Amorphous Phase Induced Lithium Dendrite Suppression in Glass-Ceramic Garnet-Type Solid Electrolytes

Lithium metal-based solid-state batteries (SSBs) haveattractedmuch attention due to their potentially higher energy densities andimproved safety compared with lithium-ion batteries. One of the mostpromising solid electrolytes, garnet-type Li7La3Zr2O12 (LLZO), has been investigated intensivelyin recent years. It enables the use of a lithium metal anode, butits application is still challenging because of lithium dendritesthat grow at voids, cracks, and grain boundaries of sintered bodiesduring cycling of the battery cell. In this work, glass-ceramic Ta-dopedLLZO produced in a unique melting process was investigated. Upon cooling,an amorphous phase is generated intrinsically, whose composition andfraction are adjusted during the process. Herein, it was set to about4 wt % containing Li2O and a Li2O-SiO2 phase. During sintering, it was shown to segregate into thegrain boundaries and decrease porosity via liquid phase sintering.Sintering temperature and sintering time were found to be reducedcompared with the LLZO fabricated by a solid-state reaction whilemaintaining high density and ionic conductivity. The glass-ceramicsintered at 1130 degrees C for 0.5 h showed a room-temperature ionicconductivity of 0.64 mS cm(-1). Most importantly,the evenly distributed amorphous phase along the grain boundarieseffectively hinders lithium dendrite growth. Besides mechanicallyblocking pores and voids, it helps to prevent inhomogeneous distributionof current density. The critical current density (CCD) of the Li|LLZTO|Lisymmetric cell was determined as 1.15 mA cm(-2), and in situ lithium plating experiments in a scanning electronmicroscope revealed superior dendrite stability properties. Therefore,this work provides a promising strategy to prepare a dense and dendrite-suppressingsolid electrolyte for future implementation in SSBs.

Automated summary

In this study, Ta-doped glass-ceramic LLZO was prepared using a unique melting process, which exhibited high density, ionic conductivity, and effective suppression of lithium dendrite growth. Therefore, this work provides a promising strategy for the preparation of a dense and dendrite-suppressing solid electrolyte for future implementation in solid-state batteries.