The Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory (LBNL) is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Q.L. thanks the China Scholarship Council (CSC) for financial support through the collaboration based on China 111 project No. B13029. R.Q. thanks the support from LBNL LDRD program. S.S. and Z.Z. thank the support from the ALS Doctoral fellowship.

1. Experimental Planning
Note: While sXES could be performed with lab-based equipment, sXAS and RIXS are synchrotron-based experiments, which requires access to the beamtime of a synchrotron facility. The procedure for applying for beamtime and running experiments could be different at different facilities, but they all follow a similar basic procedure.
<ol>
	<li>Check the facility website for the beamline directory (e.g., https://als.lbl.gov/beamlines/), or contact the scientists in charge of the interested beamline(s) to determine the proper beamline for the scientific need.</li>
	<li>Submit beamtime proposals to the facility and beamline(s) of Advanced Light Source (ALS) through online submission system at https://als.lbl.gov/users/user-guide/. 
	NOTE: The beamtime proposal will be reviewed based on the policy of the synchrotron facility, and authors of successful proposals will be notified by the facility for experimental scheduling.</li>
	<li>For safety controls, complete any necessary safety trainings according to the facility&#39;s requirements. Report chemicals, samples, and special equipment required by experiments, and get inspections to guarantee safety.</li>
	<li>Arrive at the facility ahead of the beamtime to get basic ideas on the experimental setup and sample loading, especially as new users to a facility/beamline.</li>
</ol>
2. Sample Preparation
<ol>
	<li>Synthesize the samples of the LIB and SIB materials, and electrochemically cycle to different state-of-charge (SOC).</li>
	<li>Perform the following steps for air-sensitive samples:
	<ol>
		<li>Handle the air-sensitive samples without air exposure, i.e. open the sample containers, and cut the samples with scissors and tweezers into a size fitting the experimental system under an inert gas environment.</li>
		<li>Mount the samples with an appropriate size onto sample holders by using double-sided conductive tape under an inert gas environment. 
		NOTE: If Carbon or Oxygen edges are to be measured, use soft metals such as Indium for sticking the powder samples on, to avoid background C and O signals from the organic compounds in conductive tape.</li>
	</ol>
	</li>
	<li>Perform the following steps for non-air-sensitive samples:
	<ol>
		<li>Cut the samples to match the specific sample holder for experimental systems.</li>
		<li>Mount the samples with the appropriate size onto sample holders by using double-sided conductive tape. Use indium foil if collecting Carbon and Oxygen signals of power samples.</li>
	</ol>
	</li>
	<li>For in-situ samples, prepare In-situ samples with specific cells that typically implement soft X-ray membrane. Check electric connections and cell integrity before loading into the experimental system. 
	NOTE: Details about in-situ cells are out of the scope of this work, but can be found in previous publications35,36,37.</li>
</ol>
3. Loading and Positioning Samples
Note: Due to the requirement of ultra-high vacuum for soft X-ray spectroscopy experiments, sample loading typically takes multiple steps to go through a buffer vacuum chamber before entering the main experimental chamber.
<ol>
	<li>Stop vacuum pumps, close vacuum valve between the sample loadlock and main experimental chamber, and vent the sample loadlock, which is typically attached directly to the experimental system with N2 gas.</li>
	<li>Use home-made sample grabber or a big tweezer to grab the sample holder and load it into loadlock.</li>
	<li>Start pumping the loadlock. Wait until the vacuum pressure gauge shows low enough vacuum for opening the loadlock into main experimental chamber, typically around mid 10-7 Torr.</li>
	<li>Open the valve between the loadlock and the main chamber. Transfer the sample holder onto the main manipulator of the main chamber by using the transfer arm.</li>
	<li>Open the valve between the main experimental chamber and the beamline. Determine the beam spot by looking at a reference sample with visible-light fluorescence.</li>
	<li>Position the sample to the beam spot by changing the coordinates of the sample manipulator of the experimental endstation.</li>
</ol>
4. Set Up the X-ray Energy and Resolution
<ol>
	<li>Change the values of the slits of the beamline monochromator, through the computer program or a manual adjustment knob, to control the energy resolution of the incident X-ray beam.</li>
	<li>Set the incident beam energy to the desired value for accessing the absorption edge of the interested element(s), e.g., 290 eV for C-K, 530 eV for O-K edges38.</li>
	<li>Connect the signal cables of the X-ray beam flux (I-0) monitor, which is typically a clean Gold mesh in the beam route.</li>
	<li>Fix the beamline monochromator mechanism and collect the beam flux intensity upon the undulator gap. Determine a particular undulator gap value for the maximum possible beam flux. 
	NOTE: Because sXAS requires a large energy range for different edges, an optimization of the undulator gap to obtain the maximum possible beam flux is often necessary.</li>
</ol>
5. Collect sXAS Data
Note: Total yield sXAS data are collected by recording the intensity of signals from both the sample current (TEY) and the channeltron or photodiode (TFY). Partial yield signals are typically collected through a gated channeltron and solid-state detector. Because the RIXS system is introduced here, and RIXS covers all kinds of partial fluorescence yield (PFY) signals, including PFY and inverse-PFY (iPFY), only the typical protocol for TEY and TFY data collection is described in this session.
<ol>
	<li>Connect the sample to the current amplifier, and feed the sample current signal (TEY) to the computer counter.</li>
	<li>Turn on power supplies and controllers of the channeltron or photodiode, feed the TFY signal to the computer counter.</li>
	<li>Start the LabVIEW sXAS data acquisition grogram BL Control Main to arrive at the software interface (Figure 2), and then click the menu button Scanning | Single Motor Scan (Figure 2).</li>
	<li>Click the menu button Scan Setup (Figure 3) to setup the scan range of the incident (beamline) X-ray photons to match the interested sXAS edge, e.g., 280-300 eV for C-K edge.</li>
	<li>Click the button Start Scan (Figure 3) to record the intensity signals from (i) the TEY (ii) the TFY, and (iii) the I-0 channels simultaneously while scanning the incident X-ray photon energy. 
	NOTE: Usually there would be a little shift of several eV on the incident X-ray photon energy. For calibration, collect the sXAS data of one or more typical reference samples before collecting the battery material samples.</li>
</ol>
6. Collect sXES and RIXS Data
Note: Because sXES is technically one of the RIXS cut at the non-resonant (high) energy range, the data collection equipment and process are essentially the same.
<ol>
	<li>Collect sXAS first to define the excitation energy range and calibrate the energy values (refer to protocol step 5).</li>
	<li>Turn on the power supply of the spectrometer detector of the sXES/RiXS system, and cool down the soft X-ray detector to reduce the background noise, per manufacturer&#39;s recommendations.</li>
	<li>Start the LabVIEW sXES/RiXS data acquisition grogram BL Control Main to arrive at the software interface (Figure 4).</li>
	<li>Click the menu button Motors (Figure 4) to set the optical parameters of the spectrograph so the detector covers the energy range of the interested elements and edges (Figure 5).</li>
	<li>Click the menu button Scanning (Figure 4) | CCD Instrument Scan (Figure 6).</li>
	<li>Click the menu button Scan Setup (Figure 6) to setup the scan range of the incident (beamline) X-ray photon energy. If collecting sXES, set it to a single value that is about 20-30 eV above the sXAS absorption edge; else, if collecting RiXS, set the incident X-ray (beamline) energy to a range that covers the sXAS absorption edge.</li>
	<li>Select the icon Apply Cosmic Ray Filter (Figure 6) to remove the cosmic ray signals from the raw RIXS 2D images, once they are collected from the spectrograph detector.</li>
	<li>Click the button Start Scan (Figure 6) to collect the fluorescence signals, which were diffracted and energy-resolved by optical grating, in the form of a 2D image by the detector on the spectrograph for each excitation energy.</li>
</ol>
7. sXAS Data Process
NOTE: The experimental data, including sXAS as well as sXES and RiXS, is processed in Igor Pro program.
<ol>
	<li>Normalize sXAS TEY and TFY signals to the I-0 signals that are collected simultaneously.</li>
	<li>Calculate the energy error between the collected sXAS of the reference samples with the standard; calibrate sXAS signals by shifting the energies according to the calculated energy error.</li>
</ol>
8. sXES and RIXS Data Process
<ol>
	<li>Integrate the intensity of the raw 2D image by summing up the photon counts along the angle-adjusted emission-energy channels to generate a single sXES or RIXS spectrum.</li>
	<li>Normalize the integrated 1D RIXS spectrum to both the incident beam flux monitored in real-time during the data collection, and the collection time (in seconds).</li>
	<li>Plot the normalized 1D spectrum in color-scaled format.</li>
	<li>For RiXS data, repeat steps 8.1-8.3 for each excitation energy to obtain a series of 1D RIXS spectra upon emission-energy channels; then, stack all the color-scaled 1D RIXS spectra one-by-one into a 2D image map, with one axis along excitation energy, another axis showing the emission-energy channels.</li>
	<li>Calibrate the values of excitation energy of the sXES spectrum or RIXS maps by using sXAS calibration, typically through reference samples (refer to Protocol step 7.2).</li>
	<li>Select a set of points (x = channel number, y = energy value) along the elastic features on the RIXS map, where the excitation and emission energies are the same; conduct linear curve fitting with the set of points to attain the formal energy value per channel; according to the relation, rescale the x axis from channel to energy.</li>
</ol>

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The authors have nothing to disclose.

The formidable challenge of improving the performance of energy storage materials requires advances of incisive tools to directly probe the chemical evolutions in battery compounds upon electrochemical operation. Soft X-ray core-level spectroscopy, such as sXAS, sXES, and RIXS, is a tool-of-choice for detecting the critical valence states of both the anions and cations involved in LIBs and SIBs.
Core-level spectroscopy techniques involve the strong excitation of core electrons to unoccupied st...

Developing high-performance batteries is one of the crucial requirements for realizing modern energy applications with environmentally benign resources and devices. Developing high-efficiency, low-cost, and sustainable energy storage devices has become critical for both electric vehicles (EVs) and the electric grid, with a projected energy storage market expansion of ten times in this decade. The ubiquitous Li-ion battery (LIB) technology remains a promising candidate for high energy-density and high power energy storage solutions1, while Na-ion batteries (SIBs) hold the promise of realizing low-cost and stable storage for green-grid applications2. However, the overall level of battery technology is well below what is required to meet the need of this new phase of mid-to-large scale energy storage1,3.
The pressing challenge of developing high-performance energy-storage system arises from the complex mechanical and electronic characteristics of the battery operations. Extensive efforts have focused on material synthesis and mechanical properties. However, the evolution of the chemical states of particular elements in battery electrodes is often under active debate for newly developed battery materials. In general, both LIBs and SIBs operate with evolving electronic states triggered by the transportation of the electrons and ions during the charge and discharge process, leading to the oxidation and reduction (redox) reactions of specific element(s). As the bottleneck for many performance parameters, battery cathodes have been paid much attention in research and developments4,5. A practical battery cathode material is often a 3d transition-metal (TM) oxide with particular structural channels for ion diffusion. Conventionally, the redox reaction is limited to the TM elements; however, recent results indicate that oxygen could possibly be utilized in reversible electrochemical cycling6. The redox mechanism is one of the most critical pieces of information for understanding an electrochemical operation, and a direct probe of the chemical states of battery electrodes with elemental sensitivity is thus highly desirable.
Synchrotron-based, soft X-ray spectroscopy is an advanced technique that detects the valence electron states in the vicinity of the Fermi level in battery materials7. Because of the high sensitivity of soft X-ray photons to the electrons of a specific element and orbital, soft X-ray spectroscopy could be utilized as a direct probe of the critical electron states in battery electrodes8, or at the interfaces in batteries9. Furthermore, compared with hard X-rays, soft X-rays are lower in energy and cover excitations of the low-Z elements, e.g., C, N, O, and of the 2p-to-3d excitation in the 3d TMs10.
The excitations of soft x-ray spectroscopy first involve electron transitions from a particular core state to an unoccupied state by absorbing energy from soft X-ray photons. The intensity of such soft X-ray absorption spectroscopy thus corresponds to the density of state (DOS) of the unoccupied (conduction-band) states with the existence of the excited core-holes. The X-ray absorption coefficient can be measured by detecting the total number of photons or electrons emitted during the decay process. The total electron yield (TEY) counts the total number of emitted electrons, and is thus a photon-in-electron-out (PIEO) detection mode. TEY has a shallow probe depth of several nanometers, and therefore is relatively surface sensitive, due to the shallow escape depth of electrons. However, as a photon-in-photon-out (PIPO) detection mode, the total fluorescence yield (TFY) measures the total number of emitted photons in the sXAS process. Its probe depth is about hundreds of nanometers, which is deeper than that of TEY. Due to the difference in probe depths, the contrast between TEY and TFY could provide important information for a comparison between the surface and bulk of the material.
sXES is a PIPO technique, corresponding to the decay of the exited state to fill the core hole, leading to the emission of X-ray photons at characteristic energies. If the core electron is excited to the continuum electron state far away from the sXAS threshold, it is a non-resonant X-ray fluorescence process corresponding to the decay of occupied (valence-band) electrons to the core holes, i.e., sXES reflects the DOS of the valence-band states. Otherwise, if the core electron is resonantly excited to exactly the absorption threshold, the resulting emission spectra feature strong excitation energy dependence. For this case, the spectroscopy experiments are denoted as resonant inelastic x-ray scattering (RIXS).
Because sXAS and sXES corresponds to the unoccupied (conduction-band) and occupied (valence-band) electron states, respectively, they provide complementary information on the electron states involved in the reduction and oxidation reactions in the battery electrodes upon electrochemical operation11. For low-Z elements, especially C12,13, N14, and O15,16,17, sXAS has been widely used for studying the critical electron states corresponding to both the electron transfer12,13 and chemical compositions15,16,17. For 3d TMs, sXAS of TM L-edges has been successfully demonstrated to be an effective probe of the TM redox reactions of V18, Mn19,20,21,22,23, Fe23,24,25,26, Co20,27, and Ni20,28. Because the TM-L sXAS features are dominated by the well-defined multiplet effect, which are sensitive to the different TM oxidation18,19,20,21,22,24,25,26,27,28 and spin states14,29, the TM sXAS data could enable even quantitative analysis of the TM redox couples in LIB and SIB electrodes27.
Compared with the popular employment of sXAS for battery material studies, RIXS is less often utilized due to the complexity of both the experiments and data interpretation for obtaining meaningful information related to battery performance10. However, due to the extremely high chemical-state selectivity of RIXS, RIXS is potentially a much more sensitive probe of the chemical state evolution in battery materials with inherent elemental sensitivity. Recent sXES and RIXS reports by Jeyachandran et al., have showcased the high sensitivity of RIXS to specific chemical configurations in the ion-solvation systems beyond sXAS30,31. With the recent rapid developments of high-efficiency RIXS systems32,33,34, RIXS has quickly shifted from a fundamental physics tool to a powerful technique for battery research, and occasionally becomes the tool-of-choice for specific studies of both the cation and anion evolution in battery compounds.
In this work, the detailed protocols for sXAS, sXES, and RIXS experiments are introduced. We cover the details of experimental planning, technical procedures for carrying out experiments, and more importantly, data processing for different spectroscopic techniques. Furthermore, three representative results in battery material studies are presented to demonstrate the applications of these three soft X-ray spectroscopy techniques. We note that the technical details of these experiments could be different at different end-stations and/or facilities. Additionally, ex-situ and in-situ experiments have very different setup procedures on sample handling due to the stringent requirements of ultra-high vacuum for soft X-ray spectroscopy35. But the protocol here represents the typical procedure and could serve as a common reference for soft X-ray spectroscopy experiments in various experimental systems at different facilities.

<table><tbody><tr><td>&lt;strong&gt;Material&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Electrode active materials</td><td>various</td><td></td><td>Synthesized in-house or obtained from various suppliers.</td></tr><tr><td>Lithium foil</td><td>Sigma-Aldrich</td><td>320080</td><td>Anode for half cells. Store and handle in an inert atmosphere glovebox under Ar. (www.sigmaaldrich.com)</td></tr><tr><td>Sodium foil</td><td>Sigma-Aldrich</td><td>282065</td><td>Anode for half cells. Store and handle in an inert atmosphere glovebox under Ar. (www.sigmaaldrich.com)</td></tr><tr><td>Electrolyte solutions</td><td>BASF</td><td>Contact vendor for desired formulations</td><td>http://www.catalysts.basf.com/p02/USWeb-Internet/catalysts/en/content/microsites/catalysts/prods-inds/batt-mats/electrolytes</td></tr><tr><td>Synthetic flake graphite</td><td>Timcal</td><td>SFG-6</td><td>Conductive additive for electrodes. (www.timcal.com)</td></tr><tr><td>Indium foil</td><td>Sigma-Aldrich</td><td>357308</td><td>Used if collecting Carbon and Oxygen signals of power samples</td></tr><tr><td>Argon gas</td><td>Air Products</td><td>Custom order, contact vendors</td><td>Argon used to fill glovebox where to assemble and store air-sensitive samples. (http://www.airproducts.com/products/gases.aspx)</td></tr><tr><td>&lt;strong&gt;Eqiupment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>CCD</td><td>iKon-L</td><td>DO936N</td><td>Used to capture the emission photons when carrying out the sXES or RiXS experiment (http://www.andor.com/scientific-cameras/ikon-xl-and-ikon-large-ccd-series/ikon-l-936)</td></tr><tr><td>Inert atmosphere glovebox</td><td>MBRAUN</td><td>MB200B</td><td>Used during air-sensitive samples assembly and storage. (http://www.mbraun.com/products/glovebox-workstations/mb200b-mod)</td></tr><tr><td>Battery Charge &amp;amp; Discharge Tester</td><td>Bio-Logic</td><td>VMP3</td><td>Used to electrochemical cycling of battery materials. (https://www.bio-logic.net/en/)</td></tr><tr><td>Swagelok cell</td><td>MTI</td><td>EQ-HSTC</td><td>Used to contain the battery for electrochemical cycling</td></tr><tr><td>Sample holder</td><td>manufactured in lab</td><td></td><td>Used to hold the samples in the experiment</td></tr><tr><td>Hardware tools</td><td>various</td><td></td><td>Including tweezers, scissors (used to assemble samples), tongs (used to transfer sample holders), etc.&amp;nbsp;</td></tr><tr><td>Carbon and Copper tape</td><td>3M</td><td>Custom order, contact vendors</td><td>Used to paste the samples onto sample holders</td></tr><tr><td>Igor Pro</td><td>WaveMetrics</td><td>7.06</td><td>Used to process the experiment data. (https://www.wavemetrics.com/index.html)</td></tr></tbody></table>

elemental-sensitive detection of the chemistry in batteries through soft x-ray absorption spectroscopy and resonant inelastic x-ray scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

The sample holder and pasted samples are shown in Figure 1. Figure 7a is a typical RIXS image collected at a particular excitation energy with the spectrometer set to the interested edges. The image shown here was collected on a battery electrode material, LiNi0.33Co0.33Mn0.33O2, with an excitation energy of 858 eV and the detector set at about 500-900 eV range to cover...

Watch this Scientific Journal Video about Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering at JoVE.com

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

elemental-sensitive-detection-chemistry-batteries-through-soft-x-ray

Research

JoVE Journal

Chemistry

12.6K Views.  Stanford University. Hier presenteren we een protocol voor typische experimenten van zachte X-ray Absorptie spectroscopie (sXAS) en resonant inelastisch X-ray verstrooiing (RIXS) met toepassingen in batterij materiële studies.

Video: Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Engineering

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric vehicles.1,2 However, many challenges, such as energy density and battery lifetimes, need to be overcome before this particular battery technology can be widely implemented in such applications.3 This research is challenging, and we outline a method to address these challenges using in situ NPD to probe the crystal structure of electrodes undergoing electrochemical cycling (charge/discharge) in a battery. NPD data help determine the underlying structural mechanism responsible for a range of electrode properties, and this information can direct the development of better electrodes and batteries.
We briefly review six types of battery designs custom-made for NPD experiments and detail the method to construct the &#8216;roll-over&#8217; cell that we have successfully used on the high-intensity NPD instrument, WOMBAT, at the Australian Nuclear Science and Technology Organisation (ANSTO). The design considerations and materials used for cell construction are discussed in conjunction with aspects of the actual in situ NPD experiment and initial directions are presented on how to analyze such complex in situ data.

In Situ Neutron Powder Diffraction Using Custom-made Lithium-ion Batteries

We describe the design and construction of an electrochemical cell for the examination of electrode materials using in situ neutron powder diffraction (NPD). We briefly comment on alternate in situ NPD cell designs and discuss methods for the analysis of the corresponding in situ NPD data produced using this cell.

Li-ion batteries are widely used in portable electronic devices and are considered as promising candidates for higher-energy applications such as electric ...

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.
Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of &gt; 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.
Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

The use of energy dispersive X-ray tomography in the scanning transmission electron microscope to characterize elemental distributions within single nanoparticles in three dimensions is described.

Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Detection and Recovery of Palladium, Gold and Cobalt Metals from the Urban Mine Using Novel Sensors/Adsorbents Designated with Nanoscale Wagon-wheel-shaped Pores

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in industrialized countries. Here, the development of optical mesosensors/adsorbents (MSAs) for efficient recognition and selective recovery of Pd(II), Au(III), and Co(II) from urban mine was achieved. A simple, general method for preparing MSAs based on using high-order mesoporous monolithic scaffolds was described. Hierarchical cubic Ia3d wagon-wheel-shaped MSAs were fabricated by anchoring chelating agents (colorants) into three-dimensional pores and micrometric particle surfaces of the mesoporous monolithic scaffolds. Findings show, for the first time, evidence of controlled optical recognition of Pd(II), Au(III), and Co(II) ions and a highly selective system for recovery of Pd(II) ions (up to ~95%) in ores and industrial wastes. Furthermore, the controlled assessment processes described herein involve evaluation of intrinsic properties (e.g., visual signal change, long-term stability, adsorption efficiency, extraordinary sensitivity, selectivity, and reusability); thus, expensive, sophisticated instruments are not required. Results show evidence that MSAs will attract worldwide attention as a promising technological means of recovering and recycling palladium, gold and cobalt metals.

Because of the importance and extensive use of palladium, gold and cobalt metals in high-technology equipment, their recovery and recycling constitute an important industrial challenge. The metal recovery system described herein is a simple, low-cost means for the effective detection, removal, and recovery of these metals from the urban mine.

Developing low-cost, efficient processes for recovering and recycling palladium, gold and cobalt metals from urban mine remains a significant challenge in ...

Fabrication of a Dipole-assisted Solid Phase Extraction Microchip for Trace Metal Analysis in Water Samples

This paper describes a fabrication protocol for a dipole-assisted solid phase extraction (SPE) microchip available for trace metal analysis in water samples. A brief overview of the evolution of chip-based SPE techniques is provided. This is followed by an introduction to specific polymeric materials and their role in SPE. To develop an innovative dipole-assisted SPE technique, a chlorine (Cl)-containing SPE functionality was implanted into a poly(methyl methacrylate) (PMMA) microchip. Herein, diverse analytical techniques including contact angle analysis, Raman spectroscopic analysis, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis were employed to validate the utility of the implantation protocol of the C-Cl moieties on the PMMA. The analytical results of the X-ray absorption near-edge structure (XANES) analysis also demonstrated the feasibility of the Cl-containing PMMA used as an extraction medium by virtue of the dipole-ion interactions between the highly electronegative C-Cl moieties and the positively charged metal ions.

The fabrication protocol of a dipole-assisted solid phase extraction microchip for the trace metal analysis is presented.

This paper describes a fabrication protocol for a dipole-assisted solid phase extraction (SPE) microchip available for trace metal analysis in water ...

Bioengineering

Nanoscale Characterization of Liquid-Solid Interfaces by Coupling Cryo-Focused Ion Beam Milling with Scanning Electron Microscopy and Spectroscopy

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar energy and fuel generation, and electrochemical energy storage. Nanoscale characterization of such interfaces has recently been achieved using cryogenic electron microscopy, thereby providing a new path to advancing our fundamental understanding of interface processes.
This contribution provides a practical guide to mapping the structure and chemistry of solid-liquid interfaces in materials and devices using an integrated cryogenic electron microscopy approach. In this approach, we pair cryogenic sample preparation which allows stabilization of solid-liquid interfaces with cryogenic focused ion beam (cryo-FIB) milling to create cross-sections through these complex buried structures. Cryogenic scanning electron microscopy (cryo-SEM) techniques performed in a dual-beam FIB/SEM enable direct imaging as well as chemical mapping at the nanoscale. We discuss practical challenges, strategies to overcome them, as well as protocols for obtaining optimal results. While we focus in our discussion on interfaces in energy storage devices, the methods outlined are broadly applicable to a range of fields where solid-liquid interface play a key role.

Cryogenic Focused Ion Beam (FIB) and Scanning Electron Microscopy (SEM) techniques can provide key insights into the chemistry and morphology of intact solid-liquid interfaces. Methods for preparing high quality Energy Dispersive X-ray (EDX) spectroscopic maps of such interfaces are detailed, with a focus on energy storage devices.

Physical and chemical processes at solid-liquid interfaces play a crucial role in many natural and technological phenomena, including catalysis, solar ...

Quantitative Atomic-Site Analysis of Functional Dopants/Point Defects in Crystalline Materials by Electron-Channeling-Enhanced Microanalysis

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident high-energy electron beam is rocked with the submicrometric pivot point fixed on a specimen. This method enables us to quantitatively derive the site occupancies and site-dependent chemical information of impurities or intentionally doped functional elements in a specimen, using energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy attached to a scanning transmission electron microscope, which is of significant interest to current materials science, particularly related to nanotechnologies. This scheme is applicable to any combination of elements even when the conventional Rietveld analysis by X-ray or neutron diffraction occasionally fails to provide the desired results because of limited sample sizes and close scattering factors of neighboring elements in the periodic table. In this methodological article, we demonstrate the basic experimental procedure and analysis method of the present beam-rocking microanalysis.

We provide a general outline of quantitative microanalysis methods for estimating the site occupancies of impurities and their chemical states by taking advantage of electron-channeling phenomena under incident electron beam-rocking conditions, which reliably extract information from minority species, light elements, oxygen vacancies, and other point/line/planar defects.

A novel elemental and chemical analysis scheme based on electron-channeling phenomena in crystalline materials is introduced, where the incident ...

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

With the ever-increasing use of Li-ion batteries, especially due to their adoption in electric vehicles, their safety is in prime focus. Thus, the all-solid-state batteries (ASSBs) that use solid electrolytes instead of liquid electrolytes, which reduce the risk of flammability, have been the center stage of battery research for the last few years. However, in the ASSB, the ion transportation through the solid-solid electrolyte-electrode interface poses a challenge due to contact and chemical/electrochemical stability issues. Applying a suitable coating around the electrode and/or electrolyte particles offers a convenient solution, leading to better performance. For this, researchers are screening potential electronic/ionic conductive and nonconductive coatings to find the best coatings with suitable thickness for long-term chemical, electrochemical, and mechanical stability. Operando transmission electron microscopy (TEM) couples high spatial resolution with high temporal resolution to allow visualization of dynamic processes, and thus is an ideal tool to evaluate electrode/electrolyte coatings via studying (de)lithiation at a single particle level in real-time. However, the accumulated electron dose during a typical high-resolution in situ work may affect the electrochemical pathways, evaluation of which can be time-consuming. The current protocol presents an alternative procedure in which the potential coatings are applied on Si nanoparticles and are subjected to (de)lithiation during operando TEM experiments. The high volume changes of Si nanoparticles during (de)lithiation allow monitoring of the coating behavior at a relatively low magnification. Thus, the whole process is very electron-dose efficient and offers quick screening of potential coatings.

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

Utilizing the volume change of Si nanoparticles during (de)lithiation, the present protocol describes a screening method of potential coatings for all-solid-state batteries using in situ transmission electron microscopy.

With the ever-increasing use of Li-ion batteries, especially due to their adoption in electric vehicles, their safety is in prime focus. Thus, the ...

X-ray Photoelectron Spectroscopy

Source: Faisal Alamgir, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA
X-ray photoelectron spectroscopy (XPS) is a technique that measures the elemental composition, empirical formula, chemical state and electronic state of the elements that exist within a material. XPS spectra are obtained by irradiating a material with a beam of X-rays while simultaneously measuring the kinetic energy and number of electrons that escape from the top several nanometers of the material being analyzed (within ~ the top 10 nm, for typical kinetic energies of the electrons). Due to the fact that the signal electrons escape predominantly from within the first few nanometers of the material, XPS is considered a surface analytical technique.
The discovery and the application of the physical principles behind XPS or, as it was known earlier, electron spectroscopy for chemical analysis (ESCA), led to two Nobel prizes in physics. The first was awarded in 1921 to Albert Einstein for his explanation of the photoelectric effect in 1905. The photoelectric effect underpins the process by which signal is generated in XPS. Much later, Kai Siegbahn developed ESCA based on some of the early works by Innes, Moseley, Rawlinson and Robinson, and recorded, in 1954, the first high-energy-resolution XPS spectrum of NaCl. Further demonstration of the power of ESCA/XPS for chemical analysis, together with the development of the associated instrumentation for the technique, led to the first commercial monochromatic XPS instrument in 1969 and the Nobel Prize for Physics in 1981 to Siegbahn in acknowledgement of his extensive efforts to develop the technique as an analytical tool.

X-ray Photoelectron Spectroscopy and Elemental Composition

Source: Faisal Alamgir, School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA
X-ray photoelectron spectroscopy (XPS) ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

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