A peptide-based supercapacitor and its performance improvement via TiO2 coating

Abstract

Based on their ability to self-assemble and mimic strategies that occur in nature, peptide nanomaterials offer a variety of potential applications in environmentally friendly energy storage technologies. Herein, we report the experimental investigations into an elaborate self-assembled dipeptide Fmoc-EF-NH₂, which displayed good performance as an electrode material in a supercapacitor. In order to protect the peptide electrode from electrolyte dissolution, a thin layer of TiO₂ was coated on the peptide film by atomic layer deposition. The as-prepared peptide electrodes achieved an outstanding mass-specific capacitance of 125 F g⁻¹ at 0.1 A g⁻¹ current density and an areal capacitance of 8.6 mF cm⁻². Furthermore, the capacitor exhibits excellent stability, in that 95% of the capacitance was retained after 5000 cycles. Additionally, the fabricated all-solid-state SCs possess excellent mechanical flexibility. To the best of our knowledge, this is the first investigation that comprehensively assessed the electrochemical performance of peptide materials.