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Abstract: In situ neutron powder diffraction measurements of a commercial lithium-ion battery reveal perturbations to the phase evolution of the Li x C6 electrode caused by overcharge. Above ∼4.5 V the anode is entirely composed of LiC6. During discharge from the post-overcharged state LiC6 persists to the 90% discharge state, compared with its persistence to the 27% discharge state during conventional cycling. At the completely discharged state the post-overcharged anode is a mixture of LiC12, LiC18, and graphite, while the conventionally cycled anode is composed of graphite alone. The phase evolution of a post-overcharged battery during charge also differs relative to conventional cycling, most noticeably until the 9% state of charge. [Copyright &y& Elsevier]

Abstract: The structural response to electrochemical cycling of the components within a commercial Li-ion battery (LiCoO2 cathode, graphite anode) is shown through in situ neutron diffraction. Lithuim insertion and extraction is observed in both the cathode and anode. In particular, reversible Li incorporation into both layered and spinel-type LiCoO2 phases that comprise the cathode is shown and each of these components features several phase transitions attributed to Li content and correlated with the state-of-charge of the battery. At the anode, a constant cell voltage correlates with a stable lithiated graphite phase. Transformation to de-lithiated graphite at the discharged state is characterised by a sharp decrease in both structural cell parameters and cell voltage. In the charged state, a two-phase region exists and is composed of the lithiated graphite phase and about 64% LiC6. It is postulated that trapping Li in the solid|electrolyte interface layer results in minimal structural changes to the lithiated graphite anode across the constant cell voltage regions of the electrochemical cycle. [ABSTRACT FROM AUTHOR]

Quasielastic neutron scattering was used to study the hydration reaction of tricalcium and dicalcium silicate mixtures by following the fixation of hydrogen into the reaction products, and by applying hydration models to the data. The reaction kinetics were well-described by an Avrami-derived model for the nucleation and growth regime during early hydration times and a diffusion-limited model for later periods. This study showed that the hydration reaction is not a simple linear combination of the reactions for the individual components. Compressive strength tests correlated with the neutron scattering data, suggesting that the details of the interaction affect the microstructure and therefore the strength of the product. Results suggest that favorable reaction mechanics provide optimal strength when an 80−95% tricalcium silicate and 20−5% dicalcium silicate mixture is used. [ABSTRACT FROM AUTHOR]

The lattice parameters, cell volume, and structure of a sample of phase pure triclinic tricalcium silicate were determined using in situ, high-temperature synchrotron powder diffraction and full-profile Rietveld refinement. The temperature range covered was from ambient to 740 &degC. Evidence of superstructure was found. The T2 type structure with disordered SiO4 tetrahedra was observed, and an average structure for the subcell (P&1macr;, a = 11.7416(2) &Aring, b = 14.2785(2) Å, c = 13.7732(2) Å, α = 105.129(1)°, β = 94.415(1)°, and γ = 89.889(1)°) is presented. Differential thermal analysis and X-ray fluorescence was also performed. [ABSTRACT FROM AUTHOR]

Owing to their vast chemical and structural flexibility, crystalline perovskite-type metal oxides (AB O 3) are amongst the most promising solid electrolytes for use in all-solid-state batteries for large scale energy storage applications. The perovskite-type sodium-ion solid electrolyte series Na 1/2- x La 1/2- x Sr 2 x ZrO 3 have the highest reported ionic conductivities, and we re-examine their room temperature crystal structures using X-ray and high-resolution neutron powder diffraction. In contrast to a previous report, four members of the series, x = 1/16, 1/8, 1/6, and 1/4, were found to adopt orthorhombic symmetry with the space group Pbnm. Variable temperature neutron diffraction data (room temperature to 1100 °C) were used to probe temperature-dependent structural changes for the member of the series with the highest reported ionic conductivity (x = 1/6). A phase transition from orthorhombic Pbnm to tetragonal I 4/ mcm was identified at 800 °C. • The crystal structures of the perovskite-type sodium-ion solid electrolyte series Na 1/2- x La 1/2- x Sr 2 x ZrO 3 were determined. • The x = 1/16, 1/8, 1/6, and 1/4 members adopt orthorhombic symmetry in space group Pbnm instead of cubic P 2 1 3 symmetry. • A phase transition to tetragonal I 4/ mcm at 800 ◦C was found for Na 1/3 La 1/3 Sr 1/3 ZrO 3 using neutron powder diffraction data. • Enhanced understanding of the structure-property relationship informs chemical and structural modifications. [ABSTRACT FROM AUTHOR]

The article focuses on the synthesis and characterization of a high-entropy oxide (HEO) called Iron(II) Oxide (FeO)-HEO, which contains divalent Manganese (Mn) and Iron (Fe) in a rocksalt crystal structure. Topics include the concept of HEOs and their unique compositional features, the challenge of introducing divalent Mn(II) and Fe(II) into a rocksalt HEO, and the phase stability of FeO-HEO under different conditions.

The reaction evolution and kinetics of the LiFePO 4 positive electrode material is dependent on the synthesis method and cycling conditions. In operando neutron powder diffraction is used investigate the structure-electrochemistry relationship of the electrode materials in a Valence Technology Inc. 18650 Energy cell (IFR18650EC) containing a graphite negative electrode and a Mg-doped LiFePO 4 (Li(MgFe)PO 4 ) positive electrode. Two cells were studied at ambient (298 K) and elevated (323 K) temperature, and higher temperatures were found to improve reaction kinetics and hence capacity. Rietveld refinement of structural models against the diffraction data revealed information about the nucleation of the lithiated and delithiated phases in the Li(MgFe)PO 4 positive electrode material as a function of each cell's state of charge. Polarisation was indicated by a shift in the potential at which the lithiated and delithiated (MgFe)PO 4 phases nucleate during cycling, the extent of which was found to be linearly proportional to the applied current. This work provides new evidence for polarisation of the positive electrode material in a Li-ion battery system. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the application of neutron powder diffraction on studying the time-resolved structural evolution of a cell comprised with LiNi0.5Mn1.5O4 cathode and Li4Ti5O12 anode during charge–discharge cycling is demonstrated. As expected, the lattices of the LiNi0.5Mn1.5O4 cathode and the Li4Ti5O12 anode in the cell are found to simultaneously contract during charging and expand during discharging. It is found that for the LiNi0.5Mn1.5O4 cathode a solid-solution reaction is associated with the lattice change and the Ni2+/Ni3+ redox couple between 3.06 and 3.16 V (vs. Li4Ti5O12), and a two-phase reaction between Li x Ni0.5Mn1.5O4 and Ni0.25Mn0.75O2 is corresponding to the Ni3+/Ni4+ redox couple at voltage higher than 3.22 V (vs. Li4Ti5O12) without a corresponding change in lattice. The oxidation states of the metals in the electrodes are determined by tracking the associated change in the oxygen position. In addition, the Ti oxidation state is correlated to the intensity of the Li4Ti5O12 222 reflection at the anode, and the determined oxidation state of the Ni is correlated to the lithium occupancy within the cathode. Furthermore, the small volume changes of the cathode and the anode upon cycling suggest that the cell chemistry is favorable for practical applications. [Copyright &y& Elsevier]

The steam oxidation resistance of UN and UN-(20 vol%)ZrN fuel pellets is evaluated to enhance understanding of steam corrosion mechanisms in advanced nuclear fuel materials. In situ neutron diffraction shows the modified UN fuel pellets form a (U 0.77 ,Zr 0.23)N solid-solution and the sole crystalline oxidation product detected in bulk is (U 0.77 ,Zr 0.23)O 2. U 2 N 3 is not detected in significant quantities during the steam oxidation of UN or (U 0.77 ,Zr 0.23)N and stable lattice parameters show that hydriding does not take place. Steam oxidation rates, obtained via sequential Rietveld refinement show how (U 0.77 ,Zr 0.23)N has a higher activation energy (79 ± 1 kJmol−1 vs. 50 ± 5 kJmol−1), higher onset temperature (430 °C vs. 400 °C) and slower reaction rates for steam oxidation up to 616 °C, than pure UN. Throughout, both UN and (U 0.77 ,Zr 0.23)N exhibit linear (non-protective) oxidation kinetics, signifying that degradation of the fuel pellets is caused by the evolution of gaseous products at the interface followed by oxide scale spallation. This quantitative and mechanistic understanding of material degradation enables better defined operating regimes and points towards (U,Zr)N solid solutions as a promising strategy for the design of advanced nuclear fuel materials with enhanced steam corrosion resistance. • In situ neutron diffraction measures (U0.77Zr0.23)N and UN steam corrosion. • Rate equations show enhanced steam oxidation resistance for (U0.77Zr0.23)N. • Both (U0.77Zr0.23)N and UN exhibit linear (non-protective) oxidation kinetics. • (U0.77Zr0.23)O2 and UO2 are the only crystalline products detected in bulk. [ABSTRACT FROM AUTHOR]

Abstract: The structures of the defect pyrochlores AAl0.33W1.67O6 where A=K, Rb or Cs have been investigated using X-ray and neutron powder diffraction methods as well as the ab initio modelling program VASP. The three cubic pyrochlores exhibit a non-linear increase in lattice parameter with respect to ionic radius of the A cation as a consequence of displacive disorder of the A-type cations. Solid state 27Al MAS NMR studies of this pyrochlore system reveal shifts in the δ∼21–22ppm range that are indicative of pseudo-5 coordinate Al environments and emanate from distorted Al octahedral with one abnormally long Al–O bond. Solid state 39K, 85Rb, 87Rb and 133Cs MAS and static NMR studies reflect the local cation disorder demonstrated in the structural studies. [Copyright &y& Elsevier]

Existing lithium-ion battery technology is struggling to meet our increasing requirements for high energy density, long lifetime, and low-cost energy storage. Here, a hybrid electrode design is developed by a straightforward reengineering of commercial electrode materials, which has revolutionized the "rocking chair" mechanism by unlocking the role of anions in the electrolyte. Our proof-of-concept hybrid LiFePO4 (LFP)/graphite electrode works with a staged deintercalation/intercalationmechanismof Li+ cations and PF6 - anions in a broadened voltage range, which was thoroughly studied by ex situ X-ray diffraction, ex situ Raman spectroscopy, and operando neutron powder diffraction. Introducing graphite into the hybrid electrode accelerates its conductivity, facilitating the rapid extraction/insertion of Li+ from/into the LFP phase in 2.5 to 4.0 V. This charge/discharge process, in turn, triggers the in situ formation of the cathode/electrolyte interphase (CEI) layer, reinforcing the structural integrity of the whole electrode at high voltage. Consequently, this hybrid LFP/graphite-20% electrode displays a high capacity and long-term cycling stability over 3,500 cycles at 10 C, superior to LFP and graphite cathodes. Importantly, the broadened voltage range and high capacity of the hybrid electrode enhance its energy density, which is leveraged further in a full-cell configuration. [ABSTRACT FROM AUTHOR]

Commercial 18650 lithium ion cells containing a blended positive electrode of layered LiNi 0.5 Mn 0.3 Co 0.2 O 2 and spinel Li 1.1 Mn 1.9 O 4 alongside a graphite negative electrode were stored at various depth-of-discharge (DoD) at 60 °C for 1, 2, 4, and 6 months. After storage, the cells were cycled at C/25 at 25 °C between 2.75 and 4.2 V for capacity determination and incremental capacity analysis (ICA). In addition to ICA analysis, the mechanism for capacity fade was investigated by combining the results of neutron powder diffraction under in-situ and operando conditions, in conjunction with post-mortem studies of the electrodes using synchrotron X-ray powder diffraction and inductively-coupled plasma optical emission spectroscopy. Among the cells, those stored at 25% DoD suffered the highest capacity fade due to their higher losses of active Li, NMC, and LMO than cells stored at other DoD. The cells stored at 0% DoD shows second high capacity fade because they exhibit the highest of active LMO and graphite anode among the stored cells and higher losses of active Li and NMC than cells stored at 50% DoD. [ABSTRACT FROM AUTHOR]

Ex situ and time-resolved in operando neutron powder diffraction (NPD) has been used to study the structural evolution of the graphite negative electrode and LiFePO 4 positive electrode within ANR26650M1A commercial batteries from A123 Systems, in what to our knowledge is the first reported NPD study investigating a 26650-type battery. Batteries with different and accurately-known electrochemical and storage histories were studied, enabling the tell-tale signs of battery degradation to be elucidated using NPD. The ex-situ NPD data revealed that the intensity of the graphite/lithiated graphite (Li x C 6 or Li y C) reflections was affected by battery history, with lower lithiated graphite (LiC 12 ) reflection intensities typically corresponding to more abused batteries. This indicates that the lithiation of graphite is less progressed in more abused batteries, and hence these batteries have lower capacities. In operando NPD allows the rate of structural evolution in the battery electrode materials to be correlated to the applied current. Interestingly, the electrodes exhibit different responses to the applied current that depend on the battery cycling history, with this particularly evident for the negative electrode. Therefore, this work illustrates how NPD can be used to correlate a battery history with electrode structure. [ABSTRACT FROM AUTHOR]

Y(btc) (btc = 1,3,5-benzenetricarboxylate) is a metal-organic framework that exhibits significant adsorption of industrially-relevant gases such as H2, CH4, and O2. Previous studies have noted a surprising lack of close interactions between the adsorbed guest molecules and Y, despite the apparent availability of a "bare-metal" binding site. We have extended our previous work in a detailed investigation of the adsorption behaviours of CO2, CD4, and O2 in Y(btc) over a range of concentrations using in situ neutron powder diffraction methods. The O-Y-O bond angles enclosing the bare-metal site are found to change considerably depending on the type and quantity of guest molecules present. Multiple binding sites are found for each guest species, and the largest changes in O-Y-O angles are accompanied by changes in the filling sequences of the binding sites, pointing to an important interplay between guest-induced framework distortions and binding site accessibility. These results suggest the potential for coordinatively flexible rare-earth metal centres to promote guest-selective binding in metal-organic frameworks. [ABSTRACT FROM AUTHOR]

U 3 Si 2 nuclear fuel is corroded in deuterated steam with in situ neutron diffraction. Density functional theory is coupled with rigorous thermodynamic description of the hydride including gas/solid entropy contributions. H absorbs in the 2 b interstitial site of U 3 Si 2 H x and moves to 8 j for x ≥ 0.5. Hydriding forces lattice expansion and change in a/c ratio linked to site preference. Rietveld refinement tracks the corrosion reactions at 350–500 °C and preference for the 8 j site. Above 375 °C, formation of UO 2 , U 3 Si 5 and USi 3 take place in the grain boundaries and bulk. Hydriding occurs in bulk and precedes other reactions. [Display omitted] • In situ neutron diffraction measures U 3 Si 2 corrosion in deuterated steam. • Rigorous thermodynamic description of hydride using key entropy contributions. • H absorption at 2 b interstitial site of U 3 Si 2 H x , moves to 8 j site for x ≥ 0.5. • From 350 °C, U 3 Si 2 H x fragmented by 1–2% anisotropic lattice expansion. • From 375 °C, UO 2 , U 3 Si 5 and USi 3 form in bulk and in grain boundaries. [ABSTRACT FROM AUTHOR]

Abstract: In-situ neutron powder diffraction was employed to investigate the structural evolution of the electrode materials in a commercial lithium-ion battery used for electric buses in Taiwan. The battery, containing a vanadium-added LiFePO4 cathode, does not exhibit a delayed phase transition between LiFePO4 (triphylite) and FePO4 (heterosite) suggesting that the delayed phase transition can be suppressed through the use of vanadium-added LiFePO4 cathodes, which also enhances the capacity and prolongs the cycle life of these batteries. Furthermore, we characterize the readily reversible structural change of the anode (Li x C6 where 0 < x ≦ 1) and correlate this to battery voltage. [Copyright &y& Elsevier]

Anthoinite, AlWO3(OH)3, from the Mt. Misobo Mine, Democratic Republic of the Congo, has triclinic symmetry with cell parameters a = 8.196(1) Å, b = 9.187(1) Å, c = 11.316(1) Å, β = 92.82(1)°, β = 94.08(1)°, γ = 90.23(1)°, space group I1̅, Z = 8. The structure was solved by applying ab initio structure solution methods (Reverse Monte Carlo/Simulated Annealing) to both X-ray and neutron powder diffraction data and was refined using the Rietveld method. The structure is built up of two types of M4(O,OH)16 planar tetrameric clusters of edge-sharing octahedra, one containing predominantly Al and the other predominantly W. The Al-rich and W-rich clusters interconnect via corner sharing to form stepped layers parallel to (001). The layers are held together by strong hydrogen bonding. The structure can be described as a rocksalt derivative structure, with the close-packed anion layers parallel to (012), and with Al and W atoms ordered into one third of the octahedral sites within the cubic close-packed anion lattice. The structure is complicated by partial disorder between Al and W in the tetrameric clusters and associated disorder in the H atom sites. Infrared and 27Al MAS NMR results are also presented for anthoinite. [ABSTRACT FROM AUTHOR]