Vanadium-based metal-organic frameworks as superior electrode materials for high-performance supercapacitors: a...

Recent advancement in electrode materials for achieving high energy density, rapid power supply, and optimal cycling reliability have seen a staggering surge because of significant advancements in energy storage devices. In the modern era, metal-organic frameworks (MOFs) and transition metal sulfides and phosphates have emerged as viable candidates for high-performance electrode materials. Among these, MOFs have gained prominence as electrode materials due to their porous architecture, large surface area, and abundant active sites. Herein, three vanadium-based electrode materials, vanadium-1,2,4,5-benzenetetracarboxylic acid (V-BTCA), vanadium sulfide (VS), and vanadium phosphate (VPO₄), were synthesized and comparatively investigated for electrochemical hybrid supercapacitor (HSC) applications. We conducted an in-depth investigation to elucidate the effects of the linker, sulfide, and phosphate on the electrochemical properties of vanadium-based materials. Of the three materials, V-BTCA was identified as the optimum material and coupled with activated carbon (AC) to form an HSC device. The V-BTCA//AC device delivered excellent performance with a specific capacity (Q _s) of 730 C g^-1 at 0.8 A g^-1, an energy density (E _d) of 73.1 Wh kg^-1, a power density (P _d) of 6800 W kg^-1, and the lowest equivalent series resistance (ESR) value of 0.45 Ω, along with 92.83% stability and a coulombic efficiency of 98.15%. Furthermore, the power law was applied to verify the charge-storage behavior of hybrid devices, with b-values of 0.66-0.71, confirming their hybrid nature. The assembled hybrid device showed strong potential for energy storage applications, highlighting the critical role of electrode compatibility and device-level integration in achieving balanced HSC performance, with V-BTCA//AC exhibiting the most favorable overall performance among the investigated devices.