Correlative imaging of ionic transport and electronic structure in nano Li0.5FePO4 electrodes

Bulk and surface phase separation and electronic structure variation of Li_0.5FePO₄ particles under concurrent lithiation are imaged by X-ray microscopies.

Unexpected phase separation in Li1−xNi0.5Mn1.5O4 within a porous composite electrode

The Ni oxidation state in Li_1−xNi_0.5Mn_1.5O₄ within a composite electrode mapped by scanning transmission X-ray microscopy (STXM) has shown unexpected variations in phase separation among and within individual battery particles, which has been experimentally correlated to both their morphology and interface structure.

Surface heterogeneity in Li0.5CoO2 within a porous composite electrode

Surface phase heterogeneity mapping of the same LCO particles in a charged composite electrode deciphers the interactions among the electrode components.

Chemical Imaging of Nanoscale Interfacial Inhomogeneity in LiFePO4 Composite Electrodes from a Cycled Large-Format Battery

The nanoscale interfacial inhomogeneity in a cycled large-format LiFePO₄ (LFP) composite electrode has been studied by X-ray photoemission electron microscopy at single particle spatial resolution with a probe depth of ∼5 nm. The loss of active lithium in cycled LFP causes the coexsitence of fully delithiated LFP (FePO₄) and partially delithiated LFP (Li_0.6FePO₄ or Li_0.8FePO₄) as a function of the extent of lithium loss. The distribution of various lithium loss phases along with local agglomeration of LFP and degradation of binder and carbon black are correlatively visualized. This is the first experimental exploration of chemical interplay between components in the composite electrode from a large-format battery, and implications on the LFP degradation in this battery are discussed.

Nanoscale chemical imaging of the additive effects on the interfaces of high-voltage LiCoO2 composite electrodes

X-ray photoemission electron microscopy (X-PEEM) of cycled LiCoO₂ composite electrodes has revealed the interfaces of various components within the composite electrodes and their dependence on additives in the electrolyte and the interplay of multiple components in the electrodes.

PtxNi10−xO nanoparticles supported on N-doped graphene oxide with a synergetic effect for highly efficient hydrolysis of ammonia borane

The Pt₃Ni₇O–NGO sample shows a high TOF value in the hydrolysis of ammonia borane due to a synergetic effect.

Cux Co1-x O Nanoparticles on Graphene Oxide as A Synergistic Catalyst for High-Efficiency Hydrolysis of Ammonia-Borane

Ammonia-borane (AB) is an excellent material for chemical storage of hydrogen. However, the practical utilization of AB for production of hydrogen is hindered by the need of expensive noble metal-based catalysts. Here, we report Cux Co1-x O nanoparticles (NPs) facilely deposited on graphene oxide (GO) as a low-cost and high-performance catalyst for the hydrolysis of AB. This hybrid catalyst exhibits an initial total turnover frequency (TOF) value of 70.0 (H2 ) mol/(Cat-metal) mol⋅min, which is the highest TOF ever reported for noble metal-free catalysts, and a good stability keeping 94 % activity after 5 cycles. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) investigations suggested that the high catalytic performance could be attributed to the interfacial interaction between Cux Co1-x O NPs and GO. Moreover, the catalytic hydrolysis mechanism was studied by in situ XAS experiments for the first time, which reveal a significant water adsorption on the catalyst and clearly confirm the interaction between AB and the catalyst during hydrolysis.

Imaging the surface morphology, chemistry and conductivity of LiNi1/3Fe1/3Mn4/3O4 crystalline facets using scanning transmission X-ray microscopy

Scanning transmission X-ray microscopy (STXM) using the X-ray fluorescence mode has been employed to elucidate the chemical structures at Ni, Fe, Mn and O sites from the (111) and (100) facets of micron-sized LiNi_1/3Fe_1/3Mn_4/3O₄ energy material particles.

Revealing the synergetic effects in Ni nanoparticle-carbon nanotube hybrids by scanning transmission X-ray microscopy and their application in the hydrolysis of ammonia borane

The hybrids of carbon nanotubes (CNTs) and the supported Ni nanoparticles (NPs) have been studied by scanning transmission X-ray microscopy (STXM) and tested by the hydrolysis reaction of ammonia borane (AB, NH3BH3). Data clearly showed the existence of a strong interaction between Ni NPs and thin CNTs (C-O-Ni bonds), which favored the tunable (buffer) electronic structure of Ni NPs facilitating the catalytic process. The hydrolysis process of AB confirmed the hypothesis that the hybrids with a strong interfacial interaction would show superior catalytic performance, while the hybrids with a weak interfacial interaction show poor performance. Our results provide a wealth of detailed information regarding the electronic structure of the NP-CNT hybrids and provide guidance towards the rational design of high-performance catalysts for energy applications.

Synchrotron soft X-ray absorption spectroscopy study of carbon and silicon nanostructures for energy applications

Carbon and silicon materials are two of the most important materials involved in the history of the science and technology development. In the last two decades, C and Si nanoscale materials, e.g., carbon nanotubes, graphene, and silicon nanowires, and quantum dots, have also emerged as the most interesting nanomaterials in nanoscience and nanotechnology for their myriad promising applications such as for electronics, sensors, biotechnology, etc. In particular, carbon and silicon nanostructures are being utilized in energy-related applications such as catalysis, batteries, solar cells, etc., with significant advances. Understanding of the nature of surface and electronic structures of nanostructures plays a key role in the development and improvement of energy conversion and storage nanosystems. Synchrotron soft X-ray absorption spectroscopy (XAS) and related techniques, such as X-ray emission spectroscopy (XES) and scanning transmission X-ray microscopy (STXM), show unique capability in revealing the surface and electronic structures of C and Si nanomaterials. In this review, XAS is demonstrated as a powerful technique for probing chemical bonding, the electronic structure, and the surface chemistry of carbon and silicon nanomaterials, which can greatly enhance the fundamental understanding and also applicability of these nanomaterials in energy applications. The focus is on the unique advantages of XAS as a complementary tool to conventional microscopy and spectroscopy for effectively providing chemical and structural information about carbon and silicon nanostructures. The employment of XAS for in situ, real-time study of property evolution of C and Si nanostructures to elucidate the mechanisms in energy conversion or storage processes is also discussed.

X-ray techniques for innovation in industry

The smart specialization declared in the European program Horizon 2020, and the increasing cooperation between research and development found in companies and researchers at universities and research institutions have created a new paradigm where many calls for proposals require participation and funding from public and private entities. This has created a unique opportunity for large-scale facilities, such as synchrotron research laboratories, to participate in and support applied research programs. Scientific staff at synchrotron facilities have developed many advanced tools that make optimal use of the characteristics of the light generated by the storage ring. These tools have been exceptionally valuable for materials characterization including X-ray absorption spectroscopy, diffraction, tomography and scattering, and have been key in solving many research and development issues. Progress in optics and detectors, as well as a large effort put into the improvement of data analysis codes, have resulted in the development of reliable and reproducible procedures for materials characterization. Research with photons has contributed to the development of a wide variety of products such as plastics, cosmetics, chemicals, building materials, packaging materials and pharma. In this review, a few examples are highlighted of successful cooperation leading to solutions of a variety of industrial technological problems which have been exploited by industry including lessons learned from the Science Link project, supported by the European Commission, as a new approach to increase the number of commercial users at large-scale research infrastructures.

Hybrid material design for energy applications: impact of graphene and carbon nanotubes

This article reviews the origin and progress of inorganic/nanocarbon hybrid material research in my Ph.D. career. Building chemical bonds between inorganic active materials and nanocarbon substrates is the key to controlled hybrid material synthesis that allows for controlling the size and morphology of the materials and enhancing electron transport within the electrodes. Our inorganic/nanocarbon hybrid materials manifest superior electrochemical performance for asymmetrical supercapacitors, ultrafast nickel-iron batteries, lithium ion batteries, lithium-sulfur batteries, and electrocatalysis of oxygen reduction and evolution reactions. X-ray absorption near edge structure (XANES) spectroscopy has been utilized to characterize the chemical bonding and charge transfer at the interface of inorganic nanocrystals and nanocarbon substrates. Probing the physical and chemical states of the hybrid materials under electrochemical reaction conditions is an important future direction in this area.

Chemical bonding in amorphous Si-coated carbon nanotubes as anodes for Li ion batteries: a XANES study

The Si–O–C bonding and its evolution upon electrochemical cycling in a Si-coated carbon nanotube anode are unveiled by X-ray absorption spectroscopy studies.

Electronic structure variation of the surface and bulk of a LiNi0.5Mn1.5O4cathode as a function of state of charge: X-ray absorption spectroscopic study

The electronic structure of Li_1−xNi_0.5Mn_1.5O₄as a function of the charge state shows different roles of the constituent atoms, and the surface and bulk structures change upon electrochemical cycling.

X-ray chemical imaging and the electronic structure of a single nanoplatelet Ni/graphene composite

Local chemistry and electronic structure of Ni/graphene composite reveal that Ni is grown onto graphene substrates mainlyviacovalent bonding of Ni–C and Ni–O–C.