The Li and Li 𝑇 1 relaxation rates of the argyrodite Li6PS5Cl materials, on the other hand, could not be fit by the symmetric BPP (𝛽 = 1) model across the full temperature range (bottom panel in Figure ). Not only this, but Li6PS5Cl was found to exhibit signatures of two transport processes, requiring the consideration of two BPP modes that add according to Matthiessen's rule (see Supplemental Note 2). Thus, the data had to be analyzed systematically. Here, the least-squares optimized value of 𝛽 was found to be 0.6 for the high temperature BPP mode, as determined from the 𝑇 1 -1 data of the 7 Li6PS5Cl material (compare the symmetric and asymmetric fits for Li in the bottom panel of Figure , note that the lowest two temperature data points were excluded in the regression analysis). The corresponding activation barrier was determined to be 0.267 ± 0.004 eV for Li6PS5Cl, in excellent agreement with the SAE result. Using this 𝛽 value for the high temperature BPP mode during the fitting procedure of the 6 Li6PS5Cl data corresponds to an activation barrier of 0.237 ± 0.013 eV. By using a symmetric (𝛽 = 1) BPP model to describe the low temperature peak in 𝑇 1 -1 of 6 Li6PS5Cl and minimizing the least-squares residuals across the full temperature range, an activation barrier of 0.163 ± 0.023 eV was obtained for the low temperature transport process. It is not surprising that the SAE value of the activation barrier for Li6PS5Cl falls between the values of the two transport processes characterized by the BPP analysis.