One-pot Aerosol Synthesis of Carbon Nanotube-Zn₂GeO₄ Composite Microspheres for Enhanced Lithium-ion Storage Properties

Three-dimensional (3D) carbon nanotube (CNT)-multicomponent metal oxide composite microspheres with non-aggregation characteristics are prepared using a simple one-pot spray pyrolysis process, applying water-soluble metal salt and oxidized CNT fibers. The hierarchical porous 3D structure of the CNT is formed by networking the flexible CNTs with a high aspect ratio during the drying stage of a droplet. Subsequently, the Zn and Ge salts are deposited over the CNTs to form the ZnO-CNT and GeO₂-CNT composite microsphere. Decomposition of Zn and Ge salts into their respective oxides and the conversion reaction to form Zn₂GeO₄ at 700 °C, produce the Zn₂GeO₄-CNT composite microsphere. The initial discharge capacities of the Zn₂GeO₄, Zn₂GeO₄-CNT, ZnO-CNT, and GeO₂-CNT microspheres, at a current density of 1.5 A g^-1, are 1351, 1211, 1387, and 1631 mA h g^-1, respectively, and their discharge capacities at the 300^th cycle are 415, 762, 261, and 480 mA h g^-1, respectively. The CNT-Zn₂GeO₄ composite microspheres, selected as the first target material, show electrochemical properties superior to those of the bare Zn₂GeO₄, CNT-ZnO, and CNT-GeO₂ composite microspheres. The synergetic effect of the multicomponent composition of Zn₂GeO₄ and the CNT support result in excellent Li-ion storage properties of the Zn₂GeO₄-CNT composite microspheres.