For Li + extraction, operating in Regime 1 (Cinter < CpseudoIX) offers the highest capacity in a single intercalation pass and requires minimal ion exchange (Fig. ) The Li + extraction results for Regime 2 (Cinter ~ CpseudoIX) and Regime 3 (Cinter > CpseudoIX) are summarized in Supplementary Fig. . The main findings are that Regime 3 requires multiple pulses to increase the capacity and approach high Li + selectivity; both Regime 2 and Regime 3 require ion exchange after intercalation, which begins to degrade the CpseudoIX rate with each extraction sequence. Therefore, even though operating at Regimes 2 and 3 can lead to reasonably good depth of intercalation and they have faster Cinter rates, the total time to the final depth of intercalation to ensure a good Li selectivity is longer than Regime 1 due to their long ion exchange time. Therefore, Regime 1 is selected as a better condition for Li + extraction. Moreover, it is worth mentioning that autointeraction was observed for the Li + extraction process that results in increased Li + content than predicted by the electrochemical capacity (FE>100%). A spontaneous side reaction involving the (LiNa)1-vCoO2 was observed which allows for the reduction of the Co 4+ that promotes Li + intercalation (Supplementary Fig. ). In the most extreme cases, Li0.48CoO2, formed via delithiation in 1 M NaClO4 solution, can transform into Li0.90Na0.05CoO2 without any use of electricity over 90 hours. The reactivity of the ion exchanged sample could be related to the high strain at the interface . Additionally, this excess Li + can be electrochemically recovered by using a voltage cutoff instead of a time cutoff during the recovery step in the pure Li + solution. By operating in Regime 1, the vacancy can approach 0.06 so that most of the capacity is used for Li + extraction (Fig. ). By using the extended deintercalation to a voltage cutoff, additional Li + is recovered from the Li + intercalated from the autointercalation reaction and not the applied C-rate. The OCP curve quickly changes to a positive potential after intercalation and does not become more sluggish with additional Li + recovery sequences since minimal to no ion exchange is needed (Fig. ). The Na + composition does not change anymore after the first extraction sequence and that less than 5% available sites hold Na + in the structure. Therefore, we can achieve 99% Li + purity on the 3 rd extraction sequence with FE of 120% during intercalation (Fig. ). The extraction sequence has increasing purity after each extraction sequence approaching levels appropriate for battery grade precursors (Supplementary Table ). Therefore, a Li + recovery can be achieved with 99% purity while using ~40% of the theoretical capacity of the (NaLi)1-vCoO2 material without large variability in the post intercalation equilibrium kinetics or large loss of capacity between extraction sequences.