Understanding the Factors Affecting Li Dendtire Formation in the Garnet-Type Solid Electrolytes

The demand for rechargeable Li batteries having more safety and higher energy density has been increased to meet the strong demand of novel applications such as electric vehicles and energy storage systems. In this aspect, Li ion batteries containing typical liquid electrolytes have fundamental limitations because liquid electrolytes can act as fuels in thermal runaway behavior leading to a fire or an explosion of battery and can be decomposed at high potential (&gt; 4.5V) leading to the restricted use of high potential cathodes. To address these problems, there are several approaches. One of promising approaches is to apply proper oxide-based solid electrolytes (SEs) instead of liquid electrolytes because they can enable to deliver superior safety with Li metal and to achieve high energy density simultaneously. Among solid electrolytes, garnet-type solid electrolytes such as Li7La3Zr2O12 (LLZO) show great promise for solid-state Li metal batteries because of their chemical stability with Li metal and their high Li ionic conductivity.[1,2] However, oxide-based solid electrolytes have suffered from the Li dendrite formation and propagation inside SE in using Li metal as an anode because of the formation of short circuits that can pose a major obstacle to the commercialization of LLZO.[3,4]<br/>In this study, we try to understand the factors affecting Li dendrite formation and propagation in the garnet-type LLZO SE with respect to materials’ properties such as electrical properties and mechanical integrity, and interfacial properties. To achieve this, different samples that have different materials properties such as bulk and grain boundary and different surface properties were prepared. By using these samples, dominant factors affecting the short-circuit of Li metal inside SE have been understood. Finally, we will discuss about the correlation of the Li dendritic behavior with the critical current density, which is the important factor for using the solid electrolyte in real applications.<br/><br/><br/><b>Reference</b><b>s</b>:<br/>[1] Connell, Justin G., et al. "Kinetic versus thermodynamic stability of LLZO in contact with lithium metal." Chemistry of Materials 32.23 (2020): 10207-10215.<br/><br/>[2] Chen, Rusong, et al. "The thermal stability of lithium solid electrolytes with metallic lithium." Joule 4.4 (2020): 812-821.<br/><br/>[3] McConohy, Geoff, et al. "Mechanical regulation of lithium intrusion probability in garnet solid electrolytes." Nature energy 8.3 (2023): 241-250.<br/><br/>[4] Han, Fudong, et al. "High electronic conductivity as the origin of lithium dendrite formation within solid electrolytes." Nature Energy 4.3 (2019): 187-196.