Defect engineering on sea-urchin-like transition-metal oxides for high-performance supercapacitors

Reasonable design of nanostructures and application of Defect Engineering have been proved to be essential for the construction of high-performance electrochemical energy storage devices. Herein, a defect engineering strategy is developed to fabricate a 3D multi-layered sea urchin-like structure assembled by 1D nanowire, which shows a high specific surface area for electrochemical active sites. More significantly, the phosphate-doping treatment introduces N/P elements in P-NiCo2O4, thus generates Co/Ni-P and Co/Ni-N bonds to create more oxygen vacancies. Vacancy defects manipulate the electronic structure of the electrode materials to obtain good physical and electrochemical properties. The prepared sea urchin-like P-NiCo2O4 electrode in this work exhibits exceptionally excellent charge storage capability in aqueous solutions with high specific capacitance (467 C g 1 at 1 A g 1), good rate capability, and ultra-high cycling stability at 20 A g 1 (87.2% capacitance retention over 10,000 cycles). Furthermore, the assembled asymmetric supercapacitor using P-NiCo2O4 cathode and AC anode shows a high energy density of 31.25 Wh kg 1 at a much large power density of 7500 W kg 1, and an outstanding cycling performance at 10 A g 1 (83.4% capacitance retention over 10,000 cycles). The prepared P-NiCo2O4 electrode materials are expected to be used in high-performance supercapacitors.

Automated summary

Reasonable design of nanostructures and application of Defect Engineering have been proved to be essential for high-performance electrochemical energy storage devices. In this study, a defect engineering strategy is developed to fabricate a 3D multi-layered sea urchin-like structure with high specific surface area for electrochemical active sites, which demonstrates exceptional charge storage capability and cycling stability.