Vulcanization treatment: An effective way to improve the electrochemical cycle stability of polyaniline in supercapacitors

Polyaniline (PANI)-based supercapacitor electrode materials are attracting great research interests due to their easy preparation, low cost and high theoretical capacitance. However, the irreversible structural changes and mechanical degradation of PANI during the redox processes result in rapid capacitance decay. To overcome this drawback of PANI, a vulcanized PANI polymer backbone (S-PANI) is fabricated through a vulcanization process in this paper. For the obtained S-PANI, PANI chains are interconnected by the sulfide and/or disulfide bonds, and form a stable, cross-linked porous structure. The special cross-linked structure can effectively accommodate the volumetric expansion and shrinkage of PANI during the charge and discharge process. Consequently, the S-PANI sample shows excellent electrochemical cycle stability with capacitance retention of approximately 96% after 5000 cycles, which is much higher than that of PANI (51%). Moreover, in a symmetric two-electrode full cell system, the S-PANI electrode still possesses a high capacitance retention ratio of approximately 96% even after 10,000 cycles at 3 A g−1. Thus, S-PANI is a very attractive material for highly stable supercapacitor application.