National Synchrotron Light Source Research Articles

Crystal structure solution and high-temperature thermal expansion in NaZr2(PO4)3-type materials.

The NaZr2P3O12 family of materials have shown low and tailorable thermal expansion properties. In this study, SrZr4P6O24 (SrO·4ZrO2·3P2O5), CaZr4P6O24 (CaO·4ZrO2·3P2O5), MgZr4P6O24 (MgO·4ZrO2·3P2O5), NaTi2P3O12 [½(Na2O·4TiO2·3P2O5)], NaZr2P3O12 [½(Na2O·4ZrO2·3P2O5)], and related solid solutions were synthesized using the organic-inorganic steric entrapment method. The samples were characterized by in-situ high-temperature X-ray diffraction from 25 to 1500°C at the Advanced Photon Source and National Synchrotron Light Source II. The average linear thermal expansion of SrZr4P6O24 and CaZr4P6O24 was between -1 × 10-6 per°C and 6 ×10-6 per °C from 25 to 1500°C. The crystal structures of the high-temperature polymorphs of CaZr4P6O24 and SrZr4P6O24 with R3c symmetry were solved by Fourier difference mapping and Rietveld refinement. This polymorph is present above ∼1250°C. This work measured thermal expansion coefficients to 1500°C for all samples and investigated the differences in thermal expansion mechanisms between polymorphs and between compositions.

Short communication: Synchrotron-based elemental mapping of single grains to investigate variable infrared-radiofluorescence emissions for luminescence dating

Abstract. During ionizing irradiation, potassium (K)-rich feldspar grains emit infrared (IR) light, which is used for infrared radiofluorescence (IR-RF) dating. The late-saturating IR-RF emission centred at ∼880 nm represents a promising tool to date Quaternary sediments. In the present work, we report the presence of individual grains in the K-feldspar density fraction displaying an aberrant IR-RF signal shape, whose combined intensity contaminates the sum signal of an aliquot composed of dozens of grains. Our experiments were carried out at the National Synchrotron Light Source (NSLS-II) at the submicron-resolution X-ray spectroscopy (SRX) beamline. We analysed coarse (>90 µm) K-feldspar-bearing grains of five samples of different ages and origin in order to characterize the composition of grains yielding the desired or contaminated IR-RF emission. Using micro-X-ray fluorescence (μ-XRF), we successfully acquired element distribution maps of up to 15 elements (<1 µm resolution) of sections of full grains previously used for IR-RF dating. In keeping with current theories of IR-RF signal production, we observed a trend between the relative proportions of Pb and Fe and the shape of the IR-RF signal, namely that most grains with the desired IR-RF signal shape had high Pb and low Fe contents. Interestingly, these grains were also defined by high Ba and low Ca contents. Our study also represents a proof of concept for mapping the oxidation states of Fe using micro-X-ray absorption near-edge structure spectroscopy (μ-XANES) on individual grains. The high spatial resolution enabled by synchrotron X-ray spectroscopy makes it a powerful tool for future experiments to elucidate long-standing issues concerning the nature and type of defect(s) associated with the main dosimetric trap in feldspar.

Isotropic negative thermal expansion in ZrW2O8 and HfW2O8 from 1100 to 1275°C

AbstractZrW2O8 (ZrO2•2WO3) and HfW2O8 (HfO2•2WO3) have been the focus of thermal expansion studies due to their isotropic negative thermal expansion (NTE) measured previously at temperatures below 775°C. This work presents measurements of these materials at their thermodynamically stable temperature ranges of 1105 and 1257°C for ZrW2O8 and 1105–1276°C for HfW2O8, where they were characterized with in situ, powder X‐ray diffraction. The linear coefficients of thermal expansion were measured to be −5.52 × 10−6 and −4.87 × 10−6°C−1 for ZrW2O8 and HfW2O8, respectively. The mechanism leading to this NTE is discussed. Powder samples were synthesized by a solution‐based process called the organic–inorganic steric entrapment method. In situ characterization in air was carried out at the National Synchrotron Light Source II using a hexapole lamp, optical furnace and the Advanced Photon Source using a quadrupole lamp, optical furnace to achieve elevated temperatures.

Nonlinear optics from hybrid dispersive orbits

In this paper we present an expansion of the technique of characterizing nonlinear optics from off-energy orbits (NOECO) [1] to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine, however, it doesn’t account for harmonic sextupoles, which are widely used on many other machines. Through generating vertical dispersion with chromatic skew quadrupoles, a measurable dependence of nonlinear optics on harmonic sextupoles can be observed from hybrid horizontal and vertical dispersive orbits. Proof of concept of our expanded technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.

Nonlinear optics from hybrid dispersive orbits

In this paper we expand the technique of characterizing nonlinear optics from off-energy closed orbits (NOECO) to cover harmonic sextupoles in storage rings. The existing NOECO technique has been successfully used to correct the chromatic sextupole errors on the MAX-IV machine (Olsson et al., 2020), however, it does not account for harmonic sextupoles, which are still widely used on many other machines. By generating vertical dispersion with chromatic skew quadrupoles, a measurable chromatic function dependence on harmonic sextupoles can be observed on hybrid dispersive orbits. Proof of concept of this technique was accomplished by simulations and beam measurements on the National Synchrotron Light Source II (NSLS-II) storage ring.

Operando EXAFS to Determine the Mechanism of Bi Dopant at Low Concentration in Rechargeable MnO2 Cathodes

The rechargeable Zn-MnO2 battery system is one few systems in development capable of meeting the extreme cost requirements needed for global integration of battery storage in the power grid. Doping the MnO2 cathode with Bi allows it to cycle reversibly between layered Mn oxides 𝛿-MnO2 and Mn(OH)2, without detrimental formation of Mn3O4. This provides a cathode capacity of 617 mAh/g, which modeling has shown to enable costs below $50/kWh. However, to achieve commercial adoption, cycling stability must be improved. The mechanism through which the Bi dopant improves rechargeability remains largely unknown, and this must be clarified to rationally improve the system. Our previous work has established that the mechanism involves structurally disordered intermediates, and thus characterization techniques based on short-range order need to be used. This talk will demonstrate rapidly collected, operando extended x-ray absorption fine-structure (EXAFS) data collected on MnO2 cathodes with and without Bi dopant. Operando techniques are scientifically powerful as they reduce experimental uncertainty resulting from destructive preparation of samples for ex-situ analysis. In addition, rapid EXAFS collection allows for analysis of the kinetics of Mn coordination changes.Previously, the formation of a disordered 𝛿-MnO2 phase with no diffraction signal was identified during the first charge of Bi-modified MnO2 cathodes.1 In this work, operando X-Ray Absorption Spectroscopy (XAS) was employed to further compare Mn coordination environments in standard and Bi-modified cathodes at points of interest throughout cycling (pristine, intermediate, discharge, intermediate, charged). Specifically, the EXAFS region of the data was used to visualize the dynamic first shell (Mn-O) and second shell (Mn-Mn) interatomic distances during the first cycle. The values throughout cycling were compared with interatomic distances of Mn oxides that have been reported in literature, allowing the data to be used both for “fingerprinting” as a method of identifying the same pristine, intermediate, and discharged phases in both cases. Rapid EXAFS data collection allows for precise analysis of the potentials and states of charge at which these compounds form in each cathode. This portion of the analysis allows for observation of the faster kinetics of changes in Mn coordination in the Bi-modified MnO2 cathode. Furthmore, analysis of the first charge shows that deformation of the Mn(OH)2 discharge product is observed at the same potential energy in both cases, demonstrating that the thermodynamic stability of Mn(OH)2 is not improved in the first cycle of Bi-modified MnO2 cathodes, despite improved capacity. These findings suggest that Bi dopant may primarily act to improve kinetics within the MnO2 electrode rather than enhancing the thermodynamic stability to prevent degradation into Mn3O4. References Andrea M. Bruck et al 2020 Electrochem. Soc. 167 Acknowledgements We acknowledge financial support from the National Science Foundation under Award Number CBET-ES-2044602. This research used resources of beamline 7-BM (QAS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Promoting Hydrogen Evolution and Oxidation by Reconstructing Hydrogen-Bonding Network of Interfacial Water

The hydrogen evolution and oxidation reactions (HER/HOR) at the electrode-water control the performance of water electrolyzers and hydrogen fuel cells, two important devices for deep decarbonization of our economy (1). Platinum (Pt) catalyzes the HER/HOR with exceptional activity and stability across a wide pH range. However, its activity progressively decreases by about two orders of magnitude as the pH increases from 0 to 13 (2, 3). The lack of understanding of this pH dependence reflects our fundamental knowledge gaps in electrochemistry and has hindered the advancement of alkaline electrolyzers and fuel cells.Herein, we promoted the HER/HOR of Pt in base by introducing N-methylimidazoles in the Pt-water interface. In situ spectroscopic characterization of the interface together with computations showed that the N-methylimidazoles form strong hydrogen-bonding with neighboring water molecules thereby reconstructing the H-bond network of interfacial water. We accordingly established a unified mechanism by which the HER/HOR in acid and base proceeds via diffusion of protons and hydroxides, respectively through the H-bond network of interfacial water by the Grotthuss mechanism. This mechanism accounts for the pH-dependent HER/HOR kinetics of platinum, a long-standing puzzle. Utilization of N-methylimidazoles as the HER/HOR probes and promoters not only leads to the elucidation of the HER/HOR mechanism but also holds great promise for applications. We have demonstrated 40% performance improvement of an anion exchange membrane water electrolyzer by adding 10-5 M 1,2-dimethylimidazole into the 0.1 M potassium hydroxide solution fed into its Pt cathode. Acknowledgements This work was supported by the Office of Naval Research (ONR) grant N000141712608 (Q.J.)This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory Contract DE-SC0012704. Beamline operations were supported in part by the Synchrotron Catalysis Consortium Grant DE-SC0012335. V. R. Stamenkovic, D. Strmcnik, P. P. Lopes and N. M. Markovic, Nat. Mater., 16, 57 (2017). J. Durst, A. Siebel, C. Simon, F. Hasché, J. Herranz and H. A. Gasteiger, Energy Environ. Sci., 7, 2255 (2014). W. Sheng, Z. Zhuang, M. Gao, J. Zheng, J. G. Chen and Y. Yan, Nat. Commun., 6 (2015). Figure 1

Li-Ion and Na-Ion Intercalation in Layered MnO2 Cathodes Enabled by Using Bismuth as a Cation Pillar

Rechargeability of low-cost MnO2 cathodes in aqueous cells has the potential to be an enabling technology for low-cost (<$50/kWh) grid-scale batteries. This rechargeability is imparted by modifying the MnO2 with Bi. In this talk we detail using Bi doping for structural stabilization of MnO2 cathodes for Li-ion and Na-ion batteries in dry, non-aqueous electrolyte. We do this by preparing a series of Bi-doped layered MnO2 compounds, which also contain K ions and crystal water. These phyllomanganates or birnessite-type compounds have the general formula KxBiy-MnO2 • nH2O. The materials are structurally characterized by synchrotron X-ray powder diffraction (XPD) and confocal Raman microscopy. It is found that incorporation of Bi in the structure increases the crystallinity of the material by ordering the interlayer cations. This ordering results in the emergence of a structural superlattice in the material, which has been reported previously for birnessite inserted with other heavy, multivalent cations such as as Sr2+, Ba2+, and Ca2+.We selected three Bi doping levels to study in Li-ion and Na-ion batteries: undoped (y = 0), low-doping (y = 0.013 or 1.3%), and high doping (y = 0.043 or 4.3%). Both doped materials had capacity over 200 mAh/g and allowed for far more stable cell cycling than the undoped Kx-MnO2. The cells made with 4.3% doping of Bi were by far more stable. These cycled at 175-190 mAh/g specific capacity through 100 cycles with a nominal voltage of 2.9 V. Operando XRD experiments to characterize the cathodes within sealed coin cells showed that high-level doping (4.3%) promoted dehydration of the KxBiy-MnO2 interlayer, which had a distance of 6.4 Å. This showed that loss of the crystal water from the interlayer was key to achieving maximum stability during cycling. Lower Bi doping (1.3%) did not cause loss of the crystal water once the cathode was wetted with electrolyte. Previous reports have suggested that Bi doping of 20% results in stabilized Li-ion cycling in layered MnO2. However, these reports involved largely amorphous active material. Our results showed that Bi doping of only 1.3% still provided a large stability benefit, and the high crystallinity of our material allowed it to be structurally characterized, both in the as-prepared state and operando during battery cycling. Results from Na-ion cells will also be presented.Stabilized MnO2-based cathodes that cycle with good capacity and somewhat lower cell voltage than traditional Li-ion cells are a promising strategy for low-cost batteries for the grid. The possibility of using Na as the working ion is also useful for large-scale deployment of batteries to balance renewable power. Acknowledgments This work was supported by the U.S. Department of Energy (DOE) Office of Electricity Delivery and Energy Reliability, Dr. Imre Gyuk, Energy Storage Program Manager. This research used resources of the Advanced Photon Source beamline 6-BM, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This research also used resources at beamlines 7-BM (QAS) and 28-ID-2 (XPD) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Development of the high energy engineering X-ray (HEX) superconducting wiggler, magnetic measurement, installation, and commissioning.

The High energy Engineering X-ray (HEX) diffraction beamline at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Lab (BNL) is the first high-energy beamline capable of reaching 200keV for a monochromatic beam. With the 3 GeV electron beam energy for the NSLS-II ring, only the superconducting wiggler (SCW) producing greater than 4T peak field can cover these ranges with a sufficient number of photons. The 1.2 m-long HEX-SCW has a period length of 70mm and a field strength on-axis of 4.3T. It utilizes no liquid helium, and the vertical aperture size of the electron beam vacuum chamber is 8mm. Unlike regular undulators/wigglers, there is no standard configuration for the magnetic measurement system for superconducting insertion devices. The NSLS-II Insertion Devices group has developed, in collaboration with the vacuum group, a novel in-vacuum Hall mapper with a 1.75m in-vacuum linear motor and an in-vacuum flip coil system utilizing many commercial-off-the-shelf products. The measurements were conducted at the BNL, and the device was installed in the ring and commissioned. This paper provides a description of the SCW and its magnetic measurement systems, as well as a brief account of the installation and commissioning efforts.

Correction of storage ring optics with an improved closed-orbit modulation method

We improved a previously proposed method of using closed-orbit modulation for linear optics and coupling correction. Instead of fitting individual closed orbits, the improved method decomposes the orbit oscillation data into two orthogonal modes and fits the amplitudes of the modes at all beam position monitors. While the original method is limited to process around tens to a hundred orbits, the improved method can process thousands of orbits, which are easily available when alternating-current waveforms are applied to the two modulating correctors. The method has been experimentally demonstrated on the National Synchrotron Light Source (NSLS)-II storage ring.

Flatfielding of hybrid pixel detectors in tender x-ray scattering

The ability of the soft matter interfaces beamline at National Synchrotron Light Source II to access x-ray energy in the tender x-ray regime, i.e., from 2.1 to 5keV, enables new resonant x-ray scattering studies at the sulfur K-edge and others. We present a new approach to correct data acquired in the tender x-ray regime with a Pilatus3 detector in order to improve the data quality and to correct the various artifacts inherent to hybrid pixel detectors, such as variations in modules' efficiency or noisy detector module junctions. This new flatfielding significantly enhances the data quality and enables detection of weak scattering signals.

Specimen-displacement correction for powder X-ray diffraction in Debye-Scherrer geometry with a flat area detector.

The effect of small changes in the speci-men-to-detector distance on the unit-cell parameters is examined for synchrotron powder diffraction in Debye-Scherrer (transmission) geometry with a flat area detector. An analytical correction equationis proposed to fix the shift in 2θ values due to speci-men capillary displacement. This equationdoes not require the use of an internal reference material, is applied during the Rietveld refinement step, and is analogous to the speci-men-displacement correction equations for Bragg-Brentano and curved-detector Debye-Scherrer geometry experiments, but has a different functional form. The 2θ correction equationis compared with another speci-men-displacement correction based on the use of an internal reference material in which new integration and calibration parameters of area-detector images are determined. Example data sets showing the effect of a 3.3 mm speci-men displacement on the unit-cell parameters for 25°C CeO2, including both types of displacement correction, are described. These experiments were performed at powder X-ray diffraction beamlines at the National Synchrotron Light Source II at Brookhaven National Laboratory and the Advanced Photon Source at Argonne National Laboratory.

Physical optics simulations for synchrotron radiation sources.

We describe approaches to high-accuracy physical optics calculations used for the development of x-ray beamlines at synchrotron radiation sources, as well as simulation of experiments and processing of experimental data at some of these beamlines. We pay special attention to the treatment of the partial coherence of x rays, a topic of high practical importance for modern low-emittance high-brightness synchrotron radiation facilities. The approaches are based, to a large extent, on the works of Emil Wolf and co-authors, including the basic scalar diffraction theory and the coherent mode decomposition method. The presented simulation examples are related to the case of the novel Coherent Diffractive Imaging beamline that is currently under development at the National Synchrotron Light Source II at the Brookhaven National Laboratory.

Combining diagnostics, modeling, and control systems for automated alignment of the TES beamline

X-ray beamlines are essential components of all synchrotron light sources. Practical operations involve frequent variation in beamline component positions and orientation, particularly when photon beam parameters shift due to experimental needs, or due to variations in the incoming photon beam. The alignment process can be time consuming and takes away from valuable beam time for experimental data collection. We describe progress in the automation of certain alignment tasks on the tender-energy X-ray spectroscopy (TES) beamline at the National Synchrotron Light Source II (NSLS-II). The beamline is controlled using the BlueSky software in which high level experimental plans guide the beamline components during an experiment. Numerous software packages exist for beamline modeling, and they may be tied to the beamline control system using a package we are continuing to develop called Sirepo-Bluesky. The photon beam distribution may be measured with fluorescent screens, and a relation between beam and machine state can be found by varying the mirror and aperture settings over a multi-dimensional range. We describe the results of such parameter varying measurements and how we are combining Sirepo-Bluesky with machine learning methods and reduced models to automate mirror alignment on the TES beamline.

Observation and Mitigation of Beam Damage Effects on the in Situ Experiment of Li-Ion Battery Cathodes: A Transmission X-Ray Microscopy Study

Advanced characterizations play critical roles in understanding the fundamental properties of important materials. For accurate characterization, it is always necessary to address the possibility of probe-induced damage. A typical example is the successful application of cryo electron microscopy with low dose electron to characterize highly sensitive samples (ref1-3). Unfortunately, there have been very few studies on the effects of radiation damage on Li-ion battery systems caused by synchrotron x-ray beam. In this presentation, we provide direct evidence of synchrotron x-ray beam damage during in situ characterization of battery materials, observed by transmission x-ray microscopy (TXM). The unique capabilities of this technique in obtaining both morphological and chemical information enabled us to study the beam damage issue caused by x-ray. Li-rich Li1.2Ni0.13Mn0.54Co0.13O2 material was characterized in situ to study the redox reaction mechanism of this material. Beam damage in the form of bubble formation in the liquid electrolyte was observed when the material was irradiated with x-ray during 2D/3D XANES (x-ray absorption near edge structure) image collection at Ni K-edge. The bubble formation in liquid electrolyte is most likely due to the decomposition of the electrolyte triggered by x-ray irradiation. This suggests beam damage issue needs to be considered not only for TXM which is commonly used to study the depth-dependent redox reaction in individual particles, but also spectroscopic techniques that employ similar energy range. Such damage may be related to the huge x-ray flux used in the in situ experiment. When filters were used to reduce the flux, the bubble formation was significantly reduced. We further show the evolution of the Ni redox during the cycling with suppressed beam damage, which should be more faithfully reflecting the situation. Acknowledgement This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the US Department of Energy (DOE) through the Advanced Battery Materials Research (BMR) Program, including Battery500 Consortium under contract no. DE-SC0012704. This research used beamline 18-ID of the National Synchrotron Light Source II, a US DOE Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. References J. Z. Chen et al., J. Struct. Biol., 161, 92–100 (2008).X. Wang, Y. Li, and Y. S. Meng, Joule, 2, 2225–2234 (2018).X. Wang et al., Nano Lett., 17, 7606–7612 (2017).

(Invited) Identification of Lithium Hydride and Nanocrystalline Lithium Fluoride in the SEI of Lithium Metal Anodes and the Stabilization of High Ni Layered Structure at Ultra-High Voltage through Cathode Electrolyte Interphase Engineering

Solid-electrolyte interphase (SEI) plays a pivotal role in the performance of lithium metal anode, which is promising for high energy batteries. Understanding SEI composition is important but very challenging. Here we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identify and differentiate the two elusive components, LiH and LiF, in the SEI of lithium metal anodes. LiH is identified as a component of SEI in high abundance, and the possibility of its misidentification as LiF in the literature is discussed. LiF in the SEI is found to have different structural features from LiF in bulk phase, including larger lattice parameter and smaller grain size (<3 nm). These characteristics favor Li+ transport, and explain why an ionic insulator, like LiF, has been found to be a favored component for SEI. PDF analysis of the SEI reveals key amorphous components related to solvent or anion decomposition.Nickel-rich layered cathode materials with high energy density are very promising for next generation batteries when coupled with lithium metal anode. However, the practical capacities accessible are far less than the theoretical value due to their structural instability during cycling, especially when charged at high voltages. Such challenge has been attributed to the concomitant electrolyte instability and cathode structural and morphological degradation. Therefore, various approaches have been developed through electrolyte engineering and bulk cathode material modifications. In this presentation, we will report a simple interphase engineering approach by using an ionic electrolyte additive, lithium difluorophosphate (LiDFP). Through theoretical calculation, we found that self-decomposition product PO2F of LiDFP additive is adsorbed strongly and uniformly on the Ni-rich cathode, which is further decomposed to Li3PO4 and LiF through the catalytic effect of transition metals. The new interphasial chemistry contributed from LiDFP stabilizes the bulk structure of Ni-rich cathode materials and prevents the performance degradation by suppressing the dissolution of transition metals and undesired structural changes. Even after 200 cycles with charge limit as high as 4.8 V, no rock-salt phase can be detected in LiNi0.76Co0.10Mn0.14O2 (NMC76), and the cell consisting of NMC76 cathode and lithium metal anode retains 97% of the initial capacity (235 mAh/g). Various advanced characterizations were used, on both atomic and electrode levels, to reveal the mechanism how a new interphase stabilizes the layer structures in bulk electrode. The dissolution of nickel was identified to be most serious at high voltage, rather than the widely believed manganese dissolution. The transition metal dissolution can be effectively suppressed by LiDFP additive. Furthermore, the cathode surface protected by LiDFP-derived interphase is shown to regulate a more uniform lithium distribution within the bulk cathode particles and effectively mitigate the strain and crack formation. Machine-learning assisted nano-tomography discovered that such interphase-bulk interaction is most effective for those small-sized, spherically-shaped particles.Acknowledgement:The work done at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. DOE through the Advanced Battery Materials Research (BMR) Program, (Battery500 Consortium), and Applied Battery Research for Transportation (ABRT) program under contract No. DE-SC0012704. This work used the resources of the Center for Functional Nanomaterials, a U.S. DOE office of Science User Facility, at Brookhaven National Laboratory, and beamlines 5-ID, 7-BM, 23-ID-2, and 28-ID-2 of the National Synchrotron Light Source II, a US DOE Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. The work done at Pacific Northwest National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy through the Advanced Battery Materials Research (BMR) Program (Battery500 Consortium) under contract No. DE-AC02-05CH11231. The work at ARL was performed under JCESR, an Energy Research Hub funded by Basic Energy Science, US Department of Energy.

Lithium Substitution in P3-Structured Copper-Based Cathodes for Sodium-Ion Batteries

Sodium-ion batteries promise low-cost energy storage for the grid and electric vehicles, building upon the established “rocking-chair” Li-ion design, while benefitting from the natural abundance of sodium and the ability to utilize iron or copper redox reactions to further reduce the material cost. Nonetheless, Na-ion adoption has been hindered due to low energy density and large structural changes leading to poor long-term cyclability. It has been recently shown that additional reversible capacity can be obtained through oxygen redox with low voltage hysteresis in selected Na-ion layered oxide cathodes. However, the mechanisms and the intermediate species that enable this reversible oxygen redox are highly debated and not fully understood. Here we focus on several P3-structured sodium-deficient NaxY1/3Mn2/3O2 cathodes, where Y can be Cu or derivatives with partial lithium substitution, to elucidate how lithium substitution influences both the redox mechanism and the structural evolution during electrochemical cycling. Our results show a small amount (~7%) of lithium substitution can change the reaction pathway from a two-phase reaction to a solid solution mechanism, increasing stability and capacity retention. A multimodal characterization approach combining synchrotron-based X-ray spectroscopy, microscopy, and scattering techniques along with nuclear magnetic resonance spectroscopy, provides insights into the redox mechanisms, chemical species distribution, structural evolution, and phase transitions during electrochemical cycling.Acknowledgment: The work at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704. This research used resources of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Electrochemical and Structural Study on PVDF-Based Polymer Electrolytes for Solid-State Batteries

Lithium-ion batteries are widely used today in powering devices from portable electronics to electric vehicles. Despite their great success, this battery chemistry relies on organic solvent-based liquid electrolytes which are highly flammable, leading to major safety concerns. In contrast, solid-state batteries, which are based on solid-state electrolytes, are regarded to have much better safety characteristics and potentially higher energy density than the conventional lithium-ion batteries. Solid-state electrolytes usually include ceramics, polymers, gels, and composites. Among them, polymer materials have attracted considerable attention due to their great interfacial contact, flexibility, and easy fabrication. In particular, polyvinylidene fluoride (PVDF) polymer electrolyte is a promising candidate as it can potentially provide a high voltage window and enable high energy density solid-state batteries. However, the current PVDF-based polymer electrolyte is still not compatible with high voltage cathodes, such as layered lithium transition metal oxides and the interaction between the salt and PVDF polymer has not been fully elucidated.We have systematically studied the PVDF-based electrolytes with different salts and salt combinations, including lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and lithium bis(pentafluoroethanesulfonyl)imide (LiBETI). The optimized electrolyte delivers excellent performance for solid-state Li||LiFePO4 cells, achieving a specific capacity of over 150 mAh/g and lasting more than 50 cycles with over 99% capacity retention. Similar tests have also been applied to lithium nickel manganese cobalt oxides (NMC), and the preliminary results show promising cycling stability and capacity retention. In addition to electrochemical study, we employed a range of synchrotron-based X-ray techniques, including diffraction, pair distribution function analysis, and absorption spectroscopy, to investigate the interactions between the polymer and lithium salt in the polymer electrolytes. This knowledge will provide valuable information for designing new polymer electrolyte systems.Acknowledgments: The work at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. Department of Energy through the Advanced Battery Materials Research (BMR) Program under contract DE-SC0012704. This research used beamline 23-ID-2 and 28-ID-2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704.

Isoxazole-Based Electrolytes for Lithium Metal Protection and Lithium-Sulfurized Polyacrylonitrile (SPAN) Battery Operating at Low Temperature

A new electrolyte system using isoxazole as the salt dissolving solvent has been developed and studied for lithium metal batteries. By using fluoroethylene carbonate (FEC) as an additive and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as a diluent for localized high concentration electrolyte (LHCE), isoxazole-based electrolytes were successfully implemented in lithium metal batteries, demonstrating excellent lithium metal protection capability. Utilizing several advanced characterization techniques (including synchrotron-based X-ray absorption spectroscopy and photoelectron spectroscopy), the solid electrolyte interphase (SEI) formed on the Li-metal anode in cells using these electrolytes was thoroughly investigated. The high ionic conductivity of isoxazole at low temperature and the low impedance of SEI formed in LHCE significantly improved the low-temperature performance of Li-sulfurized polyacrylonitrile (SPAN) batteries, delivering 273.8 mAh g-1 capacity at -30°C with 99.85% capacity retention after 50 cycles.Acknowledgment: The work done at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the US Department of Energy (DOE) through the Advanced Battery Materials Research (BMR) Program, including Battery500 Consortium under contract number DE-SC0012704. This research used beamline 8-BM (TES) and 7-ID-2 (SST-2) of the National Synchrotron Light Source II, U.S. DOE Office of Science User Facilities, operated for the DOE Office of Science by Brookhaven National Laboratory under contract number DE-SC0012704. SEM measurements for this manuscript were performed at Center for Functional Nanomaterials, a U.S. DOE office of Science User Facility, at Brookhaven National Laboratory under the contract number DE-SC0012704.

Construction of Cryogen-Free 4.3T Superconducting Wiggler for NSLS-II Ring

With the 3 GeV electron beam energy for the National Synchro-tron Light Source II (NSLS-II) ring, only superconducting wig-glers (SCW) producing greater than 4T peak field can cover the photon energy range of 20keV and 200keV with sufficient num-ber of photons. The High energy Engineering X-ray (HEX) Dif-fraction beamline, which is primarily funded by the New York State Energy Research and Development Authority (NYSERDA) and NSLS-II, will be equipped with a 1.2m-long SCW with 70mm period length and 4.3T on-axis field. This SCW is free from the use of liquid Helium and is cooled only with cryo-coolers. The Electron Beam Chamber (EBC) with vertical aper-ture of 8mm is made from 316LN stainless steel and copper plat-ing is applied both entire upper surface and +- 12.5mm wide from the center in the inner surface. The expected heat load from the electron beam of the NSLS-II ring is estimated to be 10W/m. This paper describes the design principles and engineering chal-lenges for the device.