Thermally Corrected Degradation Mode Quantification in Lithium Cells
Thermally corrected degradation mode quantification decouples kinetic impedance masking from true lithium inventory loss to prevent false warranty claims.
Degradation Mode Quantification
Meaning
Analytical technique used to identify and measure the specific physical and chemical processes that reduce the performance of a battery over time. Degradation mode quantification separates total capacity loss into distinct categories such as loss of active material and loss of lithium inventory.
Diagnostic Approach
Incremental capacity analysis and differential voltage analysis provide the mathematical basis for these measurements. By examining the shifting peaks in a voltage curve, degradation mode quantification can pinpoint whether the cathode or the anode is failing first. This method works without the need to disassemble the cell.
Signal Processing
Precise voltage measurements taken at low current rates are necessary to generate a clean signal for analysis. If the data is noisy, degradation mode quantification becomes unreliable for predicting the remaining useful life of the system. Filtered signals allow the detection of subtle changes in electrode stoichiometry.
Capacity Fade
Total loss of energy storage is the sum of various parasitic reactions occurring within the cell. While degradation mode quantification identifies the cause of the fade, it also suggests whether the failure is due to chemical side reactions or mechanical cracking. Accurate assessment of these modes enables more realistic warranty projections for electric vehicles and aids in the optimization of the battery management system.