Widening potential window of flexible solid-state supercapacitor through asymmetric configured iron oxide and poly(3,4-ethylenedioxythiophene) polystyrene sulfonate coated multi-walled carbon nanotubes assembly

摘要

Current smart energy storage technology needs flexible, compact and even wearable devices with a wide potential window. As a requisite, a novel flexible all-solid-state asymmetric capacitor (ASC) based on worm-like nanostructured iron oxide (gamma-Fe2O3) as negative electrode have been selected properly in combination with poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (MWCNTs/PEDOT:PSS) coated multi-walled carbon nanotubes as a positive electrode to achieve wide potential window of 1.8 V and the use of facile, low cost and binder free approach for the synthesis are the novelties of the present report. These two electrodes have been sandwiched by CMC-Na2SO4 gel electrolyte. Chemical bath deposition method has been used to deposit gamma-Fe2O3 thin film while 'dip and dry' coating technique to deposit MWCNTs/PEDOT:PSS composite thin film. Strikingly, the resulting gamma-Fe2O3//MWCNTs/PEDOT:PSS asymmetric cell yields a wide voltage window of 1.8 V with a high specific capacitance of 65 F g(-1) at 2.4 A g(-1) current density with good specific energy and specific power. Furthermore, ASC device was capable of 80% retention at 5000 cycles through charge-discharge studies at current density of 2.5 A g(-1) along with the flexibility test by bending the device to 170 degrees delivering only 15% capacity loss as per initial one.