The ECHIDNA high‐resolution neutron powder diffractometer at the 20 MW OPAL research reactor in Australia produces high‐quality data for a broad spectrum of crystal and magnetic structural studies. ...The paper presents an overview of the current status of the hardware, latest developments in data‐reduction software, statistics on instrument usage and the user programme, and instrument limitations.
Data collection and reduction on the ECHIDNA neutron powder diffractometer are described in detail, along with achievements and highlights from over ten years of operation. This paper replaces the previous design report as the canonical reference for ECHIDNA‐derived data.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
A computer program, 3DBVSMAPPER, was developed to generate bond‐valence sum maps and bond‐valence energy landscapes with minimal user intervention. The program is designed to calculate the spatial ...distributions of bond‐valence values on three‐dimensional grids, and to identify infinitely connected isosurfaces in these spatial distributions for a given bond‐valence mismatch or energy threshold and extract their volume and surface area characteristics. It is implemented in the Perl scripting language embedded in Accelrys Materials Studio and has the capacity to process automatically an unlimited number of materials using crystallographic information files as input.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Most P2-type layered oxides exhibit Na(+)/vacancy-ordered superstructures because of strong Na(+)-Na(+) interaction in the alkali metal layer and charge ordering in the transition metal layer. These ...superstructures evidenced by voltage plateaus in the electrochemical curves limit the Na(+) ion transport kinetics and cycle performance in rechargeable batteries. Here we show that such Na(+)/vacancy ordering can be avoided by choosing the transition metal ions with similar ionic radii and different redox potentials, for example, Cr(3+) and Ti(4+). The designed P2-Na(0.6)Cr(0.6)Ti(0.4)O2 is completely Na(+)/vacancy-disordered at any sodium content and displays excellent rate capability and long cycle life. A symmetric sodium-ion battery using the same P2-Na(0.6)Cr(0.6)Ti(0.4)O2 electrode delivers 75% of the initial capacity at 12C rate. Our contribution demonstrates that the approach of preventing Na(+)/vacancy ordering by breaking charge ordering in the transition metal layer opens a simple way to design disordered electrode materials with high power density and long cycle life.
Sodium ion batteries, because of their sustainability attributes, could be an attractive alternative to Li-ion technology for specific applications. However, it remains challenging to design high ...energy density and moisture stable Na-based positive electrodes. Here, we report an O3-type NaLi
Mn
O
phase showing anionic redox activity, obtained through a ceramic process by carefully adjusting synthesis conditions and stoichiometry. This phase shows a sustained reversible capacity of 190 mAh g
that is rooted in cumulative oxygen and manganese redox processes as deduced by combined spectroscopy techniques. Unlike many other anionic redox layered oxides so far reported, O3-NaLi
Mn
O
electrodes do not show discernible voltage fade on cycling. This finding, rationalized by density functional theory, sheds light on the role of inter- versus intralayer 3d cationic migration in ruling voltage fade in anionic redox electrodes. Another practical asset of this material stems from its moisture stability, hence facilitating its handling and electrode processing. Overall, this work offers future directions towards designing highly performing sodium electrodes for advanced Na-ion batteries.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK, ZAGLJ
Creep rupture life is a key material parameter for service life and mechanical properties of Ni-based single crystal superalloy materials. Therefore, it is of much practical significance to ...accurately and efficiently predict creep life. Here, we develop a divide-and-conquer self-adaptive (DCSA) learning method incorporating multiple material descriptors for rational and accelerated prediction of the creep rupture life. We characterize a high-quality creep dataset of 266 alloy samples with such features as alloy composition, test temperature, test stress, and heat treatment process. In addition, five microstructural parameters related to creep process, including stacking fault energy, lattice parameter, mole fraction of the γ' phase, diffusion coefficient and shear modulus, are calculated and introduced by the CALPHAD (CALculation of PHAse Diagrams) method and basic materials structure-property relationships, that enables us to reveal the effect of microstructure on creep properties. The machine learning explorations conducted on the creep dataset demonstrate the potential of the approach to achieve higher prediction accuracy with RMSE, MAPE and R2 of 0.3839, 0.0003 and 0.9176 than five alternative state-of-the-art machine learning models. On the newly collected 8 alloy samples, the error between the predicted creep life value and the experimental measured value is within the acceptable range (6.4486 h–40.7159 h), further confirming the validity of our DCSA model. Essentially, our method can establish accurate structure-property relationship mapping for the creep rupture life in a faster and cheaper manner than experiments and is expected to serve for inverse design of alloys.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The dependence on lithium-ion batteries leads to a pressing demand for advanced cathode materials. We demonstrate a new concept of layered-rocksalt intergrown structure that harnesses the combined ...figures of merit from each phase, including high capacity of layered and rocksalt phases, good kinetics of layered oxide and structural advantage of rocksalt. Based on this concept, lithium nickel ruthenium oxide of a main layered structure (RFormula: see textm) with intergrown rocksalt (FmFormula: see textm) is developed, which delivers a high capacity with good rate performance. The interwoven rocksalt structure successfully prevents the anisotropic structural change that is typical for layered oxide, enabling a nearly zero-strain operation upon high-capacity cycling. Furthermore, a design principle is successfully extrapolated and experimentally verified in a series of compositions. Here, we show the success of such layered-rocksalt intergrown structure exemplifies a new battery electrode design concept and opens up a vast space of compositions to develop high-performance intergrown cathode materials.
Prussian blue analogues (PBAs) are appealing active materials for post-lithium electrochemical energy storage. However, PBAs are not generally suitable for non-aqueous Li-ion storage due to their ...instability upon prolonged cycling. Herein, we assess the feasibility of PBAs with various lithium content for non-aqueous Li-ion storage. We determine the crystal structure of the lithiated PBAs via neutron powder diffraction measurements and investigate the influence of water on structural stability and Li-ion migration through operando X-ray diffraction measurements and bond valence simulations. Furthermore, we demonstrate that a positive electrode containing Li
FeFe(CN)
⋅nH
O (0 ≤ x ≤ 2) active material coupled with a Li metal electrode and a LiPF
-containing organic-based electrolyte in coin cell configuration delivers an initial discharge capacity of 142 mAh g
at 19 mA g
and a discharge capacity retention of 80.7% after 1000 cycles at 1.9 A g
. By replacing the lithium metal with a graphite-based negative electrode, we also report a coin cell capable of cycling for more than 370 cycles at 190 mA g
with a stable discharge capacity of about 105 mAh g
and a discharge capacity retention of 98% at 25 °C.
Single-ion conducting solid electrolytes are gaining tremendous attention as essential materials for solid-state batteries, but a comprehensive understanding of the factors that dictate high ion ...mobility remains elusive. Here, for the first time, we use a combination of the Maximum Entropy Method analysis of room-temperature neutron powder diffraction data, ab initio molecular dynamics, and joint-time correlation analysis to demonstrate that the dynamic response of the anion framework plays a significant role in the new class of fast ion conductors, Na11Sn2PnX12 (Pn = P, Sb; X = S, Se). Facile PX43– anion rotation exists in superionic Na11Sn2PS12 and Na11Sn2PSe12, but greatly hindered SbS43– rotational dynamics are observed in their less conductive analogue, Na11Sn2SbS12. Along with introducing dynamic frustration in the energy landscape, the fluctuation caused by PX43– anion rotation is firmly proved to couple to and facilitate long-range cation mobility, by transiently widening the bottlenecks for Na+-ion diffusion. The combined analysis described here resolves the role of the long-debated paddle-wheel mechanism, and is the first direct evidence that anion rotation significantly enhances cation migration in rotor phases. The joint-time correlation analysis developed in our work can be broadly applied to analyze coupled cation–anion interplay where traditional transition state theory does not apply. These findings deliver important insights into the fundamentals of ion transport in solid electrolytes. Invoking anion rotational dynamics provides a vital strategy to enhance cation conductivity and serves as an additional and universal design principle for fast ion conductors.
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IJS, KILJ, NUK, PNG, UL, UM
Na super ion conductor (NaSICON), Na1+nZr2SinP3–nO12 is considered one of the most promising solid electrolytes; however, the underlying mechanism governing ion transport is still not fully ...understood. Here, the existence of a previously unreported Na5 site in monoclinic Na3Zr2Si2PO12 is unveiled. It is revealed that Na+‐ions tend to migrate in a correlated mechanism, as suggested by a much lower energy barrier compared to the single‐ion migration barrier. Furthermore, computational work uncovers the origin of the improved conductivity in the NaSICON structure, that is, the enhanced correlated migration induced by increasing the Na+‐ion concentration. Systematic impedance studies on doped NaSICON materials bolster this finding. Significant improvements in both the bulk and total ion conductivity (e.g., σbulk = 4.0 mS cm−1, σtotal = 2.4 mS cm−1 at 25 °C) are achieved by increasing the Na content from 3.0 to 3.30–3.55 mol formula unit−1. These improvements stem from the enhanced correlated migration invoked by the increased Coulombic repulsions when more Na+‐ions populate the structure rather than solely from the increased mobile ion carrier concentration. The studies also verify a strategy to enhance ion conductivity, namely, pushing the cations into high energy sites to therefore lower the energy barrier for cation migration.
A new high‐energy Na site is found in the Na super ion conductor (NaSICON) structure. Theoretical studies reveal that correlated migration is the dominant conduction mechanism and can be invoked by increasing Na+‐ion concentration. More importantly, a strategy is experimentally validated that enhances ion conductivity, namely, by forcing cations into high‐energy sites via repulsive forces, as a result the energy barrier for cation migration can be lowered.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The combination of a materials database with high-throughput ion-transport calculations is an effective approach to screen for promising solid electrolytes. However, automating the complicated ...preprocessing involved in currently widely used ion-transport characterization algorithms, such as the first-principles nudged elastic band (FP-NEB) method, remains challenging. Here, we report on high-throughput screening platform for solid electrolytes (SPSE) that integrates a materials database with hierarchical ion-transport calculations realized by implementing empirical algorithms to assist in FP-NEB completing automatic calculation. We first preliminarily screen candidates and determine the approximate ion-transport paths using empirical both geometric analysis and the bond valence site energy method. A chain of images are then automatically generated along these paths for accurate FP-NEB calculation. In addition, an open web interface is actualized to enable access to the SPSE database, thereby facilitating machine learning. This interactive platform provides a workflow toward high-throughput screening for future discovery and design of promising solid electrolytes and the SPSE database is based on the FAIR principles for the benefit of the broad research community.
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