Self-assembled polypyrrole nanotubes/MoS2 quantum dots for high performance solid state flexible symmetric supercapacitors

Abstract

A new kind of chitosan–polypyrrole nanotube/molybdenum disulphide (CS–PNT/MoS₂) nanocomposite is fabricated for the first time via a facile two-step in situ chemical polymerization and hydrothermal method, and successfully applied in flexible charge storage supercapacitor (SC) devices. The CS–PNT/MoS₂ nanocomposite represents a good SC electrode material by inheriting the properties of good electrical conductivity of MoS₂ and enhanced pseudocapacitive activity of polypyrrole nanotubes (PNTs). The incorporation of chitosan (CS) increases the cycling stability of the CS–PNT/MoS₂ nanocomposite by reducing the aggregation of MoS₂ quantum dots and enhancing the surface area and porous structure of the nanocomposite, which facilitates the diffusion of the solvent and faradaic process. The CS–PNT/MoS₂ nanocomposite exhibits a highest specific capacity (C_sp) of 759 C g⁻¹ and a solid state flexible symmetric supercapacitor (SSC) was assembled using CS–PNTs/MoS₂, which achieved a high-power density of 7680 W kg⁻¹ at an energy density of 32.12 W h kg⁻¹ and also good cycling stability with a capacity retention of 91.2% after 10 000 cycles at 10 A g⁻¹. Remarkably, the SSC device showed enhanced flexibility and stability and can retain up to 97% of its initial capacity under various bending positions, clearly suggesting that the fabricated solid-state SSC device is exceptionally flexible and can be deformed without compromising its structural integrity and energy storage ability. These findings suggest that CS–PNTs/MoS₂ represents a promising electrode material for flexible supercapacitors.