Interfacial Hydrogen Bond Engineering: Enabling Rapid 3D Assembly of MXene Thick Electrodes with High Mass Loading and Fast Charge Transport

Abstract Micro‐supercapacitors (MSCs) hold great promise for powering next‐generation microelectronics. However, their practical deployment remains severely hindered by low areal energy densities (≤100 µWh cm − 2 ) under constrained footprints (<1 cm 2 )—primarily due to the challenges in constructing 3D thick electrodes with high mass loading and efficient charge transport. Herein, a scalable and cost‐effective strategy is presented for fabricating MXene‐based 3D thick electrodes (>2400 µm) by intensifying interfacial hydrogen‐bond interactions between oxygen plasma‐activated carbon felt and Ti 3 C 2 T x MXene nanosheets. This interfacial engineering approach drives the rapid and robust self‐assembly of MXene flakes into a hierarchically porous, low‐tortuosity architecture while transforming the carbon felt into a multifunctional 3D conductive framework—simultaneously enhancing structural integrity, charge carrier mobility, and post‐fabrication processability. The resulting ultra‐thick electrodes abandon inactive binder/additives and fully exploit the vertical space, maximizing active material utilization. When paired with MnO 2 nanowires/carbon nanotube hybrid cathodes, MSCs with the demonstrated MXene‐based thick anodes achieve a 2.3 V output and a high areal energy density of 818 µWh cm − 2 . This work overcomes the long‐standing trade‐off between electrode thickness and charge transport kinetics in thick electrodes and establishes a versatile framework for architecting high‐energy‐density MSCs, advancing the development of integrated microelectronics for the future.