Free-Standing Crystalline@Amorphous Core-Shell Nanoarrays for Efficient Energy Storage.

Structures comprising high capacity active material are highly desirable in the development of advanced electrodes for energy storage devices. However, the structure degradation of such material still remains a challenge. The construction of amorphous and crystalline heterostructure appears to be a novel and effectual strategy to figure out the problem, owing to the distinct properties of the amorphous protective layer. Herein, crystalline-Co3O4@amorphous-TiO2 core-shell nanoarrays directly grown on the carbon cloth substrate are rationally designed to construct the free-standing electrode. In the unique structure, the 3D porous nanoarrays provide increased availability of electrochemical active sites, and the array with a unique heterostructure of crystalline Co3O4 core and amorphous TiO2 shell exhibits intriguing synergistic properties. Besides, the amorphous TiO2 protective layer shows elastic behavior to mitigate the volume effect of Co3O4. Benefiting from these structural advantages, the as-prepared free-standing electrode exhibits superior lithium storage properties, including high coulombic efficiency, outstanding cyclic stability, and rate capability. Pouch cells with high flexibility are also fabricated and show remarkable electrochemical performances, holding great potential for flexible electronic devices in the future.