Nature-Inspired MXene Electrode with the Highly Interconnected Gradient Nanoconfined Architecture

Achieving efficient ion transport in thick electrodes remains a fundamental challenge in electrochemical systems with high energy density, primarily due to prolonged diffusion pathways and poorly integrated architectures. Leveraging the nanoconfinement effect, (sub)nanoscale channels can significantly accelerate ion transport kinetics to maximize electrochemical performance. Inspired by the hierarchical network structure of bamboo membrane, a gradient nanoconfined MXene electrode (GNC-MX) is designed, where multiscale interlayer spacing is coupled with in-plane mesopores that bridge adjacent nanoconfined channels, enabling synergistic vertical and horizontal ion migration. Finite element simulations and density functional theory calculations reveal the synergistic optimization mechanism of ion transport via the gradient nanoconfined channels and in-plane mesopores. Compared to pristine MXene, GNC-MX electrodes exhibit substantially enhanced ion transport kinetics and charge storage performance. To optimize the nanoconfined channels, an in situ deprotonation-reprotonation strategy is introduced to strengthen electrostatic repulsion and weaken hydrogen bonding and van der Waals interactions of the MXene interlayer, enabling quasi-permanent expansion of ion transport channels. Furthermore, a scalable group-welding method is developed to fabricate 400 µm-thick electrodes with an ultrahigh areal capacitance of 20.7 F cm^-2, surpassing current MXene-based electrodes. This work provides a scalable and tunable biomimetic platform for advanced ion nanoconfinement in energy storage systems.