Anisotropy, or alternatively, isotropy of phase transformations extensively exist in a number of solid-state materials, with performance depending on the three-dimensional transformation features. ...Fundamental insights into internal chemical phase evolution allow manipulating materials with desired functionalities, and can be developed via real-time multi-dimensional imaging methods. Here, we report a five-dimensional imaging method to track phase transformation as a function of charging time in individual lithium iron phosphate battery cathode particles during delithiation. The electrochemically driven phase transformation is initially anisotropic with a preferred boundary migration direction, but becomes isotropic as delithiation proceeds further. We also observe the expected two-phase coexistence throughout the entire charging process. We expect this five-dimensional imaging method to be broadly applicable to problems in energy, materials, environmental and life sciences.
The three‐dimensional quantitative analysis and nanometer‐scale visualization of the microstructural evolutions of a tin electrode in a lithium‐ion battery during cycling is described. Newly ...developed synchrotron X‐ray nanotomography provided an invaluable tool. Severe microstructural changes occur during the first delithiation and the subsequent second lithiation, after which the particles reach a structural equilibrium with no further significant morphological changes. This reveals that initial delithiation and subsequent lithiation play a dominant role in the structural instability that yields mechanical degradation. This in situ 3D quantitative analysis and visualization of the microstructural evolution on the nanometer scale by synchrotron X‐ray nanotomography should contribute to our understanding of energy materials and improve their synthetic processing.
Microstructural evolution: In situ synchrotron X‐ray nanotomography has been developed to track the microstructural evolution of battery materials during the cycling of a battery. This three‐dimensional quantitative analysis and visualization on the nanometer scale should contribute to our understanding of energy materials and lead to improvements of their synthetic processing.
Combined synchrotron X‐ray nanotomography imaging, cryogenic electron microscopy (cryo‐EM) and modeling elucidate how potassium (K) metal‐support energetics influence electrodeposit microstructure. ...Three model supports are employed: O‐functionalized carbon cloth (potassiophilic, fully‐wetted), non‐functionalized cloth and Cu foil (potassiophobic, nonwetted). Nanotomography and focused ion beam (cryo‐FIB) cross‐sections yield complementary three‐dimensional (3D) maps of cycled electrodeposits. Electrodeposit on potassiophobic support is a triphasic sponge, with fibrous dendrites covered by solid electrolyte interphase (SEI) and interspersed with nanopores (sub‐10 nm to 100 nm scale). Lage cracks and voids are also a key feature. On potassiophilic support, the deposit is dense and pore‐free, with uniform surface and SEI morphology. Mesoscale modeling captures the critical role of substrate‐metal interaction on K metal film nucleation and growth, as well as the associated stress state.
Synchrotron X‐ray nanotomography imaging, cryogenic‐electron microscopy (cryo‐EM), and mesoscale modeling are combined to explain how the potassium metal‐support energetics influence the electrodeposit microstructure. Wettability critically influences the nucleation response, the growing film morphology and associated stress state, and the propensity for dendritic growth.
Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a ...method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography. Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal. In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants.
Materials degradation-the main limiting factor for widespread application of alloy anodes in battery systems-was assumed to be worse in sodium alloys than in lithium analogues due to the larger ...sodium-ion radius. Efforts to relieve this problem are reliant on the understanding of electrochemical and structural degradation. Here we track three-dimensional structural and chemical evolution of tin anodes in sodium-ion batteries with in situ synchrotron hard X-ray nanotomography. We find an unusual (de)sodiation equilibrium during multi-electrochemical cycles. The superior structural reversibility during 10 electrochemical cycles and the significantly different morphological change features from comparable lithium-ion systems suggest untapped potential in sodium-ion batteries. These findings differ from the conventional thought that sodium ions always lead to more severe fractures in the electrode than lithium ions, which could have impact in advancing development of sodium-ion batteries.
An entire active region of an anode-supported solid oxide fuel cell was structurally analyzed by X-ray computed nano-tomography using full-field transmission X-ray microscopy (NANO-TXM). A total ...three-dimensional volume of ∼38,500 μm3 was imaged, from which Ni–YSZ anode functional layer (∼3650 μm3) and LSM–YSZ cathode functional layer (∼4100 μm3) volumes were reconstructed. These were among the largest-volume electrode reconstructions ever reported, while at the same time exhibiting high spatial resolution of 50 nm. Comparison with electrode microstructures measured using other imaging methods demonstrates that the larger NANO-TXM-measured volumes provided significantly more accurate phase connectivity information. A microstructure-based electrochemical model prediction agreed well with the measured full-cell electrochemical data. The results suggest that low LSM connectivity and slow oxygen reduction reaction kinetics in the cathode were a major limitation to the overall cell performance.
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► Reconstruction of entire SOFC active region in a single set of NANO-TXM measurements. ► Cathode had 3.3× increase in TPB density due to smaller particles sizes. ► Modeled performance suggests cathode made up 85% of electrode polarization. ► LSM connectivity and sluggish TPB reaction kinetics limit cathode performance.
Carbon coating is a simple, effective and common technique for improving the conductivity of active materials in lithium ion batteries. However, carbon coating provides a strong reducing atmosphere ...and many factors remain unclear concerning the interface nature and underlying interaction mechanism that occurs between carbon and the active materials. Here, we present a size-dependent surface phase change occurring in lithium iron phosphate during the carbon coating process. Intriguingly, nanoscale particles exhibit an extremely high stability during the carbon coating process, whereas microscale particles display a direct visualization of surface phase changes occurring at the interface at elevated temperatures. Our findings provide a comprehensive understanding of the effect of particle size during carbon coating and the interface interaction that occurs on carbon-coated battery material--allowing for further improvement in materials synthesis and manufacturing processes for advanced battery materials.
Recent advances have suggested that steroid hormones such as estrogens, and gut microbiota might synergize to influence obesity, diabetes, and cancer. We discuss recent knowledge of the interactions ...between estrogens and gut microbiota, and new insights that might offer new approaches to influence this crosstalk and improve metabolic outcomes.
Virtual reality (VR) shows promise in the application of healthcare and because it presents patients an immersive, often entertaining, approach to accomplish the goal of improvement in performance. ...Eighteen studies were reviewed to understand human performance and health outcomes after utilizing VR rehabilitation systems. We aimed to understand: (1) the influence of immersion in VR performance and health outcomes; (2) the relationship between enjoyment and potential patient adherence to VR rehabilitation routine; and (3) the influence of haptic feedback on performance in VR. Performance measures including postural stability, navigation task performance, and joint mobility showed varying relations to immersion. Limited data did not allow a solid conclusion between enjoyment and adherence, but patient enjoyment and willingness to participate were reported in care plans that incorporates VR. Finally, different haptic devices such as gloves and controllers provided both strengths and weakness in areas such movement velocity, movement accuracy, and path efficiency.
•No distinct relationship between immersion and improvement in motor recovery.•No comprehensive agreement in enjoyment and user adherence in VR rehabilitation.•Different haptic devices influenced user performance, thus.•Important to consider the type of haptic devices employed in VR rehabilitation.
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