Enhanced tensile and electrochemical performance of MXene/CNT hierarchical film

Nowadays, it is highly desirable to achieve high strength, flexibility and electrochemical performance for supercapacitor electrodes simultaneously. Herein, few-layer MXene flakes are assembled into free-standing films by facile vacuum-filtration method, in which hydrophilic-functionalized carbon nanotubes (CNTs) are further incorporated. The morphology of MXene/CNT composite films evolves from compact to 'CNT in MXene' to laminar to 'MXene in CNT' and finally to separate structures when increasing the CNT weight percentage. Among them, the laminar structure in which thin MXene and CNT layers are stacked alternately is demonstrated to be the best. The laminar MXene/CNT film possesses much higher strength, elongation and specific capacitance than MXene film due to the engineered porosity, good interaction between MXene flakes and CNTs, and proper CNTs' distribution. As a result, high specific capacitance of 423.4 F g(-1) at 1 A g(-1) and capacitance retention of nearly 60% at 10 A g(-1) are accomplished. Moreover, the composite film is flexible and withstands bending up to 180 degrees, indicating that the proposed laminar MXene/CNT composite film is a superb candidate for flexible supercapacitors.

Automated summary

The study achieved high strength, flexibility, and electrochemical performance for supercapacitor electrodes using few-layer MXene flakes and hydrophilic-functionalized carbon nanotubes. The morphology of the MXene/CNT composite films evolved into a laminar structure with alternating thin MXene and CNT layers, demonstrating the best performance. This approach resulted in a high specific capacitance of 423.4 F g(-1) at 1 A g(-1) and nearly 60% capacitance retention at 10 A g(-1), making the laminar MXene/CNT composite film a promising candidate for flexible supercapacitors.