A combined electrochemical and microscopical analysis on the effect of laser structuring on Li plating of graphite anodes for lithium-ion batteries

Li plating on the anode is the predominant ageing effect that can occur when a lithium-ion battery is charged with high current rates or subjected to cyclic long-term tests, especially at low temperatures. Several studies report reduced Li plating of structured anodes during cyclic ageing. In this study, a closer look into Li plating generation is taken by single charging of fresh cells. Several graphite anodes with an area capacity of 3.0 mAh/cm 2 are investigated, both, standard calendered anodes as well as anodes with superficial laser modification (2D) and hole patterning (3D). Thereby, typical Li plating features in the charging and relaxation voltage curves are correlated with subsequently conducted microstructural analysis under Ar atmosphere by means of optical microscopy. First, a series of anodes with different densities (1.6–1.2 g/cm 3 ) were investigated. Based on that, anodes with a density of 1.3 g/cm 3 were selected for further studies including laser treatment. When the reference anode is charged at 1C to 80 % SoC, Li plating occurs, which is significantly reduced by the superficial treatment and even avoided by hole patterning. 2C charging leads to Li plating for all anode types with lower extend for the structured ones. However, the roughened surface due to the quasi 2D approach seems to hinder re-intercalation and dissolution of the plated Li. Overall, the hole patterned anode shows the lowest intensity of Li plating, which, however occurs preferentially at the hole edges. • The effect of structuring graphite anodes on susceptibility to Li-plating is elucidated. • Different types of laser processing are compared to each other. • At 1C charging, laser surface treatment reduces- and hole patterning avoids plating. • Voltage profiles of charging, relaxation and discharging determine Li plating. • Microscopic images at different charge states are correlated to voltage profiles.