Recent commercialization efforts made in the fields of flexible sensors, low-energy Bluetooth transmitters, and low-power thin-film electronics have contributed to significant fast-paced growth in the smart wearable industry. This drastic paradigm shift in the flexible electronics component design has fuelled an evolution in the flexible personal electronics, biomedical, athletics, and logistics industries as more flexible, thin-film products are offered. Flexible thin-film electrochemical capacitors (EC) or supercapacitors are energy storage solutions that offer both high energy and power densities resulting from the exceptional high electrode specific surface area and appropriately tuned electrode/electrolyte interface. To meet both the electrochemical and mechanical requirements, several aspects of the electrode design was to be considered in the proposed flexible EC devices:​ a) Areal- and gravimetric specific capacitance;​ b) Charge-discharge cycling properties;​ c) Mechanical bending and flexing behaviours;​ and d) Environmental stability.

In this work, novel facile techniques in fabricating flexible EC electrodes with micro- and nanostructured surface modification have been proposed to produce high-performing flexible EC electrodes with additional intrinsic multi-functionalities, such as piezoresistive sensors and breathing sensors, along with energy storage. Herein, to create facile pathways for fabricating flexible, high-performance EC electrodes, this thesis has been divided into the following studies:​

The first study focuses on the design of a novel environmental-controlled self-assembly method, where polyaniline (PAni) nanorod structures were grown on polyacrylonitrile (PAN) nanofibers for high-surface-area textile electrochemical capacitor electrodes with intrinsic piezoresistive tactile sensing capabilities.

The second study relied on a novel laser-assisted photochemical reduction method to produce reduced graphene oxide micro-ribbon textile electrode directly on a liquid surface, which can be transfer printed onto any substrate for both supercapacitors and breath sensor applications.

The third study validated a method for creating hierarchically structured multilayer reduced graphene oxide for flexible intercalated supercapacitor electrodes where simultaneous reduction and nitrogen-doping were successfully achieved.

The last study explored the possibility of creating a multi-layered flexible polypyrrole microfoam/carbon nanotube composite electrodes for flexible supercapacitor devices via the creation of three-dimensional polypyrrole microsphere architecture.