Correlated electron diffraction and energy-dispersive X-ray for automated microstructure analysis

In this study the effect of merging correlated energy dispersive X-ray (EDS) spectra and electron diffraction data on unsupervised machine learning (clustering) is explored. The combination of data allows second phase coherent precipitates to be identified, that could not be determined from either the individual EDS or diffraction data alone. In order to successfully combine these two distinct data types we leveraged a data fusion method where both data sets were normalised and combined using a robust scaler followed by variance equalisation. A machine learning pipeline was implemented which performs dimensional reduction with PCA and followed by fuzzy C-means clustering, as this allows signals from overlapping regions of the microstructure to be partitioned between different clusters. User control of this partition is used to confirm a change in the stoichiometry of the embedded second phase regions

A practical perspective on the potential of rechargeable Mg batteries

Emerging energy storage systems based on abundant and cost-effective materials are key to overcome the global energy and climate crisis of the 21st century. Rechargeable Magnesium Batteries (RMB), based on Earth-abundant magnesium, can provide a cheap and environmentally responsible alternative to the benchmark Li-ion technology, especially for large energy storage applications. Currently, RMB technology is the subject of intense research efforts at laboratory scale. However, these emerging approaches must be placed in a real-world perspective to ensure that they satisfy key technological requirements. In an attempt to bridge the gap between laboratory advancements and industrial development demands, herein, we report the first non-aqueous multilayer RMB pouch cell prototypes and propose a roadmap for a new advanced RMB chemistry. Through this work, we aim to show the great unrealized potential of RMBs.This work was funded by European Union's Horizon 2020 research and innovation program under the FET Proactive call with grant agreement no 824066 via the “E-MAGIC” project

A practical perspective on the potential of rechargeable Mg batteries

Emerging energy storage systems based on abundant and cost-effective materials are key to overcome the global energy and climate crisis of the 21st century. Rechargeable Magnesium Batteries (RMB), based on Earth-abundant magnesium, can provide a cheap and environmentally responsible alternative to the benchmark Li-ion technology, especially for large energy storage applications. Currently, RMB technology is the subject of intense research efforts at laboratory scale. However, these emerging approaches must be placed in a real-world perspective to ensure that they satisfy key technological requirements. In an attempt to bridge the gap between laboratory advancements and industrial development demands, herein, we report the first non-aqueous multilayer RMB pouch cell prototypes and propose a roadmap for a new advanced RMB chemistry. Through this work, we aim to show the great unrealized potential of RMBs

The Role of the Electrode Surface in Na–Air Batteries: Insights in Electrochemical Product Formation and Chemical Growth of NaO 2

The Na–air battery, because of its high energy density and low charging overpotential, is a promising candidate for low‐cost energy storage, hence leading to intensive research. However, to achieve such a battery, the role of the positive electrode material in the discharge process must be understood. This issue is herein addressed by exploring the electrochemical reduction of oxygen, as well as the chemical formation and precipitation of NaO2 using different electrodes. Whereas a minor influence of the electrode surface is demonstrated on the electrochemical formation of NaO2, a strong dependence of the subsequent chemical precipitation of NaO2 is identified. In the origin, this effect stems from the surface energy and O2/O2− affinity of the electrode. The strong interaction of Au with O2/O2− increases the nucleation rate and leads to an altered growth process when compared to C surfaces. Consequently, thin (3 µm) flakes of NaO2 are found on Au, whereas on C large cubes (10 µm) of NaO2 are formed. This has significant impact on the cell performance and leads to four times higher capacity when C electrodes with low surface energy and O2/O2− affinity are used. It is hoped that these findings will enable the design of new positive electrode materials with optimized surfaces

The role of the electrode surface in Na–Air batteries: Insights in electrochemical product formation and chemical growth of NaO2

The Na–air battery, because of its high energy density and low charging overpotential, is a promising candidate for low‐cost energy storage, hence leading to intensive research. However, to achieve such a battery, the role of the positive electrode material in the discharge process must be understood. This issue is herein addressed by exploring the electrochemical reduction of oxygen, as well as the chemical formation and precipitation of NaO2 using different electrodes. Whereas a minor influence of the electrode surface is demonstrated on the electrochemical formation of NaO2, a strong dependence of the subsequent chemical precipitation of NaO2 is identified. In the origin, this effect stems from the surface energy and O2/O2− affinity of the electrode. The strong interaction of Au with O2/O2− increases the nucleation rate and leads to an altered growth process when compared to C surfaces. Consequently, thin (3 µm) flakes of NaO2 are found on Au, whereas on C large cubes (10 µm) of NaO2 are formed. This has significant impact on the cell performance and leads to four times higher capacity when C electrodes with low surface energy and O2/O2− affinity are used. It is hoped that these findings will enable the design of new positive electrode materials with optimized surfaces

High capacity Na-O2 batteries – Key parameters for solution-mediated discharge

The Na-O2 battery offers an interesting alternative to the Li-O2 battery, which is still the source of a number of unsolved scientific questions. In spite of both being alkali metal-O2 batteries, they display significant dif-ferences. For instance, Li-O2 batteries form Li2O2 as the discharge product at the cathode, whereas Na-O2 batteries usually form NaO2. A very important question that affects the performance of the Na-O2 cell con-cerns the key parameters governing the growth mechanism of the large NaO2 cubes formed upon reduction, which are a requirement of viable capacities and high performance. By comparing glyme-ethers of various chain lengths we show that, the choice of solvent has a tremendous effect on the battery performances. In contrast to the Li-O2 system, high solubilities of the NaO2 discharge product do not necessarily lead to in-creased capacities. Herein we report the profound effect of the Na+ ion solvent shell structure on the NaO2 growth mechanism. Strong solvent-solute interactions in long-chain ethers shift the formation of NaO2 to-wards a surface process resulting in submicrometric crystallites and very low capacities (ca. 0,2 mAh/ cm2(geom)). In contrast, short-chains, which facilitate desolvation and solution-precipitation, promote the for-mation of large cubic crystals (ca. 10 um), enabling high capacities (ca. 7.5 mAh/cm2(geom)). This work provides a new way to look at the key role that solvents play in the metal-air system

High Capacity Na–O 2 Batteries: Key Parameters for Solution-Mediated Discharge

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