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The application of solid-state electrolytes in Li batteries has been hampered by the occurrence of Li-dendrite-caused short circuits. To avoid cell failure, the electrolytes can only be stressed with rather low current densities, severely restricting their performance. Since grain size and pore distributions significantly affect dendrite growth in ceramic electrolytes like Li7 La3 Zr2 O12 and its variants, here we have proposed a "detour and buffer" strategy to bring the superiority of both coarse and fine grains into play. To validate the mechanism, a coarse/fine bimodal grain microstructure was obtained by seeding unpulverized large particles in the green body. The rearrangement of coarse grains and fine pores was fine-tuned through changing the ratio of pulverized and unpulverized powders. The optimized bimodal microstructure, obtained when the two powders are equally mixed, allowed, without extra interface decoration, cycling for over 2000 h as the current density was increased from 1.0 mA·cm-2 gradually up to 2.0 mA·cm-2 . The "detour and buffer" effects was confirmed from postmortem analysis. The complex grain boundaries formed by fine grains discourage the direct infiltration of Li. Simultaneously, the coarse grains further increase the tortuosity of the Li path. Our study sheds light on the microstructure optimization for the polycrystalline solid-state electrolytes. This article is protected by copyright. All rights reserved.

Laser shock peening (LSP), a surface modification technique, is promising to enhance the strength and wear resistance for Ni-based superalloys. To understand the strengthening mechanism in a laser shock peened Ni-based superalloy DZ417G, we utilize synchrotron poly- and monochromatic X-ray microdiffraction, as well as electron microscopy and microhardness to quantify the local microstructures and mechanical properties at various depths. In the 1.2-mm-deep hardened layer, the microhardness increases monotonically by ∼50% from the unaffected interior to the surface. Quantitative microdiffraction analysis shows that large amounts of dislocations are introduced by LSP. High densities of 7.1 × 1015 m−2 and 11.8 × 1015 m−2 are seen close to the peened surface for the γ- and γ′-phases, respectively, which are 5 and 20 times of those in the unaffected region. Different gradients of dislocation density are observed for the two phases from interior to surface, and their combined effect accounts well for the hardness increment. Due to the unaltered γ′-precipitates and chemical composition in the LSP affected zone, the large density of dislocations dominates the observed strengthening. Combined poly- and monochromatic X-ray microdiffraction allows quantifying the local microstructures of plastic deformation over a large sampling scale that can hardly be achieved using other materials characterization techniques.

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”.

Rational design of sulfur electrodes is exceptionally important in enabling a high-performance lithium/sulfur cell. Constructing a continuous pore structure of the sulfur electrode that enables facile lithium ion transport into the electrode and mitigates the reconstruction of sulfur is a key factor for enhancing the electrochemical performance. Here, we report a three-dimensionally (3D) aligned sulfur electrode cast onto conventional aluminum foil by directional freeze tape casting. The 3D aligned sulfur-graphene oxide (S-GO) electrode consisting of few micron thick S-GO layers with 10-20 μm interlayer spacings demonstrates significant improvement in the performance of the Li/S cell. Moreover, the freeze tape cast graphene oxide electrode exhibits homogeneous reconfiguration behavior in the polysulfide catholyte cell tests and demonstrated extended cycling capability with only 4% decay of the specific capacity over 200 cycles. This work emphasizes the critical importance of proper structural design for sulfur-carbonaceous composite electrodes.

Indexing Laue patterns of a synchrotron microdiffraction scan can take as much as ten times longer than collecting the data, impeding efficient structural analysis using this technique. Here a novel strategy is developed. By comparing the peak positions of adjacent Laue patterns and checking the intensity sequence, grain and phase boundaries are identified, requiring only a limited number of indexing steps for each individual grain. Using this protocol, the Laue patterns can be indexed on the fly as they are taken. The validation of this method is demonstrated by analyzing the microstructure of a laser 3D printed multi-phase/multi-grain Ni-based superalloy.

Progress in computing speed and algorithm efficiency together with advances in area detector and X-ray optics technologies have transformed the technique of synchrotron radiation-based scanning Laue X-ray microdiffraction. It has now evolved into a near real-time quantitative imaging tool for material structure and deformation at the micrometer and nanometer scales. We will review the achievements of this technique at the Advanced Light Source (Berkeley, CA, USA), and demonstrate its application in the thorough microstructural investigations of laser-assisted 3D printed nickel-based superalloys.

Preparation of well-dispersed ZnO nanograins is necessary to improve their reactivity toward room-temperature H 2 S removal. However, the challenge to design such a ZnO-based adsorbent with high ZnO loading is yet to be fulfilled. Herein, a facile sol-gel strategy is reported for the preparation of ZnO/SiO 2 adsorbents for efficient H 2 S removal, by innovating a gel-drying method and simultaneously controlling ZnO grain formation through optimizing the molar ratio of ethylene glycol (EG)/nitrates in its precursors. The fabricated adsorbent embedded well-dispersed ZnO nanograins, of approximately 10-15 nm, into a SiO 2 matrix (57 wt % ZnO loading) and thus yielded a high H 2 S removal capacity of 108.9 mg S/g sorbent. Therein, EG was used as a modifier for inhibiting the formation of a denser SiO 2 network during the gel drying process and was used as a fuel for promoting the decomposition of nitrates and increasing the surface area of the composites in the subsequent calcination. Modulating the molar ratio of EG/nitrates ≤ 2 in precursors or traditional drying of the gel in an oven should be avoided because these would lead to the oxidation of EG by metallic nitrates and form carboxylate complexes during the gel-drying process. Although the produced ZnO grains had a very small size of less than 5 nm, a layer of monodentate ZnCO 3 impurity was formed on the ZnO surface, which will drastically decrease the reactivity of ZnO toward H 2 S. According to the encouraging results from CuO and Co 3 O 4 , this strategy has proved to be versatile for the preparation of other metal oxide/SiO 2 adsorbents.