4.2.2. Parameters (*l*, *m*)

Thanks to Algorithm 1, parameters (*lmax*, *l*, *m*) are calculated on all the aged cells with *n* = 2. The results are presented in Figure 8.

**Figure 8.** Kinetic parameters. (**a**) *lmax* parameter for different ageing conditions. (**b**) *l* parameter for different ageing conditions. (**c**) *m* parameter for different ageing conditions.

The dispersion of parameter *lmax* is very small: 0.007 (Figure 8a). Conversely, *l* (Figure 8b) does not have the same value depending on the ageing process.

Parameter *m* follows the same trend as *l* (Figure 8c). Two groups are formed:


The dispersion per condition observed for parameters *m* and *l* is due to the quality of reproduction of the ARC test and the precision of the measurements previously explained.

Post-mortem analyses show that the main difference between the two groups formed here is the development of extra SEI. Group G1 has not developed extra SEI contrary to group G2. That is in accordance with the interpretation of the *m* parameter. The *m* parameter contains information regarding the basic geometrics of nuclei (spherical, prismatic... ) and the physico-chemical aspects of processes (nucleation, diffusion, transport process. . . ) [5]. The development of extra SEI changes the morphology of the cell.

Cells aged at 0 ◦C have the smallest *m* in group G1, although no ageing mechanism is preponderant. The EIS study shows that the property of interface capacitance is different. The morphology is different.

In group G2, the values of *m* are dispersed, which makes interpretation difficult.
