The challenge is to extend the life of batteries while increasing their reliability, hence the need to develop non-intrusive diagnostic technologies capable of detecting what is happening inside commercial batteries during use. The sources of failure are numerous, and include mechanical fracture of the electrodes and their partial dissolution, the formation of a solid ionic interface resulting from electrolyte decomposition (SEI), and we can also mention problems of disbonding or redox shuttling.
We will show that considerable progress has been made in the development of new techniques and cells suitable for all traditional and less traditional laboratory analytical techniques for the study of batteries. Thanks to these advances, these analytical methods can now be applied in situ. These techniques (mass spectrometry, IR, UV, EQCM, thermal analysis, SERS, NMR, EPR) enable us to visualize and better understand electrolyte and electrode degradation. However, although leading to spectacular results, many recent developments do not allow real-time monitoring of the inside of commercial batteries in use. This lecture will look at classic electrochemical characterization methods (GITT, PITT, impedance, 3-electrode and others) and show how they can be cleverly used to monitor SEI evolution, anticipate dendrite formation and predict battery health. The benefits of coupling these electrochemical techniques with thermal analysis and/or pressure measurements will also be explained.
