After the intercalation steps, the suspension was sonicated in a probe sonicator during 20 minutes with 20% of amplitude and pulsed sonication of 6s on 2s off. Finally, a centrifuge step was performed for removing the Li + ions and the sample was resuspended in water, a second washing step was performed by centrifugation and the precipitate was resuspended in water or in aqueous solutions with different capping agents (PVP, PEI) with a 10 g/L concentration. Finally, the excess of capping agent was removed by three successive centrifugation steps for 30 minutes at 13.400 rpm.