Methodological optimisation and interpretation of coulometric titration time analysis

Coulometric titration time analysis (CTTA) has recently emerged as a powerful technique for quantifying the rate of solid electrolyte interphase (SEI) growth and elucidating the underlying mechanisms governing degradation in solid-state batteries with argyrodite solid electrolytes. However, subsequent studies employing metallic interlayers and variable stack pressures have revealed that CTTA results are highly sensitive to the effective contact area between the solid electrolyte and the current collector. In this work, we further explore CTTA as a SEI characterisation technique to gain more information on its strengths and weaknesses. The findings highlight key challenges when comparing results across samples and propose strategies to mitigate these effects. Moreover, this study contextualises CTTA within the broader suite of SEI characterisation techniques, offering guidance on its optimal implementation and interpretation.