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Recent worldwide efforts to establish solid-state batteries as a potentially safe and stable high-energy and high-rate electrochemical storage technology still face issues with long-term performance, specific power and economic viability. Here, we review key challenges that still involve the need for fast-conducting solid electrolytes to provide sufficient transport in composite cathodes. In addition, we show that high-performance anodes together with protection concepts are paramount to establish dense high-energy solid-state batteries and that lithium-based solid-state batteries as well as metal anodes may not be the ultimate solution. We further discuss that diversity in terms of materials, research teams and approaches is key to establish long-term solid-state batteries. About ten years after the first ground-breaking publication of lithium solid electrolytes with an ionic conductivity higher than that of liquid electrolytes, it is time to realistically address the remaining key challenges for full-scale commercialization, cell performance and implementation.

Strong compositional influences are known to affect the ionic transport within the thio-LISICON family, however, a deeper understanding of the resulting structure - transport correlations have up until now been lacking. Employing a combination of high-resolution neutron diffraction, impedance spectroscopy and nuclear magnetic resonance spectroscopy, together with bond valence site energy calculations and the maximum entropy method for determining the underlying Li+ scattering density distribution of a crystal structure, this work assesses the impact of the Li+ substructure and charge carrier density on the ionic transport within the Li4-xGe1-xSbxS4 substitution series. By incorporating Sb5+ into Li4GeS4, an anisometric expansion of the unit cell is observed. An additional Li+ position is found as soon as (SbS4)3− polyhedra are present, leading to a better local polyhedral connectivity and a higher disorder in the Li+ substructure. Here, we are able to relate structural disorder to an increase in configurational entropy, together with a two order-of-magnitude increase in ionic conductivity. This result reinforces the typically believed paradigm that structural disorder leads to improvements in ionic transport.

Lithium ion conducting argyrodites are among the most studied solid electrolytes due to their high ionic conductivities. A major concern in a solid-state battery is the solid electrolyte stability. Here we present a systematic study on the influence of cationic and anionic substitution on the electrochemical stability of Li6PS5X, using step-wise cyclic voltammetry, optical band gap measurements, hard X-ray photoelectron spectroscopy along with first-principles calculations. We observe that going from Li6PS5Cl to Li6+xP1-xMxS5I (M = Si4+, Ge4+), the oxidative degradation does not change. Considering the chemical bonding shows that the valence band edges are mostly populated by non-bonding orbitals of the PS43- units or unbound sulfide anions and that simple substitutions in these sulfide-based solid electrolytes cannot improve oxidative stabilities. This work provides insights on the role of chemical bonding on the stability of superionic conductors and shows that alternative strategies are needed for long-term stable solid-state batteries.

Solid electrolytes are at the heart of future energy storage systems. Li-bearing argyrodites are frontrunners in terms of Li+ ion conductivity. Although many studies have investigated the effect of elemental substitution on ionic conductivity, we still do not fully understand the various origins leading to improved ion dynamics. Here, Li6+xP1–xGexS5I served as an application-oriented model system to study the effect of cation substitution (P5+ vs Ge4+) on Li+ ion dynamics. While Li6PS5I is a rather poor ionic conductor (10–6 S cm–1, 298 K), the Ge-containing samples show specific conductivities on the order of 10–2 S cm–1 (330 K). Replacing P5+ with Ge4+ not only causes S2–/I– anion site disorder but also reveals via neutron diffraction that the Li+ ions do occupy several originally empty sites between the Li rich cages in the argyrodite framework. Here, we used 7Li and 31P NMR to show that this Li+ site disorder has a tremendous effect on both local ion dynamics and long-range Li+ transport. For the Ge-rich samples, NMR revealed several new Li+ exchange processes, which are to be characterized by rather low activation barriers (0.1–0.3 eV). Consequently, in samples with high Ge-contents, the Li+ ions have access to an interconnected network of pathways allowing for rapid exchange processes between the Li cages. By (i) relating the changes of the crystal structure and (ii) measuring the dynamic features as a function of length scale, we were able to rationalize the microscopic origins of fast, long-range ion transport in this class of electrolytes.

Establishing links between the structure and physical properties of solid-state ionic conductors contributes not only to a rationale of their fundamental nature, but also provides design principles to accelerate the discovery of new materials. Lithium ion conduction in complex halides is not well-elucidated and so the interplay between lattice dynamics, electronic structure and electrochemical properties in such halides has been explored in the isostructural family of lithium tetrahaloaluminates LiAlX4 (X = Cl, Br, I). Using a combination of experimental methods (Diffuse reflectance UV-Vis spectroscopy, Pulse-Echo Speed of Sound measurements, Raman spectroscopy, Inelastic Neutron Scattering) and periodic density functional theory (DFT) based calculations, we demonstrate that softer lattices (quantified in terms of Debye frequencies or Li-phonon band centres as a function of X) provide lower activation energies for Li+ migration. However, the relationship between polarisability and Li+ conductivity is not straightforward. In line with expectations emergent from the Meyer-Neldel rule, the activation energy for Li+ hopping, Ea, and the pre-exponential terms collated as σ0 in the Arrenhius equation for activated conductivity, correlate. It is also evident that the electrochemical oxidative potential limit correlates with the X– phonon band centre in the vibrational density of states (VDOS) and that the electrochemical stability window (EW) and optical band gap are interlinked, as expected.

Mechanochemically synthesized sodium halide solid solutions with the general formula Na2+xZr1–xMxCl6, as a class of potential catholytes, show promising ionic transport in comparison to their parental materials such as Na3YCl6. However, the influence of subsequent heat treatment protocols on the structure and transport properties of these materials is still not fully understood. In this work, a series of Na2+xZr1–xInxCl6 solid solutions are prepared by ball milling with subsequent annealing at different temperatures. X-ray diffraction analyses show a full indium solubility in Na2+xZr1–xInxCl6 when synthesized at low temperatures and crystallizing in the P21/n phase. In contrast, at higher heat treatment temperatures, exsolution is observed as the indium-rich Na2+xZr1–xInxCl6 compound tends to partially transform to the trigonal P3̅1c phase. By assessing the ionic conductivity of the differently synthesized Na2+xZr1–xInxCl6 series, we can show the synergistic effect of the Na+/vacancy ratio and crystallinity on sodium ion transport in this class of materials.

Sb(+V) substitution in Li10GeP2S12 has only a minor effect on the structure and ionic transport.

Aliovalent substitution is a common strategy to improve the ionic conductivity of solid electrolytes for solid-state batteries. The substitution of SbS43– by WS42– in Na2.9Sb0.9W0.1S4 leads to a very high ionic conductivity of 41 mS cm–1 at room temperature. While pristine Na3SbS4 crystallizes in a tetragonal structure, the substituted Na2.9Sb0.9W0.1S4 crystallizes in a cubic phase at room temperature based on its X-ray diffractogram. Here, we show by performing pair distribution function analyses and static single-pulse 121Sb NMR experiments that the short-range order of Na2.9Sb0.9W0.1S4 remains tetragonal despite the change in the Bragg diffraction pattern. Temperature-dependent Raman spectroscopy revealed that changed lattice dynamics due to the increased disorder in the Na+ substructure leads to dynamic sampling causing the discrepancy in local and average structure. While showing no differences in the local structure, compared to pristine Na3SbS4, quasi-elastic neutron scattering and solid-state 23Na nuclear magnetic resonance measurements revealed drastically improved Na+ diffusivity and decreased activation energies for Na2.9Sb0.9W0.1S4. The obtained diffusion coefficients are in very good agreement with theoretical values and long-range transport measured by impedance spectroscopy. This work demonstrates the importance of studying the local structure of ionic conductors to fully understand their transport mechanisms, a prerequisite for the development of faster ionic conductors.

The lithium argyrodites Li6PS5X (X = Cl, Br, and I) have attracted interest as fast solid ionicconductors for solid-state battery. Within this class of materials, it has been previously suggestedthat more polarizable anions and larger substituents should influence the ionic conductivity (e.g.,substituting S by Se). Building upon this work, we explore the influence of Sn substitution inlithium argyrodites Li6+xSnxP1−xSe5I in direct comparison to the previously-reportedLi6+xSnxP1−xS5I series. The (P5+/Sn4+)Se43/4- polyhedral volume, unit cell volume, and lithiumcoordination tetrahedra Li(48h)-(S/Se)3-I increase with Sn substitution in this new selenideseries. Impedance spectroscopy reveals that increasing Sn4+ substitution results in a five-foldimprovement in the ionic conductivity when compared to Li6PSe5I. This work provides furtherunderstanding of compositional influences for optimizing the ionic conductivity of solidelectrolytes.

Understanding the correlation between ionic motion and crystal structure is crucial for improving solid electrolyte conductivities. Several substitution series in the Li

Rechargeable batteries are a key enabler to achieve the long-term goal to transform into a climate- neutral society. Within this transformation, battery costs are considered a main hurdle for the market- breakthrough of battery-powered products. Encouraged by this, various studies have been published attempting to predict these, providing the reader with a large variance of forecasted cost that results from differences in methods and assumptions. This article creates transparency by identifying 53 studies that provide time- or technology-specific estimates for lithium-ion, solid-state, lithium–sulfur and lithium–air batteries among more than 2000 publications related to the topic. The relevant publications are clustered according to four applied forecasting methods: technological learning, literature-based projections, expert elicitations and bottom-up modeling. Method-specific assumptions are analyzed in-depth and discussed with regard to their results and empirical evidence. Further, 360 extracted data points are consolidated into a pack cost trajectory that reaches a level of about 70 $ (kW h)1 in 2050, and 12 technology-specific forecast ranges that indicate cost potentials below 90 $ (kW h)1 for advanced lithium-ion and 70 $ (kW h)1 for lithium-metal based batteries. Recent studies show confidence in a more stable battery market growth and, across time-specific studies, authors expect continuously declining battery cost regardless of raw material price developments. However, large cost uncertainties are found to exist on technological and chronological levels that will remain a key challenge for researchers and industry in the future. https://issuu.com/peacock-tv-premium-plus-ios-free https://issuu.com/crunchyroll-premium-ios-free-download https://issuu.com/funimation-premium-plus-ultra-ios-free https://issuu.com/tinder-unlimited-likes-ios https://issuu.com/bumble-premium-free-ios-download https://issuu.com/splice-premium-ios-free-download https://issuu.com/prequel-premium-ios-free-download https://issuu.com/airbrush-premium-ios-free-download https://issuu.com/tezza-full-pack-ios-free-download https://issuu.com/videoleap-pro-free-ios-download

Materials today / Physics 35, 101107 (2023). doi:10.1016/j.mtphys.2023.101107, Published by Elsevier, Amsterdam

Given the inherent performance limitations of intercalation‐based lithium‐ion batteries, solid‐state conversion batteries are promising systems for future energy storage. A high specific capacity and natural abundancy make iron disulfide (FeS2) a promising cathode‐active material. In this work, FeS2 nanoparticles were prepared solvothermally. By adjusting the synthesis conditions, samples with average particle diameters between 10 nm and 35 nm were synthesized. The electrochemical performance was evaluated in solid‐state cells with a Li‐argyrodite solid electrolyte. While the reduction of FeS2 was found to be irreversible in the initial discharge, a stable cycling of the reduced species was observed subsequently. A positive effect of smaller particle dimensions on FeS2 utilization was identified, which can be attributed to a higher interfacial contact area and shortened diffusion pathways inside the FeS2 particles. These results highlight the general importance of morphological design to exploit the promising theoretical capacity of conversion electrodes in solid‐state batteries., Particle‐size reduction of iron sulfide nanoparticles improves its performance as an active material in solid‐state conversion cathodes: For reduced particle dimensions, the electrochemical utilization of FeS2 is increased. The potential of FeS2 as an electrode in solid‐state batteries is highlighted and the importance of the morphological design of battery materials is underscored.

Superionic lithium argyrodites are attractive as solid electrolytes for all-solid-state-batteries. These materials of composition Li6PS5X (X = Cl, Br, and I) exhibit structural disorder between the X−/S2− positions, with higher disorder realizing better Li+ transport. Further replacement of the sulfide by chloride anions (for the series Li7−xPS6−xClx) has been shown to increase the ionic conductivity. However, the underlying changes to the lithium substructure are still relatively unknown. Here we explore a larger range of nominal halide compositions in this material from x = 0.25 to x = 1.5 and explore the changes with neutron diffraction and impedance spectroscopy. The replacement of S2− by Cl−causes a lowered average charge in the center of the prevalent Li+ “cages”, which in turn causes weaker interactions with Li+ ions. Analysis of neutron diffraction data reveals that the increased Cl− content causes these clustered Li+ “cages” to become more interconnected, thereby increasing Li+ conductivity through the structure. This study explores the understanding of the fundamental structure–transport correlations in the argyrodites, specifically structural changes withinthe Li+ ion substructure upon changing anionic charge distribution.

State-of-the-art oxides and sulfides with high Li-ion conductivity and good electrochemical stability are among the most promising candidates for solid-state electrolytes in secondary batteries. Yet emerging halides offer promising alternatives because of their intrinsic low Li+ migration energy barriers, high electrochemical oxidative stability, and beneficial mechanical properties. Mechanochemical synthesis has enabled the characterization of LiAlX4 compounds to be extended and the iodide, LiAlI4, to be synthesized for the first time (monoclinic P21/c, Z = 4; a = 8.0846(1) Å; b = 7.4369(1) Å; c = 14.8890(2) Å; β = 93.0457(8)°). Of the tetrahaloaluminates, LiAlBr4 exhibited the highest ionic conductivity at room temperature (0.033 mS cm–1), while LiAlCl4 showed a conductivity of 0.17 mS cm–1 at 333 K, coupled with the highest thermal and oxidative stability. Modeling of the diffusion pathways suggests that the Li-ion transport mechanism in each tetrahaloaluminate is closely related and mediated by both halide polarizability and concerted complex anion motions.

Owing to high ionic conductivity and good oxidation stability, halide‐based solid electrolytes regain interest for application in solid‐state batteries. While stability at the cathode interface seems to be given, the stability against the lithium metal anode has not been explored yet. Herein, the formation of a reaction layer between Li3InCl6 (Li3YCl6) and lithium is studied by sputter deposition of lithium metal and subsequent in situ X‐ray photoelectron spectroscopy as well as by impedance spectroscopy. The interface is thermodynamically unstable and results in a continuously growing interphase resistance. Additionally, the interface between Li3InCl6 and Li6PS5Cl is characterized by impedance spectroscopy to discern whether a combined use as cathode electrolyte and separator electrolyte, respectively, might enable long‐term stable and low impedance operation. In fact, oxidation stable halide‐based lithium superionic conductors cannot be used against Li, but may be promising candidates as cathode electrolytes., Superionic halide solid electrolytes show excellent cathodic electrolyte properties in solid state batteries, but they are unstable in contact with the lithium metal anode. The forming solid electrolyte interphase is analyzed herein, using X‐ray photoelectron spectroscopy and impedance spectroscopy. Additionally, the hetero‐interface between Li3InCl6 and Li6PS5Cl is analyzed to highlight the concept of hybrid electrolyte cells.

The quantitative influence of microstructure, porosity, surface area, and changes in the crystal lattice on the electric conduction mechanisms in cathode-active materials for lithium ion batteries ...

Solid electrolytes are key elements for next-generation energy storage systems. To design powerful electrolytes with high ionic conductivity, we need to improve our understanding of the mechanisms that are at the heart of the rapid ion exchange processes in solids. Such an understanding also requires evaluation and testing of methods not routinely used to characterize ion conductors. Here, the ternary Li4MCh4 system (M = Ge, Sn; Ch = Se, S) provides model compounds to study the applicability of 7Li nuclear magnetic resonance (NMR) spin-alignment echo (SAE) spectroscopy to probe slow Li+ exchange processes. Whereas the exact interpretation of conventional spin–lattice relaxation data depends on models, SAE NMR offers a model-independent, direct access to motional correlation rates. Indeed, the jump rates and activation energies deduced from time-domain relaxometry data perfectly agree with results from 7Li SAE NMR. In particular, long-range Li+ diffusion in polycrystalline Li4SnS4 as seen by NMR in a dynamic range covering 6 orders of magnitude is determined by an activation energy of Ea = 0.55 eV and a pre-exponential factor of 3 × 1013 s–1. The variation in Ea and 1/τ0 is related to the LiCh4 volume that changes within the four Li4MCh4 compounds studied. The corresponding volume of Li4SnS4 seems to be close to optimum for Li+ diffusivity.

The recent interest in halide-based solid electrolytes Li3MX6 (M = Y, Er, and In; X = Cl, Br, and I) shows these materials to be promising candidates for solid-state battery application, due to the...

A deeper understanding of the relationships among composition–structure–transport properties in inorganic solid ionic conductors is of paramount importance to develop highly conductive phases for f...

Rechargeable batteries are a key enabler to achieve the long-term goal to transform into a climate-neutral society. Within this transformation, battery costs are considered a main hurdle for the market-breakthrough of battery-powered products. Encouraged by this, various studies have been published attempting to predict these, providing the reader with a large variance of forecasted cost that results from differences in methods and assumptions. This article creates transparency by identifying 53 studies that provide time- or technology-specific estimates for lithium-ion, solid-state, lithium–sulfur and lithium–air batteries among more than 2000 publications related to the topic. The relevant publications are clustered according to four applied forecasting methods: technological learning, literature-based projections, expert elicitations and bottom-up modeling. Method-specific assumptions are analyzed in-depth and discussed with regard to their results and empirical evidence. Further, 360 extracted data points are consolidated into a pack cost trajectory that reaches a level of about 70 $ (kW h)−1 in 2050, and 12 technology-specific forecast ranges that indicate cost potentials below 90 $ (kW h)−1 for advanced lithium-ion and 70 $ (kW h)−1 for lithium-metal based batteries. Recent studies show confidence in a more stable battery market growth and, across time-specific studies, authors expect continuously declining battery cost regardless of raw material price developments. However, large cost uncertainties are found to exist on technological and chronological levels that will remain a key challenge for researchers and industry in the future.

The development of high-performance inorganic solid electrolytes is central to achieving high-energy- density solid-state batteries. Whereas these solid-state materials are often prepared via classic solid-state syntheses, recent efforts in the community have shown that mechanochemical reactions, solution syntheses, microwave syntheses, and various post-synthetic heat treatment routines can drastically affect the structure and microstructure, and with it, the transport properties of the materials. On the one hand, these are important considerations for the upscaling of a materials processing route for industrial applications and industrial production. On the other hand, it shows that the influence of the different syntheses on the materials' properties is neither well understood fundamentally nor broadly internalized well. Here we aim to review the recent efforts on understanding the influence of the synthetic procedure on the synthesis – (micro)structure – transport correlations in superionic conductors. Our aim is to provide the field of solid-state research a direction for future efforts to better understand current materials properties based on synthetic routes, rather than having an overly simplistic idea of any given composition having an intrinsic conductivity. We hope this review will shed light on the underestimated influence of synthesis on the transport properties of solid electrolytes toward the design of syntheses of future solid electrolytes and help guide industrial efforts of known materials., Influence of synthesis and processing on the nature of ultimate product and the ionic transport properties of superionic conductors.

Strategies to enhance ionic conductivities in solid electrolytes typically focus on the effects of modifying their crystal structures or of tuning mobile-ion stoichiometries. A less-explored approach is to modulate the chemical bonding interactions within a material to promote fast lithium-ion diffusion. Recently, the idea of a solid-electrolyte inductive effect has been proposed, whereby changes in bonding within the solid-electrolyte host framework modify the potential energy landscape for the mobile ions, resulting in an enhanced ionic conductivity. Direct evidence for a solid-electrolyte inductive effect, however, is lacking-in part because of the challenge of quantifying changes in local bonding interactions within a solid-electrolyte host framework. Here, we consider the evidence for a solid-electrolyte inductive effect in the archetypal superionic lithium-ion conductor Li10Ge1-xSnxP2S12. Substituting Ge for Sn weakens the {Ge,Sn}-S bonding interactions and increases the charge density associated with the S2- ions. This charge redistribution modifies the Li+ substructure causing Li+ ions to bind more strongly to the host framework S2- anions, which in turn modulates the Li+ ion potential energy surface, increasing local barriers for Li+ ion diffusion. Each of these effects is consistent with the predictions of the solid-electrolyte inductive effect model. Density functional theory calculations predict that this inductive effect occurs even in the absence of changes to the host framework geometry due to Ge → Sn substitution. These results provide direct evidence in support of a measurable solid-electrolyte inductive effect and demonstrate its application as a practical strategy for tuning ionic conductivities in superionic lithium-ion conductors.

We employ THz-range temperature-dependent Raman spectroscopy and first-principles lattice-dynamical calculations to show that the undoped sodium ion conductors Na$_3$PS$_4$ and isostructural Na$_3$PSe$_4$ both exhibit anharmonic lattice dynamics. The anharmonic effects in the compounds involve coupled host lattice -- Na$^+$ ion dynamics that drive the tetragonal-to-cubic phase transition in both cases, but with a qualitative difference in the anharmonic character of the transition. Na$_3$PSe$_4$ shows almost purely displacive character with the soft modes disappearing in the cubic phase as the change of symmetry shifts these modes to the Raman-inactive Brillouin zone boundary. Na$_3$PS$_4$ instead shows order-disorder character in the cubic phase, with the soft modes persisting through the phase transition and remaining active in Raman in the cubic phase, violating Raman selection rules for that phase. Our findings highlight the important role of coupled host lattice -- mobile ion dynamics in vibrational instabilities that are coincident with the exceptional conductivity in these Na$^+$ ion conductors.

Fast-ion conductors are critical to the development of solid-state batteries. The effects of mechanochemical synthesis that lead to increased ionic conductivity in an archetypical sodium-ion conductor Na3PS4 are not fully understood. We present here a comprehensive analysis based on diffraction (Bragg, pair distribution function), spectroscopy (impedance, Raman, NMR, INS) and ab-initio simulations aimed at elucidating the synthesis-property relationships in Na3PS4. We consolidate previously reported interpretations about the local structure of ball-milled samples, underlining the sodium disorder and showing that a local tetragonal framework more accurately describes the structure than the originally proposed cubic one. Through variable-pressure impedance spectroscopy measurements, we report for the first time the activation volume for Na+ migration in Na3PS4, which is ~30% higher for the ball-milled samples. Moreover, we show that the effect of ball-milling on increasing the ionic conductivity of Na3PS4 to ~10-4 S/cm can be reproduced by applying external pressure on a sample from conventional high temperature ceramic synthesis. We conclude that the key effects of mechanochemical synthesis on the properties of solid electrolytes can be analyzed and understood in terms of pressure, strain and activation volume.

The demand for lithium-ion batteries has risen dramatically over the years. Unfortunately, many of the essential component materials, such as cobalt and lithium, are both costly and of limited abundance. For this reason, the recycling of lithium-ion battery electrodes is crucial to ensuring the availability of such resources and protecting the environment. Herein, a simple and scalable recycling process was developed for the prototypical cathode active material Li1.02 (Ni0.8 Co0.1 Mn0.1 )0.98 O2 (NCM-811). By a combination of thermal decomposition and dissolution steps, spent NCM could be converted into Li2 CO3 and a transition metal oxalate blend, which served as precursors for new NCM. Importantly, it was also possible to individually separate each transition metal during the recycling process, thereby extending the utility of this method to a wide variety of NCM compositions. Each intermediate in the process was investigated by scanning electron microscopy and X-ray diffraction. Additionally, the elemental composition of the recycled NCM-811 was confirmed using inductively coupled plasma optical emission spectroscopy and energy-dispersive X-ray spectroscopy. The electrochemical performance of the recycled NCM-811 exhibited up to 80 % of the initial capacity of pristine NCM-811. The method presented herein serves as an efficient and environmentally benign alternative to existing recycling methods for lithium-ion battery electrode materials.

Driven by the rising demand for consumer electronics, the field of all solid-state batteries employing solid electrolytes as the ion-conducting separator has attracted enormous attention in the las...

On the way to a large-scale industrial application of all-solid-state batteries (ASSBs) it is necessary to overcome a number of challenges. An important task is to maximize the utilization of activ...

Sulfidic sodium ion conductors are currently investigated for the possible use in all-solid-state sodium ion batteries. The design of high performing electrolytes in terms of temperature-dependent ...

Increasing the specific energy, energy density, specific power, energy efficiency and energy retention of electrochemical storage devices are major incentives for the development of all-solid-state batteries. However, a general evaluation of all-solid-state battery performance is often difficult to derive from published reports, mostly due to the interdependence of performance measures, but also due to the lack of a basic reference system. Here, we present all-solid-state batteries reduced to the bare minimum of compounds, containing only a lithium metal anode, β-Li3PS4 solid electrolyte and Li(Ni0.6Co0.2Mn0.2)O2 cathode active material. We use this minimalistic system to benchmark the performance of all-solid-state batteries. In a Ragone-type graph, we compare literature data for thiophosphate-, oxide-, phosphate- and polymer-based all-solid-state batteries with our minimalistic cell. Using fundamental equations for key performance parameters, we identify research targets towards high energy, high power and practical all-solid-state batteries. Considering the interdependence of performance measures and the lack of a basic reference system for all-solid-state batteries, Jurgen Janek and co-workers analyse literature performance data for major types of all-solid-state batteries and benchmark them against minimalistic reference cells.

Driven by the increasing attention that the superionic conductors Li3MX6 (M = Y, Er, In, La; X = Cl, Br, I) have gained recently for the use of solid-state batteries, and the idea that a softer, mo...

Owing to highly conductive solid ionic conductors, all-solid-state batteries attract significant attention as promising next-generation energy storage devices. A lot of research is invested in the search and optimization of solid electrolytes with higher ionic conductivity. However, a systematic study of an interlaboratory reproducibility of measured ionic conductivities and activation energies is missing, making the comparison of absolute values in literature challenging. In this study, we perform an uncertainty evaluation via a Round Robin approach using different Li-argyrodites exhibiting orders of magnitude different ionic conductivities as reference materials. Identical samples are distributed to different research laboratories and the conductivities and activation barriers are measured by impedance spectroscopy. The results show large ranges of up to 4.5 mScm-1 in the measured total ionic conductivity (1.3 – 5.8 mScm-1 for the highest conducting sample, relative standard deviation 35 – 50% across all samples) and up to 128 meV for the activation barriers (198 – 326 meV, relative standard deviation 5 – 15%, across all samples), presenting the necessity of a more rigorous methodology including further collaborations within the community and multiplicate measurements.

International audience; Highly conductive solid electrolytes are fundamental for all solid-state batteries with low inner cell resistance. Such fast solid electrolytes are often found by systematic substitution experiments in which one atom is exchanged for another, and corresponding changes in ionic transport are monitored. With this strategy, compositions with the most promising transport properties can be identified fast and reliably. However, the substitution of one element does not only influence the crystal structure and diffusion channel size (static) but also the underlying bonding interactions and with it the vibrational properties of the lattice (dynamic). Since both static and dynamic properties influence the diffusion process, simple one-dimensional substitution series only provide limited insights to the importance of changes in the structure and lattice dynamics for the transport properties. To overcome these limitations, we make use of a two-dimensional substitution approach, investigating and comparing the four single-substitution series Na3P1-xSbxS4, Na3P1-xSbxSe4, Na3PS4-ySey, and Na3SbS4-ySey. Specifically, we find that the diffusion channel size represented by the distance between S/Se ions cannot explain the observed changes of activation barriers throughout the whole substitution system. Melting temperatures and the herein newly defined anharmonic bulk modulus-as descriptors for bonding interactions and corresponding lattice dynamics-correlate well with the activation barriers, highlighting the relevance of lattice softness for the ion transport in this class of fast ion conductors.

Next-generation thermal management requires the development of low lattice thermal conductivity materials, as observed in ionic conductors. For example, thermoelectric efficiency is increased when thermal conductivity is decreased. Detrimentally, high ionic conductivity leads to thermoelectric device degradation. Battery safety and design also require an understanding of thermal transport in ionic conductors. Ion mobility, structural complexity, and anharmonicity have been used to explain the thermal transport properties of ionic conductors. However, thermal and ionic transport are rarely discussed in direct comparison. Herein, the ionic conductivity of Ag+ argyrodites is found to change by orders of magnitude without altering the thermal conductivity. Thermal conductivity measurements and two-channel lattice dynamics modeling reveal that the majority of Ag+ vibrations have a non-propagating diffuson-like character, similar to amorphous materials. It is found that high ionic mobility is not a requirement for diffuson-mediated transport. Instead, the same bonding and structural traits that can lead to fast ionic conduction also lead to diffuson-mediated transport. Bridging the fields of solid-state ionics and thermal transport, it is proposed that a vibrational perspective can lead to new design strategies for functional ionic conducting materials. As a first step, the authors relate the so-called Meyer–Neldel behavior in ionic conductors to phonon occupations.

The lithium argyrodites Li

Halide-based solid electrolytes are currently growing in interest in solid-state batteries due to their high electrochemical stability window compared to sulfide electrolytes. However, often a bilayer separator of a sulfide and a halide is used and it is unclear why such setup is necessary, besides the instability of the halides against lithium metal. It is shown that an electrolyte bilayer improves the capacity retention as it suppresses interfacial resistance growth monitored by impedance spectroscopy. By using in-depth analytical characterization of buried interphases by time-of-flight secondary ion mass spectrometry and focused ion beam scanning electron microscopy analyses, an indium-sulfide rich region is detected at the halide and sulfide contact area, visualizing the chemical incompatibility of these two electrolytes. The results highlight the need to consider more than just the electrochemical stability of electrolyte materials, showing that chemical compatibility of all components may be paramount when using halide-based solid electrolytes in solid-state batteries.

Ni-rich layered oxide cathodes are promising candidates to satisfy the increasing energy demand of lithium-ion batteries for automotive applications. Thermal and cycling stability issues originating from increasing Ni contents are addressed by mitigation strategies such as elemental bulk substitution ("doping") and surface coating. Although both approaches separately benefit the cycling stability, there are only few reports investigating the combination of two of such approaches. Herein, the combination of Zr as common dopant in commercial materials with effective Li2 WO4 and WO3 coatings was investigated with special focus on the impact of different material processing conditions on structural parameters and electrochemical performance in nickel-cobalt-manganese (NCM) || graphite cells. Results indicated that the Zr4+ dopant diffusing to the surface during annealing improved the electrochemical performance compared to samples without additional coatings. This work emphasizes the importance to not only investigate the effect of individual dopants or coatings but also the influences between both.

The exploitation of high-capacity conversion-type materials such as sulfur in solid-state secondary batteries is a dream combination for achieving improved battery safety and high energy density in the push towards a sustainable future. Yet, the exact rate-limiting step, bottlenecking further development of solid-state lithium-sulfur batteries, has not been determined. Here, we directly visualize the spatial distribution of lithium via neutron imaging during operation and show that sluggish macroscopic ion transport within the composite cathode is rate-limiting. Observing a reaction front propagating from the separator side towards the current collector confirms detrimental influences of a low effective ionic conductivity. Furthermore, irreversibly concentrated lithium in the vicinity of the current collector, revealed via state-of-charge-dependent tomography, highlights a hitherto-overlooked loss mechanism triggered by sluggish effective ionic transport within a composite cathode. This discovery will be a cornerstone for future research on solid-state batteries, irrespective of the type of active material.