Tổng hợp và nghiên cứu hình thái, tính chất của lớp phủ PbO2 kết tủa điện hóa trên nền thép mềm và khả năng ứng dụng làm điện cực trong pin chì dự trữ

Abstract

Lead dioxide electrodeposition has been caried out at constant currents from lead nitrate solution 0.5 mol/L on mild steel substrate; Fe₃O₄ films coating on steel substrate that prepared by electrochemical oxidation method (Fe₃O₄ĐH) and chemical oxidation method (Fe₃O₄HH)  in hot alkaline solution. The morphology and structure analysis of the PbO₂ layers were investigated using scaning electron microscopy (SEM) and X-ray diffraction techniques. PbO₂/steel, PbO₂/Fe₃O₄ĐH/steel, PbO₂/Fe₃O₄HH/steel electrodes were tested the electrochemical behaviors with the role of the positive electrodes in Pb/HSiF₆/PbO₂ reserve battery. When synthesized in the conditions: 0.5 M Pb(NO₃)₂ solution, the imposed current density from 5 to 40 mA/cm², temperature 30 °C, pH 4; PbO₂ coatings formed on the mild steel substrate mainly with betta-PbO₂ crystals of tetrahedral structure with different sizes and tight, solid arrangement. The best adhesion PbO₂ coatings had obtained on mild steel substrate with Fe₃O₄ conversion layer, which formed by electrochemical methods (Fe₃O₄ĐH). Results of discharge test showed that the stable discharge times at maximum voltage decreased if current density, which was used in electrodeposition of PbO₂ increased. In the electrodeposition of PbO₂ at imposed current density of 10 mA/cm², the obtained PbO₂/Fe₃O₄ĐH/steel electrodes have the stable discharge times up to 390 seconds at potentials 1.69-1.7 Volts.