Batteries in Application

Battery analysis is carried out mainly by electrochemical measurements, such as dU/dQ plots, capacity fade, voltage relaxation curves, and Arrhenius plots. Especially, Arrhenius plots of aging rates can help finding optima for cycle life as well as temperature dependent transitions of aging mechanisms. Examples for such temperature dependent aging mechanisms are SEI growth (by decomposition of electrolyte on the negative electrode) at high temperatures and Lithium plating on negative electrodes at low temperatures. Especially, Li plating is a severe aging mechanism which can degrade safety, and must therefore be hindered. In addition, materials from aged cells are being studied in collaboration with other groups at HIU, ZSW and other institutes.

The work focusses on state-of-the-art chemistries in commercially available cells, e.g. Si/graphite negative electrodes and Ni-rich positive electrodes in case of high-energy cells or graphite negative electrodes and LiFePO₄ positive electrodes in case of high-power cells.