Enhanced electrochemical performance of polyaniline-based electrode for supercapacitors in mixed aqueous electrolyte

Abstract

Aqueous electrolytes can provide high capacitance owing to their high ionic conductivity. In the present work, the aqueous electrolyte was optimized for the polyaniline (PANI)-based electrode, with a flexible PANI coated polylactic acid/multi-walled carbon nanotubes (PLA/MWCNTs) composite film as a model electrode. The electrochemical performance of the PLA/MWCNTs composite film electrode was investigated in the most used acidic and neutral electrolytes, H2SO4 and Na2SO4. As a result, the optimized aqueous electrolyte for the PANI-based electrodes in supercapacitor was achieved as 1.1 mol L−1 H2SO4/0.1 mol L−1 Na2SO4 mixed electrolyte (1.1–0.1), in which the specific capacitance was enhanced by 17.28% in comparison with the commonly used acidic electrolyte (1.0 mol L−1 H2SO4). The analysis of the electrode and electrolytes after electrochemical cycles demonstrated that the addition of the neutral electrolyte Na2SO4 could efficiently inhibit the acid-induced hydrolysis of PANI, improving the specific capacitance and cycling stability. The finding is expected to promote the development of the advanced aqueous polyaniline-based supercapacitors.