Electrochemical pretreatment of thienothiophene/single-walled carbon nanotubes: a flexible and binder-free electrode with enhanced energy performance as a positive electrode for asymmetric supercapacitors

Abstract

Achieving high-performance supercapacitors is still a significant challenge. Herein, an effective strategy based on the electrochemical pretreatment (EP) of TT-CN-TPA-SWCNT, composed of a highly conjugated thienothiophene (TT) core and single-walled carbon nanotubes (SWCNTs), is disclosed to construct a flexible and free-standing hybrid positive electrode with outstanding supercapacitor properties. Its electrochemically pretreated hybrid electrode (EP-TT-CN-TPA-SWCNT) showed remarkable supercapacitor performances and energy storage properties with an excellent specific capacitance of 355.3 F g⁻¹ at 0.25 A g⁻¹. Nyquist plots showed the cycling stability results, confirming an inductive behavior in the high-frequency region of the cell. The surface morphology of the electrode was clarified by SEM, which indicated no degradation or breakdown in the hybrid film before and after EP. Interconnected and tangled nanotube bundles were clearly observable, demonstrating the high stability and durability of the nanohybrid film. The fabricated asymmetric device achieved a power density of 4800 W kg⁻¹ at 8 A g⁻¹ and an energy density of 4.73 W h kg⁻¹ at 0.1 A g⁻¹. Regarding the galvanostatic charge and discharge results, a cycle stability of 8000 cycles was achieved, with the coulombic efficiency exceeding 110% and capacitance retention reaching 120%. Our findings are poised to inspire further research on high-performance energy storage devices using TT- and SWCNT-based electrode materials.