In Situ Growth of Polyaniline Nanofibers in Sulfonated UiO-66 MOF for High-Performance Symmetric Supercapacitor...

In modern energy catastrophes, supercapacitors are excellent energy storage devices, offering high power and energy density. Recently, metal organic framework (MOF)-based materials and their composites have gained significant attention as electrode materials in supercapacitor applications due to their high surface area and porosity, which assist the electrochemical process. However, their poor electrical conductivity limits their practical applications. To overcome this drawback, we incorporated a conducting polymer into a high surface area containing UiO-66 SO₃H MOF to prepare a UiO-66 SO₃H-PANI composite using an in situ polymerization method. The -SO₃H groups of the MOF acted as an internal proton source, enabling acid-free in situ PANI synthesis and producing a well-integrated composite with ameliorated symmetric supercapacitor performance in a two-electrode system. In the UiO-66 SO₃H-PANI composite, the MOF provided well-decorated porosity and surface area for electrical double layer capacitance (EDLC), while PANI introduced abundant electroactive sites and conductivity, enhancing the electron transfer process and pseudocapacitance. The in situ grown UiO-66 SO₃H-PANI composite exhibited a high specific capacitance of 1110 F g^-1 at a current density of 1 A g^-1 in a 1 M H₂SO₄ electrolyte in a three-electrode system. The as-fabricated two-electrode symmetric supercapacitor device (SSCD) exhibited a specific capacitance of 150 F g^-1 at a specific current density of 1 A g^-1, maintaining approximately 79% capacitance retention after 2000 continuous charge-discharge cycles. The SSC achieved a maximum power density of 5.3 kW kg^-1 at 5 A g^-1 and a maximum energy density of 20.9 Wh kg^-1 at 1 A g^-1, with the capability to illuminate commercial LEDs.