Pseudocapacitive effects of polyoxometalate implanted on graphene oxide matrix with polypyrrole for symmetric Supercapacitor applications

Abstract

Modern technological requirements emphasize designing and manufacturing electrochemical energy storage devices with high energy and power densities and longer cycle life. Supercapacitors with hybrid electrode materials have gained considerable attention as one of these systems due to their potential usage in futuristic applications such as electric vehicles and smart electric grids, among others. In this work, we synthesize potassium 9-tungsto-2-molybdo-1-vanadosilicate K<inf>5</inf>[α-SiMo<inf>2</inf>VW<inf>9</inf>O<inf>40</inf>]⋅10H<inf>2</inf>O and graphene oxide (GO) complex treating the latter as the supporting matrix for the former. We prepare the SiMo<inf>2</inf>VW<inf>9</inf>-polypyrrole (PPy) complex and then combine that with the GO matrix. The resulting nanohybrids GO-SiMo<inf>2</inf>VW<inf>9</inf> and GO-PPy/SiMo<inf>2</inf>VW<inf>9</inf> are found to have enhanced electrochemical properties when used in symmetric cells. Combining GO and pseudocapacitive materials can augment SC performance owing to their excellent redox properties. GO-SiMo<inf>2</inf>VW<inf>9</inf> and GO-PPy/SiMo<inf>2</inf>VW<inf>9</inf> showed 55.8 % and 85.5 % capacitive behavior at a scan rate of 10 mV/s, suggesting their use as high-performance pseudocapacitive materials as hybrid electrodes. GO-PPy/SiMo<inf>2</inf>VW<inf>9</inf> electrode material shows a specific capacitance of 351.6 F/g with energy and power densities of 48.83 Wh/kg and 999.93 W/kg, respectively, at 0.5 A/g current density. Both the electrode materials yield capacitance retention of 60 % (GO-SiMo<inf>2</inf>VW<inf>9</inf>) and 80 % (GO-PPy/SiMo<inf>2</inf>VW<inf>9</inf>) after 5000 cycles at an 8A/g current density with almost 100 % coulombic efficiency, implying the stability of the electrode material. © 2024 Elsevier B.V.