Role of Interfacial Defects on Electro–Chemo–Mechanical Failure of Solid‐State Electrolyte

Abstract

High‐stress field generated by electroplating of lithium (Li) in pre‐existing defects is the main reason for mechanical failure of solid‐state electrolyte because it drives crack propagation in electrolyte, followed by Li filament growth inside and even internal short‐circuit if the filament reaches another electrode. To understand the role of interfacial defects on mechanical failure of solid‐state electrolyte, an electro–chemo–mechanical model is built to visualize distribution of stress, relative damage, and crack formation during electrochemical plating of Li in defects. Geometry of interfacial defect is found as dominating factor for concentration of local stress field while semi‐sphere defect delivers less accumulation of damage at initial stage and the longest failure time for disintegration of electrolyte. Aspect ratio, as a key geometric parameter of defect, is investigated to reveal its impact on failure of electrolyte. Pyramidic defect with low aspect ratio of 0.2–0.5 shows branched region of damage near interface, probably causing surface pulverization of solid‐state electrolyte, whereas high aspect ratio over 3.0 will trigger accumulation of damage in bulk electrolyte. The correction between interfacial defect and electro–chemo–mechanical failure of solid‐state electrolyte is expected to provide insightful guidelines for interface design in high‐power‐density solid‐state Li metal batteries.

Correlating the Microstructure and Current Density of the Li/Garnet Interface

“…For example, Ning et al. show that when the current exceeds a critical value, fracture initiation arises from the Li deposition side into subsurface pores, by means of microcracks that connect the preexisting pores near the interface, and the crack front propagates ahead of Li. , Xiong et al publish similar results in LAGP, where the high-stress field generated by electroplating Li in preexisting defects is the main cause of mechanical failure in solid electrolytes, as it drives crack propagation in the electrolyte . Based on the XCT test results, a schematic that describes the electrochemical process of the failure mechanism of LSV is proposed, as shown in Figure c.…”

“…16,41 Xiong et al publish similar results in LAGP, where the highstress field generated by electroplating Li in preexisting defects is the main cause of mechanical failure in solid electrolytes, as it drives crack propagation in the electrolyte. 42 Based on the XCT test results, a schematic that describes the electrochemical process of the failure mechanism of LSV is proposed, as shown in Figure 2c. The applied bias voltage triggers lithium deposition on the low potential side of the cell and lithium stripping on the high potential side.…”

Optimizing Li1.3Al0.3Ti1.7(PO4)3 Particle Sizes toward High Ionic Conductivity

“…This circuit contained a single resistance R 1 describing the bulk ion transport in the grains. The grain boundary properties are represented by a parallel combination of a resistance R 2 and a constant-phase element CPE 1 . ,,,− Finally, a constant-phase element CPE 2 represented the electrode polarization. The equivalent circuit fit well for the semicircle at high frequency while imperfectly fitting the line at low frequency.…”

Composite polymer electrolytes incorporating two-dimensional metal–organic frameworks for ultralong cycling in solid-state lithium batteries

“…The enhanced mechanical strength of the 8% CPL could be attributed to the fact that CMS, as a crosslinking center, could connect the PVDF grains, increasing the electrolyte density, and inhibiting the relative slippage of the polymer under external force, avoiding the “extreme effect” of electrolyte interface defects, which could otherwise potentially lead to polymer electrolyte failure during the Li + -plating process. 40,41 As a result of its enhanced mechanical strength and excellent stretchability, 8% CPL was able to withstand the huge volume variations and inhibit the growth of Li dendrites during repeated Li-plating/stripping cycles.…”