In the mosaic structure, inorganic nanoparticles are randomly distributed in the organic matrix. Accordingly, two distinct SEI structures are currently recognized, mosaic and multilayer structures 24, 35, 37. Recently, cryo-electron microscopy has characterized SEI structures at the atomic scale 35, 36. Solid-electrolyte interphase (SEI) formed at the electrode-electrolyte interface has been considered the most important factor for regulating the Li plating morphology. This anion-dominated solvation structure facilitates the formation of denser inorganic-rich interphase layer to passivate Li metal 31, 34. Essentially, these strategies can increase the proportion of anions in the solvation sheath while decreasing the relative proportion of solvents. Currently, numerous advanced strategies are used to modulate the electrolyte solvation structure to stabilize both Li metal anode and high-voltage cathodes, such as high-concentration electrolytes (HCEs) 14, 15, 16, 17, 18, 19, 20, localized high-concentration electrolytes (LHCEs) 21, 22, 23, 24, 25, fluorinated solvents 26, 27, 28, 29, 30, 31, 32, highly sterically hindered solvents 33 and so on. The electrolyte solvation structure is an accessible and widely used descriptor to evaluate Li metal compatibility of electrolytes. Many descriptors are identified to be essential for modulating the Li deposition morphologies during the Li nucleation and growth process, including electrolyte solvation structure 7, 8, substrate effect 9, ionic diffusion 10, temperature 11, 12, pressure 13, etc. However, the origin of Li dendrite growth and the rational design of Li deposition morphologies are still mysterious and elusive so far. 6 plays a vital role in improving the reversibility and CE of Li metal plating/stripping. Therefore, the regulation of Li deposition morphologies, such as dendritic Li, mossy Li, granular Li, spherical Li, columnar Li, etc. The dendritic growth of Li metal and the stripping inhomogeneity tend to form inactive Li (dead Li), leading to low Coulombic efficiency (CE) and failure of the battery, as well as serious safety issues 4, 5. However, compared to traditional intercalation graphite anodes, Li metal anodes suffer from notorious dendrite growth issues and continuous side reactions during charging and discharging processes 3. Lithium (Li) metal is considered as an ultimate anode material due to its ultrahigh specific capacity (3860 mAh g −1) and lowest standard electrode potential (−3.04 V) 1, 2, 3. These results are helpful to tackle the long-standing question on the origin of lithium dendrite formation and guide the rational design of high-performance electrolytes for advanced lithium metal batteries. On the contrary, solvent-dominated solvation structure in the low concentration electrolytes tends to exacerbate the solvolysis process, forming organic-rich mosaic SEI with low interface energy, which leads to aggregated whisker-like nucleation and growth. It is observed that, in the high concentration electrolytes, concentrated Li + and anion-dominated solvation structure initiate the uniform Li nucleation kinetically and favor the decomposition of anions rather than solvents, resulting in inorganic-rich amorphous SEI with high interface energy, which thermodynamically facilitates the formation of granular Li. The mechanism of lithium deposition is thoroughly investigated using cryo-electron microscopy characterizations and computational simulations. Herein, we use a single-salt and single-solvent model electrolyte system to systematically study the correlation between the electrolyte solvation structure, SEI formation process and lithium deposition morphology. However, the link between the electrolyte solvation structure and SEI composition and its implications on lithium morphology evolution are poorly understood. The electrolyte solvation structure and the solid-electrolyte interphase (SEI) formation are critical to dictate the morphology of lithium deposition in organic electrolytes.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |