Cationic intermediates assisted self-assembly two-dimensional Ti₃C₂T_x/rGO hybrid nanoflakes for advanced lithium-ion...

Two-dimensional (2D) material MXenes have been intensively concerned in energy-storage field due to these unique properties of metallic-like conductivity, good hydrophilicity and high volumetric capacity. However, the self-restocking of ultra-thin 2D materials seriously hinders these performances, which significantly inhibits the full exploitation of MXenes in the field of energy storage. To solve this issue, a strategy to prepare delaminated Ti₃C₂T_x (MXene) nanoflakes/reduced graphene oxide (rGO) composites is proposed using the electrostatic self-assembly between positively charged Ti₃C₂T_x with tetrabutylammonium ion (TBA⁺) modification and negatively charged graphene. The nanoflakes of Ti₃C₂T_x/rGO are well dispersed and arranged in a face-to-face structure to effectively alleviate the self-restacking and provide more electroactive sites for accessible of electrolyte ions. The prepared delaminated Ti₃C₂T_x/rGO anode shows a high reversible capacity up to 1394 mAh g^-1 at a current density of 50 mA g^-1. Moreover, a lithium-ion capacitor (LIC) was assembled with delaminated Ti₃C₂T_x/rGO anode and activated carbon (AC) cathode which can exhibit a specific capacity of 70.7 F g^-1 at a current density of 0.1 A g^-1 and deliver an ultrahigh energy density of 114 Wh kg^-1 at a relatively high power density of 3125 W kg^-1. These good electrochemical performances demonstrate the potential of delaminated Ti₃C₂T_x/rGO as an anode material for lithium-ion capacitors.