Stable solid electrolyte interphase (SEI) has been well established to be critical for the reversible operation of Li (ion) batteries, yet our understanding of its mechanical properties currently remains incomplete. Here, we used an electrochemical quartz crystal microbalance combined with dissipation monitoring (EQCM-D) to investigate SEI formation. By quantitatively estimating in-situ, the change in mass, shear modulus, and viscosity of the SEI, we show that the SEI formation in propylene carbonate (PC)- and ethylene carbonate/diethyl carbonate (EC/DEC)-based electrolytes involves the growth of a rigid layer followed by a viscoelastic layer, whereas a distinct "one-layer" rigid model is applicable to the SEI formulated in tetraethylene glycol dimethyl ether (TEGDME)-based electrolyte. With the continuous formation of the SEI, its shear modulus decreases accompanied by an increase in viscosity. In TEGDME, the lightest/thinnest SEI (mass lower than in PC by a factor of nine) yet having the greatest stiffness (more than five times that in PC) is obtained. We attribute this behavior to differences in the chemical composition of the SEIs, which have been revealed by tracking the mass-change-per-mole-of-electron-transferred using EQCM-D and further confirmed by X-ray photoelectron spectroscopy.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |