Novel rough nanorods NiO-(NiFeCo)O as positive electrode of high-performance asymmetric supercapacitors assembled with SiO2/rGO negative electrode

Supercapacitors are essential to future energy systems, enabling efficient energy storage and management. Transition metal oxides are pivotal in advancing supercapacitor performance due to their redox activity and conductivity. Here, we synthesize a multi-element transition metal oxide composite (NiO-(NiFeCo)O) via a one-step hydrothermal method, forming self-assembled 3D rough nanorod networks. This architecture enhances ion transport, provides abundant active sites, and delivers a specific capacitance of 1414.54 F g −1 at 1 A g −1 , with 98.35 % capacitance retention after 3000 cycles. We further developed an asymmetric supercapacitor (ASC) using NiO-(NiFeCo)O as the positive electrode and rGO self-assembled on SiO 2 as the negative electrode. The ASC achieved a remarkable energy density of 66.0 Wh·kg −1 at 800 W kg −1 , alongside 88.46 % capacitance retention after 11,000 cycles. This design balances high energy/power density with exceptional stability, addressing critical challenges in next-generation energy storage. Our findings highlight the potential of NiO-(NiFeCo)O//SiO 2 /rGO ASCs for scalable, sustainable applications in advanced energy systems.