In-situ XRD investigation of insertion and extraction mechanisms of Lithium in nanoscaled gold thin films

Currently lithium ion batteries (LIBs) have applications in a wide range of consumer electronics. The requirements of future electromobility and other high power applications in capacity, stability, safety, and lifetime call for considerable improvements of the performance. For achieving substantial advances towards this goal a fundamental atomic-scale insight into the mechanisms during charging and discharging will be highly beneficial. Applying in-situ techniques is often inevitable due to the high reactivity and since also metastable phases are in some cases involved [1,2]. Beyond the classical carbon based anode materials currently metals and silicon are investigated. In these materials Li can be stored by forming Li alloys. The related uptake capability for Li is here considerably higher than for carbon based electrodes [3]. However charging results in a high volume change of these materials leading to new problems due to the high stress induced. The consequence is partial cracking of the electrode materials, loss of contact to the current collector material and a relatively quick capacity loss. One approach to address these problems is to nanostructure the active material. Morphologies like thin films or nanowires offer more space and freedom to compensate the volume changes during battery cycling.