Methods for post-mortem analysis of large-format cells
Andrew Lodge
Scania CV AB
Detailed investigations of end-of-life cells provides insights into features and events that occurred during the lifespan of the cell. Metrics such as individual electrode capacity, lithium plating, loss of lithium inventory (LLI), loss of active material (LAM), local state of health (SOH) and particle morphology quantify different aspects of cell performance, failure modes and cycling characteristics. Cell teardown, post-mortem inspection of the electrodes and separator, SEM imaging and electrochemical analysis of the electrode materials can be used to determine these metrics.
We present a methodology for general analysis of cells. Optical image analysis of electrode surfaces compared with local state-of-health (SoH) measurements, combined with conventional electrochemical analysis allow for a detailed spatial analysis of degradation. These combined techniques allow for a more complete understanding of the cell, its cycling behaviour and failure or degradation modes
