An investigation into the temperature phase transitions of synthesized materials with Al- and Mg-doped lithium manganese oxide spinels by in situ powder X-ray diffraction

Abstract

Three spinel materials were prepared and characterized by in situ powder X-ray diffraction (PXRD) techniques to track their phase changes that occurred in the typical batch synthesis process from a sol–gel mixture to the final crystalline spinel oxide. The materials were also characterized by thermal gravimetric analysis, whereby the materials decomposition mechanisms that were observed as the precursor, was gradually heated to the final oxide. The results showed that all the materials achieved their total weight loss at about 400 °C. The in situ PXRD analysis showed the progression of the phase transitions where certain of the materials changed from a crystalline precursor to an amorphous intermediate phase and finally to the spinel cathode oxide (Li1.03Mg0.2Mn1.77O4). For other materials, the precursor would start as an amorphous phase and upon heating, convert into an impure intermediate phase (Mn2O3) before forming the final spinel oxide (Li1.03Mn1.97O4). On the other hand, the LiAl0.4Mn1.6O4 would start with an amorphous precursor, with no intermediate phases and immediately formed the final spinel oxide phase. The in situ PXRD study also showed the increases in the materials respective lattice parameters of the crystalline unit cells upon heating and the significant increases in their crystallite sizes when heated above 600 °C.

Cold Sintered LiMn2O4 for High-Rate Capability Electrodes

“…This thermal program was selected with respect to the literature for conventional sintering of LMO. 18,34,35 Cold sintering experiments were conducted in a FAST/SPS device (HP-D5, FCT Systeme, Rauenestein, Germany) using a tool with 12 mm diameter made of TZM alloy (0.50% Titanium, 0.08% Zirconium-99% Molybdenum). Graphite foil was used between the die and the punch to ensure proper thermal, mechanical and electrical contact and to protect the inner linings of the die from corrosion.…”

An investigation into the temperature phase transitions of synthesized lithium titanate materials doped with Al, Co, Ni and Mg byin situpowder X-ray diffraction

“…An in-depth knowledge of the phase transitions involved in the sol–gel synthesis would be beneficial to optimize the manufacturing process. In order to identify and understand the temperature phase transitions that the material undergoes during the calcination synthesis process, in situ powder X-ray diffraction (PXRD) was shown to be a well-suited technique to study the phase transitions of lithium manganese oxide spinel used as cathode materials in lithium-ion batteries and was employed in this study (Snyders et al ., 2016).…”