Performance degradation study of NiCo₂O₄-based asymmetric supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Asymmetric supercapacitors utilizing NiCo2O4//GO composites show performance decline after extended cycling.
• The NiCo2O4 electrode component exhibits rapid performance degradation, while the GO electrode remains relatively stable.

Purpose of the Study:

• To synthesize porous spherical NiCo2O4 nanoparticles via a hydrothermal method.
• To fabricate and evaluate the electrochemical performance and stability of a NiCo2O4//GO asymmetric supercapacitor.
• To investigate the degradation mechanism of the NiCo2O4 electrode during supercapacitor cycling.

Main Methods:

• Hydrothermal synthesis of porous spherical NiCo2O4 nanoparticles.
• Fabrication of NiCo2O4//GO asymmetric supercapacitors.
• Electrochemical testing (charge-discharge cycles) at a current density of 10 A g-1.
• Material characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS).

Main Results:

• The synthesized NiCo2O4//GO asymmetric supercapacitor demonstrated stable cycling performance for 3000 cycles at 10 A g-1.
• Characterization revealed that performance degradation of the NiCo2O4 electrode is linked to the formation of new substances and the destruction of its crystal structure.
• Comparison of electrode morphology, crystal structure, and elemental composition before and after cycling elucidated the degradation pathways.

Conclusions:

• Maintaining the crystal structure stability of NiCo2O4 is crucial for ensuring the long-term performance stability of asymmetric supercapacitors.
• The study provides a valuable strategy for understanding and mitigating the degradation of supercapacitor electrode materials.