Size-controllable synthesis of amorphous GeOx hollow spheres and their lithium-storage electrochemical properties

Abstract

Amorphous GeO_x hollow spheres with uniform particle size were prepared via a soft-template strategy using H₂ bubbles as templates. The diameter of the hollow spheres can be controlled by using a micromolecular organic amine, and averages at 142 nm with a shell thickness of about 20 nm. The X-ray photoelectron spectroscopy data showed that the Ge : O stoichiometry ratio is 1 : 1.25. In the voltage window of 0.01–1.8 V, the discharge capacity of the amorphous GeO_x hollow sphere was approximately 794 mA h g⁻¹ at 500 mA g⁻¹ after 100 cycles, demonstrating an excellent capacity retention and stability. In addition, even at different high current rates (2C, 4C), high specific capacities (857, 724 mA h g⁻¹, respectively) can be achieved. The superior electrochemical performance of amorphous GeO_x hollow spheres could be attributed to their unique porous hollow nanostructure and homogeneous particle size distribution, which not only enhance the specific capacity, but also alleviate the pulverization problems that prevent particle aggregation and facilitate better rate capabilities.