Effects of counterions on pseudocapacitance performance of polyaniline in sulfuric acid and p-toluene sulphonic acid electrolyte

In order to research the effects of counterions, the pseudocapacitance performance of polyaniline (PANI) electrodeposited on glassy carbon (GC) substrate was investigated in sulfuric acid (H2SO4) and p-toluene sulphonic acid (p-TSA) electrolyte, respectively. It was found that the performance of PANI/GC electrode in p-TSA was inferior to that in H2SO4 at a low scan rate, while its superiority was shown gradually with the increase of scan rate, especially at a high scan rate of 100 mV s−1 in our work. The results predicted that PANI material had a more suitable heavy load charge–discharge performance in p-TSA electrolyte. Cyclic voltammetric (CV) experiments, electrochemical impedance spectroscopy (EIS) and single potential step studies were carried out to investigate the effects of the counterions. The results revealed that there were such different control processes in these two electrolytes as the diffusion control in H2SO4 and the surface electron transfer control in p-TSA. The diffusion coefficient D or Dapp was calculated and equals 1.57 × 10−7 (cm2 s−1) in H2SO4 compared with 2.97 × 10−8 (cm2 s−1) in p-TSA.