MXene loaded onto clean wiper by a dot-matrix drop-casting method as a free-standing electrode for stretchable and flexible supercapacitors

MXene-loaded textiles can be used as free-standing electrodes for multi-functional supercapacitors (SCs), due to their good conductivity, high electrochemical activity, excellent flexibility, and stretchability. However, the typically self-restacking phenomenon would emerge with the increase in MXene amount, resulting in a significant reduction of the ion-accessible surface areas and active sites of MXene. Herein, a dot-matrix drop-casting method with the advantages of quickness and high uniformity is developed to load high amount (6.1 mg cm-2) of Ti3C2 (a typical MXene) on a clean wiper (CW, a typical textile), and simultaneously to alleviate the resultantly self-restacking phenomenon of Ti3C2. The results show that the obtained composite (CWM) has a high conductivity of 2.3 S cm-1 and large specific capacitance of 282 mF cm-2 at 1 mA cm-2, whereas it remains a high tensile strength of 20.1 MPa and developed porous structure (33.4 m2 g-1). These attractive properties make CWM an ideal free-standing electrode. Further, CW is used as a separator to fabricate an all-CW-derived SC (CWM//CW//CWM), because its porous structure provides abundant routes for facile ion transport. Such a SC has an excellent rate capability with a high capacitance retention of 78.2% from 1 to 20 mA cm-2, large specific capacitance of 118 mF cm-2 at 1 mA cm-2, and high energy density of 10.1 mu Wh cm-2 at 389.9 mu W cm-2. Moreover, an all-solid-state SC (CWM//CWM) is fabricated, and shows an excellent stability on capacitive behaviors during bending (0-120 degrees) or stretching (10-40% strains), manifesting its great potential on wearable and portable electronics.