Development and characterization of high-stability all-solid-state porous electrodes for marine electric field sensors

Abstract

Marine electromagnetic (EM) methods can be used for marine geophysical exploration. We proposed an all-solid-state porous Ag/AgCl electrode with high stability and a long service life as a marine electric field sensor with the ability to withstand deep sea high pressures while improving the accuracy of electric field measurements for long-period marine EM method engineering projects. Compared with a plate electrode, the all-solid-state porous electrode has excellent polarization resistance in seawater. To avoid the short service life of the sensor used in marine EM method engineering, the all-solid-state porous Ag/AgCl electrodes were manufactured by a ball-milling and sintering process, and the electrochemical channel of the electrodes was observed under a scanning electron microscope. A sensor casing based on the porous electrodes used in the deep sea environment was designed. An experimental system for evaluation and characterization was designed to measure the polarization resistance, sensitivity, noise, self-potential and drift of the proposed electrodes, which are important properties and will affect the accuracy of marine electric field measurements. The results show that the source resistance of the electrode is 2.13 Ω/cm2, the electrode noise level is 1.57 nV/rt(Hz), the self-potential of the proposed electrode pair is less than 35 μV, and the potential drift is less than 10 μV/day. After more than 180 days of use, the electrodes showed outstanding stable drift potentials of below 15 μV/day. The proposed all-solid-state porous electrodes can ensure the measurement accuracy of marine electric field signals and promote the exploration of marine resources.