Development of composite phase change materials for thermal management of lithium-ion batteries by latent thermal energy storage method

Our primal energy source of fossil fuels has used for a long time thus caused a big environmental pollution problem nowadays. We are now facing huge global warming problems because of this pollution, and it damages our planet with irreversible. This environmental pollution is recognized as a serious problem by many major world countries and puts pressure on all other world countries to reduce carbon emissions. Many countries are working to reduce their carbon footprint in the next 10-20 years. The most effective method to reduce carbon emissions is to increase renewable energy sources and use energy in the most effective and efficient way. In this context, the installed capacity of renewable energy resources is increasing rapidly around the world. With the spread of renewable energy sources, the development and use of electricity storage technologies is becoming increasingly widespread. The increase in the use of electric vehicles instead of fossil-based vehicles, especially in reducing carbon emissions, has led to an increase in the production of lithium batteries used in electricity storage. Lithium batteries have many advantages in terms of electrical storage, such as high capacity, fast charging, and instantaneous high current. However, the delicate chemistry of lithium batteries requires detailed electrical and thermal management. When lithium batteries are not well managed electrically and thermally, they cause capacity loss, a decrease in the number of battery charge-discharge cycles, and more seriously it can lead hard-to-extinguish fires. Since these problems will cause life-threatening risks, especially in electric-powered vehicles, battery management systems become a much more important issue. Battery Management System [BMS] circuits and algorithms are used in the electrical management of lithium batteries. Active and passive cooling systems are frequently preferred in the thermal management of batteries. Materials with high heat conduction such as aluminum and copper and latent heat storage techniques are used as passive systems to dissipate the heat generated in batteries. Water and air-cooled active systems or hybrid active and passive systems are the most common methods used to provide thermal management in battery storage systems. In this thesis, the creation of battery packs used in electric vehicles from commercially available lithium cells with series and parallel connections on a small scale and the use of phase change materials for thermal management were examined. For this purpose, the preparation and characterization of paraffin-based composite phase change materials were carried out. As a result, it was evaluated that the obtained composite PCMs have the potential to be used in thermal management processes of lithium-ion batteries, based on their latent heat of melting and appropriate phase transition temperatures.