A closed-host bi-layer dense/porous solid electrolyte interphase for enhanced lithium-metal anode stability

Abstract

Thanks to its high specific capacity and low electrochemical potential, lithium metal is an ideal anode for next-generation high-energy batteries. However, the unstable heterogeneous surface of lithium gives rise to safety and efficiency concerns that prevent it from being utilized in practical applications. In this work, the formation of a closed-host bi-layer solid electrolyte interphase (SEI) improves the stability of lithium metal anode. This is successfully realized by forming an interconnected porous LiFrich artificial SEI in contact with Li metal, and a dense, stable in-situ formed upper layer SEI. The porous layer increases the number of Li/LiF interfaces, which reduces local volume fluctuations and improves Li + diffusion along these interfaces. Additionally, the tortuous porous structure guides uniform Li + flux distribution and mechanically suppresses dendrite propagation. The dense upper layer of the SEI accomplishes a closed-host design, preventing continuous consumption of active materials. The duality of a dense top layer with porous bottom layer led to extended cycle life and improved rate performance, evidenced with symmetric cell testing, as well as full cell testing paired with sulfur and LiFePO 4 (LFP) cathodes. This work is a good example of a rational design of the SEI, based on comprehensive consideration of various critical factors to improve Li-metal anode stability, and highlights a new pathway to improve cycling and rate performances of Li metal batteries.

Prolonging the cycling lifetime of lithium metal batteries with a monolithic and inorganic-rich solid electrolyte interphase

“…4(f) and Table S2, ESI†). 28,34–47 Moreover, compared to the Li|Li cell with the blank electrolyte, the Li|Li cell with the modified electrolyte displays a much smaller overpotential at each current density ranging from 0.5 to 5 mA cm −2 , further demonstrating the greatly enhanced rate capability (Fig. 4(g)).…”

Mechanism understanding for stripping electrochemistry of Li metal anode

“…Several other models have been proposed for the SEI. "Mosaic model [192][193][194][195] " where insoluble multiphase products were deposited on Li anode randomly was defined by Peled and was used to modify his previous "2D model" (Figure 8B). Apart from the "mosaic model," another widely accepted description of SEI is "dual-layer structure model,", which has been confirmed by several experimental and theoretical investigations.…”

Long-Lifespan Lithium Metal Batteries Enabled by a Hybrid Artificial Solid Electrolyte Interface Layer

“…14−16 Another way to modify the anode is to construct an artificial SEI before assembling the battery. It has been reported that a high content of LiF, 17,18 LiCl, 19 treating the lithium metal with a fluorine-containing organic solvent, 21 and it makes a remarkable contribution in raising the performance of the lithium anode. In addition, the lithiophilic metal 22 (such as Au, 23 Ag, 24,25 and Zn 26 )-modified SEI also has positive significance for stabilizing the lithium anode, which is usually obtained by magnetron sputtering, 23,27 e-beam evaporation, 28 and other methods.…”

“…However, problems such as the continuous consumption of additives may cause the invalidation and rupture of the SEI layer during cycling, further escalating the failure of the battery. − Another way to modify the anode is to construct an artificial SEI before assembling the battery. It has been reported that a high content of LiF, , LiCl, and Li 3 N in the SEI can play key roles in inhibiting the growth of lithium dendrites. For instance, the LiF-containing modified SEI layer can be obtained through treating the lithium metal with a fluorine-containing organic solvent, and it makes a remarkable contribution in raising the performance of the lithium anode.…”