Visualizing Lithium Dendrite Formation within Solid-State Electrolytes

Abstract

Solid-state electrolyte (SSE) is promising for application in all-solid-state lithium metal batteries because of its reliable safety and longevity. The failure of SSE to suppress dendrite formation of Li metal anodes has been conventionally explained by uneven Li deposition at Li/SSE interfaces and its subsequent dendritic growth. While Li deposition within SSE has been recently proposed as another key cause for SSE failure, little is known regarding the Li growth details inside the SSE itself. In this work, we performed in situ microscopic observation of Li deposition inside the SSE and obtained visualized evidence regarding the dynamic process of Li dendrite formation and growth. Li is seen to directly nucleate and propagate within the SSE, leading to its structural cracking. Such behavior should be caused by the presence of P- and S-based crystalline defects in Li3PS4 SSE, which is consistent with the cryo-transmission electron microscopy observations and theoretical calculations. This observation provides important insights into the growth mechanisms of Li dendrites within a working lithium battery.

In Situ Formed Ag‐Li Intermetallic Layer for Stable Cycling of All‐Solid‐State Lithium Batteries

“…At the pristine state, both cells displayed a flat and uniform SE/anode interface as identified in the XRM data. However, the Li cell exhibited the protruded matters strongly believed to be Li in the SE, as previously reported, after only 20 cycles, [12,15,49] whereas the Ag-Li cell showed wellpreserved interfacial morphology similar to that of the pristine state without any change in the ALI thickness after 50 cycles. Furthermore, even after 80 cycles, for the Ag-Li cell, the interface was stably maintained without any Li filaments or protruded Li inside the SE (Figure S14, Supporting Information).…”

“…Although Li filaments were not detected due to resolution limitations, the Li cell showed a non-uniform SE/Li interface as shown in Figure 3c, displaying protruded Li inside the SE owing to uneven Li plating or crack generation that provides additional room for Li storage during cycling. [12][13][14][15][16] In contrast, the Ag-Li cell exhibited a uniform SE/Ag-Li interface even after 30 cycles. These features were more conspicuous in the top-viewed XRM image obtained along the vertical direction (Figure 3a,d).…”

A Versatile Li6.5In0.25P0.75S5I Sulfide Electrolyte Triggered by Ultimate‐Energy Mechanical Alloying for All‐Solid‐State Lithium Metal Batteries

“…[ 1,2 ] However, the use of combustible organic electrolytes in LIBs has raised significant concerns about the safety. [ 3,4 ] In addition, the limited energy density further hinders the extensive application of LIBs. [ 5 ] All‐solid‐state Li metal batteries (ASSLMBs) have been considered as one of the most significant energy storage methods, [ 6–8 ] resulting from high energy density, the excellent safety, and ultrastable cycling performance.…”

A critical discussion on the analysis of buried interfaces in Li solid-state batteries. Ex situ and in situ/operando studies

“…OM has been mainly adapted to perform operando measurements on SSBs. 45,70,71,[71][72][73][74][75] A notable example of this approach is the study of lithiation of a graphite electrode in a graphite/LPS/InLix battery reported by Akitoshi Hayashi's group. 45 Optical mapping of a cross-section of the cell showed a gradual decrease of the degree of lithiation in the whole electrode after 4 cycles; however, the loss of capacity in Li insertion was more severe at the current collector/solid electrolyte interface.…”

“…Interestingly, a recent operando optical microscopy experiment on a NMC 622/LPS/Li battery suggests that Li plating inside the solid state electrolyte occurs before the growth of dendrites at the Li/LPS interface. 70 Please do not adjust margins…”