Drying influence on binder distribution in electrodes for Lithium ion batteries - Mechanistic insight into the progress of component distribution

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Properties of electrodes used in lithium-ion batteries are mainly defined by the complex micro structure of the active layer. It is defined by the local distribution of the particulate active material and functional additives throughout the film. Within the work conducted in the first funding period the influence of the parameters drying rate and drying temperature on the film structure was investigated. As a major outcome of this investigation both parameters were found to impact differently and have, therefore, to be considered separately. The results form the basis for the development of a predictive drying model that allows for description of the evolution of the component distribution and formation of the film structure. The objective of this proposal is the detailed elaboration of the film solidification mechanism. The examination of the chronological sequence of the structural development requires specific measurement techniques with a high local and chronological resolution of the distribution of single components over the film height. These techniques are not available for the drying process at relevant and defined boundary conditions. Therefore, several hypotheses concerning characteristic, intermediate film states were elaborated that will be checked up on by means of adhesive force measurements, EDS and additional methods that have been successfully applied in preliminary experiments. In addition, a novel, innovative experimental approach is applied that allows for revelation of the chronological evolution of specific film properties on the basis of the dry film properties.