A morphology control engineered strategy of Ti3C2Tx/sulfated cellulose nanofibril composite film towards high-performance flexible supercapacitor electrode

Abstract

2D Ti₃C₂T_x MXene is an ideal material for fabricating supercapacitor electrodes due to its excellent physical-chemical properties. However, the inherent self-stacking, narrow interlayer spacing, and low general mechanical strength limit its application in flexible supercapacitors. Herein, facile structural engineering strategies by drying (vacuum drying, freeze drying, and spin drying) were proposed to fabricate 3D high-performance Ti₃C₂T_x/sulfated cellulose nanofibril (SCNF) self-supporting film supercapacitor electrodes. Compared with other composite films, the freeze-dried Ti₃C₂T_x/SCNF composite film exhibited a looser interlayer structure with more space which was conducive to charge storage and ion transport in the electrolyte. Therefore, the freeze-dried Ti₃C₂T_x/SCNF composite film exhibited a higher specific capacitance (220 F/g) compared to the vacuum-dried Ti₃C₂T_x/SCNF composite film (191 F/g) and the spin-dried Ti₃C₂T_x/SCNF composite film (211 F/g). After 5000 cycles, the capacitance retention rate of the freeze-dried Ti₃C₂T_x/SCNF film electrode was close to 100 %, showing excellent cycle performance. Meanwhile, the tensile strength of freeze-dried Ti₃C₂T_x/SCNF composite film (13.7 MPa) was much greater than that of the pure film (7.4 MPa). This work demonstrated a facile strategy for control of Ti₃C₂T_x/SCNF composite film interlayer structure by drying for fabricating well-designed structured flexible and free-standing supercapacitor electrodes.

Keywords: Drying methods; Sulfated cellulose nanofibril; Supercapacitor electrodes; Ti(3)C(2)T(x).