катод

DOI: https://doi.org/10.18500/1608-4039-2018-18-1-20-25

Low-frequency electrochemical impedance spectroscopy in the frequency range from 12.5 to 5 ⋅ 10⁻⁴ Hz was used to study changes in standard lithium-thionyl chloride cells during their discharge. Analysis of possible equivalent circuits describing the experimental data shows that the behavior of the cells discharged to 70% can be simulated by finite diffusion impedance in this frequency range.

The electrochemical activity of nickel mesh cathodes activated by electrocatalysts of chemically deposited coatings Ni-S-Fe is investigated. The maximum reduction of overvoltage at current density 6 kA/m² and temperature 70°C is 0.34 V. Comparison of the electrochemical activity of such cathodes with similar cathodes described in the scientific literature revealed that at the same temperature and same overvoltage the current density is twice higher than for the known electrodes. It is shown that with increasing temperature from 20 to 90°C overvoltage at the current density 4kA/m² reduced by 110mV. Testing of the electrodes with electrocatalysts Ni-S-Fe in the laboratory electrolyser for 850 hours of continuous operation at current density 12kA/m² indicate the stability of their electrochemical activity.

Electrochemical activity of cathodes with Pt or Pt-Pd-electrocatalysts was studied by voltammetry method under galvanostatic conditions. The dependence of the overvoltage of hydrogen evolution reaction on the logarithm of current density and on the test time of the cathode with Pt-Pd-electrocatalysts are defined. It is shown that the electrochemical activity of cathode with Pt-Pd-electrocatalyst is two times higher than with Pt-electrocatalyst at the hydrogen evolution reaction in 30% KOH solution at 90°C. As the temperature increases from 15 to 90° C the current density at 40 mV overvoltage at the cathode with Pt-Pd-electrocatalyst increases by 8 times. The test results with this cathode electrocatalyst in the laboratory electrolyzer at a current density of 400 mA/cm² and 65° C temperature within 11 days of intermittent regime work confirm the overvoltage stability in time.