Nanodiamond-based TiO2 nanocomposite separators for enhancing performance of flexible paper-based supercapacitors

Abstract

Supercapacitors (SCs) stand out as a storage solution owing to their rapid charge transfer, high power density, low weight, and long lifecycle compared to batteries. Among the SC technologies, interdigitated in-plane SCs offer planar design, compactness, durability, and wide temperature range, which all make them ideal choices for device integration. This work demonstrates the pivotal role of a green, sustainable nanocomposite separator synthesized from detonation nanodiamonds (DNDs) and TiO₂ nanoparticles in supercapacitor (SC) devices incorporating interdigitated screen-printed carbon electrodes on paper substrates. The TiO₂@DND nanocomposite provides mechanical and thermal stability and exhibits a nanoporous morphology that facilitates ion conduction. The synergic effect between TiO₂ and DND is maximized through hydrogen annealing, which enhances interfacial coupling and reduces charge-transfer resistance. Consequently, the TiO₂@DND separator enables supercapacitors with high energy and power densities showcasing 597 µF cm⁻² capacitance and 99% stability after 10 000 cycles, significantly boosting SC performance and durability. These results highlight the potential of nanodiamonds for improving SC devices and potentially also other energy storage technologies.