High capacitance of dipicolinic acid-intercalated MXene in neutral water-based electrolyte

Abstract

As an emerging family of conductive 2D materials, MXenes, have gained much attention as electrode in supercapacitor devices. Their representative, Ti3C2Tx, usually achieves significant capacitance in common acid electrolyte. In this work, through a simple dipicolinic acid (DC) intercalation strategy, Ti3C2Tx-DC can obtain outstanding capacitance in a more environmentally friendly KCl aqueous electrolyte. As a consequence, as an electrode for supercapacitor, Ti3C2Tx-DC exhibits an outstanding specific capacitance of 353 F g−1 at a current density of 0.5 A g−1 in KCl aqueous electrolyte (MXene-DC/KCl), which is higher than MXene of 320 F g−1 in H2SO4 electrolyte (MXene/H2SO4) and MXene of 127 F g−1 in KCl aqueous electrolyte (MXene/KCl). Moreover, the MXene-DC/KCl shows an impressive cycling stability with about 100% capacitance retention after 10,000 cycles at 1.0 A g−1. Such excellent electrochemical performance in a greener electrolyte is mainly attributed to the interlayer hydration of DC and counter ion adsorption of electrolyte.