Kinetic-Controlled Dissolution-Diffusion-Recrystallization of Hollow Two-Dimensional Conductive Metal-Organic Frameworks@MXene Heterojunctions for High-Performance Lithium Storage

Abstract

Two-dimensional conductive metal-organic frameworks (2D c-MOFs) hold great promise as anodes for next-generation high-energy density devices, yet their practical application is hindered by insufficient exposure of the active site caused by layer stacking and limited specific capacity attributed to non-redox-active ligands. Herein, 2D c-MOF@MXene (M-HHTP@MX) heterojunction with hollow structures is synthesized for the first time via in situ ligand exchange using ZIF precursors. By unraveling the dissolution-diffusion-recrystallization kinetic mechanism, precise control over the formation and morphology of the hollow architectures is achieved. Unlike the limitations of conventional solvothermal methods, the adoption of room-temperature conditions and the Ti3C2Tx introduction endow the heterojunction with high crystallinity, low defects and good mechanical properties. Furthermore, M-HHTP@MX possesses a hierarchical pore structure with characteristic sizes of 1.87 nm and 37.72 nm, which are conducive to sufficient electrolyte penetration and the active site exposure. Notably, Co-HHTP@MX delivers a superior reversible capacity of 972.19 mAh·g−1 at 100 mA·g−1, along with excellent long-term cycling stability with a 90.7% capacity retention at 2000 mA·g−1 after 2000 cycles. This work provides a novel strategy for high-performance anodes through constructing hollow 2D c-MOF heterojunctions via ligand exchange that enhance cycling stability and promote lithium migration.