Equivalent circuit analysis of Li-ion battery degradation by electrochemical impedance spectroscopy
Li, Chaoran (2026)
Kandidaatintyö
2026
School of Energy Systems, Sähkötekniikka
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi-fe2026051847137
https://urn.fi/URN:NBN:fi-fe2026051847137
Tiivistelmä
The electric vehicle industry is developing rapidly. However, a large number of spent electric vehicle batteries urgently require precise battery health status diagnostic equipment.
This paper utilizes the large electrochemical impedance spectroscopy dataset provided by EMPIR 17IND10 to study the internal degradation of commercial NMC811 silicon/graphite 18650 batteries. A framework for automatically extracting battery health status parameters was constructed using MATLAB. The most critical microphysical parameters after more than 2150 aging cycles were extracted using a nonlinear least squares (NLLS) optimization algorithm and a second-order RC equivalent circuit model (ECM).
The results show that the solid electrolyte interfacial resistance generally increases from the start of cycling, and decreases in the early to middle stages of cycling due to the continuous increase. The charge transfer resistance is relatively stable in the initial stage, but reaches an inflection point and rises sharply after about 1100 cycles. This study demonstrates that electrochemical impedance spectroscopy and automatic electrochemical parameter tracking are efficient, time-saving, and non-destructive diagnostic tools.
This paper utilizes the large electrochemical impedance spectroscopy dataset provided by EMPIR 17IND10 to study the internal degradation of commercial NMC811 silicon/graphite 18650 batteries. A framework for automatically extracting battery health status parameters was constructed using MATLAB. The most critical microphysical parameters after more than 2150 aging cycles were extracted using a nonlinear least squares (NLLS) optimization algorithm and a second-order RC equivalent circuit model (ECM).
The results show that the solid electrolyte interfacial resistance generally increases from the start of cycling, and decreases in the early to middle stages of cycling due to the continuous increase. The charge transfer resistance is relatively stable in the initial stage, but reaches an inflection point and rises sharply after about 1100 cycles. This study demonstrates that electrochemical impedance spectroscopy and automatic electrochemical parameter tracking are efficient, time-saving, and non-destructive diagnostic tools.