Evaluation of the Thermal Impedance Spectroscopy for Lithium‐Ion Batteries Using an Embedded Temperature Sensor

Using lithium‐ion batteries requires a sophisticated understanding of thermal behaviour to avoid dangerous states leading to hazards. To obtain an estimate of the temperature development, precise knowledge of the relevant thermal model parameters is required. In this work, thermal impedance spectroscopy is combined with inserted temperature sensors to investigate the influence of thermal gradients in a cylindrical cell on the frequency‐based temperature response. The combination shows a shift in spectra, avoiding negative real parts, resulting from a time‐delay measurement of the surface temperature. This makes the fit of the results more reliable, showing a heat capacity of 0.946 Jg −1 K −1 and a thermal conductivity of 1.842 Wm −1 K −1 using the temperature response inside the cell. The results are further compared to a prepared prismatic cell to investigate the influence of the cell format on the resulting spectra. The data further revealed that using insulation around the cells yields more reliable initial parameterisation values.