Microstructure of Lithium Dendrites Revealed by Room-Temperature Electron Microscopy

Abstract

The uncontrolled deposition/dissolution process of lithium dendrites during electrochemical cycling in batteries limits the large-scale application of Li metal anodes. Investigating the microstructure of Li dendrites is a focal point. Currently, the only way to protect and observe sensitive Li dendrites is through low-temperature transmission electron microscopy (LT-TEM), whereas room-temperature characterization is still lacking. In this work, the room-temperature microstructure of Li dendrites was obtained by TEM using both vacuum- and inert-gas-transfer methods. Detailed comparison between LT- and room-temperature (RT-)­TEM characterizations was provided to show the pros and cons of each method. Especially, RT-TEM shows the advantage of flexible incorporation with multifunctional characterizations, such as 3D tomography. By using RT-TEM, microstructural evolution of Li dendrites during the electrodeposition/dissolution process, including increase of the quantity of inorganic Li2O compounds in the solid electrolyte interphase, lateral growth behavior, and two types of inactive Li, has been revealed, enriching the understanding of the structure–property relationship of Li dendrites.

Microstructure of the Li–Al–O Second Phases in Garnet Solid Electrolytes

“…Therefore, the cryogenic imaging still needs to be optimized to achieve better image quality. The situation here is similar to that which has been pointed out in our previous work on beam-sensitive lithium metals; a low temperature can better protect the structure from beam damage while side effects exist. In contrast, room-temperature imaging provides feasibility for multimodal characterizations while the dose/dose rate should be kept lower than that under the cryogenic condition.…”

Stability of solid electrolyte interphases and calendar life of lithium metal batteries

“…With a controlled electron dose rate (0.89 e À Å À2 s À1 ), Li metal and SEI layers can be imaged at room temperature. 39 In this work, in situ TEM with a very low electron dose rate (0.33 e À Å À2 s À1 ) was used to probe the Li stripping/deposition process across the SEI layer to avoid electron beam damage to Li and SEI layers at room temperature. Therefore, the electron beam damage to Li and SEI layers has been well mitigated.…”

Lithium deposition mechanism on Si and Cu substrates in the carbonate electrolyte

“…Previous studies have reported many different Li deposit morphologies: hemi-sphere, 3,4 granular, 5–7 columnar (or nanorod), 8,9 whisker (needle-like), 10,11 Eden cluster, 12 mossy (bush-like), 13 and dendrite (tree-like). 14,15 The morphology of the Li deposit governs the performance of the lithium metal anode.…”

“…To outperform a LIB in terms of energy density and cycle life (80% capacity retention at 1000th cycle), a LMB should have o3.5 Â excess of Li, 1 an anode coulombic efficiency (CE) of 499.83%, and an anode porosity of o65%. 2 Previous studies have reported many different Li deposit morphologies: hemi-sphere, 3,4 granular, [5][6][7] columnar (or nanorod), 8,9 whisker (needle-like), 10,11 Eden cluster, 12 mossy (bush-like), 13 and dendrite (tree-like). 14,15 The morphology of the Li deposit governs the performance of the lithium metal anode.…”