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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]

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]

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]

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]

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]

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]