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

## TL;DR

A new supercapacitor design using R-TiO2 nanotubes and graphene improves energy storage for miniaturized electronics.

## Contribution

A novel electrode design combining R-TiO2 nanotubes with Ni(OH)2 and FLG-GNP for high-performance micro-supercapacitors.

## Key findings

- The ASC achieved an areal capacitance of 118.26 mF cm−2 and energy density of 42.05 µWh cm−2.
- The symmetric device showed significantly lower capacitance and energy density compared to the ASC.
- The ASC demonstrated excellent cycling stability and rapid charge-discharge kinetics.

## Abstract

Conventional thin-film supercapacitors are limited by low energy density and poor charge balance between electrodes, restricting their integration into miniaturized electronic devices. In this study, reduced TiO2 nanotubes (R-TiO2 NTs) were fabricated via a straightforward anodization process followed by electrochemical reduction (self-doping) and further decorated with Ni(OH)2 nanospheres. These R-TiO2 NTs/Ni(OH)2 NSs electrodes were employed as both positive and negative electrodes for symmetric supercapacitors, and as positive electrodes in asymmetric configurations. To develop a suitable negative electrode, few-layer graphene (FLG) and graphene nanoplatelets (GNP) were combined, and the optimal FLG/GNP weight ratio was identified to balance charge storage. This electrode design enabled the fabrication of an asymmetric supercapacitor (ASC) with significantly enhanced energy storage performance. The superior performance of the ASC is attributed to a synergistic charge storage mechanism, where surface-controlled pseudocapacitive reactions of Ni(OH)2 nanosheets complement the double-layer capacitance of the FLG-GNP electrode, ensuring rapid charge–discharge kinetics, high rate capability, and excellent cycling stability. The ASC achieved an areal capacitance of 118.26 mF cm−2 and an energy density of 42.05 µWh cm−2 at 0.25 mA cm−2, compared to 19.38 mF cm−2 and 6.89 µWh cm−2 for the symmetric device. This work demonstrates a promising strategy for high-performance, scalable micro-supercapacitors with potential applications in flexible and miniaturized electronics.

A high-performance, scalable micro-supercapacitor delivering enhanced capacitance, energy density, and long-term cycling stability.