Bimetal MOF nanosheets as efficient anode materials for lithium-ion batteries
摘要
The advancement of high-performance anode materials is essential for driving lithium-ion batteries (LIBs) technological progress. Metal–organic frameworks (MOFs) have gained prominence as attractive candidates for energy storage applications owing to their tunable porosity, exceptional surface area, and structural adaptability. In this study, bimetallic MOF nanosheets (CoₓFe1-x-MOFs) with ultrathin architectures were synthesized through a solvothermal approach and systematically evaluated as LIB anode materials. The synergistic interaction between transition metal nodes was engineered to enhance electronic conductivity and Li⁺ diffusion kinetics, while the two-dimensional nanosheet morphology exposed abundant electroactive sites and minimized ion transport distances. Electrochemical characterization revealed outstanding performance metrics: The optimized Co1/2Fe1/2-MOF composition delivered a remarkable reversible capacity of 1132 mAh g⁻1 at 0.1 A g⁻1 over 200 cycles, exceptional rate capability (660 mAh g⁻1 at 2 A g⁻1), and ultralong cycling stability with 90% capacity retention after 500 cycles. These superior properties stem from the dual-metal coordination chemistry that mitigates structural pulverization while facilitating rapid charge transfer kinetics. Morphology controllable synthesis can be achieved through a simple solvothermal method. The multilayer structure of cobalt-iron bimetallic MOF nanosheets optimizes the charge transport path, enhances conductivity through electronic coupling at metal nodes, and can buffer volume expansion during charging and discharging, which is conducive to maintaining structural integrity. The performance of the synthesized material is superior to that of most of the MOF-based electrode materials reported so far. This work not only demonstrates the effectiveness of bimetallic MOF design principles but also paves the way for developing hierarchical nanoarchitectures in next-generation energy storage systems.