, which is dominant during de-intercalation. An important prediction of CIET theory is the linear decay of the reaction rate in the approach to complete filling of the (degraded) lattice, i ∼ (c -c), which requires a vacancy for the transition state . This leads to a strong effect of electro-autocatalysis , which leads to more homogeneous concentration profiles with higher resistance during intercalation and more unstable heterogeneous profiles with lower resistance during de-intercalation, as observed in recent experiments on both phase-separating 89 and solid-solution 87 cathode active materials.