Degradation diagnosis of lithium-ion batteries using AC impedance technique in fixing the state of charge of an electrode

Frequency-dependent capacitance C(ω) is a rapid and reliable method for the determination of the state-of-charge (SoC) of electrochemical storage devices. The state-of-the-art of SoC monitoring using impedance spectroscopy is reviewed, and complemented by original 1.5-year long-term electrical impedance measurements of several commercially available supercapacitors. It is found that the kinetics of the self-discharge of supercapacitors comprises at least two characteristic time constants in the range of days and months. The curvature of the Nyquist curve at frequencies above 10 Hz (charge transfer resistance) depends on the available electric charge as well, but it is of little use for applications. Lithium-ion batteries demonstrate a linear correlation between voltage and capacitance as long as overcharge and deep discharge are avoided.

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High-Precision Monitoring of Volume Change of Commercial Lithium-Ion Batteries by Using Strain Gauges

Sustainability ◽

10.3390/su12020557 ◽

2020 ◽

Vol 12 (2) ◽

pp. 557 ◽

Cited By ~ 7

Author(s):

Lisa K. Willenberg ◽

Philipp Dechent ◽

Georg Fuchs ◽

Dirk Uwe Sauer ◽

Egbert Figgemeier

Keyword(s):

Lithium Ion Batteries ◽

Lithium Ion Battery ◽

Volume Expansion ◽

Characteristic Curve ◽

Lithium Ion ◽

The State ◽

State Of Charge ◽

Strain Gauges ◽

Curve Shape ◽

Diameter Change

This paper proposes a testing method that allows the monitoring of the development of volume expansion of lithium-ion batteries. The overall goal is to demonstrate the impact of the volume expansion on battery ageing. The following findings are achieved: First, the characteristic curve shape of the diameter change depended on the state-of-charge and the load direction of the battery. The characteristic curve shape consisted of three areas. Second, the characteristic curve shape of the diameter change changed over ageing. Whereas the state-of-charge dependent geometric alterations were of a reversible nature. An irreversible effect over the lifetime of the cell was observed. Third, an s-shaped course of the diameter change indicated two different ageing effects that led to the diameter change variation. Both reversible and irreversible expansion increased with ageing. Fourth, a direct correlation between the diameter change and the capacity loss of this particular lithium-ion battery was observed. Fifth, computer tomography (CT) measurements showed deformation of the jelly roll and post-mortem analysis showed the formation of a covering layer and the increase in the thickness of the anode. Sixth, reproducibility and temperature stability of the strain gauges were shown. Overall, this paper provides the basis for a stable and reproducible method for volume expansion analysis applied and established by the investigation of a state-of-the-art lithium-ion battery cell. This enables the study of volume expansion and its impact on capacity and cell death.

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Lithium-Ion Battery Cell Health Monitoring Using Vibration Diagnostic Test

Volume 4B: Dynamics, Vibration and Control ◽

10.1115/imece2013-63962 ◽

2013 ◽

Author(s):

Huan L. Pham ◽

J. Eric Dietz ◽

Douglas E. Adams ◽

Nathan D. Sharp

Keyword(s):

Mechanical Properties ◽

Lithium Ion Batteries ◽

Lithium Ion Battery ◽

Diagnostic Test ◽

Excitation Frequency ◽

High Capacity ◽

Lithium Ion ◽

The State ◽

State Of Charge ◽

Battery Cell

With their superior advantages of high capacity and low percentage of self-discharge, lithium-ion batteries have become the most popular choice for power storage in electric vehicles. Due to the increased potential for long life of lithium-ion batteries in vehicle applications, manufacturers are pursuing methodologies to increase the reliability of their batteries. This research project is focused on utilizing non-destructive vibration diagnostic testing methods to monitor changes in the physical properties of the lithium-ion battery electrodes, which dictate the states of charge (SOC) and states of health (SOH) of the battery cell. When the battery cell is cycled, matter is transported from one electrode to another which causes mechanical properties such as thickness, mass, stiffness of the electrodes inside a battery cell to change at different states of charge; therefore, the detection of these changes will serve to determine the state of charge of the battery cell. As mass and stiffness of the electrodes change during charge and discharge, they will respond to the excitation input differently. An automated vibration diagnostic test is developed to characterize the state of charge of a lithium-ion battery cell by measuring the amplitude and phase of the kinematic response as a function of excitation frequency at different states of charge of the battery cell and at different times in the life of the cell. Also, the mechanical properties of the electrodes at different states of charge are obtained by direct measurements to develop a first-principles frequency response model for the battery cell. The correlation between the vibration test results and the model will be used to determine the state of charge of the cell.

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