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Effects of Grid Design on Lead-Acid Battery Performance
(Izmir Institute of Technology, 2017) İşler, Tuğçe; Top, Ayben; Ebil, Özgenç; Ebil, Özgenç; Top, Ayben; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In today’s world, approximately 88 percent of the total energy demand is supplied by fossil fuels; however, it has become clear that; other energy sources are needed due to limited fossil fuels. The demand for energy can most effectively be filled by renewable energy sources as installed energy storage capacity is growing rapidly. If renewable energy sources advance enough to fulfill the high demand, earth-friendly, clean and sustainable energy will help to protect the environment, thus ensuring a healthier life for future generations. Energy storage systems are essential in this endeavor, and in order to become more prevalent, storage systems for renewable energy sources must supply electricity without interruption as much as possible. As an electrochemical storage, a battery with a high level of performance, high energy density and life cycle could offer a viable solution for electricity storage provided that battery cost should be economically viable. This thesis aims to improve the geometry of the grid used in lead acid batteries in order to obtain a more uniform current and potential distribution, and minimize the potential drop for improved battery performance. A 3D mathematical model was developed using finite element method to evaluate the behavior of the grid under various conditions. Five different porous grid geometries were simulated under different loads and optimum grid geometry was identified. The 3D mathematical model of the lead-acid battery based on finite element method was simulated under certain conditions in order to evaluate the effect of grid geometry on battery performance.
Modification of Chemical and Morphological Properties of Lead-Acid Battery Negative Active Material
(Izmir Institute of Technology, 2014) Kama, Burak Muhammet; Polat, Mehmet; Polat, Mehmet; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Lead-acid batteries which are indispensable equipment for motor vehicles are one of the most important electrochemical processes commercially thanks to their advantages, such as low cost and capability of providing high energy. The new generation cars which such as climates, smart screens, stronger engines etc., require the batteries which should have longer cycle life and higher cold-cranking ampere. In this study, the aims were elucidating the exact working mechanism of lead-acid battery negative active material and improving the commercial lead-acid battery for micro-hybrid vehicles. For this purpose, experimental studies were separated to three parts. First one is the characterizing of negative electrode raw materials, leady oxide, lignosulfonate, carbon, barium sulfate. Second one is determination of rheological properties of negative paste in different cases. Third one is the preparation of pastes and then performance testes (reserve capacity, cold-cranking ampere and cycle life) of negative plates prepared from the pastes characterized in second part. As a result of first part of studies, it was shown that the all of carbon materials and leady oxide suffer from agglomeration in lignosulfonate solutions prepared in different concentrations. In second part, the rheological properties of negative paste were determined in different preparation cases and shown that the amount of additives and preparation method has big effects. Finally, the negative plates were prepared with two methods, wet and dry mixing. After that the plates were formed and then electrical tests were performed. Consequently, a battery which has better properties, physically and chemically, was obtained. However, this improvement was not enough due to the dispersion problems of carbon samples tested in this study.
Development of Lead Foams for Automobile Batteries
(Izmir Institute of Technology, 2012) Savacı, Umut; Güden, Mustafa; Güden, Mustafa; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Open cell lead foam samples with, 48, 55, 60, 65 and 74% porosity, were successfully prepared by powder metallurgy and casting using ammonium bicarbonate, silica beads and salt particles as space holder filler. Additionally electrowinning and powder compact foaming methods were tried. The resulting foam samples resembled open foam cell structure; each cell had interconnections with neighboring cells. Small size lead (II) fluoride precipitates were observed interior of cells in the foam samples prepared using silica beads, resulting from the reaction between silica and HF acid during space holder removal. The compression stress-strain curve of foam samples prepared by powder metallurgy showed a brittle behavior following the initial elastic, while foam samples prepared by casting showed elastic-plastic characteristic metal foam deformation; crushing of cell edges on the bent cell walls and tearing of thin cell walls. The collapse stresses of the prepared foams were fitted with scaling relations. The imperfections such as curved, wrinkled and missing cell walls, voids on the cell edges and cell walls and non-uniform density lead to discrepancy between experimental and theoretical scaling parameters.

Master Degree / Yüksek Lisans Tezleri

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