Abstract
Currently, numerous studies are being conducted in the field of battery technology, with a huge emphasis given to the ageing of batteries. Among batteries, Li-ion battery is most often used in electric vehicle technology as it has several advantages. Many models are being developed to understand how Li-ion batteries degrade over time. In real-life applications, the operating conditions are quite different from the laboratory operating conditions. Hence, a model thatcan estimate the Li-ion battery deterioration for the same battery chemistry (such as NMC.) matching real-life scenarios is necessary.
The main objective of this thesis is to investigate five different commercial Li-ion batteries that come under NMC chemistry. To make the experiment closer to the practical scenario, a hybrid testing methodology that combines cycling and rest periods in a single round is followed. Once the experiment is done, the data is analyzed, and the behaviour of parameters – internal resistance and capacity over a period of several cycles are observed while keeping in note other parameters such as SoC, voltage, current and temperature. The parameters of internal resistance and capacity are chosen as they are crucial in determining the degradation of the battery. Next, to estimate these two parameters, a fourth-order polynomial equation is formulated to closely represent the behaviour of these parameters using the curve fitting method in Microsoft Excel. This is then validated using MATLAB curve fitting toolbox. Once verified, the formula can be
used to estimate internal resistance and capacity, and thus provide a simple and accurate way of determining battery deterioration that closely fits actual practical situations.
| Date of Award | Jun 2023 |
|---|---|
| Original language | English |
| Supervisor | Md Sazzad Hosen (Co-promotor) & Maitane Berecibar (Promotor) |