Binder-Free High-Performance MXene Supercapacitors Fabricated by a Simple Electrospray Deposition Technique

Abstract

In this work, an electrospray deposition (ESD) technique is applied to fabricate binder-free porous 2D MXene (Ti3C2Tx) electrodes for supercapacitor applications. As a result of the crumpling of MXene flakes induced by the capillary force during drying, a porous structure is formed between MXene flakes within the electrode which leads to the formation of channels for rapid ion-diffusion. Together with binder-free networks of highly electrical conductive MXene sheets, these ion diffusion channels greatly improve the rate capability of the electrospray MXene electrode. Cyclic voltammetry measurements show that micron-thickness electrodes retain their capacitive rectangular-shaped curves even at a very high scan rate of 10000 mV s(-1)in KOH electrolyte. A specific capacitance as high as 400 F g(-1)is also recorded in H(2)SO(4)electrolyte and this high specific capacitance maintains 85% of its value when the scan rate is increased to 1000 mV s(-1). Furthermore, the electrospray MXene electrode shows good cycle stability in H(2)SO(4)without a binder. About 90% of the capacitance is maintained after 10000 charge-discharge cycles at a current density of 15 A g(-1). All of these results show that the ESD MXene electrodes are a promising candidate for supercapacitor applications that require both high capacitance and enhanced rate capability.