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Understanding of structural and morphological evolution in nanomaterials is critical in tailoring their functionality for applications such as energy conversion and storage. Here, we examine irradiation effects on the morphology and structure of amorphous TiO2 nanotubes in comparison with their crystalline counterpart, anatase TiO2 nanotubes, using high-resolution transmission electron microscopy (TEM), in situ ion irradiation TEM, and molecular dynamics (MD) simulations. Anatase TiO2 nanotubes exhibit morphological and structural stability under irradiation due to their high concentration of grain boundaries and surfaces as defect sinks. On the other hand, amorphous TiO2 nanotubes undergo irradiation-induced crystallization, with some tubes remaining only partially crystallized. The partially crystalline tubes bend due to internal stresses associated with densification during crystallization as suggested by MD calculations. These results present a novel irradiation-based pathway for potentially tuning structure and morphology of energy storage materials. 

Recent studies illustrate how machine learning (ML) can be used to bypass a core challenge of molecular modeling: the trade-off between accuracy and computational cost. Here, we assess multiple ML approaches for predicting the atomization energy of organic molecules. Our resulting models learn the difference between low-fidelity, B3LYP, and high-accuracy, G4MP2, atomization energies and predict the G4MP2 atomization energy to 0.005 eV (mean absolute error) for molecules with less than nine heavy atoms (training set of 117,232 entries, test set 13,026) and 0.012 eV for a small set of 66 molecules with between 10 and 14 heavy atoms. Our two best models, which have different accuracy/speed trade-offs, enable the efficient prediction of G4MP2-level energies for large molecules and are available through a simple web interface. 

Lithium–air batteries are considered to be a potential alternative to lithium-ion batteries for transportation applications, owing to their high theoretical specific energy1. So far, however, such systems have been largely restricted to pure oxygen environments (lithium–oxygen batteries) and have a limited cycle life owing to side reactions involving the cathode, anode and electrolyte2,3,4,5. In the presence of nitrogen, carbon dioxide and water vapour, these side reactions can become even more complex6,7,8,9,10,11. Moreover, because of the need to store oxygen, the volumetric energy densities of lithium–oxygen systems may be too small for practical applications12. Here we report a system comprising a lithium carbonate-based protected anode, a molybdenum disulfide cathode2 and an ionic liquid/dimethyl sulfoxide electrolyte that operates as a lithium–air battery in a simulated air atmosphere with a long cycle life of up to 700 cycles. We perform computational studies to provide insight into the operation of the system in this environment. This demonstration of a lithium–oxygen battery with a long cycle life in an air-like atmosphere is an important step towards the development of this field beyond lithium-ion technology, with a possibility to obtain much higher specific energy densities than for conventional lithium-ion batteries. 

Chalcogenide superionic sodium (Na) conductors have great potential as solid electrolytes (SEs) in all‐solid‐state Na batteries with advantages of high energy density, safety, and cost effectiveness. The crystal structures and ionically conductive properties of solid Na‐ion conductors are strongly influenced by synthetic approaches and processing parameters. Thus, understanding the synthesis process is essential to control the structures and phases and to obtain Na‐ion conductors with desirable properties. Thanks to the high‐flux and deep‐penetrating time‐of‐flight neutron diffraction (ND), in‐situ experiments were able to track real‐time structural changes of two chalcogenide SEs (Na₃SbS₄and Na₃SbS_3.5Se_0.5) during the solid‐state synthesis. For these two conductors, the ND results revealed a fast one‐step reaction for the synthesis and the molten process when heating up, and the recrystallization as well as the cubic‐to‐tetragonal phase transition up on cooling. Moreover, Se‐doping was found to influence the reaction temperatures, lattice parameter, and structure stability based on neutron experimental observations and theoretical simulation. This work presents a detailed structural study using in‐situ ND technology for the solid synthesis process of chalcogenide Na‐ion conductors, beneficial for the design and synthesis of new solid‐state conductors.

 

Lithium–CO₂batteries are attractive energy‐storage systems for fulfilling the demand of future large‐scale applications such as electric vehicles due to their high specific energy density. However, a major challenge with Li–CO₂batteries is to attain reversible formation and decomposition of the Li₂CO₃and carbon discharge products. A fully reversible Li–CO₂battery is developed with overall carbon neutrality using MoS₂nanoflakes as a cathode catalyst combined with an ionic liquid/dimethyl sulfoxide electrolyte. This combination of materials produces a multicomponent composite (Li₂CO₃/C) product. The battery shows a superior long cycle life of 500 for a fixed 500 mAh g⁻¹capacity per cycle, far exceeding the best cycling stability reported in Li–CO₂batteries. The long cycle life demonstrates that chemical transformations, making and breaking covalent CO bonds can be used in energy‐storage systems. Theoretical calculations are used to deduce a mechanism for the reversible discharge/charge processes and explain how the carbon interface with Li₂CO₃provides the electronic conduction needed for the oxidation of Li₂CO₃and carbon to generate the CO₂on charge. This achievement paves the way for the use of CO₂in advanced energy‐storage systems.