Solid Electrolyte Bimodal Grain Structures for Improved Cycling Performance

Abstract

The application of solid‐state electrolytes in Li batteries has been hampered by the occurrence of Li‐dendrite‐caused short circuits. To avoid cell failure, the electrolytes can only be stressed with rather low current densities, severely restricting their performance. Since grain size and pore distributions significantly affect dendrite growth in ceramic electrolytes like Li7La3Zr2O12 and its variants, here we have proposed a “detour and buffer” strategy to bring the superiority of both coarse and fine grains into play. To validate the mechanism, a coarse/fine bimodal grain microstructure was obtained by seeding unpulverized large particles in the green body. The rearrangement of coarse grains and fine pores was fine‐tuned through changing the ratio of pulverized and unpulverized powders. The optimized bimodal microstructure, obtained when the two powders are equally mixed, allowed, without extra interface decoration, cycling for over 2000 h as the current density was increased from 1.0 mA·cm−2 gradually up to 2.0 mA·cm−2. The “detour and buffer” effects was confirmed from postmortem analysis. The complex grain boundaries formed by fine grains discourage the direct infiltration of Li. Simultaneously, the coarse grains further increase the tortuosity of the Li path. Our study sheds light on the microstructure optimization for the polycrystalline solid‐state electrolytes.This article is protected by copyright. All rights reserved

Review on Interface Issues between a Garnet Li7La3Zr2O12 Solid Electrolyte and Li Anode: Advances and Perspectives

“…Based on this theory, optimizing the grain boundaries of LLZO by increasing LLZO density to reduce the loose grain boundary gaps emerges as an effective strategy for inhibiting lithium dendrites. In addition to optimizing LLZO grain boundaries, Jia et al 118 optimized the grain size of LLZO. By controlling the formation of coarse and fine LLZO grains, they prepared a mixed-size grain LLZO (panels d and e of Figure 8).…”

“…(d) Schematic diagram of LLZO with coarse grains and (e) fine grains. (f) Principle schematic of lithium dendrite optimization in mixed-size grain LLZO . Reproduced with permission from ref .…”

“…(f) Principle schematic of lithium dendrite optimization in mixed-size grain LLZO . Reproduced with permission from ref . Copyright 2024 Wiley-VCH.…”

A comprehensive review on liquid electrolyte design for low-temperature lithium/sodium metal batteries

“…With the development of society and the rising popularity of electric vehicles (EVs), the demand for high energy density batteries is becoming increasingly urgent. 1–4 Furthermore, the energy density of graphite anodes in lithium-ion batteries (LIBs) has approached its limit, leading to a bottleneck in development. 5–8 Therefore, there is an urgent need to search for new anode materials or battery systems.…”