In situ investigations of the degradation of intercalation batteries and their modelling

Prof. Dr. H. Ehrenberg (Div. Structure Science)
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The aim of this project is to clarify the working principles and degradation mechanisms of cathode materials for Li-ion batteries in order to make better batteries possible, especially for high energy-density applications (e. g. portable devices like cell phones or notebooks). The main focus is on Li(Ni, Co, Mn)O2 materials which are derived from the to date commercially commonly used LiCoO2. So far, Li(Ni, Co)O2 was is the centre of our interest. But, as it is pointed out by recent work, the additional introduction of manganese into the structure is required to fulfil the safety precautions in the charged state. Based on the methods applied to the quasi-binary system LiNiO2-LiCoO2 – especially the in situ structure investigations using synchrotron radiation – the studies will be extended on the quasi-ternary system Li(Ni, Co, Mn)O2, which in the meantime has become technically more relevant. Because of the great success of the in situ experiments with synchrotron radiation, neutron radiation will now be used for these experiments, too. Neutron diffraction offers qualitatively new, additional insights because of the high scattering power of lithium and oxygen and the possibility to distinguish between the transition metals. Investigations with impedance spectroscopy pointed out the importance of interface phenomena. So, the project will also be focused on investigations of the interface between cathode material and the electrolyte for different charging and degradation states, respectively.