Unravelling the Mechanism of Electrochemical Degradation of PANI in Supercapacitors: Achieving a Feasible Solution

Abstract

Herein, we have investigated the mode of electrochemical degradation of polyaniline (PANI) when it was utilized as electrodes for supercapacitors. The PANI‐based electrodes in supercapacitor devices were biased at a constant potential of 0.80 V, and the performance characteristics and property changes were carefully investigated as a function of the difference in the polarity of the electrodes. Subsequent to this, the analysis of the individual electrodes [positive (POS‐PANI) and negative (NEG‐PANI)] shows that the degradation mainly occurs at POS‐PANI in comparison to NEG‐PANI. Moreover, NEG‐PANI retains a maximum capacitance of 510 F g−1, with a low charge‐transfer resistance (RCT) of 1.84 Ω and similar redox behavior in comparison to the fresh PANI (f‐PANI). In contrast to this case, POS‐PANI shows significant loss in capacitance (250 F g−1) and increase in RCT (3.5 Ω) with a disappearance of the characteristic redox behavior normally displayed by PANI. Furthermore, the drastic drop in the electrical conductivity for POS‐PANI (1.2 S cm−1) compared to f‐PANI (3.4 S cm−1 and NEG‐PANI (2.4 S cm−1) shows that the degradation of PANI occurs mainly at the anode (POS‐PANI) and, thus, contributes to reduce the net performance of the cell. Hence, to ensure this potential‐induced degradation of PANI in supercapacitors and also to promote the system stability, we made an asymmetric supercapacitor (ASC) by keeping PANI as a negative electrode and using carbon as a positive electrode. The derived system is found to display stable capacitance behavior before and after the potential application, in contrast to the ASC fabricated by using conventional method, that is, by keeping PANI as the positive electrode and carbon as the negative electrode. Furthermore, the durability analysis of the prototype solid‐state ASC shows an enhanced durability of 27 000 cycles with excellent columbic efficiency. The findings of the present study will be helpful in the development of highly stable supercapacitors and other similar energy systems when a material like PANI should be utilized for the electrode applications.

Engineering Ultrathin Polyaniline in Micro/Mesoporous Carbon Supercapacitor Electrodes Using Oxidative Chemical Vapor Deposition

“…Further, the volumetric capacitance increased by 5.2 times (from 18 to 96 F cm −3 at 10 mV s −1 ), assuming there is negligible increase in geometric volume with the ultrathin PANI coatings. The increase in capacitance is due to a faradaic redox reaction that occurs between PANI and protons, causing a large increase in current and the peaks in the CV curve. Even at a high scan rate of 100 mV s −1 , the added pseudocapacitance from the PANI coating is still evident.…”

Water-in-Acid Gel Polymer Electrolyte Realized through a Phosphoric Acid-Enriched Polyelectrolyte Matrix toward Solid-State Supercapacitors

“…The procedure adopted for the synthesis of PANI (see the Experimental Section for the detailed synthetic procedure) and the SC device fabrication strategy are schematically represented in Figure a. The phytic acid-assisted synthesis of the cross-linked PANI has already been reported by several researchers. − The as-synthesized PANI was washed with DI water followed by vacuum drying at 60 °C for 1 h. The FE-SEM images of the PANI at different magnifications are presented in parts b and c, respectively, of Figure . The XRD and Raman spectra of the PANI are given in parts a and b, respectively, of Figure .…”

Enhanced performance of ultra-thin polyaniline supercapacitor via aniline blue-WS SAMs with rich nucleation site

“…With the progression of the incubation period, the same absorbance spectrum is obtained on all electrodes. According to figure 2, the peak of aromatic benzene at 336.5 nm is characteristic of π-π * transition [29,30]. The peak at 420 nm is due to the cation-radicals formed in the PANI matrix.…”