Unusual Formation of CoO@C “Dandelions” Derived from 2D Kagóme MOLs for Efficient Lithium Storage

摘要

Despite great breakthroughs, the search for anode materials with high performance for lithium-ion batteries (LIBs) remains challenging. Hence, engineering advantageous structures via effective routes can bring new possibilities to the development of the LIB field. Herein, the precise synthesis of three-dimensional (3D) hybrids of ultrathin carbon-wrapped CoO (CoO@C) dandelions is reported by the pyrolysis of two-dimensional (2D) Kagome metal-organic layers (MOLs) at 400 degrees C under an Ar atmosphere. Due to the special coordination structure of the paternal MOLs, the resulting CoO nanowires show a small diameter of 5-10 nm and are uniformly confined within the ultrathin carbon layer. Based on the time-dependent pyrolysis experiments, a crystal transformation mechanism of in situ self-templated-recrystallization-self-assembly accompanied by phase and morphology changes is first presented to reveal the formation of the 3D dandelion-like spheres with assembly of nanowire arrays from a 2D Kagome MOL. By virtue of structural and compositional features, including a 3D array structure, the small size of the primary ultrathin nanowires, and a uniform ultrathin graphitic carbon layer, these unique CoO@C dandelions display high specific capacity, good rate capability, and excellent cycling stability. Importantly, this approach can be extended to accurately synthesize other desired composite structures.