We estimate the mechanical pressure to propagate a channel crack in an LLZTO film on the cantilever substrate, as shown in Fig. . We treat the dendrite shown in Fig. as a channel crack propagating through a thin film bonded to a semi-infinite elastic substrate. Both the film and the substrate are treated as isotropic, homogeneous, linear elastic materials with known Young's modulus E and Poisson ratio 𝜈𝜈. Treating this cracking as a plane strain problem, the material dependence depends on the two dimensionless parameters 𝛼𝛼 𝑎𝑎 and 𝛽𝛽 𝑎𝑎 (the Dundurs parameters) , such that