High-performance supercapacitors based on superior Co3O4 nanorods electrode for integrated energy harvesting-storage system

The Co₃O₄ nanorods (NR-Co₃O₄) electrode is synthesized by using a calcination-process assisted hydrothermal method. Each Co₃O₄ nanorod possesses porous structure with well-defined nanoparticles. The unique NR-Co₃O₄ electrode exhibits the superior electrochemical performances, including a specific capacity of 1272 C g⁻¹ at a current density of 1.89 A g⁻¹ and 90.3% of capacity retention after 18,000 cycles at 23.58 A g⁻¹. The NR-Co₃O₄//active carbon (AC) device is also assembled to probe the virtues of NR-Co₃O₄ electrode, manifesting a maximum energy density and power density of 55.4 Wh kg⁻¹ and 4490 W kg⁻¹, respectively. Amazingly, the NR-Co₃O₄//AC device exhibits the super-long cycling stability with 90.4% retention ratio after 36,000 cycles. Furthermore, an energy harvesting-storage system is constructed by integrating the commercial solar panel with the power package composing of four NR-Co₃O₄//AC devices in-series, witnessing the fast photo-charge and discharge capability of NR-Co₃O₄//AC device. These facts strongly demonstrate the synthesized NR-Co₃O₄ is promising towards the practical application for self-powered technology in future.