Thermal runaway poses a major safety concern, and the assessment of cells after such events is challenging, e.g. when post mortem analysis requires deep discharge for health and safety at the testing lab. Conventional methods such as Galvanostatic Intermittent Titration Technique (GITT) and Incremental Capacity Analysis (ICA) provide valuable insights into redox behavior and internal resistance changes but are time consuming and sensitive to environmental conditions. Therefore, Differential Thermal Voltammetry (DTV) is used as an alternative to GITT and ICA.

Four NCA prismatic cells were subjected to a thermal runaway scenario, after which two cells (Cell 3 & 4) remained suitable for electrochemical investigation. ICA revealed peak shifts and peak flattening at higher voltages for the damaged cell, while GITT confirmed elevated internal resistance across the entire SOC range. For DTV Cell 3 experienced significantly higher thermal exposure, resulting in increased noise levels, larger cycle to cycle variations and a pronounced rise in internal resistance, particularly at low states of charge.

DTV demonstrated high sensitivity to localized thermal damage, capturing spatial inhomogeneities between hot and cold cell walls and clearly differentiating between the more severely damaged Cell 3 and the minimally affected reference Cell 4. The method detected reduced peak intensities, delayed charge onset, and enhanced thermal gradients, all indicative of weakened redox kinetics and change of inner resistance degradation.

Overall, the findings confirm that DTV is a powerful tool for rapidly identifying thermal damage and complementing established electrochemical methods. Its robustness and sensitivity make it particularly promising for extending diagnostic capabilities from module level measurements toward cell level characterization in complete battery systems. In the future, methods such as ICA, GITT and similar will still be necessary in order to clearly assign the individual damage mechanisms to the DTV signals.