The effect of anions on the electrochemical properties of polyaniline for supercapacitors

Abstract

To investigate the effect of anions on the electrochemical properties of polyaniline (PANI) for supercapacitors, electrochemical performance tests of PANI with different dopant anions were carried out in the corresponding acid solutions by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods. In particular, ionic fluxes and solvent molecules involved in redox processes can be analyzed by the electrochemical quartz crystal microbalance (EQCM) technique and discriminated by simultaneously recording cyclic voltammograms and mass changes during redox switching. The emeraldine base (EB) form of PANI prepared in a protonic acid with bigger anions can be easily doped by a protonic acid with smaller anions, and conversely, PANI-EB is hard to be doped. The anodic reversal potential of potentiodynamic cycling heavily influences the electrochemical stability of PANI. High anodic potentials result in PANI degradation. Its supercapacitive properties including specific capacitance, power density and cycling stability are strongly dependent upon the type of dopant anion. PANI with the dopant anions of oxalic acid has the highest specific capacitance and the best cycling stability among the used acids. The diffusion coefficient of anions plays a key role in determining power density. PANI films with organic dopant anions exhibit better cycling stability than their inorganic counterparts. It is believed that the hydrolysis of PANI facilitated by the additional water molecules accompanied by dopant anions into and out of the PANI matrix is a key factor responsible for the cycling instability.

Effect of Graphene Oxide Thin Film on Growth and Electrochemical Performance of Hierarchical Zinc Sulfide Nanoweb for Supercapacitor Applications

“…The cyclic voltammetry (CV) was performed in a 2 M KOH electrolyte, and the CV curves measured at different scan rates are plotted in Figure . It is quite evident from Figure (a) that individual ZnS showed good redox peaks in potential window 0.0–0.60 V revealing its pseudocapacitive behavior . The specific capacitance, as determined using CV plots, was calculated using Equation , …”

Recent Progress on Graphene/Polyaniline Composites for High-performance Supercapacitors

“…By changing the deposition cycle numbers, the maximum areal capacitance reached 237.5 mF cm −2 at 10 mV s −1 . In another work, a gold electrode was used to electrodeposit PANI film in different dopants [29], and the electrochemical performance of PANI (H 2 SO 4 )-EB film was also tested in corresponding dopant anions. The PANI film deposited in oxalic acid exhibited the best electrochemical performance among the candidate acids including H 2 SO 4 , HClO 4 , H 3 PO 4 , HNO 3 , p -toluene sulfonic acid (PTSA) and dodecyl benzene sulfonic acid (DBSA).…”

One-pot mechanochemical exfoliation of graphite andin situpolymerization of aniline for the production of graphene/polyaniline composites for high-performance supercapacitors

“…2b), which is unconducive for the diffusion of electrolyte ions into the polymer blocks, resulting in low electrochemical utilization of PANI. 27 Therefore, it is worthwhile to combine the mechanochemical fabrication of graphene and PANI into a onepot process, which can not only enhance the production efficiency but also inhibit the self-aggregation of graphene and PANI. As shown in Fig.…”