Diagnostics of Lithium Ion Batteries
Author
Krikis, Georgios
Term
4. term
Education
Publication year
2018
Abstract
Dette speciale undersøger moderne diagnostiske metoder til lithium-ion-batterier med fokus på at karakterisere degradering og centrale ydeevneparametre. Først defineres og diskuteres state of health, kapacitet, state of charge, åben kredsløbsspænding, intern modstand og pulseevne samt deres afhængigheder. To måleteknikker – DC-strømpulser og elektrokemisk impedansspektroskopi – anvendes på en NMC lithium-ion-posecelle, hvor spændingstransienter og impedansspektrer analyseres for at udlede parametre relateret til ohmske og ladningsoverførselsprocesser og vurdere aldring under forskellige betingelser. Som supplement undersøges pseudo-random binary sequence (PRBS) excitation i simulering for at bestemme impedans over et bredt frekvensområde som et alternativt diagnostisk værktøj. Arbejdet bruger disse tilgange til at diagnosticere degraderende ydeevne og diskuterer de særlige egenskaber, praktiske testprocedurer og potentialet for hver metode i vurdering af batteritilstand.
This thesis investigates state-of-the-art diagnostic methods for lithium-ion batteries, focusing on how to characterize degradation and key performance parameters. It first defines and discusses state of health, capacity, state of charge, open-circuit voltage, internal resistance, and pulse power capability, and their dependencies. Two measurement techniques—DC current pulses and Electrochemical Impedance Spectroscopy—are applied to a Nickel Manganese Cobalt (NMC) lithium-ion pouch cell, with analysis of voltage transients and impedance spectra to extract parameters relevant to ohmic and charge-transfer processes and to assess ageing across different operating conditions. As a complement, Pseudo Random Binary Sequence (PRBS) excitation is explored in simulation to determine impedance over a broad frequency range as an alternative diagnostic tool. The study uses these approaches to diagnose degrading performance and discusses the distinctive features, practical test procedures, and potential of each method for battery health assessment.
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