fig1

Figure 1. Mechanical properties of Li dendrites and bulk Li strips^[4]. (A) Schematic illustration of a Li dendrite tensile test conducted in a scanning electron microscope (SEM). (B) Stress-strain curves of a Li dendrite with the electron beam (e-beam) turned on and off during the tensile test. (C) SEM images showing the e-beam healing effect on a Li dendrite: the first fracture was completely healed after e-beam treatment, while the second fracture occurred at a different location. (D) Typical tensile test of a Li dendrite; (i) and (ii) show the SEM snapshots of the Li dendrite before and after fracture, respectively. Scale bar: 1 μm. (E) Typical stress-strain curves of the fracture test and the loading-unloading test of Li dendrites, where Young’s modulus is derived from the unloading segment. (F) Typical tensile test of a Li strip; (i) shows the typical stress-strain curve of the bulk Li strip, and (i-iv) illustrate the optical snapshots of the Li strip at different stages, as marked in (i).