ELECTROCHIMICA ACTA, cilt.389, 2021 (SCI-Expanded)
Here, we present the synthesis of novel poly(2,2':5',2 ''-terthiophene) derivatives containing oxyethylene pendant groups for the fabrication of high performance flexible redox-active electrode materials. The poly(3',4'-bis(2-methoxyethoxy)-2,2':5',2 ''-terthiophene) (PSEDEN1), poly(3',4'-bis(2-(2-methoxyethoxy)ethoxy)-2,2':5',2 ''-terthiophene) (PSEDEN2) and poly(3',4'-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-2,2':5',2 ''-terthiophene) (PSEDEN3) have been electrochemically polymerized on flexible stainless steel substrates without any binder and directly employed as redox-active materials. The effect of pendant group chain length on morphological characteristics of conducting polymer films have been systematically evaluated and correlated to the charge storage properties of redox-active electrode materials. Capacitive performance tests reveal that PSEDEN1, PSEDEN2 and PSEDEN3 could reach up to specific capacitances of 135 F g(-1), 212.8 F g(-1) and 403.3 F g(-1), respectively, at constant current density of 2.5 mA cm(-2) in the potential range of 0.4-1.8 V with good rate capability performances. In addition, symmetrical flexible solid-state supercapacitor devices based on polymer gel electrolyte have also been assembled using PSEDEN1, PSEDEN2 and PSEDEN3 coated flexible stainless steel substrates and tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy techniques in detail. Fabricated devices (Cell 1, Cell 2 and Cell 3) have delivered maximum specific capacitances of C-spec = 29.3 F g(-1), 92.1 F g(-1) and 162.4 F g(-1), energy densities of SE = 6.35 W h kg(-1), 22.9 W h kg(-1) and 41.1 W h kg(-1) and power densities of SP = 929 W kg(-1), 937.7 W kg(-1) and 986.4 W kg(-1) at a current density of 2.5 mA cm(-2) in two-electrode cell configuration. Furthermore, flexible supercapacitor devices have achieved high cycle life performances with good capacitance retention values of 80.2%, 84.7% and 91.4% over 10 000 consecutive galvanic charge/discharge cycles at 2.5 mA cm(-2) constant current density from 0.4 to 1.8 V. Similarly, excellent mechanical stabilities have also been observed with 3.4%, 4.66% and 1.97% capacitance losses under various bending conditions from 0 degrees to 170 degrees for all flexible supercapacitor devices. These results confirm that PSEDEN1, PSEDEN2 and PSEDEN3 redox-active materials with gratifying capacitive performances and excellent flexibilities have a great potential for utilization in innovative flexible or wearable energy storage solutions. (C) 2021 Elsevier Ltd. All rights reserved.