Gradual CEI formation is consistent with our previous report of Li-FeF3 full cells cycled with unencapsulated LHCE, where ~20-30 cycles were required to stabilize capacity fade at a rate of C/20 (equivalent to 0.05 mA cm -2 in the present report). Although we cannot completely rule out the influence of current density on the rate of CEI stabilization, Figure suggests that this process is more dependent on the number of initial cycles than on the particular current density.