Incremental Capacity Analysis (ICA) as a diagnostic tool for the State of Health (SoH) estimation of sec-ond Life Batteries
Author
Kristensen, Kaja Mona
Term
3. semester
Education
Publication year
2020
Submitted on
2020-12-23
Pages
79
Abstract
Klimakrisen påvirker transportsektoren. Flere elbiler betyder flere lithium-ion-batterier. Batterierne er ikke uden miljøpåvirkning, så det er bedst at udnytte dem så længe som muligt. I køretøjer betragtes et batteri som “end of life” (EoL), når kapaciteten er faldet til cirka 80 % af det oprindelige. Selv da kan det stadig bruges i stationære løsninger (en “second life”), hvor vægt og plads betyder mindre end i en bil. For at planlægge sådan brug skal man kende batteriets “state of health” (SoH), altså hvor meget kapacitet der er tilbage, sammen med andre parametre. I dag anslås SoH af bilproducenten eller en mekaniker, men der findes ingen standardiseret, kommerciel metode på tværs af batterier. Dette speciale undersøger en hurtig og præcis procedure til at bestemme den resterende kapacitet for mange battericeller på én gang. I et eksperimentelt studie med ældede lithium-titanat-oxid (LTO) celler blev det testet, om en velkendt og valideret SoH-metode også virker for celler, der allerede er nede på 80 % kapacitet. Specialet vurderer også, hvor realistisk metoden er i praksis, og om måletiden kan kortes ned ved at bruge kortere måleintervaller.
Climate change affects the transport sector. More electric vehicles mean more lithium-ion batteries. These batteries still have environmental impacts, so it is best to use them for as long as possible. In vehicles, a battery is labeled “end of life” (EoL) when its capacity has dropped to about 80% of its original level. Even then, it can still be useful in stationary systems (a “second life”), where weight and space matter less than in a car. To plan such uses, we need to know the battery’s “state of health” (SoH), meaning how much capacity it has left, along with other parameters. Today, SoH is estimated by car makers or mechanics, but there is no standardized, commercial method that works across different batteries. This thesis explores a fast and accurate procedure to estimate the remaining capacity of many battery cells at once. In an experimental study with aged lithium-titanate-oxide (LTO) cells, it tested whether a well-known, validated SoH estimation method still works for cells that have already dropped to 80% capacity. The thesis also considers how feasible this is in real-world use and whether testing time can be reduced by shortening the measurement interval.
[This summary has been rewritten with the help of AI based on the project's original abstract]
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