Past colloquia and seminars


Morphology and Electrochemical properties of mesoporous Li4Ti5O12

General public Thesis defense

The development of materials with a high-energy storage capacity for energy storage is fundamental for accelerating the transition to and the use of renewable energy sources such as solar and wind energy. Currently, graphite is commonly used as anode lithium-ion batteries (LIBs) to store electrical energy. However, there is a drawback with respect to safety. The batteries lose stability over time and expand during the charging cycles. The spinel Li4Ti5O12 (LTO) material has recently been explored as a promising anode material due to its negligible volume expansion. In this research, LTO was synthesized by sol-gel chemistry: using two types of block copolymers, the molecular weight of 13.5 kg/mol and 74.5 kg/mol, to form micelles in the reaction media that are degraded during annealing and tune the porous size. Therefore, different annealing temperatures (700 and 800 _C) and time (2.5h and 4h) conditions were also investigated to tune the purity and particle size. The material synthesized at higher temperature and longer time presented higher purity (not secondary crystalline phases, e.g. TiO2) and larger particle size but lower porous surface area and electrochemical performance. Lower temperature and shorter time resulted in a smaller particle size and good purity. The LTO material produced at 700 _C, 2.5h and by BCP 74,5 kg/mol demonstrated the highest electrochemical performance. Its delivery discharge capacity was 170 (mAh/g) at 0.1C (_17.5 mA/g) and performance rate of 127 (mAh/g) at 20C (_3500 mA/g) between 1.0 and 2.5 V versus Li/Li+. However, the average particle size was about 13.7 nm and it can be decreased to further improve the (de)lithiation of Li-ions.

When? 23.11.2018 15:00 - 16:00
Where? PER 08 0.51, bâtiment de Physique
Chemin du Musée 3
1700 Fribourg
speaker Minh Tri NGUYEN
Département de Physique
Université de Fribourg
Contact Prof. Ullrich Steiner
026 300 95 03