High-performance MXene/reduced graphene oxide/carbon nanofibers@MoS2 composite films for flexible asymmetric supercapacitors

Abstract

Electrode materials for supercapacitors often suffer from limitations such as restricted ion accessibility, suboptimal cycling stability, and inadequate electrical conductivity, which compromise their electrochemical performance and practical utility. To overcome these challenges, strategic incorporation of intercalation materials to enhance ion transport and active site availability presents a viable approach. In this study, we used MoS₂ coated carbon nanofibers (CNFs) and reduced graphene oxide (rGO) nanosheets as intercalation agents to construct a strong 3D interlayer framework within MXene nanosheets and prepared MXene/rGO/CNF@MoS₂ composite films by vacuum-assisted filtration. The designed architecture notably enlarged the interlayer distance, facilitated rapid ion diffusion, and enhanced the availability of electroactive sites. The resulting film exhibited an exceptional specific capacitance of 1015 F g^-1 at 1 A g^-1. Additionally, an asymmetric supercapacitor (ASC) was constructed with the composite film as the positive electrode and activated carbon (AC) as the negative electrode, delivering a broad operating voltage of 1.5 V and a capacitance of 212.7 F^-1 at 1 A g^-1. The device reached an impressive energy density of 66.45 Wh kg^-1 at 750 W kg^-1, while retaining 80.4% of its capacitance over 20,000 charge-discharge cycles at 5 A g^-1, confirming outstanding long-term stability. This work demonstrates a scalable and effective strategy to enhance MXene-based electrodes, offering great potential for high-performance, flexible energy storage systems.