Hybrid composite polyaniline-nickel hydroxide electrode materials for supercapacitor applications.

Pristine and nanocomposite (NC) hybrid electrodes of polyaniline (PANI)-nickel hydroxide [Ni(OH)] have been prepared by single and two-step electrodeposition processes, respectively, onto stainless-steel (SS) substrates. Enhanced reversibility and stability of amorphous PANI- Ni(OH) NC electrodes compared to single electrode materials have been explored. PANI has a nanofibrous morphology, Ni(OH) has nanoplatelet-type morphology, and the NC electrodes retain an overall nanofibrous morphology. The maximum specific capacitance (SC), obtained from integrated charge under voltammetric conditions, for PANI (electro-deposited for 5 min), NC (electrodeposition of Ni(OH) for 10 min and 20 min onto PANI electrode surface) and Ni(OH) (electrodeposited for 10 min) electrodes, are 0.59, 39.06, 32.36, and 113.8 F/g, respectively, suggesting higher electrochemical performance of Ni(OH) electrode compared to PANI and NC electrodes. The retention in SC values with faster scan rates from 10 to 100 mV/s for PANI, NC (10 min), NC (20 min) and Ni(OH) are 38.7, 61.1, 52.4, and 29.0 %, respectively, explicitly confirming a higher reversibility in NC electrodes. The retention in SC values with increase of cycle number up to 1000 for PANI, NC (10 min), NC (20 min) and Ni(OH) electrodes are 34.9, 61.5, 67.5, and 40.7 % respectively, demonstrating higher electrochemical stability of NC electrodes over pure-phase electrodes. Nearly 2.15, 79.36, 66.66 and 406.83 mC/cm charges on PANI, NC (10 min), NC (20 min) and Ni(OH) electrodes, respectively, are obtained. Inner to total charge and outer to total charge ratios have been used to explain contributing sites to total charge in pristine and NC electrodes.