High energy lithium-ion battery characterisation and overcharge abuse test
Examensarbete för masterexamen
Sustainable energy systems (MPSES), MSc
PATIL, AKHILESH SATISH
Batteries are finding extensive applications in different domains. Lithium-ion batteries are one of the most interesting kinds. They are used in most of the portable electronic equip ment, small and large appliances, electrical energy storage system and electric vehicles due to their high power and high energy densities. Nevertheless lithium-ion technology has its own dangers due to presence of highly volatile and flammable materials. These properties can lead to emissions of gas from the cell package, further leading to thermal runaway and toxic gas emissions. Many researches have reported that gas emissions in clude highly detrimental gases like hydrogen fluoride (HF), carbon monoxide (CO) as well as phosphoryl fluoride (POF3). The lithium-ion cell construction involves graphite based anode metal oxide cathode and a liquid electrolyte with high lithium ion mobility. Due to high electrochemical reactivity and mechanical degradation under different operative conditions, the battery will eventu ally lead to decreased performance. Cathodic materials limit the energy density and are the primary reason for the battery cost. Those materials being Nickel (Ni), Manganese (Mn) and Cobalt (Co) with lithium intercalating oxides. The different proportion of these metals can influence the performance levels in the batteries. In this thesis, a number of methods have been used to characterize prismatic lithium-ion battery cells. The investigation has included analysis of the disassembled cell components using: thermal analysis for the separator material, X-ray diffraction (XRD) for electrode materials and Fourier transform infrared spectroscopy (FTIR) for liquid electrolyte anal ysis, gas analysis, as well as electrical measurements such as impedance, charge and dis charge tests on the complete cell. Overcharge abuse tests have been performed to further investigate cell safety by analysing gas emissions using gas sensors, FTIR and physical parameters such as temperature across the thermal runaway in a cell fault scenario.
Lithium-ion batteries, NMC, Overcharge, Abuse, Safety, Thermal runaway, gas emissions, FTIR, DSC, XRD