The solid electrolyte interphase (SEI) largely determines the electrochemical performance of negative electrodes in sodium-ion batteries (SIBs). Ether-based electrolytes, such as diglyme, have been shown to form a more stable and thinner SEI on sodium anodes than traditional commercial ester-based electrolytes. Nonetheless, variations in the detailed evolution of the chemical composition and mechanical strength of the SEIs formed in these two electrolytic solutions during the electrochemical process have rarely been investigated. In this work, we conduct a comparative study of the SEI formed in diglyme-based and carbonate-based electrolytes with ${\mathrm{Na}}_2{\mathrm{Ti}}_3{\mathrm{O}}_7$ (NTO) as a proof-of-concept material, using energy-tuned photoelectron spectroscopy, operando electrochemical atomic force microscopy, and electrochemical techniques. The results show that diglyme forms a thin, homogeneous, and stable SEI with a well-defined inorganic-organic bilayer structure, as opposed to ester-based electrolytes, which form a thicker, nonuniform, and dynamically changing SEI with randomly distributed inorganic-organic structure. Moreover, the less resistive and higher capacitive interfacial processes induced by the diglyme-based electrolyte decrease the overall battery impedance. These advantages enable the NTO anode to exhibit superior specific capacity, cycle stability, and rate capability. This study provides an in-depth view of the factors behind the electrolyte-dependent performance of SIB anodes, which could inform the design and pairing of electrolytes with electrode materials in rechargeable batteries.

Exploring the conduction mechanism in the chalcogenide perovskite $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ is of significant interest due to its potential suitability as a top absorber layer in silicon-based tandem solar cells and other optoelectronic applications. Theoretical and experimental studies anticipate native ambipolar doping in $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$, although experimental validation remains limited. This study reveals a transition from highly insulating behavior to $n$-type conductivity (approximately $100$ S/cm) in $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ thin films through annealing in an $\mathrm{S}$-poor environment. $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ thin films are synthesized via a two-step process: co-sputtering of $\mathrm{Ba}$-$\mathrm{Zr}$ followed by sulfurization at $600{}^{\circ }\mathrm{C}$, and subsequent annealing in high vacuum. Ultraviolet-visible spectroscopy measurements reveal a red shift of approximately $100$ meV in the band gap concurrent with sample-color darkening after vacuum annealing. The increase in defect density from the order of ${10}^{17}$ to ${10}^{21}{\mathrm{cm}}^{-3}$ with vacuum annealing, coupled with the low activation energy (approximately $8$ meV), and the $n$-type character of the defects, strongly suggests that sulfur vacancies ($V_{\mathrm{S}}$) are responsible for the $n$-type doping, in agreement with theoretical predictions. Temperature-dependent Hall measurement shows that phonon scattering governs charge transport at room temperature in $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ films and that $\mathrm{S}$ vacancies are shallow donor defects acting as a weak impurity metal. The shift of the valence-band maximum (VBM) with respect to the Fermi level, quantified by hard x-ray photoelectron spectroscopy ($\mathrm{Ga}$ $\mathrm{K}\alpha$, 9.25 keV), further corroborates the induced $n$ type of conductivity in annealed samples. Our findings indicate that vacuum annealing induces $V_{\mathrm{S}}$ defects that dominate charge transport, resulting in $n$-type conductivity in $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ under $\mathrm{S}$-poor conditions. These discoveries will inform important design choices, such as selecting appropriate contact materials, for integrating $\mathrm{Ba}\mathrm{Zr}\mathrm{S}$${}_3$ into solar cell structures or other devices.

Quantum batteries, quantum systems for energy storage, have gained interest due to their potential scalable charging power density. A quantum battery proposal based on the Dicke model has been explored using organic microcavities, which enable a cavity-enhanced energy-transfer process called superabsorption. However, energy-storage lifetime in these devices is limited by fast radiative emission losses, worsened by superradiance. Here, we demonstrate a promising approach to extend the energy-storage lifetime of Dicke quantum batteries using molecular triplet states. We examine a type of multilayer microcavity where an active absorption layer transfers energy to the molecular triplets of a storage layer, identifying two regimes based on exciton-polariton resonances. We tested one of these mechanisms by fabricating and characterizing five devices across a triplet-polariton resonance, showing that triplet population is maximized when the lower polariton and triplet state are isoenergetic. We found that one of these devices can store energy for 40.3 $\pm$ 0.4 $\mu \mathrm{s}$, a ${10}^3$-fold increase in storage time compared to previous demonstrations. We conclude by discussing potential optimization outlooks for this class of devices.

Quantum batteries are emerging as highly efficient energy-storage devices that can exceed classical performance limits. Although there have been significant advancements in controlling these systems, challenges remain in stabilizing stored energy and minimizing losses due to inevitable environmental interaction. In this paper, we propose a protocol that employs selective weak measurements to protect quantum states from such influence and mitigate battery discharging and that is feasible in state-of-the-art technologies. We establish thermodynamic constraints that allow this method to be implemented without disrupting the overall energy and ergotropy balance of the system, i.e., with no extra net recharging. Our findings demonstrate that appropriately chosen measurement intensity can reduce unwanted discharging effects, thereby preserving ergotropy and improving the stability of quantum batteries. We illustrate the protocol with single- and two-qubit systems and establish the generalization for $N$-cell batteries. Additionally, we explore how weak measurements influence the coherent and incoherent components of ergotropy, providing new insights into the practical application of quantum coherence in energy-storage technologies.

Photoelectrochemical (PEC) cells have emerged as a promising and sustainable route for the production of valuable chemicals and have attracted significant attention over the last few decades. However, photoelectrodes, essential components of PEC devices, are limited by solar-to-hydrogen conversion efficiencies significantly below the theoretical values, as well as by low stability under working conditions. An important hurdle toward achieving high efficiency is the limited number of available tools that can directly probe the interplay between the local morphology and charge carrier transport dynamics within the photoelectrode top layer. This layer has different functions: providing photocatalytic active sites and protecting underlying layers. Therefore, the development of a powerful technique to reveal the influence of morphology on transport dynamics is crucial. In this work, we show how to precisely correlate local morphology with optoelectronic properties via the investigation of photoinduced charge transport processes, by time-dependent Kelvin probe force microscopy (KPFM) measurements. Our approach allows the extraction of time-dependent photovoltage for each pixel of a KPFM scan. We used crystalline-amorphous mixed phase ${\mathrm{Ti}\mathrm{O}}_2$ as a well-established model system to apply and validate our method. Through local correlations between structure-morphology and optoelectronic properties, our results reveal more efficient photoinduced charge separation on the regions corresponding to the crystalline ${\mathrm{Ti}\mathrm{O}}_2$ phase, which exhibit faster transport, and generate a significantly higher surface photovoltage signal (approximately 440 mV) upon UV illumination (super-band-gap illumination). This finding supports the considerable role of microstructure in charge carrier dynamics, and the ability of our analytical method to resolve it. The analysis technique outlined here should find broad applicability, enabling in-depth insight into the effect of local microstructure, and contributing to the design and development of more efficient photoelectrodes by tailoring of the microstructure at the nanoscale.

For several decades, ionic transport within a charged nanopore has been represented by a resistor-capacitor transmission line circuit, where charging electrical double layers are modeled as capacitors, and the resistance to ionic current is modeled as resistors. However, these circuits fail to account for oscillations observed in experimental Nyquist plots of impedance, which are attributed ad hoc to effects such as complex porous structures or chemical reactions. Here we show that diffusivity asymmetry between ions in confinement—overlooked in previous studies—produces Nyquist plots with two turns. Additionally, we demonstrate that ionic transport in a nanopore is more accurately described by two resistor-capacitor circuits. The results show that an impedance response of ionic transport in nanopores for arbitrary Debye lengths is better captured by two Warburg elements in parallel than a single Warburg element. Our findings provide a framework for describing ionic transport in nanopores, with implications for electrochemical technologies using nanoporous electrodes such as supercapacitors, capacitive desalination, and fuel cells.

Energy consumption in solving computational problems has been gaining growing attention as one of the key performance measures for computers. Quantum computation offers advantages over classical computation in terms of various computational resources; however, proving its energy-consumption advantage has been challenging due to the lack of a theoretical foundation linking the physical concept of energy with the computer-scientific notion of complexity for quantum computation. To bridge this gap, we introduce a general framework for studying the energy consumption of quantum and classical computation, based on a computational model conventionally used for studying query complexity in computational complexity theory. Within this framework, we derive an upper bound for the achievable energy consumption of quantum computation, accounting for imperfections in implementation appearing in practice. As part of this analysis, we construct a protocol for Landauer erasure with finite precision in a finite number of steps, which constitutes a contribution of independent interest. Additionally, we develop techniques for proving a nonzero lower bound of energy consumption of classical computation, based on the energy-conservation law and Landauer’s principle. Using these general bounds, we rigorously prove that quantum computation achieves an exponential energy-consumption advantage over classical computation for solving a paradigmatic computational problem—Simon’s problem. Furthermore, we propose explicit criteria for experimentally demonstrating this energy-consumption advantage of quantum computation, analogous to the experimental demonstrations of quantum computational supremacy. These results establish a foundational framework and techniques to explore the energy consumption of computation, opening an alternative way to study the advantages of quantum computation.

The first generation of nuclear fusion reactors is expected to operate using a mixture of deuterium (D) and tritium (T) fuel. Controlling the D:T ratio is a promising option to control the fusion burn rate. The Joint European Torus (JET), as the only operational tokamak that can use tritium, is uniquely placed to test the feasibility of such control. Experiments carried out in 2023, during the third JET D-T campaign, have demonstrated effective feedback control of the D:T ratio under H-mode conditions. The D:T ratio was measured using visible spectroscopy and tritium was injected via gas valves, while deuterium was injected either via gas valves or pellets. In these experiments, the fusion power, measured via the neutron rate, responded promptly to variations in the measured D:T ratio. This demonstrates that, although the plasma is fueled mainly at the edge, rapid mixing of the isotopes occurs throughout the plasma and controlling the D:T ratio is an effective way of controlling the burn rate. To sustain a stable type-I ELMy H-mode plasma, it is desirable to maintain a given edge localised mode (ELM) frequency. However, both the total fueling rate and the D:T ratio influence this ELM frequency, with higher fueling rates and higher D:T ratios both resulting in more frequent ELMs. For this reason, the D:T ratio controller was combined with an ELM frequency controller in a multi-input multi-output controller. Successful simultaneous decoupled control of the D:T ratio and ELM frequency was demonstrated using a combination of pellet and gas fueling. This is the first and, for the time being, only demonstration of such an advanced burn control scheme in a DT plasma.

Hydrogen, as the most abundant element in the universe, holds immense potential as the fuel of the future due to its high energy density per unit weight and its environmentally friendly nature. This article offers a comprehensive overview of recent theoretical advancements in hydrogen storage, outlining a general framework for achieving practical hydrogen uptake. We examine the fundamental interaction mechanisms, emphasizing orbital hybridization, polarization induced by external electric fields, and multipole Coulomb interactions between metal atoms and dihydrogen. Special focus is placed on calcium metal, which exhibits a transition from electrostatic to Kubas-type orbital interactions as multiple hydrogen molecules adsorb. The processes of hydrogen dissociation and spillover on sorbent surfaces, catalyzed by metals, are also discussed. We present the formalism by Lee et al. [Phys. Rev. Lett. 97, 056104 (2006)] as a method for calculating maximum hydrogen adsorption per site under varying temperatures and pressures, facilitating estimates of reversible hydrogen delivery. General computational strategies are reviewed, highlighting potential sources of error, such as neglecting zero-point vibrational energies, basis set superposition errors, and inaccuracies due to inappropriate density functionals. Additionally, we address practical challenges in designing optimal hydrogen storage materials for real-world applications, including nanostructure breakdown under intense electric fields, metal clustering, and oxygen blockage of metal functional sites. The article concludes by suggesting strategies to bridge the gap between computational simulations and experimental results, guiding the design of next-generation hydrogen storage materials.

The inorganic tin halide perovskites (such as ${\mathrm{Cs}\mathrm{Sn}\mathrm{Br}}_3$ and ${\mathrm{Cs}\mathrm{Sn}\mathrm{I}}_3$) exhibit high hole concentrations, which have been attributed to the presence of intrinsic defects such as cation vacancies. Despite their promise as photovoltaic materials, this high intrinsic conductivity limits deployment. Using hybrid density functional theory, we examine the impact of these intrinsic defects on the electronic properties of ${\mathrm{Cs}\mathrm{Sn}\mathrm{Br}}_3$ and ${\mathrm{Cs}\mathrm{Sn}\mathrm{I}}_3$. We find that tin and cesium vacancies have low formation energies, especially under $\mathrm{Sn}$-poor conditions, in agreement with prior work, and that the presence of these native acceptor defects can lead to high hole concentrations. However, effective donor doping of these systems can be obtained via $\mathrm{Sc}$ or $\mathrm{Y}$ incorporation. These impurities substitute on the $\mathrm{Sn}$ site, where they act as single donors. By examining the formation energy of these dopants versus the native defects, we show that $\mathrm{Sc}$ or $\mathrm{Y}$ doping should lead to a strong compensation, reducing hole concentrations under $\mathrm{Sn}$-rich conditions.

Metastable nonradiative centers (supertraps) are significant energy loss channels in perovskite optoelectronic devices. In their active state, supertraps induce substantial energy loss through nonradiative recombination of free charge carriers. Transitions between active (energy loss) and passive (no energy loss) states result in photoluminescence (PL) blinking on timescales from milliseconds to seconds. The presence of blinking allowed us to investigate the active states of supertraps by extracting their time-dependent quenching efficiency functions on microsecond timescales from PL decay kinetics. These functions, unique to each supertrap, reveal how transitions from passive to active states modify the PL decay curve. Surprisingly, microcrystals often contain supertraps with different properties that effectively quench PL on different timescales relative to the excitation pulse: some start to quench the prompt PL immediately after excitation, while others effectively quench only the delayed PL after several microseconds. This leads to significant differences in PL blinking behavior when comparing prompt and delayed PL components. All these are inconsistent with the common view on the active state of a supertrap as a single deep energy level in the band gap. Instead, we suggest that the active state is a complex nonradiative center comprising a shallow and a deep energy level. These two-level centers likely form through the temporary association of individual defects, with variations in their quenching dynamics attributed to differences in energy levels, geometry, and local environment. By identifying supertraps with distinct time-dependent quenching dynamics, this work provides insights into defect engineering strategies that could reduce nonradiative losses in optoelectronic perovskite devices.

${\mathrm{Zn}\mathrm{Cl}}_2$ solutions are promising electrolytes for aqueous zinc-ion batteries. Here, we report a joint computational and experimental study of the structural and dynamic properties of aqueous ${\mathrm{Zn}\mathrm{Cl}}_2$ electrolytes with concentrations ranging from salt-in-water to water-in-salt (WIS). By developing a neural network potential (NNP) model, we perform molecular dynamics (MD) simulations with ab initio accuracy but at much larger lengths and longer timescales. The NNP predicted structures are validated by the structure factors measured by X-ray total scattering experiments. The MD trajectories provide a comprehensive and quantitative picture of the ${\mathrm{Zn}}^{2+}$ solvation shell structures. Additionally, we find that the $\mathrm{O}-\mathrm{H}$ covalent bonds in water are strengthened with increasing salt concentration, thus expanding the electrochemical stability window of aqueous electrolytes. In terms of dynamic properties, the calculated and experimentally measured conductivities are in good agreement. Through the analysis of the calculated cation transference number, we propose a three-stage charge carrier transport mechanism with increasing concentration: independent ion transport, strongly correlated ion transport, and small positive charge carrier diffusion through negatively charged polymeric clusters. Our study provides fundamental atomic scale insights into the structure and transport properties of the ${\mathrm{Zn}\mathrm{Cl}}_2$ electrolyte that can aid the optimization and development of WIS electrolytes.

With the growing emphasis on sustainability, criticality, and availability in materials research, providing actionable information about mineral commodities is crucial for informed decision-making and strategic planning by researchers, policy makers, and industry stakeholders. While the United States Geological Survey (USGS) offers valuable information on mineral-commodity summaries, their unstructured nature makes analysis challenging. To address this, we present a comprehensive data-analytics application (https://mineral-ai.net/) that processes the past 10 years of USGS mineral-commodity summaries into actionable insights. The application offers country-specific insights into global elemental production and reserves, along with quantitative metrics such as the Herfindahl-Hirschman index (HHI) to evaluate market concentration, identifying risks and opportunities in resource availability. It also features an artificial-intelligence assistant powered by a large language model (LLM) and a retrieval–augmented generation (RAG) system, enabling users to query various aspects of raw materials, including reserves, production, market share, usage, price, substitutes, recycling, and more. We evaluated multiple open-source LLMs for the RAG task and selected the best-performing model, llama-3, to implement in the system. This application provides valuable support for material scientists in assessing sustainability, criticality, and market risks, thereby aiding in the development of new materials. We demonstrate its application in energy materials, and by describing the application architecture and providing open access to the code, we aim to enable data-driven advancements in materials research.

Silver-based chalcohalide antiperovskites (CAPs), ${\mathrm{Ag}}_{3}BC$ ($B=\mathrm{S}$, Se; $C=\mathrm{Cl},\mathrm{Br},\mathrm{I}$), represent an emerging family of energy materials with intriguing optoelectronic, vibrational, and ionic transport properties. However, the structural features and phase stability of CAP remain poorly investigated to date, hindering their fundamental understanding and potential integration into technological applications. Here we employ theoretical first-principles methods based on density-functional theory to fill this knowledge gap. Through crystal-structure prediction techniques, ab initio molecular dynamics simulations, and quasiharmonic free-energy calculations, we unveil a series of previously overlooked energetically competitive phases and temperature-induced phase transitions for all CAP. Specifically, we identify a new cubic $P{2}_{1}3$ structure as the stable phase of all CAP containing S both at zero temperature and $T\ne 0$ K conditions. Consequently, our calculations suggest that the cubic $Pm\overline{3}m$ phase identified in room-temperature x-ray diffraction experiments is possibly metastable. Furthermore, for CAP containing Se, we propose different orthorhombic ($Pca{2}_1$ and $P{2}_1{2}_1{2}_1$) and cubic ($I{2}_{1}3$) structures as the ground-state phases and reveal several phase transformations induced by temperature. This theoretical investigation not only identifies new candidate ground-state phases and solid-solid phase transformations for all CAP but also provides insights into potential stability issues affecting technological applications based on these highly anharmonic materials.

This study investigates the dynamic behavior of aqueous electrolytes in porous carbon electrodes under voltage, with a focus on the impact of electrode flexibility on the pore texture. Utilizing a constant-voltage approach with a reactive interaction potential, we examine the heterogeneous charge distribution on carbon atoms within the electrode, revealing the role of chemical defects. Comparisons between flexible- and frozen-electrode models highlight the significant influence of flexibility on ion-adsorption intake and dynamics. The total ion docking for $\mathrm{Cs}$${}^{+}$ and $\mathrm{Cl}$${}^{-}$ is overestimated by a factor of 2–3 in the frozen approximation, depending on the voltage. Furthermore, we explore ion-induced swelling and modifications in pore-size distribution for $\mathrm{Li}$${}^{+}$, $\mathrm{Na}$${}^{+}$, $\mathrm{K}$${}^{+}$, and $\mathrm{Cs}$${}^{+}$ ions, revealing that different alkali ions induce different degrees of swelling leading to nanoscale plasticity. This permanent deformation induces aging and underlines the importance of the flexibility. The study provides valuable insights into the intricate interplay between ion interactions and porous carbon flexibility.

Electrical leakage is an inherent problem in solid-oxide fuel and electrolyzer cells, limiting their energy-conversion efficiency. High concentrations of electrons or holes can exacerbate this issue. However, it is largely unclear how the typical high operating temperatures of the systems influence their charge-carrier concentrations. In this work, we use first-principles calculations to examine how lattice vibrations impact electrical conductivity in conventional electrolytes, using $\mathrm{Ba}\mathrm{Zr}\mathrm{O}$${}_3$ as a representative material. Our analysis shows that phonon-induced shifts in the band gap and band edges lead to a dramatic increase in $p$-type carrier concentrations at temperatures above 600 K, compared to models that neglect temperature effects. Additionally, we reveal the importance of oxygen-ion motion on band-edge positions, which makes valence-band-edge shift dominate the band-gap change. Our study provides a protocol for calculating phonon-induced changes in similar oxides, paving the way for interrogating electrical leakage in electrolytes for high-temperature operation.

Because of their rapid ionic diffusion, $\mathrm{Ag}$-based argyrodites have great potential as solid-state electrolytes. The fundamental thermal transport in these materials is important for the overall all-solid-state battery design. Using an accurate ab initio framework and a unified heat-transport theory, we compute both the particle-like (${\kappa }_{\mathrm{p}}$) and the glass-like (${\kappa }_{\mathrm{c}}$) components of the lattice thermal conductivity (${\kappa }_{\mathrm{L}}$) of ${\mathrm{Ag}}_8{\mathrm{Sn}\mathrm{Se}}_6$ in the orthorhombic phase. Despite being a crystal, ${\mathrm{Ag}}_8{\mathrm{Sn}\mathrm{Se}}_6$ exhibits an exceptionally low room-temperature ${\kappa }_{\mathrm{L}}={\kappa }_{\mathrm{p}}+{\kappa }_{\mathrm{c}}$ of 0.274 W/mK, which is nearly temperature independent over the 100–350 K range. This unusual behavior is linked to the lonesome $\mathrm{Ag}$ atoms, which, in this temperature range, exhibit intense vibrations while remaining weakly bonded to the $\mathrm{Sn}$-$\mathrm{Se}$ framework. While their bonding anharmonicity significantly reduces ${\kappa }_{\mathrm{p}}$, the $\mathrm{Ag}$-dominated extended vibrations make ${\kappa }_{\mathrm{c}}$ the primary heat-transfer mode. By unveiling the role of $\mathrm{Ag}$ in the heat transport of ${\mathrm{Ag}}_8{\mathrm{Sn}\mathrm{Se}}_6$, we support the notion that the bonding and structural characteristics responsible for fast ionic conduction can also help identify extreme materials with glass-like thermal transport.

While the dynamics of hydrogen bubbles during water electrolysis have been intensively studied in recent years, adequate insights into the dynamics of oxygen bubbles are still lacking. Therefore, this study presents a comparative analysis of hydrogen and oxygen bubble dynamics during potentiostatic water electrolysis in an acidic electrolyte. Complementary optical techniques, such as high-speed shadowgraphy, particle tracking velocimetry, and schlieren imaging are applied to measure geometric features of the evolving bubbles and the microscale Marangoni convection, as well as the refractive index field around the growing bubbles. Distinct differences between oxygen and hydrogen bubbles are found in the average current, in the Marangoni convection pattern, and in the degree of refractive index reduction at the bubble foot, suggesting a synergetic action of both thermal and solutal effects at oxygen bubbles.

Heusler compounds with six valence electrons per atom have attracted interest as thermoelectric materials owing to their semimetallic and semiconducting properties. Here, we theoretically and experimentally investigate electronic transport in ${\mathrm{Ru}}_2\mathrm{Ti}\mathrm{Si}$-based full-Heuslers. We show that electronic transport in this system can be well captured by a two-parabolic-band model. The larger band gap of ${\mathrm{Ru}}_2\mathrm{Ti}\mathrm{Si}$ promises a higher thermoelectric performance, compared to its isovalent family member ${\mathrm{Fe}}_2\mathrm{V}\mathrm{Al}$, which has been studied as a thermoelectric material for over two decades. Additionally, we identify $p$-type ${\mathrm{Ru}}_2\mathrm{Ti}\mathrm{Si}$ as far more efficient than previously studied $n$-type compounds and demonstrate that this can be traced back to much lighter and more mobile holes originating from dispersive valence bands. Our findings suggest that an exceptionally high dimensionless figure of merit $zT>1$ can be realized in these $p$-type compounds around 700 K upon proper reduction of the lattice thermal conductivity, e.g., by substituting $\mathrm{Zr}$ or $\mathrm{Hf}$ for $\mathrm{Ti}$.