In order to get more insight into the impact of the materials' features on the diffusion coefficient, we then interpreted the ML model using the SHAP algorithms. The values of feature importance, determined using the average of the absolute Shapley values for each feature, are plotted in Figure . As expected, the most important features are found to be the PLD and the barrier activation energy, as demonstrated in the previous section. The void fraction also appeared to play a non-negligible role.