Lithium-rich, layered composites of xLi2MnO3· (1-x). Li(Ni1/3Mn1/3Co1/3)O2 were synthesized via spray pyrolysis to identify the chemistry yielding optimal electrochemical performance for materials produced by this method. The x values selected for optimization were x = 0.3, 0.5, 0.7, equivalent to Li 1.14Mn0.46Ni0.2Co0.2O2, Li1.2Mn0.54Ni0.13Co0.13O 2 and Li1.26Mn0.6Ni0.07Co 0.07O2, respectively. The materials were annealed at 850°C or 900°C for 2 hours, and then tested in coin cells. Li 1.2Mn0.54Ni0.13Co0.13O2 annealed at 900°C displayed the best electrochemical performance with excellent capacity retention, displaying a reversible capacity of 236 mAhg ?1 after 100 cycles when cycled between 2.0-4.8 V at C/10 rate, where 1C = 280 mAg?1. The cycling profiles display voltage fade, presumably due to a layered-spinel phase transformation. The synthesis method leads to high purity and excellent uniformity at the nanoscale, and the materials have less voltage fade compared to similar materials produced by co-precipitation. Voltage fade is more pronounced when the upper cut-off voltage is 4.8 V, as opposed to 4.6 V. A decrease in the Li2MnO3 content of the material reduces voltage fade, such that x = 0.3 (or Li 1.14Mn0.46Ni0.2Co0.2O2) shows the best structural stability over cycling.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Materials Chemistry
- Surfaces, Coatings and Films
- Renewable Energy, Sustainability and the Environment
- Condensed Matter Physics