Fig. 1. Protection mechanism of OP-10 additive and morphology characterizations of Li deposition.

Schematic illustration of lithium deposition with and without various additives (a). In situ optical microscopy images of the Li deposition process using electrolyte without additives (b) and electrolyte with 5% OP-10 additive (c) at a current density of 4 mA cm⁻². The thickness of the Li is about 600 µm. Top-view SEM images of lithium deposition on Cu foil at 0.5 mA cm⁻² for 0.4 h without (d, e) and with OP-10 additives (f, g) (Scale bars: d 20 μm, e 10 μm, f 20 μm, g 10 μm).