Recent advances of Li7La3Zr2O12-based solid-state lithium batteries towards high energy density

To satisfy the demand for high energy density and high safety lithium batteries, garnet-based all-solid-state lithium batteries (ASSLBs) are the research hot spots in recent decades. Within the garnet family, Li7La3Zr2O12 (LLZO) is a promising candidate for solid-state electrolytes (SSEs) that has been extensively investigated due to the high ionic conductivity, chemical stability, electrochemical stability, air stability, thermal stability and safety. Recently, several laboratory-scale works on LLZO-based ASSLBs are achieved. However, although LLZO-based SSEs have made tremendous advancements today, there are still several critical issues in the practical application of ASSLBs with high energy density and low cost. Herein, optimization of LLZO structure, preparation of high-quality LLZO-based SSEs, engineering of the interface between LLZO-based SSEs and realization of LLZO-based ASSLBs with high energy density are systematically analyzed, discussed, and summarized to offer a clearer comprehension of the crucial challenges and future research orientations. It is expected to not only enhance the knowledge of audiences in this field but also facilitate the achievement of practical commercial applications in LLZO-based ASSLBs

Recent advances in in situ and operando characterization techniques for Li7La3Zr2O12-based solid-state lithium batteries

Li7La3Zr2O12 (LLZO)-based solid-state Li batteries (SSLBs) have emerged as one of the most promising energy storage systems due to the potential advantages of solid-state electrolytes (SSEs), such as ionic conductivity, mechanical strength, chemical stability and electrochemical stability. However, there remain several scientific and technical obstacles that need to be tackled before they can be commercialised. The main issues include the degradation and deterioration of SSEs and electrode materials, ambiguity in the Li+ migration routes in SSEs, and interface compatibility between SSEs and electrodes during the charging and discharging processes. Using conventional ex situ characterization techniques to unravel the reasons that lead to these adverse results often requires disassembly of the battery after operation. The sample may be contaminated during the disassembly process, resulting in changes in the material properties within the battery. In contrast, in situ/operando characterization techniques can capture dynamic information during cycling, enabling real-time monitoring of batteries. Therefore, in this review, we briefly illustrate the key challenges currently faced by LLZO-based SSLBs, review recent efforts to study LLZO-based SSLBs using various in situ/operando microscopy and spectroscopy techniques, and elaborate on the capabilities and limitations of these in situ/operando techniques. This review paper not only presents the current challenges but also outlines future developmental prospects for the practical implementation of LLZO-based SSLBs. By identifying and addressing the remaining challenges, this review aims to enhance the comprehensive understanding of LLZO-based SSLBs. Additionally, in situ/operando characterization techniques are highlighted as a promising avenue for future research. The findings presented here can serve as a reference for battery research and provide valuable insights for the development of different types of solid-state batteries