Designing of a Free-Standing Flexible Symmetric Electrode Material for Capacitive Deionization and Solid-State Supercapacitors

In this work, a highly efficient free-standing flexible electrode material for capacitive deionization and supercapacitors was reported. The reported porous carbon shows a high surface area of 2070.4 m² g^-1 with a pore volume of 0.8208 cm³ g^-1. The material exhibited a high specific capacitance of 357 F g^-1 at 1 A g^-1 in a two-electrode symmetric setup. A solid-state supercapacitor device has been fabricated with a total cell capacitance of 152.5 F g^-1 at 1 A g^-1 in a solid PVA/H₂SO₄ gel electrolyte with an energy density of 21.18 W h kg^-1 at a 501.63 W kg^-1power density. A long-run stability test was carried out up to 15,000 cycles at 5 A g^-1 that showed capacitance retention of 99% with ∼100% Coulombic efficiency. Furthermore, the electrosorption experiment was conducted by a flow-through test by coating on commercially available cellulose thread that was employed, which shows electrosorption ability up to 16.5 mg g^-1 at 1.2 V in a 500 mg L^-1 NaCl solution. Complete experiments were conducted with a proper procedure, provided by scientific approaches with analytical data. Thus, the reported electrode material showed bifunctional application for energy storage and environmental remediation.