Growth and cycling of polyaniline electrode in a deep eutectic solvent: A new electrolyte for supercapacitor applications

Polyaniline electrode on a graphite substrate was produced and evaluated for use in an ionic liquid electrolyte for supercapacitor applications. The aniline monomers were added in Ethaline deep eutectic solvent electrolyte. The deep eutectic solvent is a type of ionic liquid consisting of only ions without water. Aniline was polymerized electrochemically onto graphite current collector from a non-aqueous and non-acidic Ethaline electrolyte. Polyaniline film obtained in Ethaline had homogenous agglomerated nanoparticles. Growth of polyaniline was not autocatalytic reaction in ionic liquid media and the rate of its growth slowed down upon increasing time. Electropolymerized polyaniline was transferred in two different electrolytes (acetonitrile containing LiCIO4 solution and monomer-free Ethaline) to determine the electrochemical properties of the polyaniline coated graphite electrodes by cyclic voltammetry and galvanostatic charge-discharge techniques. The capacitance of the modified electrode retains 87% of its initial value after 10,000 cycles in Ethaline electrolyte because the polyaniline electrode was probably not effected from swelling and shrinking in an anhydrous ionic liquid for long cycles. The electrode deposited from Ethaline ionic liquid medium and cycled in pure Ethaline electrolyte had a specific capacitance of 833 F g(-1) at 20 mV s(-1) scan rate. The polyaniline coated graphite electrode electrodeposited using one-step polymerization in Ethaline media is a promising electrode for high-performance supercapacitors that can be used in non-aqueous electrolytes.