Electro‐Chemo‐Mechanical Modeling of Artificial Solid Electrolyte Interphase to Enable Uniform Electrodeposition of Lithium Metal Anodes

Abstract

Nonuniform electrodeposition of lithium during charging processes is the key issue hindering development of rechargeable Li metal batteries. This deposition process is largely controlled by the solid electrolyte interphase (SEI) on the metal surface and the design of artificial SEIs is an essential pathway to regulate electrodeposition of Li. In this work, an electro‐chemo‐mechanical model is built and implemented in a phase‐field modelling to understand the correlation between the physical properties of artificial SEIs and deposition of Li. The results show that improving ionic conductivity of the SEI above a critical level can mitigate stress concentration and preferred deposition of Li. In addition, the mechanical strength of the SEI is found to also mitigate non‐uniform deposition and influence electrochemical kinetics, with a Young's modulus around 4.0 GPa being a threshold value for even deposition of Li. By comparison of the results to experimental results for artificial SEIs it is clear that the most important direction for future work is to improve the ionic conductivity without compromising mechanical strength. In addition, the findings and methodology presented here not only provide detailed guidelines for design of artificial SEI on Li‐metal anodes but also pave the way to explore strategies for regulating deposition of other metal anodes.

Transference Number Reinforced-Based Gel Copolymer Electrolyte for Dendrite-Free Lithium Metal Batteries

“…To get insight into the role of the Li + transference number in the Li plating/stripping behaviors, a finite element method (FEM) was used to investigate the Li + and electric potential in ECP-based GPE by the Butler–Volmer equation. As reported in the literature, − the growth of Li dendrites is attributed to the concentration gradient near the electrodes, caused by the competition between mass-transfer and charge-transfer processes. Specifically, the rapid depletions but not enough supplies of Li-ions on the substrate surface certainly induce the uniform Li depositions.…”

Elucidating the Role of Rational Separator Microstructures in Guiding Dendrite Growth and Reviving Dead Li

“…The maximum stress is mainly distributed in the sharp part (indicated by a white ellipse) of the SM. The maximum von Mises stress may be distributed at the root of the dendrite and bifurcation point. ,, If the dendrite root is subjected to maximum stress, the root will endure the risk of fracture, forming large blocks of dead Li, resulting in a decline in the Coulombic efficiency, which is more serious than bifurcation fracture. In all subsequent simulations, the degree of staggered overlap was considered to be γ = 0.5.…”

“…A phase-field model (PFM) is frequently used to explore the growth behavior and morphological evolution of Li dendrites. 42 Xu et al 43 and Liu et al 44 applied phase-field modeling to investigate the mass-transfer of Li-ions and the physical properties of artificial SEIs on Li deposition behavior. Liang and Chen 45 presented a nonlinear PFM for Li electrodeposition and demonstrated that the Li deposit forms a fiber-like shape and grows parallel to the direction of the electric field.…”

Two Birds with One Stone: Using Indium Oxide Surficial Modification to Tune Inner Helmholtz Plane and Regulate Nucleation for Dendrite‐free Lithium Anode

“…[4,5] Nevertheless, Li metal tends to electrodeposit in dendrite-form due to its ultrahigh exchange current density and repaid interfacial depletion of Li-ion. As a Consequence, Li dendrites lead to a series of issues, [6][7][8][9] like short circuits, serious side reactions, increasing impedance, low Coulombic efficiency, etc., which impede the practical application of Li metal batteries. [10,11] Recently, plenty of effective strategies have been proposed to suppress the growth of Li dendrites, [12] including structural and componential design of anode, [13,14] stabilization of interphase with artificial solid electrolyte interphase, [15,16] and optimization of electrolytes, [17][18][19] as well as separator modification.…”