This highlights that high energy densities can be practically achieved at low rates, but Li2FeS2/Li5.5PS4.5Cl1.5 solid-state cathodes require further improvement regarding their rate capability. This can be achieved, e.g., by improving the processing of the solid composites and by controlling the particle size distribution of its constituents. Both strategies have the ability to improve the transport properties show the best rate performance (Figure ), and in agreement with the reported rate performances by Minnmann and coworkers. In both cases, this optimum in rate performance is achieved in cathode compositions closest to the condition of σe ≈ σion (diagonal in Figure ) that minimizes the conductivity term of the δ-parameter (Eq. 4, Figure ). Moreover, this analysis shows that the investigated system is strongly limited by σion and that increasing the cell performance is intimately tied to the improvement of the ionic conductivity in the composite (to reach the condition of σe ≈ σion). The highest electrode utilization in the system LiMn2O4/Li3InCl6 44 is also reported at the composition fulfilling the condition σe ≈ σion in agreement with the δ-parameter assessment. Nonetheless, the analysis predicts that the system should suffer from transport limitations in thick electrode configurations and during fast charging (δ ≈ 160)