Polyoxomolybdate–Polypyrrole–Graphene\nOxide Nanohybrid Electrode for High-Power Symmetric Supercapacitors

Abstract

Supercapacitors\nhave emerged as one of the most promising candidates\nfor high-performance, safe, clean, and economical routes to store\nand release of nonfossil energy. Designing hybrid materials by integrating\ndouble-layer and pseudocapacitive materials is crucial to achieving\nhigh-power and high-energy storage devices simultaneously. Herein,\nwe synthesized a polyoxomolybdate–polypyrrole–graphene\noxide nanohybrid via a one-pot reaction. The inclusion of polypyrrole\nenables a uniform distribution of the polyoxomolybdate clusters; it\nalso confines the restacking of graphene oxide nanosheets. The structural\nand morphological analysis to unveil the nanohybrid architecture implies\nexcellent interfacial contact, enabling fast redox reaction of polyanions,\nand a quick transfer of charge to the interfaces. Electrochemical\ncharacteristics tested under a two-electrode system exhibit the highest\ncapacitance of 354 F g^–1 with significantly high\nspecific energy and power of 49.16 Wh kg^–1 and 999.86\nW kg^–1, respectively. In addition, the cell possesses\na high-rate capability and long cycle life by maintaining 96% of its\ncapacitance over 5000 sweeping cycles. The highest specific power\nof ∼10 000 W kg^–1 was computed with\nCoulombic efficiency of 92.30% at 5 A g^–1 current\ndensity. Electrochemical impedance spectroscopy additionally reveals\nenhanced redox charge transfer due to double hybridization. Furthermore,\nit also demonstrates the impedance and capacitive behavior of supercapacitor\ncells over a definite frequency regime.