Ti₃C₂T_x Nanosheets/Ti₃C₂T_x Quantum Dots/RGO (Reduced Graphene Oxide) Fibers for an All-Solid-State Asymmetric Supercapacitor with High Volume Energy Density and Good Flexibility

By using Ti3C2Tx quantum dots as interlayer spacers, Ti3C2Tx nanosheets/Ti3C2Tx quantum dots/RGO (reduced graphene oxide) fiber (M6M3RG1) is prepared by a wet-spinning method; it shows good capacitance and excellent flexibility. The M6M3RG1 fiber electrode possesses a novel network structure and a maximum volumetric capacitance of 542 F cm–3, and its capacitance and flexibility are affected by the amount of Ti3C2Tx quantum dots. Also, the Ti3C2Tx/PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)] fiber (M7P3) is prepared by injecting a homogeneous suspension of Ti3C2Tx nanosheets and PEDOT:PSS into a bath of 98 wt % H2SO4. The M6M3RG1 fiber is used as the positive electrode, and the M7P3 fiber is used as the negative electrode; a M6M3RG1//M7P3 asymmetric, flexible, solid-state supercapacitor is assembled in a PVA–H2SO4 gel electrolyte. The assembled device exhibits a volumetric capacitance of 53.1 F cm–3 and a good cycle stability of 96.6% after 5000 cycles. It also shows outstanding flexibility and mechanical properties; for example, the volumetric capacitance has no obvious change after the device is bent at 90° for 500 times. Moreover, its voltage window can be expanded to 1.5 V, and a maximum volumetric energy density of 16.6 mWh cm–3 can be achieved. This work will open up a new application area for new wearable energy storage devices based on the Ti3C2Tx fibers.