A high-frequency flexible symmetric supercapacitor prepared by the laser-defocused ablation of MnO₂ on a carbon cloth

The rapid development of flexible electronics has produced an enormous demand for supercapacitors. Compared to batteries, supercapacitors have great advantages in terms of power density and cycling stability. They can also respond well on a time scale of seconds, but most have a poor frequency response, and behave more like pure resistors when used at high frequencies (e.g., above 100 Hz). It is therefore challenging to develop supercapacitors that work at a frequency of over 100 Hz. We report a high-frequency flexible symmetrical supercapacitor composed of a MnO₂@carbon cloth hybrid electrode (CC@MnO₂), which is synthesized by the defocused-laser ablation method. This CC@MnO₂-based symmetric supercapacitor has an excellent specific areal capacitance of 1.53 mF cm⁻² at a frequency of 120 Hz and has good cycling stability with over 92.10% capacitance retention after 100000 cycles at 100 V s⁻¹. This remarkable electrochemical performance is attributed to the combined effect of the high conductivity of the 3D structure of the carbon cloth and the exceptional pseudo-capacitance of the laser-produced MnO₂ nanosheets. The defocused laser ablation method can be used for large-scale production using roll-to-roll technology, which is promising for the wide use of the supercapacitor in high-frequency electronic devices.