Low-temperature-operable MXene/PEDOT/Graphene fiber-based supercapacitors with ultrahigh energy density

Since the discovery of Graphene sheets, Graphene fiber- and MXene fiber-based supercapacitors (GFSCs) have undergone significant advancements in flexible fiber power. However, a key hurdle for GFSCs to be used in the electrical textile is the bad energy density and significant performance degradation at low temperatures. Herein, vertically oriented MXene/PEDOT:PSS/RGO (MPG) hybrid fibers were attained with wet spinning method on the basis of investigating the rheological properties of MXene, PEDOT:PSS, and GO dope combined with CFD simulations. The azimuthal profile of the 2D SAXs reveals a distinct peak at 90°, with a Herman's orientation factor of 0.7. The MPG fiber containing ~42 wt% MXene achieves a balanced tensile strength of 173 MPa and an electronic conductivity of 400 S/cm. The 42 wt% MXene MPG FSCs exhibit distinguished energy density of 100 mWh cm −3 , which exceeds those of previously reported Ti 3 C 2 T x MXene-based FSCs. To enhance the low-temperature electrochemical performance of MPG FSCs, solid electrolyte nano-AgI is grafted onto the fiber surface with 60 Co γ-ray. At −0,-20, −40 and − 60 °C, the assembled MGP FSCs maintain energy densities of 59, 38, 16 mWh cm −3 and 880 μWh cm −3 respectively. Four MPG FSCs in series can light up six led for 53 s at −20 °C. These MPG FSCs exhibit their potential for wearable electronics in cold environments.