Fig 1

TEM images of the SEI film onto the surface of (a) the Li4Ti5O12 and (b) the multi-walled carbon nanotube anode after discharging to below 0 V; (c) TEM image of the SEI film on the surface of the LiCoO2 cathode after 10 cycles 16. Adapted from Chemical Industry publisher."

Fig 2

Scheme of SEI formation condition in a liquid electrolyte 17. Adapted from American Chemical Society publisher."

Fig 3

Schematic diagrams of (a) Peled SEI film 19, (b) Mosaic SEI film 21, (c) double-layer SEI film 22, (d) multilayer SEI film 23, and (e) coulomb-reaction SEI film 24. Adapted from American Chemical Society and Elsevier publishers."

Fig 4

(a) Schematic of high-dimensional and low-dimensional phases 27; (b) movement of one atom from the bulk phase to the surface 27; potential energy surfaces of (c) a Li adatom on Li(001) and (d) a Mg adatom on Mg(0001) 28. The contour spacing in (c) is 0.05 eV while it is 0.02 eV in (d).Adapted from Elsevier and American Institute of Physics publishers."

Fig 5

(a) Scheme of a spherical cap-shaped nucleus plated on a flat substrate immersed in an electrolyte, and regimes of behavior during the initial stages of nucleation and growth of Li dendrites 29; (b) voltage profiles of galvanostatic Li deposition on a copper and gold substrate at 10 μA·cm-2 29; (c) schematics of patterned Li deposition (Cu: blue, Au: pink) and SEM images of a gold strip array with various separations before (top) and after (bottom) Li deposition 30. Adapted from Electrochemical Society and Springer Nature publishers."

Fig 6

(a) Schematic of symmetrical battery 35; (b) profiles of ion concentration and electrostatic potential resulting from numerical simulation in the hypothetical case of uniform deposition with negligible growth of the cathode 34; (c) mechanism of lithium dendrite growth with the change of concentration polarization 36; (d) voltage curve diagram when short circuit occurs 35; (e) voltage curve of capillary simulated battery under different deposition current densities, and (f) lithium dendrite growth state 36. Adapted from American Physical Society, Elsevier and Royal Society of Chemistry publishers."

Fig 7

(a) The wave front corresponds to amorphization of SEI dendrites by Li deposition as is highlighted 37; (b) in situ TEM observation of a single Li whisker growth under -6.0 V vs. LCO biasing; (c) change in the length and the width of the lithium whisker; (d) schematic illustration explaining root growth mechanism of lithium whiskers 38. Adapted from Royal Society of Chemistry and Elsevier publishers."

Fig 8

(a) Schematic diagram of the dead Li layer formation onto the Li metal anode surface; (b) relationship between the thickness of the dead Li layer and the voltage curve of the Li intercalation; (c) cycle-to-cycle evolution of voltage tails 47. Adapted from Elsevier publisher."

Fig 9

(a) Schematic diagram of the in situ optical microscopy; (b) in situ optical microscopy images of CFCu-Li anode 50; (c) in situ optical microscopy images of CFZO-Li anode 51. Adapted from Elsevier publisher."

Fig 10

The in situ observation of (a) electrode surface evolution under the low and high current density 52, (b) Li plating on the Li-B-Mg composite and pure Li foil 53, (c) lithium deposition process in FEC/LiNO3 and EC/DEC electrolytes 54 and (d) the electrolyte-electrode interface on lithium metal anode 7. Adapted from American Association for the Advancement of Science, Wiley and Elsevier publishers."

Fig 11

(a) Schematic diagram of the in situ SEM and the images of the electrode cycling in the ethers-based electrolyte with LiNO3 55; (b) cross section view in situ SEM images of lithium metal 56; (c) series of cross-sectional SEM images for a NMC/LiPS/Li ASSB sample and schematics for the volume change of the Li metal anode 57; (d) configuration of lithium ion microcell with three electrodes for electrochemical measurements and in situ HAADF-STEM images of Au lithiation 58. Adapted from Wiley, American Chemical Society and Royal Society of Chemistry publishers."

Fig 12

(a) Schematic diagram of the in situ AFM and the corresponding images of the Li electrode surface under different conditions 59; (b) in situ AFM images of electrode surface during the Li deposition at EC/DMC and FEC/DMC systems 60; (c) in situ AFM and adhesion mapping images of the electrode during the Li plating 61; (d) application of in situ AFM-ETEM technology in the study of lithium dendrite growth 62. Adapted from Wiley, American Chemical Society and Springer Nature publishers."

Fig 13

(a) In operando X-ray tomography characterization of the symmetric cell using Li-Al alloy electrode and corresponding 3D rendering of three samples 63; (b) schematic diagram of the research soild electrolyte/Li metal interface via in situ XPS technique, and the change of Ti 2p XPS of LLTO during the Li deposition 64; (c) in situ XRD images of GF-LiF-Li and bare Li standing in ambient atmosphere 65; (d) in situ Raman spectrum of the L-DG host during the Li plaing and stripping 66. Adapted from American Chemical Society, Elsevier and Springer Nature publishers."

Fig 14

(a) Preserving and stabilizing Li metal by cryo-EM 68; (b) cryo-TEM and ordinary TEM images of Li dendrite, and the cryo-SEM images of different cross section of Li dendrite 69; (c) low magnification, bright-field and atomic-resolution of EDLi and SEI formed in VC-containing electrolyte 66; (d) cryo-STEM and EELS images of type Ⅰ and Ⅱ dendrite 71; (e) cryo-EM images and nano-structure diagrams of dendrites growth at 20 and 60 ℃ with the 1 mol·L-1 LiTFSI salt 72. Adapted from Elsevier, American Association for the Advancement of Science, American Chemical Society and Springer Nature publishers."

Fig 15

(a) Schematic of the experimental set-up for operando NDP and time-resolved lithium concentration profiles for Li/LLZO/Cu cell 74; (b) operando NDP measurements of Li metal electrode during the cycling 75; (c) in situ NDP measurement of a Li/garnet/CNT asymmetric cell 76; (d) experimental setup for the in situ NDP measurements and in situ NDP spectra 77. Adapted from Springer Nature, American Chemical Society and Elsevier publishers."

Fig 16

(a) Illustration of the symmetric 6Li foil/composite electrolyte/6Li foil battery, possible Li+ transport pathways, comparison of the 6Li NMR spectra before (pristine) and after (cycled) cycling, and quantitative analysis of 6Li amount 78; (b) one-pulse static 7Li and 17O NMR spectra of the discharged cathode from cell A and cell B 79; (c) 17O, 1H and 13C Hahn echo spectra of cathodes at different states of charge 80. Adapted from Wiley and American Chemical Society publishers."