Lithium Plating on Graphite Negative Electrodes: Innovative Qualitative and Quantitative Investigation Methods

The effect of metallic lithium depositing on the negative electrode surface of a carbon-based lithium-ion battery instead of intercalating into the graphitic layers, namely lithium plating, can be assigned to charging at low temperatures and/or high currents. Cell parameters, such as performance and safety, are negatively influenced by this phenomenon. Elemental lithium deposited on the negative electrode requires more space than the intercalated compound and therefore increases the cell volume. Thus, the thickness changes during cycling can be used as a qualitative indicator for lithium plating. In this context, two different non-destructive experimental setups detecting the thickness profiles in situ are presented. Moreover, a quantitative titration technique to determine the exact amount of lithium deposited is established.