This work was funded by Junta de Andalucía (Group FQM-175) and Spain's Ministry of Education (Project MAT2002-04477-C02-02).
Crystallinity Control of a Nanostructured LiNi0.5Mn1.5O4 Spinel via Polymer-Assisted Synthesis: A Method for Improving Its Rate Capability and Performance in 5 V Lithium Batteries†
Article first published online: 16 AUG 2006
Copyright © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Advanced Functional Materials
Volume 16, Issue 14, pages 1904–1912, September, 2006
How to Cite
Arrebola, J. C., Caballero, A., Cruz, M., Hernán, L., Morales, J. and Castellón, E. R. (2006), Crystallinity Control of a Nanostructured LiNi0.5Mn1.5O4 Spinel via Polymer-Assisted Synthesis: A Method for Improving Its Rate Capability and Performance in 5 V Lithium Batteries. Adv. Funct. Mater., 16: 1904–1912. doi: 10.1002/adfm.200500892
- Issue published online: 12 SEP 2006
- Article first published online: 16 AUG 2006
- Manuscript Revised: 14 FEB 2006
- Manuscript Received: 12 DEC 2005
- Junta de Andalucía. Grant Number: FQM-175
- Spain's Ministry of Education. Grant Number: MAT2002-04477-C02-02
- Lithium-ion batteries;
Li–Ni–Mn spinels of nominal composition LiNi0.5Mn1.5O4, which are functional materials for electrodes in high-voltage lithium batteries, are prepared by thermal decomposition of mixed nanocrystalline oxalates obtained by grinding hydrated salts and oxalic acid in the presence of polyethyleneglycol 400. Their structure, microstructure, and texture are established from combined X-ray photoelectron spectroscopy (XPS), X-ray diffraction, transmission electron microscopy (TEM), IR spectroscopy, and N2 absorption measurements. The polymer tailors the shape of particles, which adopt a nanorodlike morphology at low temperatures (400 °C). In fact, the nanorods consist of highly distorted oriented nanocrystals connected by a polymer-based film as inferred from IR and XPS spectra. The electrochemical properties of spinels in this peculiar form are quite poor, mainly as a result of the high microstrain content of their nanocrystals. Raising the temperature up to 800 °C partially destroys the nanorods, which become highly crystalline nanoparticles approximately 80 nm in size. At this temperature, the polymer facilitates crystal growth; this leads to highly crystalline polyhedral nanoparticles as revealed from TEM images and microstrain data. Following functionalization as a cathode in lithium cells, this material exhibits a very good rate capability, coulombic efficiency, and capacity retention even upon cycling at voltages as high as 5 V. Moreover, it withstands fast-charge–slow-discharge processes, which is an important cycle-life-related property for commercial batteries.