Flexible Type Symmetric Supercapacitor Electrode Fabrication Using Phosphoric Acid-Activated Carbon Nanomaterials Derived from Cow Dung for Renewable Energy Applications

[Image: see text] Porous-activated carbon (PAC) materials have been playing a vital role in meeting the challenges of the ever-increasing demand for alternative clean and sustainable energy technologies. In the present scenario, a facile approach is suggested to produce hierarchical PAC at different activation temperatures in the range of 600 to 900 °C by using cow dung (CD) waste as a precursor, and H(3)PO(4) is adopted as the nonconventional activating agent to obtain large surface area values. The as-prepared cow dung-based PAC (CDPAC) is graphitic in nature with mixed micro- and mesoporous textures. High-resolution scanning electron microscopy depicts the morphology of CDPAC as nanoporous structures with a uniform arrangement. High-resolution transmission electron microscopy reveals spherical carbon dense nanoparticles with dense tiny spherical carbon particles. N(2) adsorption–desorption isotherms show a very high specific surface area of 2457 m(2)/g for the CDPAC 9 (CD 9) sample with a large pore volume of 1.965 cm(3)/g. Electrochemical measurements of the CD 9 sample show a good specific capacitance (C(s)) of 347 F/g at a lower scan rate (5 mV/s) with improved cyclic stability, which is run up to 5000 cycles at a low current density (0.5 A/g). Hence, we choose an activated carbon prepared at 900 °C to fabricate the modified electrode material. In this regard, a flexible type symmetric supercapacitor device was fabricated, and the electrochemical test results show a supercapacitance value (C(s)) of 208 F/g.