Die Synthese des Verbundwerkstoffes Lithiumeisenphosphat-Kohlenstoff durch Ultraschallsprühpyrolyse
Albrecht Schwinger
This thesis presents the results of the investigation of the synthesis of the compound material Lithium-iron-phosphate-carbon (LiFePO4/C) as a core shell material in the ultrasonic spray pyrolysis (USP).
LiFePO4/C is a promising cathode material for Li-ion-batteries, because of its thermochemical stability, high energy density, cell voltage and cycle stability. The conductivity of LiFePO4/C is with 10-9 S cm-1 a restrictive parameter. It is possible to lift it up to 10-3 S cm-1 with the help of carbon.
The motivation of this thesis is to synthesize core shell particles with LiFePO4 in the core and C in the shell in one process step in the USP. Ultrasound forms the precursor to a spray. After this the spray transforms to LiFePO4/C in a wall heated reactor tube. The purity of the product powder is proved with the help of X-ray-diffraction (XRD).The Differential Thermal Analysis and the thermogravimetry (DTA/TG) makes the steps of the pyrolysis process visible. Furthermore, investigations to the thermal transfer and the residence time are performed. The analysis of the droplet size and the particle size are investigated with laser diffraction. The morphology is investigated with TEM and EDX. These results answers the question of the influences of the different parameters contributing to the core shell synthesis.
A successful synthesis of defined core shell particles is done by employing optimized process parameters. For the evaluation of the core shell quality a CS-factor is developed.
Li(NiMnCo)0,33O2 is synthesized to show the applicability of the USP for different cathode materials.
