Highly capacitive MXene film by incorporating poly(3,4-ethylenedioxythiophene) hollow spheres prepared through an interfacial oxidation polymerization.

The conductive PEDOT hollow spheres fabricated by a template-assisted interfacial polymerization serve as promising spacers rendering the MXene film highly capacitive performances. [Display omitted] • The PEDOT HSs are successfully prepared by a template-assisted interfacial oxidation polymerization. • Incorporation of PEDOT HSs between MXene nanosheets yields highly flexible MP film. • The MP film exhibits a forty-folds enhancement in current response and nearly thickness-independent performances with film thickness varying from 10 to 40 μm. • The MP-based polymer-gel supercapacitor retains 90% capacitance and 100% Coulombic efficiency over the 5000 cycles, Sheets stacking of Ti 3 C 2 T x MXene dramatically reduces the ion-accessible sites and brings a sluggish reaction kinetics. While introducing transitional metal oxides or polymers in the MXene films could partially alleviate such issue, their enhanced performances are realized at the expense of electrode conductivity or cycling stability. Herein, we report an alternative spacer of conductive poly(3,4-ethylenedioxythiophene) (PEDOT) hollow spheres (HSs) which are fabricated by a facile template-assisted interfacial polymerization. The Fe3+ ions electrostatically adsorbed on the –SO 3 H groups of the sulfonated polystyrene spheres (S-PS) initiate the polymerization of uniform PEDOT shell, yielding uniform PEDOT HSs after dissolving the S-PS core. Introducing these PEDOT HSs in the MXene film generates the highly flexible MXene-PEDOT (MP) films featuring hierarchically porous network and high conductivity (283 S cm−1). Consequently, specific capacitance of 218 F g−1 at 3 mV s–1, along with a forty-folds decrease in relaxation time constant (1.0 vs 39.8 s) has been achieved. Moreover, the MP film also exhibits nearly thickness-independent capacitive performances with film thickness in the range of 10–46 μm. A maximal energy density of 21.2 μWh cm−2 at 1015 μW cm−2 together with 92 % capacitance retention over 5000 cycles are achieved for the MP-based solid-state supercapacitor. The intrinsic high conductivity, excellent mechanical flexibility and good structure integrity are responsible for such outstanding electrochemical behaviors. [ABSTRACT FROM AUTHOR]