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Abstract: Renewable sources could replace hydrocarbons, but sustainability imposes the integration with reliable and efficient energy storage (EES) facilities like rechargeable batteries. The ssuccessful operation of rechargeable batteries depends on the concerted occurrence of an enormous number of physico-chemical, electrical, thermal and mechanical processes, taking place over wide spatial (nm - cm) and temporal (10-14s - hours) ranges. Disentangling this scenario, to gain control over their relative roles on practical operation, durability and safety, calls for the capability of imaging what happens inside batteries at length-scales ranging from material structure up to battery components at the device scale, and correlating this information with the electrical performance over time. This perspective implies joint efforts in three key directions: (i) the acquisition of focused in operando data, in real-life or close to real-life conditions; (ii) their multiscale modelling and (iii) integration of this information into electrical diagnostics and control tools. Synchrotron-based scanning nanoprobes can contribute crucially to point (i) and provide unique factual input for points (ii) and (iii). Wide range of novel electrochemical cells for in operando muti-modal spectro-microscopy are designed and these systems provide fundamental answers to technologically relevant questions raised by R&D on state-of-the art as well as next-generation lithium and post-lithium battery studies and developments. Among realistic cell configurations, both coin-cells and pouch cells with an optical window, featuring specially – but straightforwardly – shaped electrodes, can be used for in situ and in operando measurements. Here, we present the current capabilities of the I14 and I08 beamlines at Diamond Light Source UK, which are in user operation mode, as well as give an outline of planned future upgrades. We describe our current instrumentation and software infrastructure, including an automated processing pipeline that provides users with a ptychographic reconstruction in near real time. We show results from a few scientific examples of in-operando and in-situ studies on batteries and catalysts samples using multi-modal X-ray Nanoprobes which allow the use of imaging and spectroscopy to access nanoscale chemical and structural information. Spectro-ptychography offers the unique capability to image in-operando electrochemical cells at high spatial resolution and with chemical specificity, further enhanced by the upcoming upgrade to Diamond II with an expected increase in coherent flux.

Open Access

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Abstract: Imaging of nanoscale magnetic textures within extended material systems is of critical importance to both fundamental research and technological applications. While high-resolution magnetic imaging of thin nanoscale samples is well established with electron and soft x-ray microscopy, the extension to micrometer-thick systems currently requires hard x rays, which limits high-resolution imaging to rare-earth magnets. Here, we overcome this limitation by establishing soft x-ray magnetic imaging of micrometer-thick systems using the pre-edge phase x-ray magnetic circular dichroism signal, thus making possible the study of a wide range of magnetic materials. By performing dichroic spectroptychography, we demonstrate high spatial resolution imaging of magnetic samples up to 1.7  μ⁢m thick, an order of magnitude higher than conventionally possible with soft x-ray absorption-based techniques. We demonstrate the applicability of the technique by harnessing the pre-edge phase to image thick chiral helimagnets, and naturally occurring magnetite particles, gaining insight into their three-dimensional magnetic configuration. This new regime of magnetic imaging makes possible the study of extended non-rare-earth systems that have until now been inaccessible, including magnetic textures for future spintronic applications, non-rare-earth permanent magnets for energy harvesting, and the magnetic configuration of giant magnetofossils.

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Abstract: Sorption of organic molecules on mineral surfaces can occur through several binding mechanisms of varying strength. Here, we investigated the importance of inner-sphere P-O-Fe bonds in synthetic and natural mineral-organic associations. Natural organic matter such as water extracted soil organic matter (WESOM) and extracellular polymeric substances (EPS) from liquid bacterial cultures were adsorbed to goethite and examined by FTIR spectroscopy and P K-edge NEXAFS spectroscopy. Natural particles from a Bg soil horizon (Gleysol) were subjected to X-ray fluorescence (XRF) mapping, NanoSIMS imaging, and NEXAFS spectro-microscopy at the P K-edge. Inner-sphere P-O-Fe bonds were identified for both, adsorbed EPS extracts and adsorbed WESOMs. Characteristic infrared peaks for P-O-Fe stretching vibrations are present but cannot unambiguously be interpreted due to possible interferences with mono- and polysaccharides. For the Bg horizon, P was only found on Fe oxides, covering the entire surface at different concentrations, but not on clay minerals. Linear combination fitting of NEXAFS spectra indicates that this adsorbed P is mainly a mixture of orthophosphate and organic P compounds. By combining atomic force microscopy (AFM) images with STXM-generated C and Fe distribution maps, we show that the Fe oxide surfaces were fully coated with organic matter. In contrast, clay minerals revealed a much lower C signal. The C NEXAFS spectra taken on the Fe oxides had a substantial contribution of carboxylic C, aliphatic C, and O-alkyl C, which is a composition clearly different from pure adsorbed EPS or aromatic-rich lignin-derived compounds. Our data show that inner-sphere P-O-Fe bonds are important for the association of Fe oxides with soil organic matter. In the Bg horizon, carboxyl groups and orthophosphate compete with the organic P compounds for adsorption sites.

Open Access

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Abstract: Li3N is an excellent protective coating material for lithium electrodes with very high lithium-ion conductivity and low electronic conductivity, but the formation of stable and homogeneous coatings is technically very difficult. Here, we show that protective Li3N coatings can be simply formed by the direct reaction of electrodeposited lithium electrodes with N2 gas, whereas using battery-grade lithium foil is problematic due to the presence of a native passivation layer that hampers that reaction. The protective Li3N coating is effective at preventing lithium dendrite formation, as found from unidirectional plating and plating–stripping measurements in Li–Li cells. The Li3N coating also efficiently suppresses the parasitic reactions of polysulfides and other electrolyte species with the lithium electrode, as demonstrated by scanning transmission X-ray microscopy, X-ray photoelectron spectroscopy, and optical microscopy. The protection of the lithium electrode against corrosion by polysulfides and other electrolyte species, as well as the promotion of smooth deposits without dendrites, makes the Li3N coating highly promising for applications in lithium metal batteries, such as lithium–sulfur batteries. The present findings show that the formation of Li3N can be achieved with lithium electrodes covered by a secondary electrolyte interface layer, which proves that the in situ formation of Li3N coatings inside the batteries is attainable.

Open Access

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Abstract: Batteries with inorganic solid-state electrolytes (ISSE) are attracting notable interest for next-generation systems implementing Lithium (Li) metal anodes, in view of achieving higher energy densities combined with superior safety. Notwithstanding extensive research and development work, this technology is not yet ready for industrial implementation, one of the key challenges being the stability of ISSEs, chiefly at the anodic interface. This work attacks this issue for the specific case of the LAGP/Li (Lithium Aluminium Germanium Phosphate/Lithium) interface with a micro-spectroscopic approach centred on post mortem Scanning Transmission X-ray Microscopy (STXM) of intact LMO/LAGP/Li thin-film batteries, microfabricated in discharged state. Pristine and cycled cells were mapped to pinpoint morphochemical changes, induced by electrochemical ageing. The evidenced shape changes, corresponding to mechanical damaging of the solid/solid electrodic interfaces correlate with LAGP decomposition at the anode, leading to reduction of Ge, whereas the chemical state at the cathodic interface is preserved. Thanks to its submicron spacial resolution, the STXM at the Ge L-edge and O K-edge spectra allowed to assess the highly localized nature of the chemical transformation of LAGP and its correlation with the formation of Li outgrowth features.