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 Sn2 Co3 -Co3 SnC0.7 -C composite microspheres uniformly dispersed with Sn2 Co3 -Co3 SnC0.7 mixed nanocrystals are formed by the first-step reduction of spray-dried precursor powders at 900 °C. The second-step oxidation process transforms the Sn2 Co3 -Co3 SnC0.7 -C composite into the porous microsphere composed of Sn-Sn2 Co3 @CoSnO3 -Co3 O4 core-shell, Sn-Sn2 Co3 @CoSnO3 -Co3 O4 yolk-shell, and CoSnO3 -Co3 O4 hollow nanospheres at 300, 400, and 500 °C, respectively. The discharge capacity of the microspheres with Sn-Sn2 Co3 @CoSnO3 -Co3 O4 core-shell, Sn-Sn2 Co3 @CoSnO3 -Co3 O4 yolk-shell, and CoSnO3 -Co3 O4 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-Sn2 Co3 @CoSnO3 -Co3 O4 microspheres with core-shell primary nanoparticles show excellent cycling and rate performances as anode materials for lithium-ion batteries.