Fig. 2: Selection of operando ultrasound images and electrochemical data at significant points during cycling of two pouch cells.

The tabs are located on the right side of the cell (not displayed). a, b Portray the charging procedure of cell 1. At points (1) and (2), the ultrasound images are relatively homogenous. A circular indication starts to appear at point (3) in the lower right corner. At points (4)–(6), more indications appear, which first get larger and then decrease in size shortly after the CV phase begins. c, d Display the first cycles of cell 2. While similar indications appear on the ultrasound images during charging (1)–(2), they decrease even more during discharging (3) and increase again during the next charging phase (4)–(5). After the CV phase, the indications decrease again (6). Additionally, the plating seems to appear mostly on the edges of the adhesive dots of cell 2. We refer to Supplementary Movies 1 and 2 for the videos based on all ultrasound images. Source data are provided as a Source Data file.