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Solid-state electrolytes (SSEs) are key to the success and reliability of all-solid-state lithium batteries, potentially enabling improvements in terms of safety and energy density over state-of-the-art lithium-ion batteries. However, there are several critical challenges to their implementation, including the interfacial instability stemming from the dynamic interaction of as-formed dendritic lithium during cycling. For this work, we emphasize the importance of studying the spatial distribution and temporal evolution of strains and defects in crystalline solid-state electrolytes at the micro-scale, and how this affects dendrite growth. A proof-of-principle study is demonstrated using the synchrotron radiation based micro Laue X-ray diffraction method, and a custom-developed in-situ cycling device. Defects and residual strains are mapped, and the evolution of intragranular misorientation is observed. The feasibility of using this technique is discussed, and recommendations for micro-strain engineering to address the Li/SSEs interfacial issues are given. Also, work directions are pointed out with the consideration of combining multi-techniques for “poly-therapy”.

We investigate the electrolyte stability and discharge products of an ionic-liquid-based Li-O2 battery through soft X-ray emission spectroscopy (XES) experiments, which offer unique site specificity for detecting subtle changes in the local nitrogen and oxygen environment. We benchmark the valence electronic structures of the molecules composing the electrolyte, namely the solvent PP13(TFSI), the salt LiTFSI, and the PP13 cation. Then, the transformation of the electrolyte is shown using cathodes stopped at different discharge and charge stages. We provide experimental evidence that the nitrogen site of the salt is unstable during electrochemical operation. The chemical environment of the nitrogen atoms is gradually changed during the electrochemical cycle, indicating the breaking of S-N bonds. The ionic liquid solvent remains mostly as an ion pair, but some decomposition into PP13 cations and TFSI anions cannot be ruled out. Our results and detailed analysis also show that the discharge products in our cell consist of lithium peroxide with some amount of hydroxide; however, no carbonate is observed.

Li atoms are believed to rearrange during Li insertion/removal in LiNiO2 cathodes in lithium-ion batteries, forming certain Li/vacancy ordering structures. Substitution of Ni by dopants is considered to hinder such orderings, which is related to a quasi-solid-solution behavior in phase transitions and improved battery cyclability. Previous studies investigate the disruptions by theoretical calculations, however, direct experimental evidence is missing. Herein, the disturbed Li/vacancy structures are first observed based on the ex situ6Li nuclear magnetic resonance measurement. [ABSTRACT FROM AUTHOR]

Lithium thiophosphates are a promising class of solid electrolyte (SE) materials for all-solid-state batteries (ASSBs) due to their high Li-ion conductivity. Yet, the practical application of lithium thiophosphates is hindered by their chemical instability, which remains a prevalent challenge in the field. Oxygen substitution has been discussed in the literature as a promising strategy to enhance stability. Nevertheless, the lack of understanding of the role of synthesis strategy on the resulting structure–property relationship makes it difficult to predict and control the material's behaviour, limiting our ability to fully utilize oxygen substitution as a viable solution. Here, we show that not only the total oxygen content but also the oxygen distribution within the material affects the ion conductivity. By carefully analysing the local structure of oxy-sulfide glasses, we find that few highly oxygenated structural units like [PO4]3− and [PO3S]3− are more detrimental to the ionic conductivity than a larger amount of less substituted units like [POS3]3−. Further, we demonstrate how the oxygen distribution is connected to the synthesis in high-energy ball milling by comparing two different sets of precursor materials. The results may explain the deviations in the past literature. The findings should be transferable to other Li-thiophosphate materials and enable more directed design of new materials. [ABSTRACT FROM AUTHOR]

Understanding how reaction heterogeneity impacts cathode materials during Li‐ion battery (LIB) electrochemical cycling is pivotal for unraveling their electrochemical performance. Yet, experimentally verifying these reactions has proven to be a challenge. To address this, we employed scanning μ‐XRD computed tomography to scrutinize Ni‐rich layered LiNi0.6Co0.2Mn0.2O2 (NCM622) and Li‐rich layered Li[Li0.2Ni0.2Mn0.6]O2 (LLNMO). By harnessing machine learning (ML) techniques, we scrutinized an extensive dataset of μ‐XRD patterns, about 100,000 patterns per slice, to unveil the spatial distribution of crystalline structure and microstrain. Our experimental findings unequivocally reveal the distinct behavior of these materials. NCM622 exhibits structural degradation and lattice strain intricately linked to the size of secondary particles. Smaller particles and the surface of larger particles in contact with the carbon/binder matrix experience intensified structural fatigue after long‐term cycling. Conversely, both the surface and bulk of LLNMO particles endure severe strain‐induced structural degradation during high‐voltage cycling, resulting in significant voltage decay and capacity fade. This work holds the potential to fine‐tune the microstructure of advanced layered materials and manipulate composite electrode construction in order to enhance the performance of LIBs and beyond. [ABSTRACT FROM AUTHOR]

Ceramic ion conductors play a pivotal role as electrolytes in solid‐state batteries (SSBs). Aside from the ionic conductivity, their (electro)chemical stability has a profound effect on the performance. Lithium thiophosphates represent a widely used class of superionic materials, yet they suffer from limited stability and are known to undergo interfacial degradation upon battery cycling. Knowledge of composition‐dependent properties is essential to improving upon the stability of thiophosphate solid electrolytes (SEs). In recent years, compositionally complex (multicomponent) and high‐entropy lithium argyrodite SEs have been reported, having room‐temperature ionic conductivities of σion>10 mS cm−1. In this work, various multi‐cationic and ‐anionic substituted argyrodite SEs are electrochemically tested via cyclic voltammetry and impedance spectroscopy, as well as under operating conditions in SSB cells with layered Ni‐rich oxide cathode and indium‐lithium anode. Cation substitution is found to negatively affect the electrochemical stability, while anion substitution (introducing Cl−/Br− and increasing halide content) has a beneficial effect on the cyclability, especially at high current rates. [ABSTRACT FROM AUTHOR]