Easy fabrication of superporous zeolite templated carbon electrodes by electrospraying on rigid and flexible substrates

Abstract

Electrospraying of colloidal suspensions of superporous zeolite templated carbon (ZTC) nanoparticles in ethanol is herein proposed for the controlled deposition of continuous carbon coatings over different substrates, both rigid and flexible. By simple tuning of the concentration, feed rate, voltage and treatment time, different electrode thicknesses can be obtained avoiding the difficult manipulation of ZTC nanopowder formed by around 200 nm size particles. The addition of sulfonated tetrafluoropolyethylene (Nafion) in low amounts into the ZTC suspension improves the adhesion, increases the allowable surface loading and enhances the electrochemical performance of ZTC electrodes. ZTC/Nafion coatings from 0.1 to 1.5 mg cm⁻² have been successfully arranged over graphite sheet and conductive carbon paper substrates. The obtained electrodes have been electrochemically characterized in 1 M H₂SO₄ electrolyte, demonstrating the unique and well-known pseudocapacitive features of ZTC, while showing capacitances as high as 700 mF cm⁻² and outstanding rate performance thanks to the improved arrangement and connectivity of the ZTC nanoparticles. A supercapacitor using electrosprayed ZTC electrodes is constructed, showing specific capacitance higher than 60 F g⁻¹, capacitance retention of 63% when the current density is raised from 2.5 to 80 A g⁻¹, energy density of 6.6 W h kg⁻¹ and maximum deliverable power greater than 240 kW kg⁻¹. These are promising results that make feasible the use of electrospraying for processing nanostructured carbon materials into electrodes of tunable thickness and deposited on substrates of different compositions and morphologies.