Nanocrystalline LaO_x/NiO composite as high performance electrodes for supercapacitors

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Development of high-performance electrode materials is crucial for advanced energy storage devices.
• Nickel oxide (NiO) based materials are promising but often suffer from limited rate capability and cycling stability.
• Composite electrodes offer synergistic effects to overcome limitations of single-component materials.

Purpose of the Study:

• To synthesize and characterize novel nanocrystalline LaOₓ/NiO composite electrodes.
• To investigate the electrochemical performance of these electrodes for supercapacitor applications.
• To evaluate the potential of these composites in asymmetric energy storage devices.

Main Methods:

• Facile cathodic electrodeposition of LaOₓ/NiO onto nickel foam followed by thermal annealing.
• Binder-free synthesis approach.
• Characterization using scanning electron microscopy (SEM) and transmission electron microscopy (TEM).
• Electrochemical testing including cyclic voltammetry, galvanostatic charge-discharge, and cycling stability measurements.
• Assembly and testing of asymmetric coin devices.

Main Results:

• Uniform distribution of ~50 nm LaOₓ nanocrystalline particles within the NiO matrix.
• Specific capacitance of 1238 F g⁻¹ at 0.5 A g⁻¹.
• Excellent rate capability (86% retention at 10 A g⁻¹) and cycling stability (93% after 10,000 cycles).
• Asymmetric devices achieved high energy density (13.12 W h kg⁻¹) at a power density of 90.72 W kg⁻¹.

Conclusions:

• LaOₓ/NiO composite electrodes demonstrate enhanced electrochemical performance due to increased redox sites and improved ion diffusion.
• The binder-free synthesis and unique layered structure contribute to superior rate capability and cycling stability.
• These advanced composite electrodes show significant promise for high-performance supercapacitor applications.