Solid-state batteries have recently attracted great interest as potentially safe and stable high-energy storage systems. However, key issues remain unsolved, hindering full-scale commercialization.

A solid future for battery development

In the critical area of sustainable energy storage, solid-state batteries have attracted considerable attention due to their potential safety, energy-density and cycle-life benefits. This Review describes recent progress in the fundamental understanding of inorganic solid electrolytes, which lie at the heart of the solid-state battery concept, by addressing key issues in the areas of multiscale ion transport, electrochemical and mechanical properties, and current processing routes. The main electrolyte-related challenges for practical solid-state devices include utilization of metal anodes, stabilization of interfaces and the maintenance of physical contact, the solutions to which hinge on gaining greater knowledge of the underlying properties of solid electrolyte materials. Solid-state batteries are attractive due to their potential safety, energy-density and cycle-life benefits. Recent progress in understanding inorganic solid electrolytes considering multiscale ion transport, electrochemical and mechanical properties, and processing are discussed.

Fundamentals of inorganic solid-state electrolytes for batteries

All-solid-state lithium batteries (ASSLBs) have the potential to revolutionize battery systems for electric vehicles due to their benefits in safety, energy density, packaging, and operable temperature range. As the key component in ASSLBs, inorganic lithium-ion-based solid-state electrolytes (SSEs) have attracted great interest, and advances in SSEs are vital to deliver the promise of ASSLBs. Herein, a survey of emerging SSEs is presented, and ion-transport mechanisms are briefly discussed. Techniques for increasing the ionic conductivity of SSEs, including substitution and mechanical strain treatment, are highlighted. Recent advances in various classes of SSEs enabled by different preparation methods are described. Then, the issues of chemical stabilities, electrochemical compatibility, and the interfaces between electrodes and SSEs are focused on. A variety of research addressing these issues is outlined accordingly. Given their importance for next-generation battery systems and transportation style, a perspective on the current challenges and opportunities is provided, and suggestions for future research directions for SSEs and ASSLBs are suggested.

Promises, Challenges, and Recent Progress of Inorganic Solid-State Electrolytes for All-Solid-State Lithium Batteries

Journal of Applied physics,Vol.33 : 1962年に発表されたレオロジー関連の論文

Commercialization of Lithium Battery Technologies for Electric Vehicles

The localisation and quantitative analysis of lithium (Li) in battery materials, components, and full cells are scientifically highly relevant, yet challenging tasks. The methodical developments of MeV ion beam analysis (IBA) presented here open up new possibilities for simultaneous elemental quantification and localisation of light and heavy elements in Li and other batteries. It describes the technical prerequisites and limitations of using IBA to analyse and solve current challenges with the example of Li-ion and solid-state battery-related research and development. Here, nuclear reaction analysis and Rutherford backscattering spectrometry can provide spatial resolutions down to 70 nm and 1% accuracy. To demonstrate the new insights to be gained by IBA, SiOx-containing graphite anodes are lithiated to six states-of-charge (SoC) between 0–50%. The quantitative Li depth profiling of the anodes shows a linear increase of the Li concentration with SoC and a match of injected and detected Li-ions. This unambiguously proofs the electrochemical activity of Si. Already at 50% SoC, we derive C/Li = 5.4 (< LiC6) when neglecting Si, proving a relevant uptake of Li by the 8 atom % Si (C/Si ≈ 9) in the anode with Li/Si ≤ 1.8 in this case. Extrapolations to full lithiation show a maximum of Li/Si = 1.04 ± 0.05. The analysis reveals all element concentrations are constant over the anode thickness of 44 µm, except for a ~6-µm-thick separator-side surface layer. Here, the Li and Si concentrations are a factor 1.23 higher compared to the bulk for all SoC, indicating preferential Li binding to SiOx. These insights are so far not accessible with conventional analysis methods and are a first important step towards in-depth knowledge of quantitative Li distributions on the component level and a further application of IBA in the battery community.

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Quantitative Lithiation Depth Profiling in Silicon Containing Anodes Investigated by Ion Beam Analysis

We discuss elastic and thermodynamic aspects of LiCoO\(_2\) in the context of fracture propagation and hot spot formation. Approaching the problem via ab initio modelling, we can access the delithiated states which is difficult experimentally. Application of density functional theory in the quasi-harmonic approximation provides good agreement in the range of experimentally available data for isobaric heat capacities, suggesting to complement thermodynamic databases required for the modelling of heat flows. The results for the mechanical characteristics suggest a brittle-to-ductile transition with varying lithium contents and crack orientations perpendicular to the basal plane, as indicated by the obtained elastic tensors experimentally.

Ab Initio Modelling of Electrode Material Properties

Correction for ‘Study of thermal material properties for Ta- and Al-substituted Li7La3Zr2O12 (LLZO) solid-state electrolyte in dependency of temperature and grain size’ by Julian Neises et al., J. Mater. Chem. A, 2022, 10, 12177–12186, https://doi.org/10.1039/D2TA00323F.

Correction: Study of thermal material properties for Ta- and Al-substituted Li7La3Zr2O12 (LLZO) solid-state electrolyte in dependency of temperature and grain size

Der erfindungsgemase wiederaufladbare Energiespeicher basiert auf einer Metall-Luft-Batterie, bei der eine Gaselektrode eingesetzt wird und eine Ionen bzw. Protonen leitende Membran als Elektrolyt verwendet wird. Im Unterschied zu den bekannten Metall-Luft-Batterien liegt bei dem erfindungsgemasen Energiespeicher die Aktivkomponente auf der der Gaselektrode gegenuberliegenden Seite der Elektrolytmembran in Form eines flussigen Mediums vor. Die erfindungsgemase Flussigmedium-Gas-Batterie weist ein Behaltnis auf, welches bei der Betriebstemperatur der Batterie ein Medium in flussiger Form als Aktivmaterial umfasst. Als ein solches Material sind unter anderem geeignet: Metalle, Halbmetalle, Sauerstoff-haltige Verbindungen inkl. einfacher oder komplexer Oxide, Stickstoff-haltige Verbindungen, Kohlenstoff-haltige Verbindungen, Wasserstoff-haltige Verbindungen, Phosphor-haltige Verbindungen, Halogen-haltige Verbindungen, andere Chalkogen-haltige Verbindungen, Silizium-haltige Verbindungen, Germanium-haltige Verbindungen oder Bor-Verbindungen, insbesondere mit einem oder mehreren Metallen oder Halbmetallen (bezogen auf die gesamte Liste von den Oxiden bis zu den Borverbindungen), oder Mischungen davon, sofern sie bei Betriebstemperaturen in flussiger Form vorliegen.

Elektro-chemischer Energiespeicher sowie Verfahren zum Betreiben desselben

Solid-state batteries (SSBs) are promising next-generation batteries due to their potential for achieving high energy densities and improved safety compared to conventional lithium-ion batteries (LIBs) with a flammable liquid electrolyte. Despite their huge market potential, very few studies have investigated SSB recycling processes to recover and reuse critical raw metals for a circular economy. For conventional LIBs, hydrometallurgical recycling has been proven to be able to produce high-quality products, with leaching being the first unit operation. Therefore, it is essential to establish a fundamental understanding of the leaching behavior of solid electrolytes as the key component of SSBs with different lixiviants. This work investigates the leaching of the most promising Al- and Ta-substituted Li7La3Zr2O12 (LLZO) solid electrolytes in mineral acids (H2SO4 and HCl), organic acids (formic, acetic, oxalic, and citric acid), and water. The leaching experiments were conducted using actual LLZO production waste in 1 M of acid at 1:20 S/L ratio at 25 °C for 24 h. The results showed that strong acids, such as H2SO4, almost completely dissolved LLZO. Encouraging selective leaching properties were observed with oxalic acid and water. This fundamental knowledge of LLZO leaching behavior will provide the basis for future optimization studies to develop innovative hydrometallurgical SSB recycling processes.

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Martin Finsterbusch

Papers

Quantitative Lithiation Depth Profiling in Silicon Containing Anodes Investigated by Ion Beam Analysis

Ab Initio Modelling of Electrode Material Properties

Correction: Study of thermal material properties for Ta- and Al-substituted Li7La3Zr2O12 (LLZO) solid-state electrolyte in dependency of temperature and grain size

Elektro-chemischer Energiespeicher sowie Verfahren zum Betreiben desselben

Acid Leaching of Al- and Ta-Substituted Li7La3Zr2O12 (LLZO) Solid Electrolyte