A comparative study on long and short carbon nanotubes-incorporated polypyrrole/poly(sodium 4-styrenesulfonate) nanocomposites as high-performance supercapacitor electrodes

Polypyrrole/poly(sodium 4-styrenesulfonate)-carbon nanotubes (PPy/PSS-CNT) nanocomposites have been fabricated with an in situ electrochemically polymerized method. The long (10–30   μm) and short (0.5–2   μm) CNT are incorporated separately into the composites, and their effect on the capacitive performance of composites prepared is compared. Scanning electron microscope characterization reveals that long CNT-incorporated composites (PPy/PSS-lCNT) have the more porous microstructure and present a large amount of CNT within the composites, in which these long tangled CNT form an interconnected conductive nano-network. Furthermore, combining with the transmission electron microscopy characterization, both of the two types of composites show the core–shell nanostructure with PPy layer coated on CNT. The results by electrochemical tests including cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrochemical impedance spectroscopy (EIS) manifest the PPy/PSS-lCNT composite electrodes have the relatively more superior capacitive behavior and cycle stability than those of the short CNT-incorporated composites (PPy/PSS-sCNT) electrodes. Thereinto, the PPy/PSS-lCNT composite electrodes exhibit a high areal capacitance of 146.1   mF   cm −2 at 10   mV   s −1 CV scan, retaining 94.0% of the initial capacitance after 5000CV cycles. This comparative study suggests that the long CNT-incorporated PPy/PSS-lCNT nanocomposites are relatively more promising as the electrode materials for the high-performance supercapacitors.