Characterization of the EIS Diffusion Region in Cylindrical Lithium-Ion Batteries as a Function of Temperature and State of Charge

• Published in: Journal of Power System Engineering Vol. 29; no. 3; pp. 35 - 46
• Main Author: Bae, Jin-Yong
• Format: Journal Article
• Language: English
• Published: 한국동력기계공학회 30.06.2025
• Subjects: 기타공학
• ISSN: 2713-8429; 2713-8437
• DOI: 10.9726/kspse.2025.29.3.035

This study investigates the effect of temperature and state of charge (SoC) on the electrochemical impedance characteristics of the diffusion region in cylindrical lithium-ion batteries. The increasing occurrence of fires and explosions related to lithium-ion batteries, which are widely employed in energy storage applications, underscores the necessity for enhancing their inherent safety features. Consequently, electrochemical impedance spectroscopy (EIS) is employed in the frequency range of 1 kHz to 0.1 Hz as an analytical technique for energy storage systems. Reflected wave analysis is then utilized to monitor internal impedance variations in the lithium-ion battery. Variations in the low-frequency diffusion region are examined in terms of their dependence on the structural and material characteristics of the diffusion layer and electroactive components of the lithium-ion battery. This study employs a 3000 mAh-class NCA (Li[Ni,Co,Al]O2) 18650 lithium-ion battery, which is widely used in energy storage systems, electric scooters, electric motorcycles, electric kickboards, and compact electric vehicles. Depending on the characteristics of the diffusion layer and electroactive material, lithium-ion batteries exhibit three distinct diffusion behaviors in the low-frequency diffusion region: (1) finite-space Warburg (FSW), (2) finite-length Warburg (FLW), and (3) constant phase element (CPE). Among these, the finite-space Warburg (FSW) element is not observed, while the constant phase element (CPE) and finite-length Warburg (FLW) behaviors are observed in two cases. Furthermore, in cylindrical lithium-ion batteries, the low-frequency diffusion region—where temperature and state of charge (SoC) influence performance—can be categorized into four types: (1) Warburg diffusion, (2) semi-spherical diffusion, (3) bounded diffusion, and (4) semi-cylindrical diffusion. KCI Citation Count: 0