High-performance asymmetric pseudocapacitor based on NiCo2O4@MnO2 cathode and N-doped graphene anode

Abstract

The design and fabrication of scalable energy storage systems are crucial for portable applications, demanding advanced materials through large-scale and facile processing. In this report, an asymmetric solid-state pseudocapacitor (ASPC) is assembled using a core–shell NiCo2O4@MnO2 composite and solution-processed nitrogen-doped graphene (N-GP) as the positive and negative electrodes, respectively. With interconnected porous structures, the electrodes based on N-GP and NiCo2O4@MnO2 offer high specific capacitance and rate capability, broad operation voltage, and a binder-free design with no added conductive agent. With these benefits, the ASPC with a PVA-KOH electrolyte exhibits a specific capacitance of 103.3F g−1 at 1 A/g and exceptional energy density of 36.73 Wh kg−1 at a power density of 792 W kg−1. In addition, the specific capacitance retention reaches 90.9 % after 5000 cycles, indicating excellent cycling stability. In the broader context of solid-state supercapacitors based on solution-processed graphene, this ASPC exhibits highly competitive performance, establishing it as a promising candidate for advanced energy storage.