Structure And Electrochemical Performance Of Ag/AgCl Composite Electrode

Ag/AgCl electrodes are widely used in the field of ocean electromagnetic field detection because of t heir advantages of low noise,high sensitivity and sensitivity to low frequency signals.The electrical parameters such as self-noise,stability and electrochemical performance of Ag/AgCl electrode are closely related to the composition,structure and microstructure of Ag and AgCl inside the electrode.Therefore,in this paper,by changing the electrode preparation process parameters(sintering,forming,composition),electrodes with different structural compositions are prepared.The phase,micro-domain structure,pore distribution state and specific surface area of the electrode were analyzed by means of scanning electron microscopy(SEM),immersion medium method and specific surface area test.Electrochemical impedance analysis(EIS),polarization performance test and other electrochemical analysis methods were used to observe the impedance of the electrode at a specific frequency and its polarization mode.The equivalent circuit model was established and the self-noise and stability of the electrode were tested.The experimental results show that the improvement of the preparation process of the electrode changes the microstructure of the electrode and has a great influence on the electrochemical performance and macroscopic electrical properties of the electrode.With the increase of holding time at 330 °C,the porosity of the electrode increases,the specific surface area increases,the exchange current density of the electrode increases,and the degree of electrochemical polarization decreases.When the temperature is kept for 30 min,the electrode noise is reduced to 6.00E-09 V/?Hz,the 24h-stability of the electrode is enhanced,and the electrode fluctuation is kept within 0.057 mV;With the increase of holding time at 450 °C,the porosity of the electrode increases,the specific surface area increases,the exchange current density first increases and then decreases,and the electrochemical polarization decreases first and then increases.When the temperature is kept for 30 min,the electrode noise is reduced to 5.48E-09 V/?Hz,the 24h-stability of the electrode is the best,and the electrode fluctuation is kept within 0.038 mV;In the samples of different molding processes,as the pressure increases,the porosity of the electrode decreases,the specific surface area increases first and then decreases,the exchange current density first increases and then decreases,and the electrochemical polarization decreases first and then increases.When the molding pressure is 4 MPa,the electrode noise is reduced to 4.28E-09 V/?Hz,the 24h-stability of the electrode is the best,and the electrode fluctuation is kept within 0.046 mV;In the samples of different composition processes,as the content of Ag in the Ag:AgCl ratio increases,the porosity of the electrode increases first and then decreases,the specific surface area increases first and then decreases,and the exchange current density increases first.After reduction,the degree of electrochemical polarization decreases first and then increases,When the ratio of Ag:AgCl is 1:1,the electrode noise is reduced to 2.51E-09 V/?Hz,the 24h-stability of the electrode is the best,and the electrode fluctuation is kept within 0.023 mV;Through the optimized preparation process,the electrode with excellent performance is obtained,the noise is 2.51E-09 V/?Hz,the 24 h electrode fluctuation is kept within 0.023 mV,and the stability is good,which provided for the development of high performance underwater Ag/AgCl detection electrode.Theoretical basis and experimental basis.