The oldest and also most used type of secondary cells is lead-acid accumulator. Basic functional principle stayed same as in foundation time, only operation parameters are still improving (for example one of the most important is lifetime). Significant technical problem is temperature of lead-acid battery and her influence on functionality and running reactions. Master thesis is focused on this section, when is necessary to evaluate new pieces of knowledge in development. The work deals with description existing types of accumulators, further deals with theory of temperature balance and in the end by measured datas and theirs analyzing.

This work deals with lead-acid batteries operating in hybrid electric vehicles mode, i.e. in a partial state of charge. The adverse effects such as premature capacity loss and large internal resistance can markedly affect the life of a lead battery. The experiment described in this work aims to clarify the influence of the titanium dioxide in the active mass of negative electrodes especially in the life of lead acid batteries.

Master´s thesis deals with the utilization of lead-acid accumulators in hybrid electric vehicle regime. It describes the side effects known as PCL, generated during PSOC regime and connected with the length of the battery lifespan. One possibility how to eliminate these effects, is the use of additives in active mass of the negative electrode, in the form of glass fibres. The project provides the parametres and reactions of additive, that have lead to the improvement of battery properties. The purpose of this thesis is to verify the positive effect of the aditive on the lifespan of the lead-acid accumulator.

The lead-acid batteries used in hybrid electronic vehicles HEV operate in high-rate mode in a state of partial charge PSoC. It occurs when the degradation mechanisms related to irreversible sulphation and negative electrodes are a limiting factor in the life of lead-acid batteries. The electrode system was applied to experimental pressure cells of different sizes. Exp. cells were subjected to measurement and evaluation of potential negative electrode, a negative active mass resistance, contact resistance of transition collector - the active mass with the evaluation and measurement of pressure fluctuations within four PSoC runs.

The main aim of this paper is to contribute to the elucidation of electrochemical processes. These processes occur in the investigated experimental lead-acid cell. For this purpose, electrochemical impedance spectroscopy was used. There are two methods of measurement presented. First one is used to measure impedance between electrodes. Second one is used to measure impedance of collector ribs inside positive or negative electrode. The results are represented by electrical equivalent circuits, whose elements are described in detail in the theoretical part.

This dissertation deals with impedance measurements of lead-acid accumulator. Main aim was to study recent problems of impedance measurements of lead-acid accumulator and most importantly to extend difference method and also to interpret its results. The original DC difference method was developed earlier at our Power Sources Laboratory of Department of Electrical and Electronic Technology. The DC difference method and also the new AC difference method are both non-destructive, which means that experimental data can be obtained in situ. New method provides more accurate set of information because of its wide frequency range nature. Electrodes of lead-acid accumulator were analysed with special attention to collector / active mass double layer and to active mass itself. Various states and operation regimes were investigated. Obtained data contributed to better understanding of involved degradation mechanisms. Main aim of other experiment was to observe and interpret corrosion rates of electrode collector composed of various lead alloys. Last but not least charge and discharge regimes e.g. 100% deep of discharge regime, partial state of charge (PSoC) regime and pulse charge regime were analysed. BioLogic VSP was the device used for almost all experimental measurements. It takes a lot of effort to optimise VSP operation regime. Best operation regime of VSP for the difference method was suggested too.

This thesis is completion of whole stage of researches and it is a result of existing need of increase efficiency, utilization rate and service life of lead acid batteries VRLA planned for utilization in hybrid electric vehicles in mode of partial state-of-charge PSoC. During the application of mode PSoC at lead acid battery occurs irreversible sulfation of negative electrodes and thus to loss their charging capability. This phenomenon, according to the latest trend called PCL3, isn´t connected with subsequently referred effects PCL1, PCL2, show up on positive electrodes. Result of this thesis is finding a new types of additives, determine their optimum amount and size in such a way that innovated composition of negative active materials be able to resist sulfation of negative electrode during operation in mode PSoC. Part of the effort to clarify actions ongoing on negative active material and causes non-returnable sulfation electrodes is also monitoring of structural changes electrode active material by using environmental scanning electron microscope, which helped to clarify processes related with loss of capacity in mode PSoC. Special attention during reserches was focused on study of the properties contact layers between collector and electrodes active material and itself active materials lead-acid battery druring exploitation. There were gain new information about influence repeated cycling of (charging, discharging) the critical area of the electrodes. Measurements was carried out on specially prepared experimental electrodes DC Difference Method, this enabled obtain data in situ.

Ce travail s'est concentré sur la compréhension de l'influence de la formulation et plus spécifiquement de la silice précipitée sur la résistivité électrique de séparateurs en polyéthylène destinés à des batteries au plomb. Les séparateurs de batteries en polyéthylène sont composés de silice précipitée, de polyéthylène ultra haute masse molaire (UHMWPE) et d'huile organique. La première partie de ce travail a été d'élaborer à l'échelle du laboratoire, des membranes modèles en polyéthylène. La seconde a été de comprendre l'influence de certains facteurs sur les propriétés structurales et physicochimiques des membranes. Ces facteurs sont principalement la quantité d'huile, la quantité et le grade de silice précipitée, les conditions de température lors de la cristallisation de la membrane et le mode de mise en œuvre utilisé. Les influences des quantités d'huile et de silice sur la cristallisation du polyéthylène sont méticuleusement étudiées, montrant que l'huile aide à augmenter la cristallinité finale de l'UHMWPE et que la silice joue un rôle de réservoir d'huile. Il a également été mis en évidence que la quantité ainsi que le grade de silice influencent la quantité de porosité de la membrane mouillable par l'électrolyte. La présence de silice en surface des pores est responsable de la mouillabilité de la membrane. Un paramètre empirique a donc été proposé dans le but de pouvoir quantifier l'efficacité de l'état de dispersion/distribution de la silice précipitée dans la membrane. Pour terminer, pour une formulation et un même mode de mise en œuvre, il est possible de discriminer l'efficacité des grades de silice précipitée pour l'application séparateur de batterie / This work is devoted to understand the effect of the formulation and more specifically of the precipitated silica on the resistivity of the PE-separators. The PE-separators are designed for the lead-acid batteries. PE-separators are composed of precipitated silica, ultrahigh molecular weight polyethylene (UHMW-PE) and organic oil. The first part of this work was to elaborate PE-separator models at a laboratory scale. Then, the factors impacting the structural and physico-chemicals properties of PE-separators were investigated. These factors are mainly the amounts of oil, precipitated silica, the grade of the precipitated silica, the temperature conditions of crystallization and the device used to elaborate the membrane. The influence of the amounts of oil and precipitated silica on the crystallization of the polyethylene wasthoroughly described showing that the oil helps to increase the final crystallinity of UHMWPE and that the silica plays a role of oil reservoir. Moreover, it was shown that the amount and the grade of precipitated silica have an influence on the wettable part of the porosity of the PE-separators. The coating of the pores by the precipitated silica is responsible of the wettability of the membranes by the electrolyte. Thus, an empirical parameter has been proposed in order to quantify the efficiency of the dispersion and distribution of the precipitated silica in the membrane. The more the membranes are wettable by the electrolyte the more the resistivity of the membranes is decreased. To finish, for a same amount of components and a same method of processing, it is possible to discriminate the efficiency of each grade of precipitated silica for the battery separator application

In commercial vehicles, where the driver overnights with the engine turned off whilestill consuming electricity, it is important to know how much the battery can bedischarged before reliable engine starting is at risk. The vehicle’s ability to crank theengine, i.e. startability, changes with the vehicle’s ambient temperature and thebatteries state of charge. The aim of this project is therefore to test the startability ofa commercial vehicle and its cranking system’s behaviour at different ambienttemperatures and battery state of charge. Physical startability tests were planned andperformed on a commercial vehicle at different temperatures inside a climatechamber. The results of these tests show the torque of the vehicle’s powertrainincreasing with lowering temperature while the cranking system’s performancedecreases. This decrease in the cranking system’s performance is a result of thebattery’s lowering ability to supply power at lower temperatures. / I tunga fordon, där chauffören spenderar natten med avstängd motor men fortsätteratt förbruka el, är det viktigt att veta hur mycket batterierna kan urladdas innanmotorn inte kan startas. Fordonets förmåga att starta motorn, det vill säga dessstartbarhet, ändras med omgivningstemperaturen och batteriernas laddnivå. Syftetmed projektet var därför att undersöka startbarheten på ett tungt fordon samt dessstartsystems beteende vid olika omgivningstemperaturer och laddningsnivåer påbatterierna. Under projektets gång planerades samt genomfördes provstarter meddet tunga fordonet vid olika omgivningstemperaturer i en klimatkammare.Provstarterna påvisade att släpmomentet på fordonets drivlina ökade med enfallande temperatur medan startsystemets prestanda försämrades. Startsystemetsförsämrade prestanda beror huvudsakligen på batteriernas försämrade förmåga attavge effekt vid lägre temperaturer.

Premature loss of capacity, mode of partial charge, additives, negative electrode, lead acid battery, lead-acid battery cycling, hybrid electric vehicle, traction battery, ebonex, titanium dioxide