Based on our findings on LNCl it convenes to reflect on its applicability in ASSBs. A key property of LNCl is its thermodynamic stability against LM which is uncommon for SEs. However, its low anodic limit (~0.6 V) inhibits its application in combination with common high-voltage cathodes and confines the applicability of LNCl to an artificial buffer layer between LM and alternative SEs that face the cathode. In such a hybrid bilayer SE architecture, LNCl would be in close contact with a partner SE. The realization of such systems thus hinges on the chemical compatibility between LNCl and other common SEs. We investigated the thermodynamic driving force of LNCl to chemically react with common SEs by constructing pseudo-binaries in phase space (Figure ) leveraging the materials project database, as explained in detail elsewhere. Figure shows the pseudo binaries between LNCl and different SEs. ∆ED, mutual as defined by Zhu and Mo is the reaction energy for the reaction between LNCl and the SE of interest. We would like to highlight that a thermodynamic driving force for chemical reaction (∆ED, mutual <0) between two SEs does not necessarily imply immediate reaction upon contact; the diffusivity of elements in Li + -conducting SEs (excluding Li + ) is limited at ambient temperatures so that an immediate solid-state reaction upon contact may be kinetically inhibited. ∆ED, mutual can be treated as a propensity for reaction especially if the hybrid bilayer electrolyte is subjected to annealing/heating steps. Figure shows that LNCl has the strongest propensity for chemical decomposition with LATP and sulfidebased SEs such as the argyrodite Li6PS5Cl and Li3PS4. With halide (Li3MCl6) electrolytes the decomposition energy is reduced and seems to be mainly driven by the formation of strong M 3+ -N 3-bonds. The decomposition energy ∆ED, mutual of Li3ScCl6 is 100 meV/atom larger than for Li3YCl6 which can be explained by a stronger Sc-N affinity compared to Y-N. The propensity for chemical decomposition is further reduced between LNCl and LIPON-type electrolytes and the garnet (LLZO) electrolyte. Figure equally shows the pseudo-binaries of Li3N and the SEs of interest (dashed lines). α-Li3N has a larger ion conductivity than LNCl (0.1-1 mS cm -1 ) and is equally thermodynamically stable against Li metal. 57 Similar to LNCl, the applicability of α-Li3N is confined by its limited anodic limit (0.44 V). However, the driving force for chemical decomposition with common SEs is larger with Li3N by 50 -200 eV/atom than with LNCl. This suggests a stronger propensity for decomposition at the Li3N|SE interface than at the LNCl|SE interface.