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Thermodynamics of New Electrode Materials for Li-Ion-Batteries


Li-Ion batteries are well recognized as a possible and efficient way to store electric energy. For use applications, however, these batteries have to meet several design criteria, such as number of charge/discharge cycles, energy density and safety. The latter is one of the crucial requirements that have so far prevented the wide spread use of these batteries, since for instance moisture will lead to explosions (thermal runaway). However the knowledge of basic thermodynamic data concerning the battery relevant systems is very weak. This knowledge is a necessary precondition for advanced materials design based on thermodynamic modeling. The thermodynamic data which are governing a phase diagram can also be directly linked to cell potentials or battery capacities. This comprises also the design of new and advanced materials for achieving higher performances of the devices.

For modeling a battery system and for computational material design, information on thermodynamic properties is required.  Experimental investigations using Knudsen Effusion Mass spectrometry and coulometric titration were performed to obtain thermodynamic activities, ΔH- and ΔG-values. Together with ab-initio simulations and experimental phase diagram information these data are necessary to create  consistent thermodynamic descriptions of the relevant systems using the CALPHAD method that can also be used for further simulations (e.g.phase field modeling) in the future.

Charge and Discharge of a Li-batterieCharge and Discharge of a Li-batterie

Schematic of phase diagram determinationSchematic of phase diagram determination