A5079941352- Advancements in Battery Materials
- Semiconductor materials and devices
- Nanowire Synthesis and Applications
- Silicon Nanostructures and Photoluminescence
- Semiconductor materials and interfaces
- Advanced Battery Materials and Technologies
- Electron and X-Ray Spectroscopy Techniques
- Advanced Battery Technologies Research
- Advancements in Semiconductor Devices and Circuit Design
- Catalytic Processes in Materials Science
- Advanced Electron Microscopy Techniques and Applications
- Graphene research and applications
- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Supercapacitor Materials and Fabrication
- Thermal properties of materials
- Extraction and Separation Processes
- Carbon Nanotubes in Composites
- Transition Metal Oxide Nanomaterials
- Integrated Circuits and Semiconductor Failure Analysis
- Thin-Film Transistor Technologies
- Electrocatalysts for Energy Conversion
- Photonic and Optical Devices
- 3D IC and TSV technologies
- Electronic and Structural Properties of Oxides
National Institute for Materials Science
2014-2024
Hiroshima University
2019-2022
Japan Science and Technology Agency
2021-2022
Saitama Medical University Hospital
2020
Osaka University
2004-2017
National Institute of Advanced Industrial Science and Technology
2006-2012
Ubiquitous Energy (United States)
2012
Midorigaoka Hospital
2012
Abstract Sodium-ion batteries are attractive energy storage media owing to the abundance of sodium, but low capacities available cathode materials make them impractical. Sodium-excess metal oxides Na 2 MO 3 (M: transition metal) appealing that may realize large through additional oxygen redox reaction. However, general strategies for enhancing capacity poorly established. Here using two polymorphs RuO , we demonstrate critical role honeycomb-type cation ordering in . Ordered with...
Abstract Increasing the energy density of rechargeable batteries is paramount importance toward achieving a sustainable society. The present limitation owing to small capacity cathode materials, in which (de)intercalation ions charge‐compensated by transition‐metal redox reactions. Although additional oxygen‐redox reactions oxide cathodes have been recognized as an effective way overcome this limit, irreversible structural changes that occur during charge/discharge cause voltage drops and...
Multimetallic alloys (MMAs) with various compositions enrich the materials library increasing diversity and have received much attention in catalysis applications. However, precisely shaping MMAs mesoporous nanostructures mapping distributions of multiple elements remain big challenge due to different reduction kinetics metal precursors complexity crystal growth. Here we design a one-pot wet-chemical approach synthesize core-shell motif PtPdRhRuCu nanospheres (PtPdRhRuCu MMNs) using diblock...
The development of highly luminescent two-dimensional covalent organic frameworks (COFs) for sensing applications remains challenging. To suppress commonly observed photoluminescence quenching COFs, we propose a strategy involving interrupting the intralayer conjugation and interlayer interactions using cyclohexane as linker unit. By variation building block structures, imine-bonded COFs with various topologies porosities are obtained. Experimental theoretical analyses these disclose high...
Deterioration mechanisms of LiCoO2 electrode materials for lithium ion batteries remain unclear. Using electron energy-loss spectroscopy and transmission microscopy, this study investigated chemical states particles on first overcharging. We present a scheme quantification the Li/Co atomic ratio. quantitative Li mapping comprehensive probing Li–K, Co–M2,3, Co–L3, O–K edges, we observed that overcharging causes progression Co3+/Co2+ reduction with oxygen extraction from particle surface to...
Abstract Connecting molecular-level phenomena to larger scales and, ultimately, sophisticated molecular systems that resemble living remains a considerable challenge in supramolecular chemistry. To this end, self-assembly at higher hierarchical levels has be understood and controlled. Here, we report unusual self-assembled structures formed from simple porphyrin derivative. Unexpectedly, one-dimensional (1D) polymer coiled give an Archimedean spiral. Our analysis of the polymerization by...
Abstract Reversibility of an electrode reaction is important for energy-efficient rechargeable batteries with a long battery life. Additional oxygen-redox reactions have become intensive area research to achieve larger specific capacity the positive materials. However, most electrodes exhibit large voltage hysteresis >0.5 V upon charge/discharge, and hence possess unacceptably poor energy efficiency. The thought originate from formation peroxide-like O 2 2− dimers during reaction....
Kinetic formation of the peroxo-like O 2 2− dimer is identified as origin a voltage hysteresis in oxygen-redox battery electrodes.
Ni-enriched layered materials are used as electrode of Li-ion batteries for electric vehicle applications. Stoichiometric LiNiO2 with cationic Ni3+/Ni4+ redox is the ideal material, but gradual loss capacity at high voltage region, associated Ni ion migration, hinders its use practical Therefore, to improve reversibility LiNiO2, less abundant Co ions and/or other electrochemically inactive ions, e.g., Al3+ in part substituted ions. Nevertheless, a unified understanding improvement by metal...
We have measured the growth rate of silicon nanowires (SiNWs), which were grown at temperatures between 365 and 495 °C via vapor-liquid-solid (VLS) mechanism. grew SiNWs using gold as catalysts monosilane (SiH4) a vapor phase reactant. Observing by means transmission electron microscopy, we found that with smaller diameters grow slower than those larger ones, critical diameter stops completely exists. estimated to be about 2 nm. also temperature dependence activation energy 230kJ∕mol.
Abstract Annular dark-field (ADF) imaging by scanning transmission electron microscopy (STEM) is a common technique for material characterization with high spatial resolution. It has been reported that ADF signal proportional to the n th power of atomic number Z , i . e ., contrast in textbooks and papers. Here we first demonstrate deviation from power-law model quantitative experiments few 2D materials (graphene, MoS 2 WS monolayers). Then elucidate single atoms using simulations clarify...
Structural and morphological control is an effective approach for improvement of electrochemical properties in rechargeable batteries. One-dimensionally assembled structure composed NASICON-type Na3 V2 (PO4 )3 nanoparticles were fabricated through electrospinning method to meet the requirements development efficient electrode materials Na-ion High-temperature treatment electrospun precursor fibers under argon flow provides a nonwoven fabric nanowires comprising crystallographically oriented...
Abstract Lithium- and sodium-rich layered transition-metal oxides have recently been attracting significant interest because of their large capacity achieved by additional oxygen-redox reactions. However, exhibit structural degradation such as cation migration, layer exfoliation or cracks upon deep charge, which is a major obstacle to achieve higher energy-density batteries. Here we demonstrate self-repairing phenomenon stacking faults desodiation from an oxide Na 2 RuO 3 , realizing much...
Abstract Unsupervised machine learning techniques have been combined with scanning transmission electron microscopy (STEM) to enable comprehensive crystal structure analysis nanometer spatial resolution. In this study, we investigated large-scale data obtained by four-dimensional (4D) STEM using dimensionality reduction such as non-negative matrix factorization (NMF) and hierarchical clustering various optimization methods. We developed software scripts incorporating knowledge of diffraction...
We have investigated the charge-discharge mechanism in first cycle and origin of its high charge–discharge capacity for Li 1.2 Mn 0.4 Fe O 2 (0.5Li MnO 3 ·0.5LiFeO ) positive electrode material lithium ion batteries. Results reveal that oxygen loss occurs entire region particles composed Mn-rich (Fe-substituted Fe-rich (Mn-substituted LiFeO nanodomains during charge. Nanodomains Mn-Li ferrites with a spinel structure start to be formed along particle surfaces. During discharge, extracted is...
Nanostructured LiMnO2 integrated with Li3PO4 was successfully synthesized by the mechanical milling route and examined as a new series of positive electrode materials for rechargeable lithium batteries. Although uniform mixing at atomic scale between not anticipated because noncompatibility crystal structures both phases, our study reveals that phosphorus ions excess dissolve into nanosize crystalline first evidenced elemental mapping using STEM-EELS combined total X-ray scattering,...
Direct exfoliation of layered zeolites into solutions monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with MWW topology (layers denoted mww) been exfoliated directly in high yield by soft-chemical treatment tetrabutylammonium hydroxide (TBAOH). This enabled preparation zeolite-based hierarchical materials and intimate composites other active species that are unimaginable via conventional solid-state routes. The extension to frameworks, which provides broader...
High-density submicron-sized FeNi particles prepared by a spray pyrolysis route exhibit high magnetic characteristics and enhance the powder core performance indicated improvement of DC bias characteristic value.
Practical techniques to identify heat routes at the nanoscale are required for thermal control of microelectronic, thermoelectric, and photonic devices. Nanoscale thermometry using various approaches has been extensively investigated, yet a reliable method not finalized. We developed an original technique waves induced by pulsed convergent electron beam in scanning transmission microscopy (STEM) mode room temperature. By quantifying relative phase delay each irradiated position, we...
The authors investigated the distribution and local valence states of transition metal ions in a positive electrode material for lithium-ion batteries, Li1.2Mn0.4Fe0.4O2 nanoparticles, by electron energy-loss spectroscopy combined with scanning transmission microscopy. experiments clarified coexistence Mn-rich Fe-rich nanodomains each single particle, it is found that contain Mn3+ which should be active redox reaction spite previous views inactive Mn4+ this material. discuss mechanism...
Local crystal structures associated with nanoscale variations of the concentration ratio Fe ions to Mn in each single Li1.2Mn0.4Fe0.4O2 particle have been studied by nanobeam electron diffraction, high-resolution transmission microscopy, and energy-loss spectroscopy combined scanning microscopy. We found direct evidence that is comprised Mn-rich nanodomains layered rocksalt structure Fe-rich cubic featured cation short-range order, within a common oxygen lattice framework close-packed...