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Instruments / Technical Area	Publication Details	Published
I15-1-X-ray Pair Distribution Function (XPDF)	Fast operando X-ray pair distribution function using the DRIX electrochemical cell Maria Diaz-Lopez , Geoffrey L. Cutts , Phoebe K. Allan , Dean S. Keeble , Allan Ross , Valerie Pralong , Georg Spiekermann , Philip A. Chater Journal Of Synchrotron Radiation 27 DOI: 10.1107/S160057752000747X Diamond Proposal Number(s): [20893, 20094] Open Access Show Abstract ▼ Abstract: In situ electrochemical cycling combined with total scattering measurements can provide valuable structural information on crystalline, semi-crystalline and amorphous phases present during (dis)charging of batteries. In situ measurements are particularly challenging for total scattering experiments due to the requirement for low, constant and reproducible backgrounds. Poor cell design can introduce artefacts into the total scattering data or cause inhomogeneous electrochemical cycling, leading to poor data quality or misleading results. This work presents a new cell design optimized to provide good electrochemical performance while performing bulk multi-scale characterizations based on total scattering and pair distribution function methods, and with potential for techniques such as X-ray Raman spectroscopy. As an example, the structural changes of a nanostructured high-capacity cathode with a disordered rock-salt structure and composition Li4Mn2O5 are demonstrated. The results show that there is no contribution to the recorded signal from other cell components, and a very low and consistent contribution from the cell background.	Sep 2020
I15-1-X-ray Pair Distribution Function (XPDF)	Reversible densification in nano-Li 2 MnO 3 cation disordered rock-salt Li-ion battery cathodes Maria Diaz-Lopez , Philip A. Chater , Yves Joly , Olivier Proux , Jean-Louis Hazemann , Pierre Bordet , Valerie Pralong Journal Of Materials Chemistry A 69 DOI: 10.1039/D0TA03372C Diamond Proposal Number(s): [20893, 20094] Open Access Show Abstract ▼ Abstract: The full structure of nano-Li2MnO3 with superior reversible capacities of 290 mA h g−1 for over 10 cycles was investigated by neutron and X-ray total scattering, which demonstrate that contrary to previous claims, a phase transformation occurs during synthesis forming a disordered cubic MnO-type rock-salt with nanodomains of Li/Mn layering of ∼1 nm. A comprehensive study of the structural and charge evolution combining in operando X-ray total scattering with advanced spectroscopic methods at the Mn K-edge such as High Energy Resolved Fluorescence Detected XANES, EXAFS and Emission Spectroscopies including main and valence-to-core transitions, point to a lattice densification with an effective loss of Li2O, with the subsequent electrochemical activation of Li2O as the main responsible mechanism for the exchanged capacity. Interestingly, and unlike previous studies, no capacity losses could be associated to the material's densification.	May 2020
I15-1-X-ray Pair Distribution Function (XPDF)	Li2O:Li–Mn–O disordered rock‐salt nanocomposites as cathode prelithiation additives for high‐energy density Li‐ion batteries Maria Diaz-Lopez , Philip A. Chater , Pierre Bordet , Melanie Freire , Christian Jordy , Oleg I. Lebedev , Valerie Pralong Advanced Energy Materials 142 DOI: 10.1002/aenm.201902788 Diamond Proposal Number(s): [20893] Open Access Show Abstract ▼ Abstract: The irreversible loss of lithium from the cathode material during the first cycles of rechargeable Li‐ion batteries notably reduces the overall cell capacity. Here, a new family of sacrificial cathode additives based on Li2O:Li2/3Mn1/3O5/6 composites synthesized by mechanochemical alloying is reported. These nanocomposites display record (but irreversible) capacities within the Li–Mn–O systems studied, of up to 1157 mAh g−1, which represents an increase of over 300% of the originally reported capacity in Li2/3Mn1/3O5/6 disordered rock salts. Such a high irreversible capacity is achieved by the reaction between Li2O and Li2/3Mn1/3O5/6 during the first charge, where electrochemically active Li2O acts as a Li+ donor. A 13% increase of the LiFePO4 and LiCoO2 first charge gravimetric capacities is demonstrated by the addition of only 2 wt% of the nanosized composite in the cathode mixture. This result shows the great potential of these newly discovered sacrificial additives to counteract initial losses of Li+ ions and improve battery performance.	Jan 2020

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