PbSO4 Crystals Research Articles

Passivation of Lead-Acid Batteries Lead Negative Electrodes by PbSO4 Crystals: Analysis from Modeling Cyclic Voltammetry Responses

Lead-acid batteries (LABs) play a pivotal role in the energy storage sector with applications spanning from starting-ignition-lightning batteries to grid energy storage. Passivation of lead negative electrodes by PbSO4 crystals is a one fundamental mechanism limiting the performance of LAB. In this regard, we developed an electrochemical mathematical model that simulates the nucleation and growth dynamics of PbSO4 crystals on a flat lead electrode, responsible for its passivation. The model considers the electrochemical dissolution of Pb2+ from lead electrode and the ternary transport of lead, bisulfate, and hydrogen ions in H2SO4 electrolyte. We have validated the model with a rich dataset of cyclic voltammetry (CV) responses collected at several scan rates and several concentrations of H2SO4. The model shows remarkable qualitative and quantitative agreement with the experimental data including the onset potential, center, height, and width of the CV peaks, discharge capacity, and particle size. The model is used to give insights on how different physical and operational parameters can influence the electrochemical response of lead negative electrodes. Keywords: lead-acid battery, nucleation and growth, passivation, cyclic voltammetry

Inducing and real-time monitoring of lead (de)sulfation processes using scanning electrochemical microscopy for applications in the refurbishment of lead-acid batteries

Lead acid batteries (LABs) remain as a mature, cost-effective energy storage technology for a wide variety of applications. Hard sulfation is one of the primary reasons for the short lifetime of LABs. This phenomenon is primarily characterized by the formation of large, non-redox active crystals of PbSO4 which reduce the negative active material utilization by slowing down the electron transfer (ET) kinetics on the surface. Here, we report a microelectrochemical technique based on the surface interrogation mode of scanning electrochemical microscopy (SI-SECM) to locally probe the phenomenon of sulfation and the loss of ET therein. Thereafter, we validate our technique through an existing in-situ refurbishing strategy for sulfated anodes using EDTA-based chelation treatment and the recovery of ET. Energy dispersive X-ray spectroscopy (EDX) was used to verify the formation of PbSO4 and its subsequent removal post treatment. We propose that our reported microelectrochemical technique promises to be useful in evaluating possible chelator candidates for the refurbishment of sulfated LABs. Finally, we also introduce ammonium acetate as a promising chelator candidate for the removal of PbSO4 and use our proposed technique to evaluate the superior recovery of ET during ammonium acetate refurbishment. We hope this technique will be useful in evaluating the surface treatment of LABs and other energy storage electrodes which undergo redox-induced passivation processes.

Amino acid based ionic liquids for revitalization of sulfated lead anodes

Lead acid batteries (LABs) are currently recycled using hazardous, polluting, and energy intensive procedures. Here we report a novel LAB recycling strategy with hydrophilic amino acid-based ionic liquids (ILs) to dissolve the water-insoluble PbSO4 crystals formed during deleterious hard sulfation at the anodes and then electrodeposit metallic Pb on a new surface. We identified two ILs, [Ch][Ser] and [Ch][Thr] ILs that show dramatic solubility towards PbSO4 at room temperature. [Ch][Ser] IL was successfully used in refurbishing hard sulfated anodes that had lost 99 % of their original capacity into a fresh Pb surface. More than 75 % of the capacity was renewed after a complete treatment on a half-cell. Electrodeposition of Pb from the Pb-[Ch][Ser] complex produced a uniform Pb microstructure. A remarkable 99 % of the IL-dissolved Pb2+ ions was electrodeposited. Furthermore, we solved the first crystal structure of the compound formed between Pb2+ and the amino acid-based IL. Based on 1H Nuclear Magnetic Resonance (NMR) spectrum of PbSO4 dissolved in the [Ch][Ser] IL and single crystal X-ray diffraction (XRD) studies, we discovered that the Pb2+ was coordinated with two [Ser] molecules and displayed a hemidirected five-coordinate geometry. ILs that can selectively dissolve PbSO4 thus hold promise for an environment-friendly alternative recycling paradigm for the LAB industry.

Reduced graphene oxide coated with amorphous lead as positive additive for enhanced performance of lead–carbon batteries

Composites of reduced graphene oxide coated with amorphous lead (Pb/rGO) were prepared by electrostatic adsorption and hydrothermal methods, and used as positive additives for lead–carbon batteries to enhance discharge specific capacity and cycle life under high-rate partial-state-of-charge (HRPSoC) of batteries. Amorphous Pb inhibits the oxygen evolution reaction (OER) that occurs on the surface of reduced graphene oxide (rGO) and increases the specific capacitance of the positive active material (PAM). In addition, the presence of amorphous Pb enhances the affinity of rGO to PAM, which avoids the separation of additive and PAM during the cycling process. Pb/rGO additives can act as pore forming agents and significantly increase the specific surface area of PAM, which enables the electrolyte to fully react with PAM to inhibit the overgrowth of PbSO4 crystals. Thus, Pb/rGO additives help to improve the electrochemical performance of batteries. To be specific, when the Pb/rGO additive content is 0.7 wt%, battery showed the best discharge specific capacity (102 mAh/g) and cycle life (18,104 cycles), which is 117% and 104% higher than that of blank battery, respectively. And the rate capability is also improved compared to its counterpart. In short, the Pb/rGO composite material has potential application value in lead–carbon batteries.

Achieving high performances of lead-carbon battery with MnO2 positive additive

The development of the related negative additives renders the positive electrode as essential factor limiting the further upgrade of advanced lead-carbon battery. In this study, conductive manganese dioxide (MnO2) materials as functional additives were introduced into the positive electrode of lead-carbon batteries to boost the electrochemical activity. The effect of MnO2 additive on the substances conversion during curing and formation stages were investigated, also the specific capacity, rate and cycling durability. The results reveal that the MnO2 additive could accelerate the charge transfer in the positive electrode and promote the conversion kinetic between PbSO4/PbO2 phases. When the doping amount of MnO2 is 0.1 wt%, the modified lead-carbon batteries delivered an initial specific capacity of 60.74 mAh g−1, which was 24% higher than the blank sample. Besides, the lead-carbon batteries with MnO2 positive additive also display impressive rate capacity and excellent cycle stability, which could retain the capacity retention rate of 89.2 % after 150 cycles under 100 % DOD condition. The excellent performances could be attributed to the fact that MnO2 could facilitate the conversion within the positive active material, reduce the generation of large PbSO4 crystals, and remarkably enhance the utilization rate of positive active materials during the charging/discharging processes.

Electrochemical performance of novel Pb alloys reinforced with Ni-coated fly ash microballoon composite foams in Lead Acid Battery

Novel Pb composite foams comprising hybrid gas pores and Ni-coated fly ash microballoons were produced by direct melt foaming method. Pb composite foams were designed to have a lower weight and larger surface area to be used in the Lead Acid Battery (LAB) as alternative to the traditional Pb grids, offering benefits in the transportation industry. The Ni-coated fly ash microballoons were added to Pb alloy melt to serve as thickening agent and pores, which were wholly enclosed within the microballoons, as well as reinforcements. The electrochemical performance of Pb grids used in traditional LAB and Pb composite foams produced in the present work was investigated for comparing purposes. The cured plates form positive and negative electrodes of Pb grid and Pb composite foams were characterized by X-ray diffraction to identify the different Pb compounds and phases. The morphology of the cured plate was found to contain flakes and dendritic structure. Zones were formed from a network of Pb particles in the negative electrode covered with PbSO4 crystals. The PbSO4 crystals exhibited miscellaneous morphology. The matrix of lead basic sulphate crystals was converted into aggregates of PbO2 particles in the positive electrode morphology, which maintained the form of the original substance. Cyclic voltammetry measurements (CV) were conducted in 3 M H2SO4 to study the anodic oxidation and cathodic reduction peaks of Pb, PbSO4 and PbO2. The galvanostatic polarization for oxidation and reduction steps was measured at different current densities. It revealed the benefit that the Pb matrix composite foam showed a longer period for oxidation of Pb into PbSO4. The composite foams exhibited a greater specific discharge electrical capacity than the Pb alloys used in traditional LAB.

Characterization of lignin and lignin-derivatives from biomass. Application as expander of Lead-acid battery

Expanders, as lignosulfonates, are crucial for a good performance of Pb/acid batteries. In the process of discharge, the Pb and the PbO2 go to PbSO4. The formed PbSO4 is adsorbed on the surface of the Pb electrode and dramatically reduces the lifetime of the battery by the formation of big PbSO4 crystals. In order to prevent that, the addition of expanders in the negative electrode is an economic solution to prevent the formation of big crystals. In this investigation, we propose the synthesis of several lignosulfonates obtained from lignin of many biomass origins. We have derivatized nine samples of lignin via microwave-assisted sulfonation, then we have characterized how efficient is the chosen synthesis method. The lignosulfonates obtained have been characterized by infrared spectroscopy (IR), proton nuclear magnetic resonance (1HNMR), two-dimensional correlated spectroscopy (COSY), and elemental analysis to acquire some relevant information about their structure in terms of functional groups. In this way, three commercial lignosulfonates, Vanisperse A, Indulin AT, and Oakwood, have been selected as references for our comparisons. Moreover, we have checked their electrochemical properties, using electrochemical techniques to compare their behavior with respect to the commercial lignosulfonates. Finally, we have selected one of them and we have tested its performance as an expander in a Pb/acid battery. That result is a very promising first approach, and we can conclude that lignosulfonates derivatives are a good and low-cost choice to improve the lifetime of Pb/acid batteries. In particular, it is shown that the incorporation of LignosB improves the cell formation as well as the first capacity (36.30% more) and the charge acceptance (63.16% more), being these relevant parameters in the performance of Pb/acid batteries.

PbO nanoparticles anchored on reduced graphene oxide for enhanced cycle life of lead-carbon battery

The composites of PbO nanoparticles anchored on reduced graphene oxide (PbO@rGO) are prepared by electrostatic interaction and ostwald ripening strategy to enhance cycle life of lead-carbon battery under high-rate partial-state-of-charge (HRPSoC). By occupying the hydrogen evolution reactive sites on the rGO surfaces, the PbO@rGO composite exhibits better inhibition for hydrogen evolution behavior than the rGO. Thus, introducing the composite additives to negative plates can effectively inhibit the hydrogen evolution reaction (HER) and alleviate the aggregation of PbSO4 crystals simultaneously, resulting in their HRPSoC cycle life show 2.6-fold enhancements compared with negative plates without any carbon additives (extend from 3501 to 12,885 cycles). The chemical bond between the rGO and PbO nanoparticles can not only help solve the "floating carbon" phenomenon, but also effectively avoid the separation of the additive and the negative active material (NAM) during the cycles. In addition, the PbO@rGO additives can act like a miniaturized stereo plate grid, which refines and expands the conductive network on the plate and provides deposition sites for Pb/PbSO4 redox couple. Outstanding performance of the batteries containing composite additives indicates that the composites have potential application value in the lead-carbon battery while providing a new idea for preparing lead-carbon composite.

Online electrochemical behavior analysis on the negative plate of lead-acid batteries during the high-rate partial-state-of-charge cycle

Transient electrochemical behavior study on the negative plate during the high-rate partial-state-of-charge (HRPSoC) cycle is of significance yet challenging to understand the health management and failure diagnosis of lead-acid batteries. Herein, we demonstrate a non-destructive monitoring method based on the charging-discharging curves and online electrochemical impedance spectrum (EIS) of the negative plate during the HRPSoC cycle. These investigations show that the potential change in the charging period (ΔVcharge) and some EIS parameters can be used to evaluate the health status of lead-acid batteries during the HRPSoC cycle. Generally, low ΔVcharge, large plate capacitance, and small plate resistance indicate a low polarization degree, a slow growth rate of PbSO4 crystals, slight H2 evolution on the negative plate, and therefore, a health battery state. These investigations introduce an online technique to evaluate the electrochemical behaviors and monitor the health state of lead-acid batteries, which may provide some valuable supports for the health management and performance improvement of lead-acid batteries.

Reconstruction of Lead Acid Battery Negative Electrodes after Hard Sulfation Using Controlled Chelation Chemistry

Lead acid batteries (LABs) remain an inexpensive energy storage technology with a wide application base. However, their short cycle lifetimes necessitate improved recycling and maintenance technologies to combat their various failure modes. One major cause of failure is hard sulfation, where the formation of large PbSO4 crystals on the negative active material impedes electron transfer. Here, we introduce a protocol to remove hard sulfate deposits on the negative electrode while maintaining their electrochemical viability for subsequent electrodeposition into active Pb. Soaking the hard sulfate negative electrode in an alkaline EDTA solution reshaped the surface by solubilizing PbSO4 to Pb-EDTA while avoiding underlying Pb phases. Thereafter, we explored electrodeposition of the Pb-EDTA complex as fresh electrode material and found reduction of Pb-EDTA required lower deposition overpotentials with decreasing pH. We used electrodeposited films on gold to demonstrate cycling of the restored active Pb in H2SO4. The film’s capacity gradually faded with cycling and PbSO4 formation, alike to commercial LABs. Lastly, we demonstrated the electrodeposition of Pb directly onto negative electrodes from a commercial LAB. Our unique approach seeds opportunity for recycling the electrode materials inside LABs without disassembly or extensive material processing.

A facile approach to suppress the sulfation in lead acid batteries using N-doped carbon derived from chitosan

To suppress sulfation in the negative electrode of the lead acid battery (LAB), N-doped carbon (NC) is synthesized by annealing chitosan under N2 atmosphere. As an additive, NC can improve LAB’s cycle stability through the suppression of irreversible sulfation. It is attributed to the formation of a carbon conductive network in the negative electrode, which can improve electronic conductivity and control growth of PbSO4 crystals. Therefore, the LAB with Pb/NC negative electrode delivers a long cycle life of 1102 at the current of 0.2 A. It is about 3.6 times that of LAB with Pb electrode. Potentially, the approach of preparing NC is simple and inexpensive. It is expected to be commercialized.

Role of Iron Impurity in Hydrometallurgical Recovery Process of Spent Lead-Acid Battery: Phase Transformation of Positive Material Made from Recovered Leady Oxide

Leady oxide samples with various Fe contents were recovered from simulated spent lead paste with the addition of various dosages of iron oxides as simulated Fe impurities via hydrometallurgical process with sodium citrate-acetic acid solution. More than 75 wt% of the Fe element in simulated spent lead paste remained in the recovered leady oxide. The recovered leady oxide samples were used to prepare positive plates in order to illuminate the effect of Fe impurities on the phase composition of positive material. When the Fe content in recovered leady oxide was > 223 mg kg−1, the generation of 4PbO·PbSO4 (4BS) during curing procedure was inhibited. The specific surface area, α-PbO2 content, and hydrated PbO2 content of positive active mass (PAM) after formation procedure decreased with the increase of Fe content. As a result, larger PbSO4 crystals formed in Fe-containing PAMs after cell discharge, which hindered the transfer of H2SO4 electrolyte and destroyed the interconnected PbO2 skeleton. The negative effect of Fe impurities on cell cycle performance was observed when the PAM was manufactured from the leady oxide containing only 49 mg kg−1 Fe element, with the cell capacity decreased from 2.2 to 1.0 Ah after only 230 charge-discharge cycles.

Benzyl benzoate as an inhibitor of the sulfation of negative electrodes in lead-acid batteries

Abstract The lead sulfate crystals formed on the surface of the negative electrodes of lead-acid batteries during discharge gradually grow in size as a result of recrystallization processes. The big PbSO4 crystals have low solubility and are involved but very slightly in the charge process, thus causing progressive sulfation of the negative electrodes on cycling. In order to reduce or suppress this sulfation, the processes of PbSO4 recrystallization should be inhibited. It has been established that, besides lignosulfonates, some organic substances, too, may be used as additives to the negative active material to effectively inhibit the growth of lead sulfate crystals during battery discharge. The research results discussed in the present paper indicate that the aromatic ester compound of carboxylic acid, Benzyl benzoate (C6H5CH2O2CC6H5), has such inhibiting properties. Lead-acid test cells with negative plates containing Benzyl benzoate (BB) have improved cycle life performance, the beneficial effect of the BB additive to NAM being most pronounced at a loading level of 0.3%. Cells with BB added to the electrolyte have also been tested. In this case, the additive exhibits its inhibiting effect on the processes of PbSO4 crystal growth most strongly when added to the electrolyte at concentration levels of 0.3% or 0.5%.

Lead oxide/carbon black composites prepared with a new pyrolysis-pickling method and their effects on the high-rate partial-state-of-charge performance of lead-acid batteries

A new pyrolysis-pickling method was developed to prepare various lead oxide (PbO)/carbon black (CB) composites as the additives in the negative plates of lead-acid batteries to improve their high-rate partial-state-of-charge (HRPSoC) performance. Compared with CB, the PbO/CB composites prepared by the pyrolysis-pickling method have higher content of alkaline surface functional groups (Calkaline) and less content of carboxyl surface functional groups (CCOOH) on CB particles which are still covered with small amount of PbO, meanwhile they have smaller BET surface area, but larger pore volume and average pore width. The hydrogen evolution process in the negative plates containing the PbO/CB composites is inhibited effectively due to the increased Calkaline on CB, while the redox processes (Pb↔PbSO4) in these negative plates are accelerated obviously owing to the changes in their microstructure. The PbO/CB composites can impede the growth of PbSO4 crystals and significantly increase the HRPSoC cycle life of the simulated test cells. In general, the PbO/CB composites with a lower PbO content may be the appropriate additives for the negative plate of lead-acid batteries.

Understanding Function and Performance of Carbon Additives in Lead-Acid Batteries

While the low cost and strong safety record of lead-acid batteries make them an appealing option compared to lithium-ion technologies for stationary storage, they can be rapidly degraded by the extended periods of high rate, partial state-of-charge operation required in such applications. Degradation occurs primarily through a process called hard sulfation, where large PbSO4 crystals are formed on the negative battery plates, hindering charge acceptance and reducing battery capacity. Various researchers have found that the addition of some forms of excess carbon to the negative active mass in lead-acid batteries can mitigate hard sulfation, but the mechanism through which this is accomplished is unclear. In this work, the effect of carbon composition and morphology was explored by characterizing four discrete types of carbon additives, then evaluating their effect when added to the negative electrodes within a traditional valve-regulated lead-acid battery design. The cycle life for the carbon modified cells was significantly larger than an unmodified control, with cells containing a mixture of graphitic carbon and carbon black yielding the greatest improvement. The carbons also impacted other electrochemical aspects of the battery (e.g., float current, capacity, etc.) as well as physical characteristics of the negative active mass, such as the specific surface area.

Structural and electrochemical investigations of the electrodes obtained by recycling of lead acid batteries

The lead acid batteries are widely used in automobile and provide spent electrodes composed of PbO2/PbSO4 and Pb/PbSO4. Today, batteries are treated and recycled using the pyrometallurgical and hydrometallurgical techniques. However, these techniques have some important disadvantages: i) the small lead recovery rate (due to the rapid oxidation of the electrolytic Pb powder in the atmosphere); ii) the important amount of energy and time spent to convert oxides and sulfates into metal, which is subsequently reconverted to oxides; iii) the harmful emissions and their negative environmental impact.In this work, we propose a method of recycling batteries by a melt quenching route in order to improve the present practice. Is the melt quenching method a new eco-innovative approach for lead recycling of spent lead acid batteries? We think that yes, since economically is more favorable (in terms of low production cost, energy and time saving) and environmentally more friendly.Focus was addressed on both the structural characterization (by X-ray diffraction) of the samples obtained by melt quenching of spent electrodes proceeded from car batteries, as well as on their electrochemical and electrical characterization by cyclic voltammetry and electrochemical impedance spectroscopy as potential raw materials in obtaining new and more performing battery electrodes. Our results suggest that the increase of Pb concentration in the recycled electrodes implies the formation of a regulated lead sulfate layer in the oxidation process and the dissolving of PbSO4 crystals followed by the hydrogen evolutions in reduction process of lead ions.

Variance-Based Sensitivity of Localized Sulphation to Microporous Separator Properties Using a Distributed Parameter Model of a Valve-Regulated Lead-Acid Battery

Modern applications such as electric and hybrid-electric vehicles require high-rate partial state-of-charge (HRPSoC) duty from battery systems. A major cause of premature capacity loss in lead-acid batteries under HRPSoC duty is irreversible passivation by progressive sulphation of the negative electrode. Notable advances have been made in the form of desulphating charge algorithms as well as carbon additives to the negative electrode that seem to restrict PbSO4 crystal growth. However, a method that substantially curbs irreversible sulphation has yet to be developed. During a high-rate discharge, the PbSO4 crystals that nucleate and grow on the porous electrodes are small and needle-like, implying a high crystal geometry factor. The available surface area for dissolution during a subsequent charge is significantly larger than if preceded by a low-rate discharge. Apart from the size, shape and distribution of the PbSO4 crystals, their dissolution also depends on the local electrolyte concentration. A high-rate discharge results in a particularly non-uniform concentration profile and, consequently, areas with low crystal solubility. Our focus is on a new valve-regulated lead-acid (VRLA) battery with immobilized electrolyte undergoing a high-rate discharge. We investigate the microporous separator’s design for healthier end-of-discharge (EOD) conditions. More specifically, we consider EOD conditions that would be favorable to the dissolution of PbSO4 crystals in a subsequent charge. We use a comprehensive electrochemical model that accounts for full mass transport over three regions: the positive electrode, the separator and the negative electrode. Partial differential equations describing the local PbSO4 crystals are also included. The model is verified in COMSOL Multiphysics®and used to simulate a high-rate discharge at 728 A until 12 Ah (50% DOD) followed by a short rest period, all at 25 °C. A variance-based sensitivity analysis (VBSA) is performed to determine the sensitivity of several output variables to changes in selected input parameters. The input space, consisting of the separator’s porosity, thickness and tortuosity, is explored in a Monte Carlo experiment using Quasi-random sampling. The output variables of interest are the local PbSO4 volume fraction and solubility, and the crystal geometry factor. First-order sensitivity explains the effect of a single parameter whereas the total sensitivity takes parameter interactions into account. Figure 1 shows the local PbSO4 volume fraction and solubility during a high-rate discharge. As the battery discharges, the electrolyte concentration decreases and the PbSO4 solubility increases. This solubility is much lower at the negative electrode and more crystals form at the separator interfaces than in other electrode regions. A greater volume fraction of PbSO4 has formed at the positive electrode but considering the local solubility, these crystals should dissolve during the following charge. Table 1 summarizes the sensitivity at the EOD for both separator interfaces calculated using 500 model evaluations. The separator tortuosity seems to have a negligible effect on the PbSO4 crystals at the interfaces during a high-rate discharge. Figure 2 shows the output variables at the EOD against the most influential parameter for each interface. For faster dissolution of the PbSO4 crystals at the negative electrode, we would like the highest crystal geometry factor and solubility but the smallest fraction of PbSO4 crystals. Figure 2 indicates the selection of a separator with thickness between 0.05 and 0.1 cm and porosity between 0.7 and 0.75. Figure 3 illustrates how the electrolyte concentration becomes more uniform in the negative electrode during a rest period after discharge, but the concentration in the positive electrode becomes more non-uniform. Equation (1) is used to calculate the concentration non-uniformity. Figure 3 also indicates that homogenization of the concentration in the negative electrode occurs faster when the separator thickness is roughly between 0.08 and 0.1 cm. At separator thicknesses greater than 0.125 cm, it seems that diffusion takes longer within the negative electrode. The VBSA results suggest that the separator thickness has the greatest effect on the PbSO4 crystals at the negative electrode simply because it influences the concentration profile so severely. We conclude from the VBSA results that optimal values for the separator thickness and porosity, to enable healthier EOD conditions, do exist. It is possible to design a microporous separator that improves the dissolution, during recharge, of the PbSO4 film on the negative electrode that initially formed during a high-rate discharge. Irreversible sulphation of the negative electrode in a lead-acid battery under HRPSoC duty might be curbed by simple yet calculated changes to the separator sandwiched between two porous electrodes. The quantitative approach we have followed can be used to quickly evaluate thousands of different separator designs and determine a suitable starting point for experimental work. Figure 1

Variance-Based Sensitivity of Localized Sulphation to Microporous Separator Properties Using a Distributed Parameter Model of a Valve-Regulated Lead-Acid Battery

Progressive sulphation of the negative electrode in a lead-acid battery under high-rate operation remains a serious problem. This study investigates how healthier end-of-discharge conditions, in a valve-regulated lead-acid battery with an immobilized electrolyte, can be achieved by calculated changes in the separator’s porosity, thickness and tortuosity. The solubility, volume fraction and geometry factor of local PbSO4 crystals are modeled using a distributed parameter model and observed during a high-rate discharge in simulation. A variance-based sensitivity analysis, consisting of a Monte Carlo experiment and Jansen’s formulae for variance decomposition, is performed to quantify the effects of separator design on localized sulphation. The concentration profile across different regions of the cell is also briefly examined by means of a statistical equation for the concentration non-uniformity. The results indicate that the separator thickness has the greatest effect on the PbSO4 crystals at the negative electrode because it severely influences the concentration profile in this region. The simulation results also indicate that separator design with the aim of manipulating the concentration profile, and enabling faster homogenization within a lead-acid cell, can be achieved. We conclude that it is possible to design a microporous separator that improves the dissolution, during recharge, of the PbSO4 crystals on the negative electrode that initially formed during a high-rate discharge. The quantitative approach we have followed can be used to quickly evaluate thousands of different separator designs and determine a suitable starting point for experimental work.

Effects of surfactants on sulfation of negative active material in lead acid battery under PSOC condition

Lead–acid battery performance is severely limited to negative plate sulfation (irreversible formation of lead sulfate).The influence of surfactants types in lead-acid battery electrolyte has been investigated on the sulfation of negative active material (NAM) under high-rate partial-state-of-charge (HRPSoC) opreation. However, it is still an open investigation to explore that how to make the lead sulfate crystals more electrochemically active and how surfactants affect on their pattern growth. This research demonstrates that various surfactants have different effects on NAM sulfation using XRD (X-ray diffraction), SEM (scanning electron microscopy), CV (cyclic voltammetry) and EIS (electrochemical impedance spectroscopy) techniques, which in some cases their behaviors are conversely. Amongst all tested surfactants, the cell with anionic sodium dodecyl sulfate surfactant (SDS) exhibits the longest cycle life with the least overcharge and fine PbSO4 crystals. The cell with cationic cethyl trimethyl ammonium bromide (CTAB) surfactant shows opposite effects.

Lead sulfate used as the positive active material of lead acid batteries

Lead sulfate is produced when a lead acid battery discharges, and it is also known that big PbSO4 crystals are less active than the smaller ones because they dissolve slower, thus result in failure of the battery. However, little is known if chemically prepared PbSO4 can be used as active material of lead acid batteries. Here, we report the preparation of PbSO4 by facile chemical precipitation of aqueous lead acetate with sodium sulfate and its utilization as the positive active material. The results show that the PbSO4 alone is not good enough for the purpose, but its mixtures with Pb3O4 are as excellent as the industrial leady oxide. For example, the mixtures containing 5, 10, 20, and 30 wt.% of Pb3O4 discharge 78.2, 92.9, 88.0, and 91.5 mAh g−1 at a current density of 100 mA g−1, respectively. Also, the one with 10 % Pb3O4 remains 93 % capacity in 150, 100 % DOD cycles.