Enhanced energy storage in supercapacitors using R-TiO₂ nanotube and graphene-based electrodes

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Conventional thin-film supercapacitors suffer from low energy density and electrode charge imbalance, hindering their use in small electronic devices.
• Developing high-performance energy storage solutions is crucial for the advancement of miniaturized and flexible electronics.

Purpose of the Study:

• To fabricate novel electrode materials for symmetric and asymmetric supercapacitors.
• To enhance the energy storage performance and charge balance of micro-supercapacitors.
• To explore synergistic charge storage mechanisms for improved device capabilities.

Main Methods:

• Fabrication of reduced titanium dioxide nanotubes (R-TiO2 NTs) via anodization and electrochemical reduction.
• Decoration of R-TiO2 NTs with nickel hydroxide nanospheres (Ni(OH)2 NSs).
• Development of a composite negative electrode using few-layer graphene (FLG) and graphene nanoplatelets (GNP) at an optimized weight ratio.
• Assembly and testing of symmetric and asymmetric supercapacitors (ASCs).

Main Results:

• The asymmetric supercapacitor (ASC) demonstrated superior performance compared to the symmetric device, achieving an areal capacitance of 118.26 mF cm-2 and energy density of 42.05 µWh cm-2.
• A synergistic charge storage mechanism involving Ni(OH)2 pseudocapacitance and FLG-GNP double-layer capacitance was identified.
• The ASC exhibited rapid charge-discharge kinetics, high rate capability, and excellent cycling stability.

Conclusions:

• The developed R-TiO2 NTs/Ni(OH)2 NSs and FLG-GNP electrodes offer a promising strategy for high-performance micro-supercapacitors.
• The asymmetric configuration significantly enhances energy storage capabilities.
• This approach holds potential for applications in flexible and miniaturized electronic devices.