Professor Doyoung Byun’s research group at Sungkyunkwan University (SKKU), in collaboration with ENJET, Gyeongsang National University, and Khalifa University (Research and Innovation Center for Graphene and 2D Materials, RIC2D), developed oxidation-stable MXene inks for electrohydrodynamic (EHD) jet printing and demonstrated ultra-high-capacitance micro-supercapacitors (MSCs) based on these inks.

In the paper “Micro-supercapacitors of exceptionally high capacitance fabricated using intrinsically stable MXene inks via electrohydrodynamic jet printing,” the authors identify a key limitation of conventional MXene inks: their vulnerability to oxidation and poor dispersibility in organic solvents, which makes it difficult to formulate high-viscosity, organic-based inks suitable for high-resolution printing. The study then presents a practical ink-and-process strategy that directly addresses these issues.

In modern microelectronic devices, achieving high-performance energy storage in the space-constrained on-chip environment requires a process that can deliver both fine patterning (high resolution) and high volumetric performance. EHD jet printing is attractive because it enables high-resolution patterning at room temperature and is compatible with flexible substrates, but it also demands a functional ink that is both high-viscosity and highly stable.

To meet these requirements, the team designed an ADS-MXene(CMC) ink by combining ADOPA (alkylated 3,4-dihydroxy-L-phenylalanine) functionalized MXene (ADS-MXene) with CMC (carboxymethyl cellulose) in a hybrid organic-solvent system. The ink reportedly achieves, simultaneously, an electrical conductivity of approximately ~3400 S·cm⁻¹, a viscosity of ~4 × 10³ cP, strong oxidation resistance, and long-term dispersion stability on the order of three months.

They then optimized the EHD jet printing conditions for this ink formulation and fabricated in-plane interdigitated electrodes with a line width/spacing of 80 μm, achieving a high areal cell density of 6 cells·cm⁻². (This process was implemented using an ENJET system.)

The resulting high-density (HD) MSCs delivered an areal capacitance of 402.7 mF·cm⁻² and a volumetric capacitance of 2013 F·cm⁻³, which the authors present as among the highest volumetric capacitance values reported for MXene-printed MSCs. Durability testing showed over 95% capacitance retention after 10,000 cycles and a Coulombic efficiency of 96.5%, supporting both high performance and reliability.

Importantly, the work goes beyond performance reporting. Using DFT calculations, the authors verify charge transfer between the ADOPA ligand and the MXene surface, providing a mechanistic basis for improved stability. They also demonstrate stable, high-resolution patterning not only on glass/Si substrates but also on flexible substrates such as PET and PI, and they present a reproducible ink process operating window. The study emphasizes that these contributions can support future standardization of MXene inks for EHD printing and help expand the broader “MXetronics” ecosystem.

This work was supported by NRF (Ministry of Education) RS-2023–00239590, MOTIE Technology Innovation 20026376 (1415188205), and KIAT RS-2024–00418086. The results were published in Materials Science & Engineering R: Reports, Volume 168 (2026), Article 101148 (IF 26.8, JCR category ≈ 2%).

Figure 1. Schematic illustration of printable MXene ink synthesis 

and EHD jet printing of symmetric interdigitated HD-MSCs

Figure 2. MXene ink stability, printing of on-chip HD-MSCs, and performance comparison

※Title: Micro-supercapacitors of exceptionally high capacitance fabricated using intrinsically stable MXene inks via electrohydrodynamic jet printing

※Joournal: Materials Science & Engineering R (168권, 2026, 101148)

※DOI: https://doi.org/10.1016/j.mser.2025.101148

※PURE: https://pure.skku.edu/en/persons/do-young-byun/