Molecular Insights into the Structure and Property Variation of the Pressure-Induced Solid Electrolyte Interphase on a Lithium Metal Anode

Abstract

Solid electrolyte interphase (SEI) is regarded as the key to developing stable and long-cycling lithium metal batteries (LMBs). The inevitable stress caused by the Li–metal anode expansion/contraction and the battery encapsulation is crucial to the SEI growth and properties. Herein, we perform reactive force field (ReaxFF) molecular dynamics simulations to investigate the structure and property variation of the pressure-induced SEI. The pressure boosts the SEI structure delamination and reduces the porosity based on the quantitative analysis of the charge spectrum and porous structure, which contributes to the formation of a thin and dense SEI. Meanwhile, the phase diagram combined with the pressure and salt concentration effects is established to obtain the proper trade-off between SEI mechanical and transport properties, demonstrating that the Li+ diffusion coefficients of the pressure-induced SEI can be improved by the high salt concentration when Young’s modulus increases at the same time. The findings not only provide molecular insights into the SEI structure variation but also offer guidance and directions for optimizing the pressure-induced SEI property toward high-performance LMBs.

Eco‐Friendly Tetrahydropyran Enables Weakly Solvating “4S” Electrolytes for Lithium‐Metal Batteries

“…[35] The Connolly method can be employed to ana-lyze the porous structure of SEI quantitatively. [36] Here, molecular dynamics (MD) using ReaxFF is performed to simulate the dynamic formation process of SEI of the four "4S" electrolytes (Figure 4a). The highly reactive Li metal reacts with electrolyte and triggers the SEI formation.…”

Correlating the Potential-Holding Formation Protocol of Solid–Electrolyte Interphases with Improving Calendar Aging on Lithium Metal Anode

“…Meanwhile, according to the discharge curve, the cell without calendar aging has a larger reversible capacity than the cell aged for 24 h. Notably, the disparity in ΔCE of different electrolytes indicates that SEI chemistry plays a significant role in calendar aging. As the SEI growth experiences certain self-limitation, , it is considerable that another factor affecting chemical corrosion is the surface area of the freshly exposed Li during Li plating. Owing to the dependence of the exposed Li on the capacity, ΔCE for the deposited Li capacity of 1, 2, and 4 mAh cm –2 in the ether-based electrolyte is measured to crudely estimate the influence of the newly exposed Li on the calendar aging (the right subfigure in Figure a, Figures S1a and S2).…”