Temperature-Dependent Impedance Characterization of Lithium-Ion NMC Cells at Different SOH Levels

Lithium-ion batteries are essential for modern energy storage systems due to their high energy density and operational efficiency. However, their electrochemical behavior is influenced by temperature and State of Health (SOH), making accurate diagnostics vital. This study investigates the impedance characteristics of prismatic 50 Ah Nickel Manganese Cobalt (NMC) cells using Electrochemical Impedance Spectroscopy (EIS) across varying temperatures (25°C, 35°C, and 45°C), SOH levels, and State of Charge (SOC). EIS measurements were performed using a Biologic HCP-1005 Potentiostat in the frequency range of 10 mHz to 10 kHz. The objective is to explore how thermal and aging conditions affect impedance signatures, particularly ohmic and charge transfer resistance, to support the development of improved battery management strategies and predictive models for SOH, SOC, and internal temperature (IT) estimation.