Effect of ultra-sonication, vacuum drying, and carbon coating on the super-capacitive behavior of Ti₃C₂T _x MXene

Abstract

Ti3C2Tx MXene has attracted a considerable attention in energy devices, such as lithium-ion batteries and supercapacitors. This study investigated the effects of ultra-sonication and drying conditions on the structure and electrochemical performance of Ti3C2Tx MXene-based supercapacitor electrode, where a significant improvement in the super-capacitive behavior of the sample that was sonicated and vacuum-dried at 80°C has been observed. Ti3C2Tx nano-sheets were obtained by aluminum etching of Ti3AlC2 MAX-Phase followed by the rinsing and drying post-treatment to derive Ti3C2Tx MXene layers. The rinsed layers were then dried using 4 different conditions: 1- in the air at 25 ̊C, 2- in the air at 80 ̊C, 3- in a vacuum at 25 ̊C, 4- in a vacuum at 80 ̊C. It was observed that the specific capacitance at different scan rates of the vacuum-dried samples was, on average, 30% more than that of air-dried ones. Meanwhile, the samples dried at 80 ̊C have exhibited a 60% increase in the specific capacitance compared to the samples dried at 25 ̊C. Besides drying parameters, the effect of ultra-sonication of MXene layers on their electrochemical performance has also been investigated. Generally, the specific capacitance of delaminated layers was higher than that of non-delaminated ones. However, we have noticed that ultra-sonication deteriorates the capacitive stability of the samples over time. To further improve the supercapacitor electrodes, carbon coating was performed on the sample with the best electrochemical performance (sonicated and vacuum-dried at 80 ̊C), through a hydrothermal glucose decomposition method. The specific capacitance of the carbonized sample was 117.19 F/g at the scan rate of 2 mV/s, which is 35% more than that of the pristine MXene. The MXene structures were examined by FE-SEM, XRD, and FTIR and TGA analysis. The electrochemical characteristics of the electrodes were investigated via cyclic-voltammetry, charge-discharge test, and electrochemical Impedance spectroscopy.