Cationic intermediates assisted self-assembly two-dimensional Ti3C2Tx/rGO hybrid nanoflakes for advanced lithium-ion capacitors

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 Ti3C2Tx (MXene) nanoflakes/reduced graphene oxide (rGO) composites is proposed using the electrostatic self-assembly between positively charged Ti3C2Tx with tetrabutylammonium ion (TBA(+)) modification and negatively charged graphene. The nanoflakes of Ti3C2Tx/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 Ti3C2Tx/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 Ti3C2Tx/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 Ti3C2Tx/rGO as an anode material for lithium-ion capacitors. (c) 2021 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.

Automated summary

Two-dimensional MXenes have sparked interest in the energy storage field for their unique properties, but the self-restacking issue hampers their performance. A new strategy involving Ti3C2Tx/rGO composites has been proposed to tackle this problem, resulting in improved dispersion of nanoflakes and increased electroactive sites. This composite material exhibits promising electrochemical performance, showing potential as an anode material for lithium-ion capacitors.