The kinetics dependent ion pathways from Na0.48CoO2 to Li0.94CoO2 can be clearly explained using the CoO2-LiCoO2-NaCoO2 phase diagram. As shown in Figure red line i, when starting from any point on the Na0.48CoO2-Li0.94CoO2 equilibrium line (with point Na0.48CoO2 as the extreme case), if the intercalation C-rate is fast, the line showing the intercalation path quickly intersect with the Na0.67CoO2-Li0.94CoO2 co-existence line with limited cation content increase. In this case, Na + intercalation dominates, and it takes a long time for ion exchange with solution Li + to bring the structure back to the equilibrium line (horizontal path line). Also, it requires many cycles of intercalation and ion exchange to push the host to Li0.94CoO2. On the other hand, when the intercalation C-rate is slower (red line ii), the intercalation line tilts towards Li + intercalation and intersects with the Na0.67CoO2-Li0.94CoO2 co-existence line at lower vacancy level. Therefore, more Li + is intercalated, less ion exchange events are needed to bring the structure back to the equilibrium line, and less cycles of intercalation and ion exchange is needed. This trend points to the possibility that when the C-rate is extremely slow, the intercalation line could overlap with the Na0.48CoO2-Li0.94CoO2 equilibrium line and no ion exchange will be needed after intercalation. For Na0.27Li0.40CoO2 (from Na0.67CoO2 via ion exchange) as the starting material, an electrochemical behavior was realized with a more slopped plateau at slow C-rates. The difference in voltage and shape of the plateau suggests different intercalation reaction path (possibly following Li0.94CoO2 and Na0.48CoO2 equilibrium) followed by Na phase transformation. (Supplementary Fig. ).