Concerted Diffusion Research Articles

(Invited) Lithium Ion Conduction by Molecular Vibrations in Ion-Conducting Glasses

Controlling Li ion conduction in glasses at atomic and molecular levels is key to realizing all-solid-state batteries, a promising technology for electric vehicles. In this context, Li3PS4 glass, a promising solid electrolyte candidate, exhibits dynamic coupling between the Li+ cation mobility and the PS4 3− anion libration, which is commonly referred to as the paddlewheel effect1. In addition, it exhibits a concerted cation diffusion effect (i.e., a cation–cation interaction), which is regarded as the essence of high Li ion conduction. However, the correlation between the Li+ ions within the glass structure can only be vaguely determined, due to the limited experimental information. We report that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyse the chemical bonds2. We found that three types of Li ions are present in Li3PS4 glass, and that the more mobile Li ions exhibit a characteristic correlation at relatively long distances of 4.0–5.0 Å. Furthermore, reverse Monte Carlo simulations combined with deep learning potentials that reproduce X-ray, neutron, and electron diffraction pair distribution functions showed an increase in the number of more mobile Li ions for partially crystallised glass structures with improved Li ion conduction properties. Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences. References J. G. Smith, D. J. Siegel, Nature Communications, 11 (1), 1483 (2020). H. Yamada, K. Ohara, S. Hiroi, A. Sakuda, K. Ikeda, T. Ohkubo, K. Nakada, H. Tsukasaki, H. Nakajima, L. Temleitner, L. Pusztai, S. Ariga, A. Matsuo, J. Ding, T. Nakano, T. Kimura, R. Kobayashi, T. Usuki, S. Tahara, K. Amezawa, Y. Tateyama, S. Mori, and A. Hayashi, Energy & Environmental Materials, e12612 (2023).

Early Steps of Individual Multireceptor Viral Interactions Dissected by High-Density, Multicolor Quantum Dot Mapping in Living Cells.

Viral capture and entry to target cells are the first crucial steps that ultimately lead to viral infection. Understanding these events is essential toward the design and development of suitable antiviral drugs and/or vaccines. Viral capture involves dynamic interactions of the virus with specific receptors in the plasma membrane of the target cells. In the last years, single virus tracking has emerged as a powerful approach to assess real time dynamics of viral processes in living cells and their engagement with specific cellular components. However, direct visualization of the early steps of multireceptor viral interactions at the single level has been largely impeded by the technical challenges associated with imaging individual multimolecular systems at relevant spatial (nanometer) and temporal (millisecond) scales. Here, we present a four-color, high-density quantum dot spatiotemporal mapping methodology to capture real-time interactions between individual virus-like-particles (VLPs) and three different viral (co-) receptors on the membrane of primary living immune cells derived from healthy donors. Together with quantitative tools, our approach revealed the existence of a coordinated spatiotemporal diffusion of the three different (co)receptors prior to viral engagement. By varying the temporal-windows of cumulated single-molecule localizations, we discovered that such a concerted diffusion impacts on the residence time of HIV-1 and SARS-CoV-2 VLPs on the host membrane and potential viral infectivity. Overall, our methodology offers the possibility for systematic analysis of the initial steps of viral-host interactions and could be easily implemented for the investigation of other multimolecular systems at the single-molecule level.

Enhancing Lithium Conductivity Using High-Valence Cations in Cubic Spinel Halide Solid Electrolytes.

Halide solid electrolytes for all-solid-state batteries have recently emerged as competitors to oxide and sulfide solid electrolytes due to their excellent electrochemical properties. This ab initio study unveils the dynamic nature of Li2Sc2/3Cl4, a rare superionic conductor among cubic spinel halide materials. Li ions in Li2Sc2/3Cl4 prefer to occupy some of the tetrahedral 8a, octahedral 16c, and octahedral 16d sites, leading to disordered Li distribution. Li ions in Li2Sc2/3Cl4 diffuse through the single-ion diffusion mechanism rather than the concerted diffusion mechanism, providing a high conductivity of 1.36 mS cm-1. Li ions at the 16d site diffuse as actively as those at the 8a/16c site, an unexpected result that runs counter to the conventional view. In Li2MgCl4, the same cubic spinel as Li2Sc2/3Cl4, Li ions at the 8a/16c site diffuse actively, but those at the 16d site are almost immobile, resulting in a very low conductivity of 5.3 × 10-4 mS cm-1. The extremely higher conductivity in Li2Sc2/3Cl4 than in Li2MgCl4 is because the concentration of Sc3+/Mg2+ cations blocking the movement of Li ions at the 16d site is lower in Li2Sc2/3Cl4 than in Li2MgCl4. Designing cubic spinel materials containing high-valence cations is proposed as a way to increase conductivity by reducing the concentration of multivalent cations that impede Li diffusion. This study sheds new light on how to control conductivity using site-dependent Li mobility in solid electrolytes.

Concerted oxygen diffusion across heterogeneous oxide interfaces for intensified propane dehydrogenation

Propane dehydrogenation (PDH) is an industrial technology for direct propylene production which has received extensive attention in recent years. Nevertheless, existing non-oxidative dehydrogenation technologies still suffer from the thermodynamic equilibrium limitations and severe coking. Here, we develop the intensified propane dehydrogenation to propylene by the chemical looping engineering on nanoscale core-shell redox catalysts. The core-shell redox catalyst combines dehydrogenation catalyst and solid oxygen carrier at one particle, preferably compose of two to three atomic layer-type vanadia coating ceria nanodomains. The highest 93.5% propylene selectivity is obtained, sustaining 43.6% propylene yield under 300 long-term dehydrogenation-oxidation cycles, which outperforms an analog of industrially relevant K-CrOx/Al2O3 catalysts and exhibits 45% energy savings in the scale-up of chemical looping scheme. Combining in situ spectroscopies, kinetics, and theoretical calculation, an intrinsically dynamic lattice oxygen “donator-acceptor” process is proposed that O2- generated from the ceria oxygen carrier is boosted to diffuse and transfer to vanadia dehydrogenation sites via a concerted hopping pathway at the interface, stabilizing surface vanadia with moderate oxygen coverage at pseudo steady state for selective dehydrogenation without significant overoxidation or cracking.

Lithium Ion Transport Environment by Molecular Vibrations in Ion‐Conducting Glasses

Controlling Li ion transport in glasses at atomic and molecular levels is key to realizing all‐solid‐state batteries, a promising technology for electric vehicles. In this context, Li3PS4 glass, a promising solid electrolyte candidate, exhibits dynamic coupling between the Li+ cation mobility and the PS43− anion libration, which is commonly referred to as the paddlewheel effect. In addition, it exhibits a concerted cation diffusion effect (i.e., a cation–cation interaction), which is regarded as the essence of high Li ion transport. However, the correlation between the Li+ ions within the glass structure can only be vaguely determined, due to the limited experimental information that can be obtained. Here, this study reports that the Li ions present in glasses can be classified by evaluating their valence oscillations via Bader analysis to topologically analyze the chemical bonds. It is found that three types of Li ions are present in Li3PS4 glass, and that the more mobile Li ions (i.e., the Li3‐type ions) exhibit a characteristic correlation at relatively long distances of 4.0–5.0 Å. Furthermore, reverse Monte Carlo simulations combined with deep learning potentials that reproduce X‐ray, neutron, and electron diffraction pair distribution functions showed an increase in the number of Li3‐type ions for partially crystallized glass structures with improved Li ion transport properties. Our results show order within the disorder of the Li ion distribution in the glass by a topological analysis of their valences. Thus, considering the molecular vibrations in the glass during the evaluation of the Li ion valences is expected to lead to the development of new solid electrolytes.

Diameter-dependent ultrafast lithium-ion transport in carbon nanotubes.

Ion transport in solids is a key topic in solid-state ionics. It is critical but challenging to understand the relationship between material structures and ion transport. Nanochannels in crystals provide ion transport pathways, which are responsible for the fast ion transport in fast lithium (Li)-ion conductors. The controlled synthesis of carbon nanotubes (CNTs) provides a promising approach to artificially regulating nanochannels. Herein, the CNTs with a diameter of 5.5 Å are predicted to exhibit an ultralow Li-ion diffusion barrier of about 10meV, much lower than those in routine solid electrolyte materials. Such a characteristic is attributed to the similar chemical environment of a Li ion during its diffusion based on atomic and electronic structure analyses. The concerted diffusion of Li ions ensures high ionic conductivities of CNTs. These results not only reveal the immense potential of CNTs for fast Li-ion transport but also provide a new understanding for rationally designing solid materials with high ionic conductivities.

Concerted ionic-electronic conductivity enables high-rate capability Li-metal solid-state batteries

Enabling the fast charge and discharge of Li-metal solid-state batteries paves the way towards their deployment in electro-mobility applications, which require high-energy and power with safety guaranteed. Solid-state batteries using polyethylene oxide as the polymer matrix are appealing candidates although currently limited to relatively slow rate capability arising from high solid-solid interfacial resistance and sluggish lithium-ion mobility at the solid electrolyte. In this work, the engineering design and optimization of composite electrodes with multi-walled carbon nanotubes lead to high performance Li metal solid-state cells, showing a high-capacity retention at rates up to 4C. The electrode formulations including the elongated architectures exhibit a concerted ionic-electronic diffusion in the catholyte polymer enabling fast Li-ion transport, enhancing the electronic percolation and increasing the interfacial reaction kinetics and exchange current density. The solid-state battery with LiFePO4 electrode shows an unprecedented capacity retention of 92% during 800 cycles at 2C. The promising performance at high-rates of this approach is also extended to electrodes with a high-voltage active material.

Turing patterns by supramolecular self-assembly of a single salphen building block

SummaryIn the 1950s, Alan Turing showed that concerted reactions and diffusion of activating and inhibiting chemical species can autonomously generate patterns without previous positional information, thus providing a chemical basis for morphogenesis in Nature. However, access to these patterns from only one molecular component that contained all the necessary information to execute agonistic and antagonistic signaling is so far an elusive goal, since two or more participants with different diffusivities are a must. Here, we report on a single-molecule system that generates Turing patterns arrested in the solid state, where supramolecular interactions are used instead of chemical reactions, whereas diffusional differences arise from heterogeneously populated self-assembled products. We employ a family of hydroxylated organic salphen building blocks based on a bis-Schiff-base scaffold with portions responsible for either activation or inhibition of assemblies at different hierarchies through purely supramolecular reactions, only depending upon the solvent dielectric constant and evaporation as fuel.

The chemical origin of temperature-dependent lithium-ion concerted diffusion in sulfide solid electrolyte Li10GeP2S12

Solid-state batteries have received increasing attention in scientific and industrial communities, which benefits from the intrinsically safe solid electrolytes (SEs). Although much effort has been devoted to designing SEs with high ionic conductivities, it is extremely difficult to fully understand the ionic diffusion mechanisms in SEs through conventional experimental and theoretical methods. Herein, the temperature-dependent concerted diffusion mechanism of ions in SEs is explored through machine-learning molecular dynamics, taking Li10GeP2S12 as a prototype. Weaker diffusion anisotropy, more disordered Li distributions, and shorter residence time are observed at a higher temperature. Arrhenius-type temperature dependence is maintained within a wide temperature range, which is attributed to the linear temperature dependence of jump frequencies of various concerted diffusion modes. These results provide a theoretical framework to understand the ionic diffusion mechanisms in SEs and deepen the understanding of the chemical origin of temperature-dependent concerted diffusions in SEs.

Water–Solid Interface Engineering Stabilizes K‐Birnessite Cathode

AbstractCrystal water mediated ion hydration and transport is a fundamental physicochemical process in a wide range of applications and natural processes, such as crystal water containing battery materials. In this context, K‐Birnessite with interlaminar H2O (K0.21MnO2⋅0.31H2O) is reported for nonaqueous potassium‐ion storage with enhanced capacity and rate performance. It is clarified that the water–solid interface plays an important role in building and stabilizing the K‐Birnessite layered structure and facilitating the K+ diffusion for the K‐ion battery system. In addition to the enlarged ionic channel dimensions and effective shielding of the electrostatic interaction with K+, the concerted diffusion of K+/H2O with the rotation of H2O molecules is further revealed to account for the quite low activation energies by first‐principles simulations. Moreover, the interlayer H2O exerts on the electronic structures, and thus on the electrochemical voltage to result in the competition between the split of crystal field (“∇JT”) and the electronic superexchange interaction (“Ow‐K‐O”) in the K‐Birnessite structure. The results provide new insights into hydrated ion kinetics and open an exciting direction for battery material design.

Binary metal oxide anchored into dense N-doped CNTs arrays: Concerted pseudocapacitance and diffusion behavior for long-cyclic Li-ion half/full batteries

Electrode material is a crucial role to improve the performance of alkali metal ion batteries. Herein, a hierarchical nanosheet of binary metal oxide (ZnO/Co3O4) anchored into dense N-doped CNTs arrays (ZCO/NCNTs) was derived by two-step calcination. The design of ZCO/NCNTs containing binary metal oxides can better coordinate the pseudo-capacitance behavior of Co3O4 and the ion diffusion behavior of ZnO to realize a long-term stability for lithium storage at various current densities. Furthermore, the presence of slight Zn sources increases the catalytic efficiency of Co towards the growth of graphitized carbon during calcination process, resulting in the formation of dense carbon nanotubes for enhanced carrier transport. The strong interaction between the metal oxides and carbon nanotubes can accommodate the bulk expansion of electrode, obtaining high reversible capacity (∼880 mAh g−1) and long cycle stability (>500 cycles). Thus, the full cell of LiFePO4||CZO/NCNTs at 0.3 A g−1 exhibits excellent cycle stability with good retention rate after 200 cycles. This study provides a new basis for the improvement of lithium storage performance of metal oxide anode.

Mechanistic Origin of Superionic Lithium Diffusion in Anion-Disordered Li6PS5 X Argyrodites.

The rational development of fast-ion-conducting solid electrolytes for all-solid-state lithium-ion batteries requires understanding the key structural and chemical principles that give some materials their exceptional ionic conductivities. For the lithium argyrodites Li6PS5X (X = Cl, Br, or I), the choice of the halide, X, strongly affects the ionic conductivity, giving room-temperature ionic conductivities for X = {Cl,Br} that are ×103 higher than for X = I. This variation has been attributed to differing degrees of S/X anion disorder. For X = {Cl,Br}, the S/X anions are substitutionally disordered, while for X = I, the anion substructure is fully ordered. To better understand the role of substitutional anion disorder in enabling fast lithium-ion transport, we have performed a first-principles molecular dynamics study of Li6PS5I and Li6PS5Cl with varying amounts of S/X anion-site disorder. By considering the S/X anions as a tetrahedrally close-packed substructure, we identify three partially occupied lithium sites that define a contiguous three-dimensional network of face-sharing tetrahedra. The active lithium-ion diffusion pathways within this network are found to depend on the S/X anion configuration. For anion-disordered systems, the active site–site pathways give a percolating three-dimensional diffusion network; whereas for anion-ordered systems, critical site–site pathways are inactive, giving a disconnected diffusion network with lithium motion restricted to local orbits around S positions. Analysis of the lithium substructure and dynamics in terms of the lithium coordination around each sulfur site highlights a mechanistic link between substitutional anion disorder and lithium disorder. In anion-ordered systems, the lithium ions are pseudo-ordered, with preferential 6-fold coordination of sulfur sites. Long-ranged lithium diffusion would disrupt this SLi6 pseudo-ordering, and is, therefore, disfavored. In anion-disordered systems, the pseudo-ordered 6-fold S–Li coordination is frustrated because of Li–Li Coulombic repulsion. Lithium positions become disordered, giving a range of S–Li coordination environments. Long-ranged lithium diffusion is now possible with no net change in S–Li coordination numbers. This gives rise to superionic lithium transport in the anion-disordered systems, effected by a concerted string-like diffusion mechanism.

#Renziscappa: The Transmedia Story of a Hashtag between Online and Offline Activism

This paper analyzes how the hashtag #Renziscappa was used to create a link between online and offline forms of political activism. Launched in November 2014 by the Italian collective Wu Ming, #Renziscappa aimed to encourage the reporting online of any form of offline protest against the Italian Prime Minister Matteo Renzi. The implementation of #Renziscappa by Wu Ming and their followers sought to counter mainstream representations of Renzi’s purported consensus, and to catalyze and organize the offline protests. Conversely, offline participation linked the hashtag to impact-making political actions. However, the uncontrolled proliferation of #Renziscappa and its appropriation by the Movimento 5 Stelle made the online campaign increasingly lose its connection with the offline protests. By contrast, the concerted transmedia diffusion of #Renziscappa through Wu Ming’s blog Giap and interactive maps preserved this connection. In particular, the maps contextualized #Renziscappa in the genealogical evolution, geo-temporal settings, and socio-political composition of the offline movement. The network of these transmedia extensions constituted a narrative alternative to the mainstream that made users perceive the collective dimension of the movement in a national perspective and fostered the formation of a political subjectivity.

Graphite Lithiation Under Fast Charging Conditions: Atomistic Modeling Insights

Charging lithium ion batteries in a fast and safe manner is critical for promoting mass adoption of electric vehicles. Li intercalation in graphite electrodes is known to be one of the bottlenecks during the fast charging process. The mechanism of Li diffusion in highly polarized graphite anode at high current rates remains, however not well understood. Herein, Density Functional Theory (DFT) calculations are used to gain insights into the Li diffusion process in graphite when far from equilibrium under fast charging conditions. The effect of uncompensated charges on Li mobility is determined in the highly polarized regions of the anode close to the interfaces. The extra charge was found to increase the interlayer spacing in the diffusion layer and adjacent channels, increasing the diffusivity, altering the staging mechanism, and promoting the formation of Li clusters. A concerted diffusion mechanism at the edge of high-concentration Li domains is proposed to enhance the diffusion of Li.

Ab Initio Computation Design for Fast Ionic Conductors

Fast ionic conductor materials are the key component in enabling a variety of electrochemical devices. It is crucial to understand why only a few materials exhibit faster ionic conduction than typical solids and how one can design fast ion conductors following simple principles. Using ab initio modeling techniques, we studied a range of novel fast Li-ion conductor materials and identified the mechanisms leading to fast Li-ion conduction in solid materials. In lithium super-ionic conductors, we show that fast diffusion in super-ionic conductors happens through unique concerted migration mechanism of multiple ions with low energy barrier in contrast to isolated ion hopping in typical solids. We elucidate that low energy barriers of the concerted ionic diffusion are a result of unique mobile-ion configurations and strong mobile-ion interactions in these super-ionic conductor materials. Our theory provides a conceptually simple framework for guiding the design of super-ionic conductor materials. Using first principles computation, we demonstrate this strategy by designing a number of novel fast ion conducting materials. Furthermore, we highlight the design principles for having such crystal structures.

K‐Birnessite Electrode Obtained by Ion Exchange for Potassium‐Ion Batteries: Insight into the Concerted Ionic Diffusion and K Storage Mechanism

AbstractNovel and low‐cost rechargeable batteries are of considerable interest for application in large‐scale energy storage systems. In this context, K‐Birnessite is synthesized using a facile solid‐state reaction as a promising cathode for potassium‐ion batteries. During synthesis, an ion exchange protocol is applied to increase K content in the K‐Birnessite electrode, which results in a reversible capacity as high as 125 mAh g−1 at 0.2 C. Upon K+ exchange the reversible phase transitions are verified by in situ X‐ray diffraction (XRD) characterization. The underlying mechanism is further revealed to be the concerted K+ ion diffusion with quite low activation energies by first‐principle simulations. These new findings provide new insights into electrode process kinetics, and lay a solid foundation for material design and optimization of potassium‐ion batteries for large‐scale energy storage.

Monte Carlo simulations of gadolinium doped ceria surfaces

Hybrid Monte Carlo and adaptive kinetic Monte Carlo calculations have been performed to examine the thermodynamic equilibrium and kinetic properties of a double sided {111} terminated 10 mol% gadolinium doped ceria system. Hybrid Monte Carlo simulations demonstrate that both the concentration of gadolinium ions and oxygen vacancies are enhanced at the surface compared to the bulk. We do not observe the formation of any domain structures at the surface by gadolinium ions. The calculated average activation energy for oxygen transitions from the surface layer is reduced to 0.36 eV, compared to the bulk value of 0.50 eV. Consequently, the ionic conductivity in the surface layers is approximately twice that of the bulk which can be attributed to the surface structure. The adaptive kinetic Monte Carlo simulations found numerous multi-atom concerted diffusion mechanisms spanning large distances which would not have been accounted for in a typical list based kinetic Monte Carlo approach. The taken combined approach is essential to fully understand these complex materials.

Universal Design Strategy for Li Super-Ionic Conductors in All-Solid-State Li-Ion Batteries : A First-Principles Study

Lithium super-ionic conductor (SIC) materials are the key component in enabling all solid-state Li-ion batteries. However, it has not yet been understood why only a few materials as super-ionic conductors can achieve exceptionally higher ionic conductivity than typical solids and how one can design fast ion conductors following simple principles. Using ab initio modeling, we show that fast diffusion in super-ionic conductors happens through unique concerted migration mechanism of multiple ions with low energy barrier in contrast to typical solids. We elucidate that low energy barriers of the concerted ionic diffusion are a result of unique mobile ion configurations and strong mobile ion interactions in super-ionic conductor materials, such as Li10GeP2S12, lithium garnet, NASICON, etc. Our theory provides a conceptually simple framework for guiding the design of super-ionic conductor materials. We demonstrate this strategy by designing a number of novel fast ion conducting materials to activate concerted migration with reduced diffusion barrier. The novel materials are predicted to have comparable Li+ ionic conductivity at room temperature to the known Li SIC materials. In summary, our proposed theory and identified mechanism are universally for fast diffusion in a broad range of ionic conducting materials, and provide a general framework and a universal strategy to design solid materials with fast ionic diffusion.

Proton diffusion mechanisms in the double perovskite cathode material GdBaCo2O5.5: A molecular dynamics study

GdBaCo2O5+x compounds have demonstrated to be very efficient cathode materials not only in solid oxide fuel cells but also in proton conducting fuel cells. In this last case, the excellent properties could be due to the presence of mixed electron-proton conduction. We study here the diffusion of the proton in this material using molecular dynamics simulations. Two different diffusion mechanisms are observed. The predominant mechanism is the standard proton transfer between two neighbouring oxygen atoms combined with the rotation of H around its first neighbour oxygen atom. The second mechanism consists in the migration of the OH group where both oxygen and hydrogen atoms diffuse together. Strong spatial correlations between successive proton jumps are evidenced. This is likely related to the presence of oxygen vacancies and to the concerted diffusion of hydrogen and oxygen atoms.

Origin of fast ion diffusion in super-ionic conductors

Super-ionic conductor materials have great potential to enable novel technologies in energy storage and conversion. However, it is not yet understood why only a few materials can deliver exceptionally higher ionic conductivity than typical solids or how one can design fast ion conductors following simple principles. Using ab initio modelling, here we show that fast diffusion in super-ionic conductors does not occur through isolated ion hopping as is typical in solids, but instead proceeds through concerted migrations of multiple ions with low energy barriers. Furthermore, we elucidate that the low energy barriers of the concerted ionic diffusion are a result of unique mobile ion configurations and strong mobile ion interactions in super-ionic conductors. Our results provide a general framework and universal strategy to design solid materials with fast ionic diffusion.