid under similar natural ambient humid conditions. If these results can be scaled up, it may lead to the development of practical applications for regions and times of high RH conditions.

Highlights

Pure water has zero net electric charge, according to the electro-neutrality principle[4]
It is known that surfaces tend to lose their electrostatic charge when the air is humid since it neutralizes the surface[17]: Under high enough relative humidity (RH > 60%), water molecules will be adsorbed and the surface will be covered with a thin film of water[18], allowing mobile ions to move and dissipate the accumulated charge
Zinc was the main focus in the further experiments: As long as the RH was low (

Summary

Introduction

Pure water has zero net electric charge, according to the electro-neutrality principle[4]. In 1843 the famous physicist Michael Faraday published a research related to a powerful electrocution of a worker next to a steam boiler in London[6]. Faraday carried out experiments and concluded that the electricity was due to the friction of the water droplets in the steam with the surrounding metal. By increasing the pressure of the steam Faraday could increase the effect He concluded that the effect was due to the condensed water becoming a good conductor, with the ions being transferred to the metal, or any other body, by friction. Faraday measured the charge on the objects, and concluded that the friction of water droplets against many different bodies left the water positively charged relative to the solid bodies. They found that using two different metals exposed to high RH leads to voltage accumulation, acting as a capacitor, reaching 0.75 V

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