Schiff base polymer doped with MWCNTs as electrode material for supercapacitors

By using a one-step synthesis approach, 2,4,6-triamino-5-nitrosopyrimidine and 4,4’-biphenyldicarboxaldehyde were combined to create Schiff base polymer (TPB) and carbon nanotubes doping Schiff base polymers (TPB/MWCNTs-X, X = 2, 5, 8). Enhancement of electrochemical properties of Schiff base polymers (TPB) can be done by doping pretreated carbon nanotubes. Carbon nanotubes disrupted the π−π stacking of polymer molecular links and some microcosmic pore structures formed in the nanotubes doping process, and the carbon nanotubes are suitable for channeling of electrolyte ion diffusion from electrolyte solution body to the center of conductive polymer bulk. Scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy were used to characterize the morphology and phase compositions. Sample TPB/MWCNTs-2 possess the optimal electrochemical performance, measurement results reveal that the specific capacitance of TPB/MWCNTs-2 electrode is 714 F g⁻¹ at a current density of 0.5 A g⁻¹ in the three-electrode system, and the capacity retention rate is still 76.6% in 5000 cycles with 10 A g⁻¹ current density. Furthermore, the asymmetric supercapacitor battery hybrid device (TPB/MWCNTs-2//AC) was established in 6 M KOH electrolyte with TPB/MWCNTs-2 and activated carbon (AC) serving as the positive and negative electrodes, respectively. The TPB/MWCNTs-2//AC device has the maximum energy density of 94.06 Wh kg⁻¹ with 0.5 A g⁻¹ current density; at the same time, the device possesses 371.87 W kg⁻¹ power density. The introduction of carbon nanotubes into Schiff base polymers disrupts the internal π−π stacking and provides more oxidatively active sites, offering more paths for electrons to move. This work offers a novel approach to the synthesis of electrode materials from Schiff base conducting polymer-carbon nanotube composites with exceptional electrochemical characteristics.