LiAlyCo1-yO2 powders were synthesized by the sol-gel process using acrylic acid as a chelating agent. The X-ray diffraction pattern for LiAl0.25Co0.75O2 powders calcined at 600°C or above shows that these materials have a well-developed layered HT-LiCoO2 structure. The capacity fading of the gel-derived LiAl0.25Co0.75O2 samples greatly decreased at lower temperatures. Galvanostatic cycling for the gel-derived LiAl0.25CO0.75O2 samples calcined at various temperatures indicates that electrodes calcined at 600°C show enhancement in capacity and cyclability. The variations in the local structures with Li deintercalation and cycling process of LiAl0.25Co0.75O2 were investigated as a function of calcination temperature using X-ray absorption spectroscopic technique. X-ray absorption near-edge structure and extended X-ray absorption fine structure results for LiAl0.25Co0.75O2 synthesized at 600 and 800°C during the charging and cycling process revealed that the large capacity fading of LiAl0.25Co0.75O2 synthesized at a higher temperature is strongly related to the remaining Co4+ ions and the local structure distortion.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry