Hydroxymethyl PEDOT microstructure-based electrodes for high-performance supercapacitors

Abstract

The development of conducting polymer-based supercapacitors offers remarkable advantages, such as good ionic and electronic conductivity, ease of synthesis, low processing cost, and mechanical flexibility. 3,4-ethylenedioxythiophene (PEDOT) is a conducting polymer with robust chemical and environmental stability during storage and operation in an aqueous environment. Yet, improving its electrochemical capacitance and cycle life remains a challenge for high-performance supercapacitors exceeding the current state-of-the-art. The fabrication of PEDOT composites with carbon nanomaterials and metal oxides is the commonly used approach to enhance capacitance and stability. This work discusses a comparative study to fabricate highly stable PEDOT derivative electrodes with remarkable specific capacitance via a straightforward electrochemical polymerization technique. The hydroxymethyl PEDOT (PEDOTOH) doped with perchlorate in a dichloromethane (DCM) solvent (197 F g−1) exhibits superior performance compared to the polymer formed in an aqueous solution (124 F g−1). Furthermore, the electropolymerized PEDOTOH on flexible Au/Kapton substrates was assembled into a free-standing symmetrical supercapacitor in an agarose additive-free gel. The use of agarose gel electrolytes can offer easy handling, no leakage, moderate ionic conductivity, and flexibility for miniaturization and integration. The supercapacitor reached a specific capacitance of 36.96 F g−1 at a current density of 13.7 A g−1, an energy density of 14.96 Wh kg−1, and a power density of 22.2 kW kg−1 among the highest values reported for PEDOT-based supercapacitors. The self-standing supercapacitor achieves an industry-par capacitance retention of ∼98% after 10000 charge/discharge cycles at 10 A g−1. This study provides insights into the effect of solvents and electropolymerization modes on the polymer structure and its electrochemical properties toward high-performance supercapacitor devices.

Deep Eutectic Mn(NO3)2−H2O Binary System as a Safe, Cost‐Effective, and Efficient Electrolyte for Supercapacitor Applications

“…The working principle of an electrochemical double‐layer supercapacitor [48] is based on the physical adsorption of high specific surface area electrodes (in this case activated carbon with a specific surface area of 2270 cm 2 ). When charging, the electrode surface accumulates charge and attracts diffused anions and cations from the electrolyte to adsorb on the electrode surface in a directional arrangement, which forms a double electric layer structure.…”

Comparative Internal Pressure Evolution at Interfaces of Activated Carbon for Supercapacitors Containing Electrolytes Based on Linear and Cyclic Ammonium Tetrafluoroborate Salts in Acetonitrile

“…In a symmetrical two‐electrode system, the active material weight is the same for both electrodes. The specific capacitance, C sp (F g −1 ) is related to the capacitance of the cell by [ 44 ] : $$\[ \begin{array}{*{20}{c}}{{C_{{\rm{sp}}}} = \frac{{2C}}{m}}\end{array} \]$$where C is the capacitance of the cell, and m describes the mass of the active material.…”

“…In a symmetrical two-electrode system, the active material weight is the same for both electrodes. The specific capacitance, C sp (F g −1 ) is related to the capacitance of the cell by [44] :…”

Capacitors based on PEDOT nanowire electrodeposits

“…40 It is important to note that these studies have determined that the decrease in the structural dimensions of the polymer is directly related to the increase in capacitive properties. 41,42 A primordial stage in the increase of the capacity of these polymers has been reported by del Valle et al, 43 who, using mesoporous silicon oxide as a template, managed to obtain thiophene nanowires on a platinum disk electrode in situ. Subsequently, they report obtaining template-free PEDOT nanowires (PEDOT-nw), which were used as a support for Pt nanoparticles for the electro-oxidation of formic acid, demonstrating high reproducibility, repeatability, and adherence of the nanowires on the electrode surface.…”