MXene (Ti3C2Tx) anodes for asymmetric supercapacitors with high active mass loading

MXene (Ti3C2Tx) is an emerging material choice for advanced energy storage. However, the relatively low areal capacitance is a bottleneck in developing asymmetric supercapacitors with enhanced energy-power characteristics in large voltage windows. A simple and straightforward approach is proposed to design and fabricate Ti3C2Tx-multiwalled carbon nanotube (Ti3C2Tx-CNT) composite electrodes. Polymethylmethacrylate (PMMA) is used as a binder for electrodes with 40 mg cm−2 high active mass loadings (AML); meanwhile, both multilayered Ti3C2Tx and CNT are efficiently dispersed in PMMA solution. The fabricated Ti3C2Tx-CNT electrodes with different CNT contents are tested in a −1.1~-0.3 V negative potential window and analyzed by different electrochemical techniques. The optimization of Ti3C2Tx-CNT-PMMA composition facilitates the design of anodes with capacitance of 2.26 F cm−2 in Na2SO4 electrolyte, which is essentially higher than literature results for Ti3C2Tx. The ability to obtain high capacitance in the Na2SO4 electrolyte is a crucial result, which facilitates the fabrication of asymmetric aqueous devices operating at 1.6 V. The Ti3C2Tx-CNT anode is combined with a MnO2-CNT cathode in an asymmetric cell, which shows a 1.24 F cm−2 capacitance at 3 mA cm−2.