Electrons/ions dual transport channels design: Concurrently tuning interlayer conductivity and space within re-stacked few-layered MXenes film electrodes for high-areal-capacitance stretchable micro-supercapacitor-arrays

Abstract

Abstract Introduction of interlayer spacers within re-stacked few-layered MXene flakes for more free interlayer space has been proved an effective strategy to improve the acquired electrochemical performance of the assembled film electrodes. However, the expanded interlayer space will inevitably lead to the decrease of interlayer conductivity because of the loose contact between isolated few-layered MXene flakes. The contradiction hinders the maximization of the areal capacitance of the re-stacked few-layered MXene film electrodes. Herein, an “electrons/ions dual transport channels design” is achieved by inserting elaborately synthesized 1D conductive core-shell structured bacterial cellulose (BC)@polypyrrole (PPy) fibers into re-stacked few-layered MXene flakes. This design concurrently realizes the expansion of interlayer space for favoring electrolyte infiltration, and alleviation of interlayer conductivity decline to ensure interlayer electrons transport, as well as additional load of conductive polymer of high specific capacitance and enhancement of interlayer bond strength, endowing the prepared MXene/BC@PPy hybrid film electrodes with fully-excavated areal capacitance of 221.21 mF cm−2 and reinforced tensile strength of 78.9 MPa. Followed a planar electrode configuration design in the MXene/BC@PPy hybrid film electrodes and introduction of islands-bridge interconnecting structure between them, stretchable micro-supercapacitor arrays (MSCAs) of areal capacitance/energy density up to 200.47 mF cm−2/0.01 mWh cm−2 and reversible level of stretchability as much as 200% elongation were further fabricated. The demonstrated “electrons/ions dual transport channels design” provides an attractive and instructive model of structural engineering of few-layered MXenes assembled electrodes for enhanced electrochemical and mechanical performance toward high-areal-capacitance stretchable MSCAs.