Design and Synthesis of Spherical Multicomponent Aggregates Composed of Core-Shell, Yolk-Shell, and Hollow Nanospheres and Their Lithium-Ion Storage Performances

Micrometer-sized spherical aggregates of Sn and Co components containing core-shell, yolk-shell, hollow nanospheres are synthesized by applying nanoscale Kirkendall diffusion in the large-scale spray drying process. The Sn2Co3-Co3SnC0.7-C composite microspheres uniformly dispersed with Sn2Co3-Co3SnC0.7 mixed nanocrystals are formed by the first-step reduction of spray-dried precursor powders at 900 degrees C. The second-step oxidation process transforms the Sn2Co3-Co3SnC0.7-C composite into the porous microsphere composed of Sn-Sn2Co3@CoSnO3-Co3O4 core-shell, Sn-Sn2Co3@CoSnO3-Co3O4 yolk-shell, and CoSnO3-Co3O4 hollow nanospheres at 300, 400, and 500 degrees C, respectively. The discharge capacity of the microspheres with Sn-Sn2Co3@CoSnO3-Co3O4 core-shell, Sn-Sn2Co3@CoSnO3-Co3O4 yolk-shell, and CoSnO3-Co3O4 hollow nanospheres for the 200th cycle at a current density of 1 A g(-1) is 1265, 987, and 569 mA h g(-1), respectively. The ultrafine primary nanoparticles with a core-shell structure improve the structural stability of the porous-structured microspheres during repeated lithium insertion and desertion processes. The porous Sn-Sn2Co3@CoSnO3-Co3O4 microspheres with core-shell primary nanoparticles show excellent cycling and rate performances as anode materials for lithium-ion batteries.