High-performance flexible redox supercapacitors induced by methylene blue with a wide voltage window

Flexible redox supercapacitors based on treated carbon cloths were prepared by introducing methylene blue into a gel electrolyte. With the improvement in pseudocapacitance and broadening of the voltage window, the device exhibited a high capacitance of 1738 mF cm−2 and an energy density of 0.78 mW h cm−2. In addition, 84.6% capacitance retention was achieved over 8000 cycles.