Cobalt-doped Zn2GeO4 nanorods assembled into hollow spheres as high-performance anode materials for lithium-ion batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2018-04, Vol.6 (14), p.5926-5934
• Main Authors: Lu, Jiaxue, Li, Deli, Li, Li, Yao Chai, Li, Meng, Yang, Shun, Liang, Jun
• Format: Article
• Language: English
• Subjects: Anodes; Charge transport; Cobalt; Discharge; Discharge capacity; Electrochemistry; Electrode materials; Germanium; Kinetics; Lithium; Lithium-ion batteries; Microspheres; Nanorods; Reaction kinetics; Reaction mechanisms; Rechargeable batteries; Self-assembly; Single crystals; Structural hierarchy; Synergistic effect
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/c8ta00666k

In the search for high-performance anodes for next-generation lithium-ion batteries (LIBs), germanium-based compounds are recognized as one of the most promising candidates due to their extremely high theoretical capacity. In this study, a facile TEOA-assisted technology is presented to successfully fabricate Co-doped Zn2GeO4 hollow microspheres. The shell of the hollow microspheres is constructed by the self-assembly of uniform 1D single-crystalline nanorods with a length and diameter of about 2 μm and 100 nm, respectively. The reaction mechanism of the Co-doped Zn2GeO4 and the formation mechanism of the uniquely hollow structure were discussed. When used as an anode material for LIBs, the optimized Co-doped Zn2GeO4 hollow microspheres deliver a high discharge capacity of 1419 mA h g−1 and a high charge capacity of 1063 mA h g−1 for the first cycle, corresponding to a very high initial coulombic efficiency of 75%. A high capacity of 882 mA h g−1 at 1.0 A g−1 after 100 discharge–charge cycles was maintained and a capacity of 464 mA h g−1 can be retained even at a high current density of 5.0 A g−1. The remarkable electrochemical lithium storage performance can be a result of the synergistic effect of the hierarchical hollow structure and unique chemical composition. The hierarchical hollow structure allows for easy diffusion of electrolytes and shortens the pathway of Li+ transport during repeated Li+ extraction/insertion. Meanwhile, the Co doping can effectively improve charge transport for enhanced reaction kinetics.