Quantitative Cell Classification Based on Calibrated Impedance Spectroscopy and Metrological Uncertainty

Abstract

Electrochemical impedance spectroscopy (EIS) is widely used for battery cell testing in industrial production and R&D labs. This work addresses the use of EIS calibration and uncertainty analysis in cell classification. Five scenarios are investigated to discuss qualitatively the impact of calibration and uncertainty on classification. For an experimental demonstration, a cylindrical cell was measured with two mechanical fixtures of different qualities and characterized regarding random errors and calibrated impedances. The impact of uncertainty and impedance calibration on the cell classification is shown, and based on the uncertainty and corresponding error bounds, a confidence level was established for the classification results. Quantitative uncertainty bounds are presented for the full EIS frequency spectrum ranging from 150 mHz to 5 kHz.

Composite Graphene‐Modified Aluminum Foil Cathode Current Collectors for Lithium‐ion Battery with Enhanced Mechanical and Electrochemical Performances

“…The Nyquist plot displays a semicircle at high frequencies and a straight line at low frequencies, indicating the charge transfer resistance (R ct ) at the interface of the electrode and electrolyte, and the Warburg impedance (W o ) caused by the diffusion of Li + in the electrodes, respectively. [27] Though the mediation of graphene has no distinct influence on diffusion in electrodes, the application of graphene coating resulted in a reduced R ct of the GM-AGD-Al-CCs as compared to the carbon-coated aluminum foil because of the improved electrical contact between electrode materials and current collectors. The R ct value for GM-AGD-Al-CCs is 112.5 Ω, which is lower than the Rct value for KB-AGD-Al-CCs (187.6 Ω) and carbon coated aluminium foils (200.6 Ω).…”

Detection of Manufacturing Defects in Lithium-Ion Batteries-Analysis of the Potential of Computed Tomography Imaging

“…If the tolerance limits specified by the manufacturer for the considered properties of a battery component are not met within a process step, the component leaves the process as scrap (e.g., exceeding the number of divots per area after the coating process). Even though the LIB component lies within the tolerance limits in all process steps, the quality of the finished LIB will differ and can be classified as low, intermediate and high [29][30][31] due to accumulations of minor deviations or non-critical inhomogeneities. If the tolerance limits specified by the manufacturer for the considered properties of a battery component are not met within a process step, the component leaves the process as scrap (e.g., exceeding the number of divots per area after the coating process).…”

“…If the tolerance limits specified by the manufacturer for the considered properties of a battery component are not met within a process step, the component leaves the process as scrap (e.g., exceeding the number of divots per area after the coating process). Even though the LIB component lies within the tolerance limits in all process steps, the quality of the finished LIB will differ and can be classified as low, intermediate and high [29][30][31] due to accumulations of minor deviations or non-critical inhomogeneities.…”