Lithium Overpotential and Dendrite Formation
Different types of lithium deposition morphologies are known: needle-like, mossy and granular lithium.[4-5] The needle-like lithium (Figure 1b), with its high surface area, has most detrimental impact on cycling and safety performance of lithium metal cells. A novel method to monitor the changes of the surface morphology during cycling is the continuous observation of the development of lithium overpotential during cycling (Figure 1a).
In this work, we will explain how the overpotential occurs and how the lithium overpotentials correlate with the change of the surface structure. Furthermore, it is demonstrated that by increasing the surface area of the lithium metal electrodes and, in parallel, using a highly concentrated electrolyte, the formation of dendritic lithium can be reduced.
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