The effect of Ca and Bi addition on the mechanical strength, corrosion resistance, and Rechargeability of Pb1.5Sn alloy for the positive grid of lead-acid batteries

Lead-acid batteries need to evolve to keep up with the electrification of vehicles and not lose ground to other technologies. The grid designed using a lead alloy thus plays a very important role in the performance of the battery, as, in the course of the various cycles, this component undergoes a natural corrosion process at positive potential, while immersed in a sulfuric acid solution. The aim of this study is therefore to examine the effect of the addition of calcium and bismuth on the microstructure, mechanical behavior and corrosion resistance of the Pb1.5%Sn alloy, with a view to using this in the positive grid of lead-acid batteries. The alloys developed during this study were evaluated using optical microscopy and scanning electron microscopy. Mechanical properties were investigated using universal tensile and hardness tests. Electrochemical tests of cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were carried out in a 5M sulfuric acid solution at 25 °C to simulate the behavior of the alloy when in operation. The composition of the corrosion products formed were subsequently characterized by morphological analysis using scanning electron microscopy and the composition was determined using energy dispersive X-ray spectroscopy and X-ray diffraction analysis. The results indicate that the Pb1.5Sn0.12Bi alloy presented better corrosion resistance characteristics than the Pb1.5Sn0.05Ca alloy, making it suitable for inclusion in the composition of the positive electrode of a lead-acid battery. Further investment is however required to compensate for the shortcomings in relation to the mechanical properties of the material.

The inhibitive action of 2-mercaptobenzothiazole on the porosity of corrosion film formed on aluminum and aluminum-titanium alloys in hydrochloric acid solution

2-Mercaptobenzothiazole (2-MBT) in a solution of 0.5 M HCl is an effective corrosion inhibitor for aluminum and aluminum-titanium alloys. Tafel polarization and electrochemical impedance spectroscopy (EIS) were employed to assess this heterocyclic compound's anticorrosive potential and complementary by scanning electron microscope (SEM) and calculating porosity percentage in the absence and presence of various inhibitor concentrations. Inhibition efficiency (IE%) was strongly related to concentration (10^-6-10^-3 M). Temperature's effect on corrosion behavior was investigated. The data exhibited that the IE% decreases as the temperature increases. An increase in activation energy (E_a) with increasing the inhibitor concentration and the decrease in the IE% value of the mentioned compound with raising the temperature indicates that the inhibitor molecules are adsorbed physically on the surface. Thermodynamic activation parameters for Al and Al-Ti alloy dissolution in both 0.5 M HCl and the inhibited solution were calculated and discussed. According to Langmuir's adsorption isotherm, the inhibitor molecules were adsorbed. The evaluated standard values of the enthalpy ([Formula: see text], entropy ([Formula: see text] and free energy changes ([Formula: see text] showed that [Formula: see text] and [Formula: see text] are negative, while [Formula: see text] was positive. The formation of a protective layer adsorbed on the surfaces of the substrates was confirmed with the surface analysis (SEM). The porosity percentage is significantly reduced in the inhibitor presence and gradually decreased with increasing concentration. Furthermore, the density functional theory (DFT) and Monte Carlo (MC) simulations were employed to explain the variance in protecting the Al surface from corrosion. Interestingly, the theoretical findings align with their experimental counterparts. The planarity of 2-MBT and the presence of heteroatoms are the playmakers in the adsorption process.

Effect of Precursors on the Electrochemical Properties of Mixed RuOx/MnOx Electrodes Prepared by Thermal Decomposition

Growing thin layers of mixed-metal oxides on titanium supports allows for the preparation of versatile electrodes that can be used in many applications. In this work, electrodes coated with thin films of ruthenium (RuOx) and manganese oxide (MnOx) were fabricated via thermal decomposition of a precursor solution deposited on a titanium substrate by spin coating. In particular, we combined different Ru and Mn precursors, either organic or inorganic, and investigated their influence on the morphology and electrochemical properties of the materials. The tested salts were: Ruthenium(III) acetylacetonate (Ru(acac)₃), Ruthenium(III) chloride (RuCl₃·xH₂O), Manganese(II) nitrate (Mn(NO₃)₂·4H₂O), and Manganese(III) acetylacetonate (Mn(acac)₃). After fabrication, the films were subjected to different characterization techniques, including scanning electron microscopy (SEM), polarization analysis, open-circuit potential (OCP) measurements, electrochemical impedance spectroscopy (EIS), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) experiments. The results indicate that compared to the others, the combination of RuCl₃ and Mn(acac) produces fewer compact films, which are more susceptible to corrosion, but have outstanding capacitive properties. In particular, this sample exhibits a capacitance of 8.3 mF cm^-2 and a coulombic efficiency of higher than 90% in the entire range of investigated current densities.