The deployment of Li‐garnet Li₇La₃Zr₂O₁₂ (LLZO) solid‐state electrolytes in solid‐state batteries is severely hampered by their poor wettability with metallic Li. In this work, Sb is presented as a compelling interfacial layer allowing superior wetting of Li onto a LLZO surface, resulting in a remarkably low Li/LLZO interfacial resistance of 4.1(1) Ω cm². An atomistic insight into Sb‐coated LLZO interface using soft and hard X‐ray photoelectron spectroscopy and focused ion beam time‐of‐flight secondary ion mass spectrometry shows the formation of a Li‐Sb alloy as an interlayer. It is determined that the Li/Sb‐coated LLZO/Li symmetrical cells exhibit a high critical current density of up to 0.64 mA cm⁻² and low overpotentials of 40–50 mV at a current density of 0.2 mA cm⁻² without applying external pressure. The electrochemical performance of Sb coated‐LLZO pellets is also assessed with an intercalation‐type V₂O₅ cathode. Li/Sb‐coated‐LLZO/V₂O₅ full cells deliver stable capacities of around 0.45 mAh cm⁻², with a peak current density of 0.3 mA cm⁻².

The high ionic conductivity and wide electrochemical stability of the lithium garnet Li₇La₃Zr₂O₁₂ (LLZO) make it a viable solid electrolyte for all‐solid‐state lithium batteries with superior capacity and power densities. Contrary to common ceramic processing routes of bulk pellets, thin film solid electrolytes could enable large‐area fabrication, and increase energy and power densities by reducing the bulkiness, weight and critically, the area‐specific resistance of the electrolyte. Fabrication of LLZO films has nonetheless been challenging because of lithium losses and formation of impurity phases that result in low densities and poor ionic conductivities as compared to bulk pellets. Here, a scalable method for fabricating submicron films of LLZO employing co‐sputtering from doped LLZO and Li₂O targets is presented. A record ionic conductivity of 1.9 × 10⁻⁴ S cm^–1 is measured for dense and uniform cubic‐phase Ga‐substituted LLZO films annealed at 700 °C in oxygen, which is comparable to the values in high‐temperature sintered pellets and outperforms by one order of magnitude the latest record for LLZO thin films as well as the typical conductivities in the well‐established LiPON electrolyte. This result is an important milestone to realize all‐vacuum deposited solid‐state batteries with higher power density.

Investigation of the matrix effect in Zr-based two-element alloys under continuous bombardment of a Ga⁺primary ion beam in a study of ionization probability towards exploring the potential and limitations of gas-assisted TOF-SIMS.

Garnet Li₇La₃Zr₂O₁₂ (LLZO) is a promising solid-state electrolyte due to its wide electrochemical stability window and high Li-ion conductivity. This electrolyte has potential to be employed in the form of thin films for solid-state batteries, a promising approach in the quest for safer batteries with higher energy densities at lower fabrication costs. In this study, we use a scalable co-sputtering process to fabricate LLZO thin films with subsequent post-annealing at a temperature of 700°C, significantly below the sintering temperatures employed in ceramic pellet processing. We investigate the roles that Li excess and incorporation of Al play in the film's crystalline phase, microstructure, phase stability and ultimately in the ionic conductivity. Our results reveal that improving the conductivity of LLZO thin films requires not only the stabilization of the cubic phase but especially the densification of the film and the minimization of the proton exchange degradation mechanism in the presence of moisture and CO₂. These issues can be mitigated by effectively controlling the amount of Li and incorporating Al as sintering agent. An ionic conductivity at RT of 1.9x10^-5 S·cm^-1 was achieved with a 400 nm Al-substituted LLZO thin film. Finally, we prove that these LLZO thin films can be succesfully deposited and crystallized on a LiCoO₂ cathode.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) is a powerful chemical characterization technique allowing for the distribution of all material components (including light and heavy elements and molecules) to be analyzed in 3D with nanoscale resolution. Furthermore, the sample’s surface can be probed over a wide analytical area range (usually between 1 µm² and 10⁴ µm²) providing insights into local variations in sample composition, as well as giving a general overview of the sample’s structure. Finally, as long as the sample’s surface is flat and conductive, no additional sample preparation is needed prior to TOF-SIMS measurements. Despite many advantages, TOF-SIMS analysis can be challenging, especially in the case of weakly ionizing elements. Furthermore, mass interference, different component polarity of complex samples, and matrix effect are the main drawbacks of this technique. This implies a strong need for developing new methods, which could help improve TOF-SIMS signal quality and facilitate data interpretation. In this review, we primarily focus on gas-assisted TOF-SIMS, which has proven to have potential for overcoming most of the aforementioned difficulties. In particular, the recently proposed use of XeF₂ during sample bombardment with a Ga⁺ primary ion beam exhibits outstanding properties, which can lead to significant positive secondary ion yield enhancement, separation of mass interference, and inversion of secondary ion charge polarity from negative to positive. The implementation of the presented experimental protocols can be easily achieved by upgrading commonly used focused ion beam/scanning electron microscopes (FIB/SEM) with a high vacuum (HV)-compatible TOF-SIMS detector and a commercial gas injection system (GIS), making it an attractive solution for both academic centers and the industrial sectors.