Insights into the Anode‐Initiated and Grain Boundary‐Initiated Mechanisms for Dendrite Formation in All‐Solid‐State Lithium Metal Batteries

Abstract

The formation of lithium dendrites severely hinders the practical application of all‐solid‐state lithium metal batteries (ASSLMBs). The conventional view is that dendrites initiate at the anode and then grow into solid electrolytes (SEs), while a recent popular opinion holds that Li+ ions can directly be reduced at grain boundaries (GBs) within electrolytes, and these internal dendrites then interconnect resulting in the short‐circuit failure. However, whether the internal GBs or the anode interface dominates the dendrite initiation is still under debate. Herein, first‐principles calculations on the representative system, Li6PS5Cl (LPSC), are performed to investigate these two dendrite initiation mechanisms. The results show that the solid electrolyte interphase (SEI) blocks the electron leakage, making the internal Li+ ions less likely to deposit. Combining ab initio molecular dynamics (AIMD) simulations with theoretical models, the critical current density (CCD) for dendrite formation at the anode interface is predicted to be much lower than at the GBs, indicating dendrites are easier to initiate at the anode. This study reveals that the dendrite formation is governed by the anode‐initiated mechanism instead of the GB‐initiated one. These findings suggest that the anode interface should be a primary concern for designing dendrite‐free batteries rather than the GBs.

Polymeric Electronic Shielding Layer Enabling Superior Dendrite Suppression for All-Solid-State Lithium Batteries

“…37 The platingstripping under high overpotential increases the possibility of electronic tunneling, and it is more likely to cause dendrite failure during the cycle. 38 Finally, inert fillers increase the hardness and strength of the SEs, potentially leading to an increase in their brittleness. 16 As stress accumulates and releases due to continuous Li deposition, it is highly likely to induce crack propagation within the SEs, accelerating the failure of cells.…”

“…Second, since inert fillers are generally electron–ion dual-insulating materials, and the addition usually exceeds 50 wt %, , the excessive addition causes a decrease in the ionic conductivities of the SEs at room temperature, which will cause a significant increase in the impedance of Li-ion migration . The plating-stripping under high overpotential increases the possibility of electronic tunneling, and it is more likely to cause dendrite failure during the cycle . Finally, inert fillers increase the hardness and strength of the SEs, potentially leading to an increase in their brittleness .…”

Nonstoichiometry Induced Amorphous Grain Boundary of Na5SmSi4O12 Solid-State Electrolyte for Long-Life Dendrite-Free Sodium Metal Battery

“…Meanwhile, pores can be generated between “unclosed” grain boundaries. Apart from suppressed ion conduction, sodium metal dendrites can easily form and grow by infiltrating the pores, the grain boundaries, and the inherent defects in the ceramic, leading to short-circuits and cell failure …”