Vacuum-filtration assisted layer-by-layer strategy to design MXene/carbon nanotube@MnO2 all-in-one supercapacitors

Abstract

Constructing intelligent clothing through integrating flexible and wearable electronics in daily clothing has raised the demand for flexible supercapacitors with high energy storage, small thickness and mechanical durability. Herein, a vacuum-filtration assisted layer-by-layer strategy is developed to prepare MXene-based flexible all-in-one supercapacitors. The MXene/carbon nanotube@MnO₂ composite film electrode is firstly synthesized by embedding the carbon nanotube@MnO₂ nanosheet composite into the interlayer of MXene films. This electrode structure blocks the restacking of MXene nanosheets, leading to a large ion-accessible surface area and efficient ion diffusion pathways. Moreover, the synergistic cooperation of MXene nanosheets and carbon nanotubes forms a 3D conductive network, which avoids the negative influence of MnO₂ on the electronic conductivity of electrodes, ensuring a rapid electron transport rate. Benefitting from these advantages, the MXene/carbon nanotube@MnO₂ composite film shows a high specific capacity of 221 F g⁻¹, good cycling stability and flexibility. The assembled all-in-one flexible supercapacitor device exhibits a high volumetric energy density and power density of 24.5 mW h cm⁻³ and 2.5 W cm⁻³, respectively.