Metal-Organic Framework-Derived NiSb Alloy Embedded in Carbon Hollow Spheres as Superior Lithium-Ion Battery Anodes

The MOFs (metal-organic frameworks) have been extensively used for electrode materials due to their high surface area, permanent porosity, and hollow structure, but the role of antimony on the MOFs is unclear. In this work, we design the hollow spheres Ni-MOFs with SbCl₃ to synthesize NiSb⊂CHSs (NiSb-embedded carbon hollow spheres) via simple annealing and galvanic replacement reactions. The NiSb⊂CHSs inherited the advantages of Ni-MOFs with hollow structure, high surface area, and permanent porosity, and the NiSb nanoparticles are coated by the formed carbon particles which could effectively solve the problem of vigorous volume changes during the Li⁺ insertion/extraction process. The porous and network structure could well provide an extremely reduced pathway for fast Li⁺ diffusion and electron transport and provide extra free space for alleviating the structural strain. The NiSb⊂CHSs with these features were used as Li-ion batteries for the first time and exhibited excellent cycling performance, high specific capacity, and great rate capability. When coupled with a nanostructure LiMn₂O₄ cathode, the NiSb⊂CHSs//LiMn₂O₄ full cell also characterized a high voltage operation of ≈3.5 V, high rate capability (210 mA h g^-1 at a current density of 2000 mA g^-1), and high Coulombic efficiency of approximate 99%, meeting the requirement for the increasing demand for improved energy devices.