Functionalized Ti3C2Tx assisted by natural phytic acid for high-power application in lithium-ion capacitors

Two-dimensional transition metal carbides/nitrides (MXenes) have become a hotpot for energy storage, which possess desirable surface chemistry property and conductivity. However, MXenes presents a lower capacity and deteriorative cycle performance due to surface passivation and Van der Waals' force. Herein, the self-oxidized PA@Ti3C2Tx materials are developed via the functionalization with phytic acid. The capture of surface free radicals and the desorption of - F terminals promote the oxygen-rich of surface terminals and the rearrangement of-O terminals, which contributes to the reconstruction of surface structure. The derived anatase TiO2 structure endows the material with stubborn lithium-ion migration pathway and satisfactory electrochemical reversibility. The atomic defects caused by the release of Ti atoms are conducive to providing active sites and promoting charge transport. The rapid charge transfer and reduced energy barrier induced by Ti-O-P bond also enhances the lithium-ion diffusion kinetics. The 1/2PA@Ti3C2Tx material shows promoted rate performance of 180.2 mAh g -1 at 3000 mA g -1 . The assembled lithium-ion capacitor also acquires a superior energy density of 172.2 Wh kg-1 and a better power density of 3419.2 W kg-1 . This strategy of structure regulation via self-oxidation can effectively improve the high-power performance of MXenes in lithium-ion capacitors.