Highly Conductive, Flexible Ionic Laser-Induced Graphene for Iontronic Applications

Iontronic devices, celebrated for their seamless integration into soft, human-friendly electronics, operate by forming an electrical double layer (EDL) at the interface between ion gels and electrodes. However, achieving stable EDL formation has remained a persistent challenge despite extensive research on ion gels and various electrode materials. In this work, we introduce an innovative approach to address this issue by employing CO₂ laser irradiation to directly fabricate highly conductive, flexible laser-induced graphene (LIG) electrodes on polyimide (PI)-based ion gels.
Our PI-based ion gel enhances EDL formation at the electrode interface through efficient ion migration. Notably, the ionic laser-induced graphene (i-LIG) electrodes, derived from PI ion gels as precursors, exhibit high-quality graphene with increased crystallinity and a vertically expanded porous structure. This enhancement is achieved through improved thermal transfer and the intercalation of graphene layers, facilitated by the presence of ionic liquids (ILs) within the PI ion gel matrix. These features significantly boost the conductivity and stability of the electrodes, providing a promising pathway to optimize the performance of soft iontronic devices.
In comparison to conventional soft electrodes used in vertical capacitors, the combination of i-LIG electrodes with PI ion gels displays notably lower interfacial resistance and higher EDL capacitance. These findings highlight the significant potential of i-LIG electrodes for advanced soft iontronic applications, where minimizing resistance and maximizing capacitance are critical for performance enhancement.
In conclusion, our work advances the understanding of EDL behavior at ion gel-electrode interfaces and provides crucial insights for developing flexible, high-performance iontronic devices. The i-LIG fabrication method, which directly integrates graphene electrodes onto soft substrates, opens new opportunities for the scalable production of flexible, energy-efficient electronic components. By leveraging CO₂ laser irradiation to create i-LIG electrodes on PI-based ion gels, we have not only resolved the longstanding issue of stable EDL formation but also significantly enhanced device performance. These results pave the way for further innovations in the field of soft, flexible electronics, underscoring the potential of iontronic technologies to revolutionize a wide range of applications.