High-performance flexible supercapacitors based on potassium nickel(ii) hexacyanoferrates(iii) nanoparticles on carbon cloth as an electrode material

Abstract

In this work, we report the synthesis of three-dimensional open-framework tunnels based on inorganic metal coordination compounds, such as potassium nickel(II) hexacyanoferrate(III) nanoparticles (PNHCF-NPs) by the co-precipitation method. The nanostructured material was characterized using various techniques, such as UV-Vis, FTIR, XPS, FESEM, EDS, and TEM. The prepared PNHCF-NPs were coated on carbon cloth and named PNHCF-NPs@CC. The electrochemical properties of PNHCF-NPs@CC were evaluated using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy techniques. In a 3-electrode cell configuration, PNHCF-NPs@CC electrode demonstrated high capacitance of 198.6 F g⁻¹ (Na₂SO₄) and 168.8 F g⁻¹ (K₂SO₄) at 0.4 A g⁻¹, excellent rate performance of 88 F g⁻¹ (Na₂SO₄) F g⁻¹ and 89 F g⁻¹ (K₂SO₄), even at 4 A g⁻¹, and outstanding cyclic stability with ∼94% capacitance retention after 1000 cycles at 0.4 A g⁻¹ for both electrolytes. The PNHCF-NP@CC hybrid showed high mechanical flexibility, superior electrical conductivity, and remarkably improved electrochemical capacitance, rendering it a promising flexible electrode material for use in high-performance supercapacitors.