Garnet-type Li7La3Zr2O12 (LLZO) is a promising solid electrolyte for the application in solid-state lithium batteries (SSBs). However, its reaction with water and carbon dioxide in ambient air and the resulting formation of insulating lithium carbonate is one of the major obstacles for its large-scale manufacturing and processing. Especially when processed as powder with large surface areas, e.g., for the application in hybrid electrolytes, where LLZO powders are incorporated into a polymer matrix, uncontaminated surfaces are crucial. In this work, the kinetics of the hydration and carbonation mechanism is studied in detail for Ta-doped LLZO powders by time-dependent analyses of morphology, structure, and composition. Common particle sizes for battery applications, i.e., powders with different specific surface areas, are investigated. It is shown that the degradation mechanism follows a two-step consecutive reaction for all particle sizes investigated. It is self-limited by diffusion processes in the reaction layer in accordance with the core shrinking model. The hydration reaction is an essential intermediate step that precedes carbonation, which is demonstrated by systematically adjusting the atmosphere from dry room conditions up to ambient air. Moreover, the reaction rate of the hydration and carbonation depends strongly on the particle size and thus on the surface area. A linear correlation of the reaction rate and the specific surface area is found. Altogether, the novel insights into the degradation mechanism of LLZTO powder scrutinized in this work provide guidance on how to select, handle, and process LLZTO powders according to the surface quality requirements in future battery applications.

Two-dimensional (2D) materials have attracted attention for potential applications in light harvesting, catalysis, and molecular electronics. Mineral proteins involved in hard tissue biogenesis can produce 2D structures with high fidelity by using sustainable production routes. This study shows that a peptide mimic based on the catalytic triad of the marine sponge protein silicatein catalyzes the formation of nanometer thin and stable sheets of silicon dioxide and titanium dioxide.

The fabrication of inorganic nanomaterials is important for a wide range of disciplines.

Lithium metal-based solid-state batteries (SSBs) have attracted much attention due to their potentially higher energy densities and improved safety compared with lithium-ion batteries. One of the most promising solid electrolytes, garnet-type Li7La3Zr2O12 (LLZO), has been investigated intensively in recent years. It enables the use of a lithium metal anode, but its application is still challenging because of lithium dendrites that grow at voids, cracks, and grain boundaries of sintered bodies during cycling of the battery cell. In this work, glass-ceramic Ta-doped LLZO produced in a unique melting process was investigated. Upon cooling, an amorphous phase is generated intrinsically, whose composition and fraction are adjusted during the process. Herein, it was set to about 4 wt % containing Li2O and a Li2O–SiO2 phase. During sintering, it was shown to segregate into the grain boundaries and decrease porosity via liquid phase sintering. Sintering temperature and sintering time were found to be reduced compared with the LLZO fabricated by a solid-state reaction while maintaining high density and ionic conductivity. The glass-ceramic sintered at 1130 °C for 0.5 h showed a room-temperature ionic conductivity of 0.64 mS cm–1. Most importantly, the evenly distributed amorphous phase along the grain boundaries effectively hinders lithium dendrite growth. Besides mechanically blocking pores and voids, it helps to prevent inhomogeneous distribution of current density. The critical current density (CCD) of the Li|LLZTO|Li symmetric cell was determined as 1.15 mA cm–2, and in situ lithium plating experiments in a scanning electron microscope revealed superior dendrite stability properties. Therefore, this work provides a promising strategy to prepare a dense and dendrite-suppressing solid electrolyte for future implementation in SSBs.