In/LiIn reference anode and Li5.5PS4.5Cl1.5 as separator. Initially, cells with constant cathode composite mass loading (15.3 mg•cm -2 ) are characterized to evaluate the influence of ΦCAM on the performance at comparable cathode thicknesses. These are, approximated by the relative density of the cathode and its mass, in the range of 73 μm to 85 μm (Table ). All composites were first cycled at a constant C-rate of 0.134 C assuming a theoretical specific capacity of 300 mAh•g -1 (corresponding to 0.1 C assuming a theoretical capacity of 400 mAh•g -1 for full delithiation). Afterwards, rate capability was tested at constant current densities instead. An overview of all 0.134 C rates in terms of current densities, and all current densities in terms of C-rates, is given in Table of the Supporting Information. In addition, scanning electron micrographs and energy dispersive X-ray spectroscopy signals are shown in Figure characterizing the composite microstructures. voltage with weakly pronounced features below 1.9 V. In this regime, delithiation is charge balanced by oxidation of Fe 2+ to Fe 3+ corresponding to the nominal compositional range of Li2FeS2 to Li1.5FeS2 and the profiles of the solid-state cathodes agree well with reports using liquid electrolyte (dashed line in Figure ). 10 At 1.9 V, a voltage plateau representing the two-phase regime of Li1.5FeS2-Li0.5FeS2 establishes.