To reach as close as Li0.94CoO2, the electrochemical intercalation and ion exchange processes can be repeated for NCO particles over a voltage window and then allowed to relax finally back to Na0.48CoO2 (Fig. ). The electrochemical curve shape was maintained for all intercalation pulses with a decreasing intercalation capacity with each subsequent pulse (Supplementary Fig. ). The XRD reveals an almost complete transformation of the original Na0.67CoO2 to Li0.94CoO2 with only a small residual (001)Na peak at 1.13 Å -1 from the Na0.48CoO2 phase (Fig. ). The final composition Na0.08Li0.86CoO2 contains an increased alkali ion content than expected (v=0.13) based on the intercalated capacity. Based on the equilibrium between Li0.94CoO2 and Na0.48CoO2, the final Na + content almost matches the expected 0.07 value; however, the Li + content is higher than the expected 0.80 value. This suggests that the additional capacity may come from additional intercalation via side reaction or Li salt precipitation but not carry over via non-specific adsorption, which would favor the higher concentration of Na + . The recovery of this excess Li + will be discussed later.