Direct-ink-write 3D printing of flexible all-solid-state micro-supercapacitor based on MXene-hydroxylated nanocellulose-carbon nanotubes

Micro-supercapacitors (MSCs) have emerged as an ideal solution to overcome the limitations of conventional energy storage devices owing to their rapid response, long cycle life, and high power density. However, their insufficient energy density remains a critical constraint for practical applications. Compared to traditional manufacturing techniques such as spin-coating and blade-coating, direct ink writing (DIW) demonstrates unique advantages in material design flexibility, process controllability, and scalability. Its layer-by-layer deposition capability enables precise construction of microporous hierarchical architectures, significantly enhancing device energy storage performance. MXene, a novel two-dimensional transition metal carbide, has become a promising candidate for addressing supercapacitor performance limitations due to its intrinsic high conductivity, abundant surface functional groups, and high theoretical specific capacitance. However, MXene nanosheets face the challenge of spontaneous stacking due to hydrogen bonding/van der Waals forces, making it difficult to directly formulate stable 3D printing inks. This necessitates the introduction of interfacial structural engineering strategies to precisely regulate the rheological properties of functional inks at the nano-micro scale, thereby expanding MXene's application value in cutting-edge fields such as flexible electronics, energy storage devices, and smart sensing.

A research team led by Professors Bowei Zhang and Fu-Zhen Xuan at East China University of Science and Technology has recently developed an innovative MXene-hydroxylated nanocellulose-carbon nanotube (MHC) composite ink system. By combining this formulation with DIW 3D printing technology, they successfully fabricated high-performance flexible MSCs. The MHC-based flexible MSCs, designed with an interdigitated structure and encapsulated with H₂SO₄-PVA solid electrolyte, successfully address the issue of electrochemical performance degradation caused by delamination between the electrode and electrolyte under deformation.

The team published their review in Carbon Future on May 14, 2025.

This study introduced a small amount of HNC as a crosslinking agent, which formed a three-dimensional network structure with oxygen-containing functional groups on MXene surfaces, effectively inhibiting nanosheet agglomeration and optimizing the ink's shear-thinning properties. By incorporating CNTs as conductive bridging channels, the system significantly enhanced charge transfer speed and efficiency. Through optimized ink formulation and printing process design, the fabricated flexible all-solid-state MSCs exhibited high precision and excellent flexibility. The devices demonstrated outstanding performance stability during mechanical bending, series/parallel module integration, and long-term charge/discharge cycling tests, providing customizable energy storage modules for flexible wearable microelectronic systems.

This work was supported by the National Natural Science Foundation of China (Grant. No. 52422505, No. 12274124), the Shanghai Pilot Program for Basic Research (Grant. No. 22TQ1400100-6), the Fundamental Research Funds for the Central Universities, and the Innovative Research Group Project of the National Natural Science Foundation of China (Grant. No. 52321002).

About the Author

Bowei Zhang, Professor at the School of Mechanical and Power Engineering, East China University of Science and Technology, is primarily engaged in research on intelligent sensing and micro-energy devices, as well as the design and manufacturing of key electrode components for hydrogen production equipment. He has been selected for the National Excellent Young Scientists Fund and the Shanghai High-Level Overseas Talent Program, and has received prestigious awards such as the National Award for Outstanding Self-Financed International Students and the Zaffarano Prize from the American Sigma Xi. He has published over 40 SCI-indexed papers with more than 1,200 citations and an h-index of 21. In the past five years, as the first or corresponding author, he has published over 20 SCI papers in renowned journals such as Nature Communications, Advanced Materials, Nano Letters (2), ACS Energy Letters, Materials Horizons, and Nano Energy, including three ESI Highly Cited Papers. Additionally, he has filed/obtained 8 patents. For more information, please pay attention to his research homepage https://www.x-mol.com/groups/zhang_bowei.

Fu-Zhen Xuan, Professor at East China University of Science and Technology, is a recipient of the National Outstanding Young Scientist Fund and a "Ten Thousand Talents Program" Leading Talent. He currently serves as the President of East China University of Science and Technology. He has received the National Science and Technology Progress Award (First Class) once, the National Science and Technology Progress Award (Second Class) once, the Provincial and Ministerial Special Prize once, the First Prize four times, and the Second Prize once. He was also awarded the China Petroleum and Chemical Industry Federation Youth Science and Technology Outstanding Contribution Award. Professor Xuan has led and completed major national projects, including the National Nuclear Power Major Project (Topic), National Instrumentation Project, 863 Program, National Science and Technology Support Program, and National Natural Science Foundation projects. He has participated in the development and research of several national/industry standards, including "Safety Assessment of Pressure Vessels in Service with Defects" and "Evaluation of the Fitness for Use of Pressure Equipment.

Xiaohui Tang, Assistant Researcher and Co-PI at the Institute of Medical Chips, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, is mainly engaged in research on energy storage devices, bioelectronics and simulation. He has received prestigious awards such as "Iowa State University Research Excellence Award", "Shanghai Pujiang Talent", and "Shanghai Municipal Overseas High-level Introduced Young Talent". As the first author (including a total of one), he has published 7 papers in SCI-indexed journals such as J. Power Sources、ACS Appl. Mater. Interfaces、Chem. Eng. J.、Nano Res. Additionally, he has contributed to 12 publications in high-impact journals such as Chem. Soc. Rev.、ACS Energy Lett.、ACS Sens.、J. Mater. Chem. A.

About Carbon Future

Carbon Future is an open access, peer-reviewed and international interdisciplinary journal sponsored by Tsinghua University and published by Tsinghua University Press. It serves as a platform for researchers, scientists, and industry professionals to share their findings and insights on carbon-related materials and processes, including catalysis, energy storage and conversion, as well as low carbon emission process and engineering. It features cutting-edge research articles, insightful reviews, perspectives, highlights, and news and views in the field of carbon. The article publishing charge is covered by the Tsinghua University Press.