Petr Vyroubal

The influence of used precursors on the properties of high-voltage cathode materials

This article deals with the influence of precursors used in the high-voltage cathode material LiNi0.5Mn1.5O4 based on the LiMn2O4 material on its properties. Precursors with various sizes of particles were used for making the cathode material. Consequently, its influence on the stability during cycling, change of load, and the influence of higher temperatures during cycling were investigated. Produced materials were further analyzed to discover the influence of the change of the used precursor on the structure of the cathode material. The structure of the material deposited on Al foil was investigated by atomic force microscopy (AFM), and also X-ray photoelectron spectroscopy (XPS) analysis was performed. The materials were then observed by SEM and analyzed by the EDAX method. The results show that smaller particle size enhances the properties of cathode material both in the stability during cycling and higher capacity and also the potential under higher load.

Effect of negative potential on the extent of PID degradation in photovoltaic power plant in a real operation mode

Abstract This paper deals with Potential Induced Degradation (PID) of p-type monocrystalline PV modules (Evergreen) from a photovoltaic power plant that has been in operation mode for 7 years. Within the PV module affected by the PID degradation, the effect of the electric field on individual PV cells is studied. The distribution of the electric field was simulated by SolidWorks software. The results show a random distribution of affected PV cells not related to the size and distribution of the electric field intensity. Furthermore, the dependencies of negative voltage potential on the range of PID degradation of individual PV modules located in the negative pole of the PV string is made. From measured current voltage characteristics (measured at STC), it is evident that the value of negative voltage potential is not directly proportional to the PID occurrence. These results are supplemented by electroluminescence images which confirm this finding.

Finite Element Model of Discharging and Temperature Field of the Lithium Ion Battery

This paper deals with a possibility of numerical simulation of temperature profile by discharging of li-ion battery. The numerical model was prepared using SolidWorks and ANSYS Fluent software and it was compared by real measurement using electrical impedance spectroscopy and thermocamera imaging. The simulation was realised as transient real-time.