Offline State-of-Health Estimation for High-Power Lithium-Ion Batteries Using Three-Point Impedance Extraction Method

• Published in: IEEE transactions on vehicular technology Vol. 66; no. 3; pp. 2019 - 2032
• Main Authors: Yuan, Hsiang-Fu, Dung, Lan-Rong
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2017; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aging; Batteries; Battery second use; Charge transfer; Electronic countermeasures; Equivalent circuits; Estimation; Impedance; impedance estimation; Lithium; lithium battery; Lithium-ion batteries; offline battery measurement; Rechargeable batteries; Resistance; State of charge; state-of-health (SoH); Time constant
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2016.2572163

This paper presents an offline state-of-health (SoH) estimation based on charge transfer resistance for high-power lithium-ion (Li-ion) batteries, such as lithium iron phosphate (LFP) batteries. As shown in the experimental results, the charge transfer resistance has a great aging change with battery degradation and good abilities against state-of-charge (SoC) drift and external resistance variation in the impedance parameter set of a single-time-constant equivalent circuit model (ECM), including ohmic resistance, charge transfer resistance, double-layer capacitance, and time constant, for SoH estimation. A fast and efficient three-point (TP) impedance extraction method is also proposed in this paper for accurately extracting the charge transfer resistance in offline SoH estimation. The results of long-term cycling test demonstrate that the TP impedance extraction method can successfully indicate the SoH of LFP batteries with low estimation error of 6.1%.