Phase Transformation Processes in the Active Material of Lead-acid Batteries (original) (raw)
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Journal of Solid State Electrochemistry, 2005
One of the main electrochemical characteristics of a lead-acid battery is amount of water consumption. The effect of solidification temperature on electrochemical behavior (mainly hydrogen overvoltage) of Pb-Ca-Sn-Al (0.09%, Ca; 0.9%, Sn; 0.02%, Al) and Pb-Sb-Sn (1.7%, Sb; 0.24%, Sn) alloys, which are used in making the grid of lead-acid batteries, has been studied by cyclic voltammetry (CV) and linear sweep voltammety for different concentrations of sulfuric acid (ranging from 0.5 mol L À1 to 4.0 mol L À1). The morphology of the grid at some solidification temperatures was studied by optical microscopy. After one sweep of CV the surface of the electrode was investigated by using scanning electron microscopy.The results show that the potential of hydrogen evolution depends on the solidification temperature of the grids during production (mold temperature of grid casting). Also, at different solidification temperatures, different passivation phenomena, electrode surface constituents, and structure were observed.
Automation benefits in the formation process of lead-acid batteries
Independent Journal of Management & Production, 2017
In this work, the automated formation process of lead-acid battery and its industrial positive impact on the battery efficiency are evaluated toward the manual process. The problems in the lead-acid batteries formation are related to the α-PbO2 and β-PbO2 production during the first electric charge. The lead-acid battery formation problems frequently occur when electrical current sources with manual control are used. The main drawback of the manual method is addressed to the electric current interruptions between the plates during the battery charging. Thus, the lead oxides phases in the plates were used as parameter to correlate the chemical composition to the failure on the batteries formation process. X-ray powder diffraction technique was used to identify the lead phases.
Mechanism of PbO2 formation in lead/acid battery positive plates
Journal of Power Sources, 1993
The processes which take place in the paste during preparation and formation of lead/ acid battery positive plates in H,SO, (sp.gr. 1.05) were studied using wet chemical analysis and X-ray diffraction. It was found that basic lead sulfate was obtained in two stages. During the first stage, free lead reacts in a basic character paste with HzS04 added to the lead powder and gives lead sulfate with an overall stoichiometry equivalent to PbS04.Hz0. During the second period, PbO undergoes an acid/base reaction to 3Pb0.PbS04.Hz0. When soaking and forming in free H,SO,, lead oxide (free PbO plus PbO in the basic sulfate) reacts with H,SO, and gives lead sulfate PbSO+ The X-ray diffraction data showed that PbS04*Hz0 is converted to a-Pb02, while PbSO., leads to the /3-PbOz form.
Rapidly Solidified Lead Tin Calcium Alloys for Lead Acid Batteries
Alfarama Journal of Basic & Applied Sciences, 2020
The effect of addition of Ca on the structure, thermal, mechanical, electrical and electrochemical properties of Pb-10Sn alloy was investigated for lead acid batteries applications in order to extend the life cycle of the gird by improving its mechanical and corrosion resistance. The material of lead acid battery grid mostly is based on Pb-Sn alloy. In the present work six rapidly solidified alloys of compositions (90-x)Pb-10Sn-xCa (x=0, 0.5, 1, 1.5, 2, 2.5 wt.%), were produced by melt-spinning technique. X-ray diffraction analysis and differential scanning calorimetry have been carried out. Also mechanical, electrical and electrochemical properties were measured. Here we show that the addition of 2.5 wt.% Ca to Pb-10Sn improves its mechanical properties this is evident in the increase of Young's modulus, microhardness number and microcreep behavior and enhances its corrosion resistance. Therefore the rapidly solidified melt-spun 87.5 wt.%Pb-10wt.%Sn-2.5wt.%Ca alloy is the most suitable alloy to be used as a grid in lead acid batteries.
Journal of Power Sources, 2003
During charge and discharge of lead-acid batteries the concentration of the H 2 SO 4 solution in the pores of the active material and in the interface grid/active mass varies widely. In this investigation, the in¯uence of pH of the H 2 SO 4 solution on the phase composition of the positive active mass (PAM) and of the interface PAM/grid is studied. The in¯uence of pH on the phase composition of the interface is determined indirectly by cycling Pb electrodes between 0.70 and 1.60 V (versus Hg/Hg 2 SO 4 ) in H 2 SO 4 solutions of various concentrations and determining the phase composition and the structure of the anodic layer formed. The in¯uence of pH on the phase composition of the PAM is investigated by immersing fully charged PAM samples into H 2 SO 4 solutions of various concentrations and determining the phase composition of the PAM and the size of the a-PbO 2 , b-PbO 2 and PbSO 4 crystals. It has been found that the outer sub-layer of the anodic layer participates in the cycling processes and its phase composition depends on the pH of the solution and on the potential scan rate. The reduction rate of PbO 2 in this sub-layer depends on the solution pH. If the reduction of PbO 2 proceeds in solutions with pH between À1.0 and À0.50, the rate of the processes is high. When it proceeds at pH > À0:50 the reduction rate is lower. This behaviour of the PbO 2 /PbSO 4 electrode in¯uences the power performance of the lead-acid battery when the positive plates are the power limiting component. The rate of oxidation of PbSO 4 to PbO 2 is determined by the pH of the solution because the solubility of PbSO 4 depends on pH. In concentrated solutions the solubility of PbSO 4 is low, the charge process is slow and some unoxidised PbSO 4 may remain in the charged plate. In diluted H 2 SO 4 solutions, the solubility of PbSO 4 is high and PbSO 4 crystals are oxidised fully during charge. It has been found that the phase composition of the PAM depends on the pH of the solution since the hydrated part of the PbO 2 particles interacts with the ions in the solution as a result of which the crystal zones/hydrated zones and hydrated zones/solution equilibria are changed. The content of a-and b-PbO 2 crystal zones in the PAM depends on the pH of the solution. In the pH region between À0.75 and 0, SO 4 2À ions which have penetrated into the hydrated gel zones react with Pb 2 ions from the nonstoichiometric part of the PAM (PbO 2Àd ) forming PbSO 4 molecules, which leave the hydrated zones and enter the solution forming PbSO 4 crystals there. When the PAM is immersed in solutions with pH between 0 and À1.0, the content of the crystal phases of a-and b-PbO 2 decreases. In this pH region the average size of the b-PbO 2 crystals decreases while that of a-PbO 2 remains constant or increases slightly. The results of this investigation evidence that the PAM is a dynamic system, which interacts with the ions in the solution, and hence the phase composition of the PAM depends on the concentration of the H 2 SO 4 solution. #
Research on thin grid materials of lead-acid batteries
Rare Metals, 2006
A detailed investigation on Pb-Ca-Sn alloys was made in order to choose suitable grid alloys materials for thin plate lead-acid batteries. The electrochemical performances of alloys were investigated by electrochemical corrosion experiment, scanning electron microscope (SEM) , and cyclic voltammetly (CV) test. The results indicate that Pb-Ca-Sn-Bi-Cu alloys can be used to make the grids used for thin grid leadacid batteries, the content of bismuth has primary effects on the corrosion resistance of grid alloys, the composition of alloys plays an important role on batteries performance, and appropriate scale of elements can be choosed to obtain optimal electrochemical performance. The lead-acid batteries using this kind of grid show good performance by cycle life test.
Lead–samarium alloys for positive grids of valve-regulated lead–acid batteries
Journal of Power Sources, 2007
The influence of the rare earth metal, samarium, as an alloying additive on the electrochemical behaviour of pure lead is studied by means of X-ray diffraction, self-depassivation, linear sweep voltammetry and a.c. impedance spectroscopy in 4.87 M H 2 SO 4 at 25 • C. Studies on Pb-Sm alloys (Sm = 0.02, 0.04, and 0.12 wt.%) indicate that the oxide film formed on the alloy surface at 0.9 V is thicker than that on pure lead when the alloy contained less than 0.1 wt.% Sm. In addition, samarium exercises little influence on the conversion of PbSO 4 to PbO 2 in the oxide film during charging. The electrochemical impedance of the oxide film is much larger than that of the oxide formed on pure lead. With the addition of more than 0.1% Sm, however, the oxide film on the alloy surface is thinner and samarium obviously promotes the conversion of passive PbSO 4 in oxide film to conductive PbO 2 . The a.c. impedance data show that a high content of samarium greatly inhibits the growth of the passivation layer and decreases the electrochemical impedance of the film.
The Refining of Secondary Lead for use in Advanced Lead Acid Batteries 1
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Journal of Applied Electrochemistry, 1995
The corrosion behaviour of Pb-Se alloys (Se: 0.00, 0.01, 0.04 and 0.06%) to be used in the manufacture of grids for pasted lead-acid batteries, was studied under open circuit, potentiostatic and galvanostatic polarization in 5.0 M HzSO 4 solutions. Selenium was found to shift the corrosion potential to more negative values and increase the sulfation and self-discharge; the extent being dependent on the percentage of selenium. The potentiostatic E/log i curve was significantly influenced, especially the passivity region from -0.90 to +1.30 V vs Hg/Hg2SO 4 (1.0 M H2804) , where the passivity current and the critical current and potential to start the nucleation of PbSO4 decreased in the presence of selenium. Both oxygen and hydrogen evolution overpotentials were found to be higher for the alloys containing selenium. In many aspects, the alloy composition Pb-0.04% Se was found to be critical. Factors affecting the constant current charging; the charging time, temperature and the number of charging-discharging cycles, N, were investigated. Generally, the corrodability of Pb-Se alloys was relatively higher and increasing N was found to increase corrosion in the order: Pb-0.04% Se > Pb-0.01% Se > Pb-0.06% Se > Pb. As the charging time increased, the rate of corrosion decreased for Pb-Se alloys while it was constant for Pb.