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–Co₃SnC_0.7–C composite microspheres uniformly dispersed with Sn₂Co₃–Co₃SnC_0.7 mixed nanocrystals are formed by the first-step reduction of spray-dried precursor powders at 900 °C. The second-step oxidation process transforms the Sn₂Co₃–Co₃SnC_0.7–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 °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 200^th 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.