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MM: Fachverband Metall- und Materialphysik

MM 5: Functional Materials - Battery Materials I

MM 5.1: Vortrag

Montag, 11. März 2013, 10:15–10:30, H26

Charge Transfer Reactions at Electrode Materials for Lithium Ion Batteries — •Fabian Wunde, Frank Berkemeier, and Guido Schmitz — Institut für Materialphysik, Universität Münster

Powerful Lithium Ion Batteries on the one hand have to provide high energy densities, and on the other hand this energy has to be available in short period of time, i.e. they have to be capable of high charge/discharge rates. In general, these high charge/discharge rates result in both, a capacity loss and in large overpotentials. Since the hopping rate of lithium atoms, which are passing the interface between the electrode and the ion conductor, is determined by an activation energy, an external overpotential will increase the number of successful lithium transitions. In our work we studied in detail the overpotentials of ion-beam-sputtered LiFePO4 thin films, which serve as a model system. By the use of cyclic voltammetry, a linear relationship between the scan rate and the measured overpotential is observed. Solving the Butler-Vollmer equation under linear sweep boundary conditions confirms this linear behavior and finally allows us to measure the hopping rate of lithium in case of LiFePO4.