Enhanced specific capacity and cycling stability of flexible nanocellulose-based pseudocapacitive electrodes by controlled nanostructuring of polyaniline

Abstract

Flexible, lightweight and electrically conductive composites based on renewable resources have recently attracted a growing interest for the development of high performance sustainable energy storage devices that can meet the needs of modern wearable and portable electronics. Herein, we developed a high performance carbon black@polyaniline (PANI) based flexible electrodes using a facile, low cost and environmentally friendly strategy. The strategy consisted of a co-deposition and nanostructuring of PANI layer with tailored morphology on the surface of carbon black and nanofibrillated cellulose (NFC) via in situ polymerization. NFC acted as a mechanical skeleton and imparted the electrode with strength and flexibility to ensure excellent electrochemical performance. The co-doping of PANI chains via a combination of a primary/secondary dopant, namely, HCl/poly(2acrylamido-2-methyl-1-propanesulfonic acid), was used to control the morphology of PANI. Correlation between the textural properties of the carbon black, NFC loading, and the properties of the resulting electrodes was established. The maximum specific capacitance of 363 +/- 9 F/g at the potential scan rate of 50 mV/s was exhibited by the electrode with 60% of active material loading, for which an effective growth of hierarchical nano structures of carbon black@PANI on the surface of NFC was achieved, leading to the highest specific surface area of the composite (861 m2/g) and a to a microporosity/mesoporosity balance. The remarkable cycling stability of the hybrid electrodes was attained as the specific capacitance retention was close to 100% with a negligible capacity decay within the tested period (over 500 cycles) regardless of the amount of the active material. This study provides an eco-friendly and cost-effective way to prepare high performance flexible electrodes for pseudo capacitors