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Preview – Solid-state / Semi-solid Li-ion Battery Innovation & Patent Review

  • Introduction

  • Focus of this Review

  • In this review, technical options are discussed that are being evaluated by key solid-state / semi-solid lithium-ion battery companies towards the launch of commercial products for various applications, in particular electronics and EVs. The analysis is based on a unique AI-supported screening approach for the identification of patent filings with high prospective commercial relevance, which are compared with public statements (incl. at conferences).
  • Comprehension of solid-state / semi-solid Li-ion battery technology decision trees allows for the identification of promising product development directions that have not yet been explored.
  • Patent portfolios by key commercial players have been classified into 6 categories:

    Level 1)    Electrolyte & electrode patents
    Level 2)    Cell patents (chemistry and architecture)
    Level 3A)    Pack / form factor / packaging patents
    Level 3B)    Application patents
    Level 3C)    Reliability patents (e.g. mitigation of short circuits / heat & gas formation)
    Level 3D)    Manufacturing patents (electrolytes, electrodes, cells)
  • A patent portfolio that covers all of these categories generally reflects a substantial product development effort that addresses all aspects necessary for a successful launch. For tailored patent searches, the AI model used for preparation of this review is available to users on b-science.net.
  • Table 2: (projected) market launches for solid-state / semi-solid battery EVs; color labels: midnight blue: oxide / phosphate-based electrolytes (may contain polymers); mocha: sulfide-based electrolytes (may contain halides, polymers); teal: halide-based electrolytes (without sulfur); plum: polymer-based electrolytes (predominant component)

    (Projected) market launches for solid-state / semi-solid battery EVs

  • AI-based Identification of Commercially Relevant Patents

  • b-science.net has developed a supervised AI methodology to assess the commercial relevance of patents, combined with an automatic translation framework that makes sure Non-English patents are also identified.

  • Technology Decision Trees

  • Figure 12: technology decision tree – solid electrolytes – halides / oxohalides
    (in red: newly added branches as compared to prior review)

    Technology decision tree – solid electrolytes – halides / oxohalides

  • Benchmarking & Product Launch Risk Factors – Cells with Liquid vs. Semi-Solid vs. Solid Electrolytes

  • A battery fails commercially if any performance & safety characteristic or costs do not match the requirements of the corresponding application. Outperformance in one dimension usually does not compensate for the biggest weakness.
  • Table 6: targeted energy density

    Targeted energy density
  • Table 7: ion conductivity of solid electrolytes (as identified in patent applications, in public statements, or by reference to an academic publication); color labels: midnight blue: oxide / phosphate-based electrolytes (may contain polymers, may contain minor amount of halide) ; mocha: sulfide-based electrolytes (may contain halides, polymers); teal: halide-based electrolytes (without sulfur, may contain oxygen); plum: polymer-based electrolytes (predominant component)

    Ion conductivity of solid electrolytes (as identified in patent applications, in public statements, or by reference to an academic publication)
  • Table 10: raw material / process aspects that could impact costs

    raw material / process aspects that could impact costs

  • Assessment of Companies

  • Author comments are displayed in maroon.

  • Contemporary Amperex Technology Limited (CATL) – China

  • Organization profile

    Contemporary Amperex Technology Limited (CATL, https://www.catl.com/en/) is the world's largest Li-ion battery producer. CATL was founded in 2011 in Ningde, China. In 2017, CATL has completed a split from its parent company ATL/TDK. With BRUNP Recycling (subsidiary), CATL jointly develops positive electrode active materials.

    Unique capability: 1) supramolecular ionic liquid / polymer / lithium salt electrolyte membranes with very favorable ionic conductivity (up to 2.4 × 10-3 S/cm) and high boiling point (>438 °C), along with corresponding cells with lithium metal negative electrodes; 2) sulfide electrolyte-based lithium metal cells based on ≥5 complementary concepts to mitigate various failure modes.

    Leap of faith: 1) the toxicity of triphenylene-containing electrolytes will be acceptable; 2) the risk of toxic hydrogen sulfide gas emissions when sulfide electrolytes are in contact with water or moisture will not be a showstopper during production, operation and / or recycling.

    Comment: approaches 1) and 2) could finally enable the operation of lithium metal negative electrodes at room temperature and below with favorable fast charge / discharge characteristics (along with favorable energy density).

  • News reports & press releases

    This information is included in the full version.

  • General patent portfolio characteristics

    42 new patent families by CATL related to semi-solid or solid-state Li-ion batteries have been published since 2022 (level 1: 21, level 2: 24, level 3A: 8, level 3B: 1, level 3C: 11, level 3D: 9). Polymer / oligomer and sulfide electrolytes constitute key patenting focus areas (Figure CA-1).

    Figure CA-1: AI-based classification of patent families by CATL published since 2022 related to solid electrolytes categories 1-5. Patents without direct relation to one category (e.g. because of solid-state cell packaging focus) were excluded.

    AI-based solid electrolyte classification (CATL)

  • Key Polymer Electrolyte Product Development Concepts

    Figure CA-2: AI-based polymer electrolyte product development concept identification (CATL)

    AI-based polymer electrolyte product development concept identification (CATL)
    Figure CA-2 illustrates how CATL pursues a range of polymer / oligomer-related product development approaches, among which 2 concepts appear complementary, even though no patent has been identified yet that confirms their simultaneous use.

    Concept 1: Supramolecular Ionic Liquids, WO 2022021231 A1 (EPO / Google)

    KEY FINDINGS
    2.4 × 10-3 S/cm ionic conductivity in membranes based on supramolecular assembly of ion-channels, comparably low density, based on abundant precursors.

    TECHNICAL DESCRIPTION
    Benzophenanthrene-based supramolecular ionic liquids with π-π stacking creating ordered ion transport pathways. Ether side chains (1-16 carbons, see Figure CA-3) balance molecular assembly with ion mobility. Synthesis via Williamson reaction and FeCl3 cyclization, resulting in 6.5 × 10-3 S/cm bulk conductivity at 25°C.

    BACKGROUND INFORMATION
    Patent WO 2022021231 A1 addresses the polymer ionic conductivity bottleneck. A self-assembly approach results in near-liquid conductivity (2.4 × 10-3 S/cm in membrane), while offering safety advantages for which solid-state Li-ion batteries are known (triphenylene shown in Figure CA-3 exhibits a boiling point of 438°C). Manufacturing is based on organic chemistry and comparably abundant precursors.

    ELECTRODE CONFIGURATION
    Negative electrode: lithium metal | Positive electrode: NMC811.

    Figure CA-3: top – two triphenylene derivatives with (optionally fluorinated) ethylene oxide / lithium sulfonate groups. The derivative on the left exhibits particularly favorable ion conductivity (6.5 × 10-3 S/cm), while the derivative on the right exhibits particularly favorable cycling stability, bottom – synthesis procedure, OR3 = R1, OR4 = R2 (CATL)

    Triphenylene derivatives with synthesis procedure (CATL)
    The full version includes a discussion of polymer electrolyte product development concepts 2-5.

  • Potential Synergies Between Concepts

    R&D concepts 1 (supramolecular ionic liquids) and 3 (gradient crosslinking systems) offer synergies in terms of overcoming the fundamental trade-offs in solid-state battery development. Concept 1 addresses the critical ionic conductivity bottleneck that has limited solid-state batteries, achieving near-liquid ionic transport through self-assembled molecular architectures. Concept 3 solves mechanical integrity and safety challenges by providing spatially optimized structural reinforcement. The combination could enable solid-state batteries that achieve both liquid-like ionic conductivity and superior structural integrity – previously mutually exclusive characteristics.

  • Possible Material / Cell / Process Characteristics (Projection Based on Public Information)

    • Electrolyte: benzophenanthrene-based supramolecular ionic liquids with π-π stacking architecture and ether side chains (1-16 carbons) that exhibit an ionic conductivity of 6.5 × 10-3 S/cm at 25°C (WO 2022021231 A1, Example 22). When integrated with a polymer matrix (PEO/PVDF/LiTFSI at 10-80 : 100 : 5-40 by mass), the composite electrolyte exhibits 2.4 × 10-3 S/cm conductivity. Gradient acrylate crosslinking systems (WO 2024243875 A1) might be incorporated into side chains to tune mechanical characteristics.
    • Negative electrode: lithium metal on copper foil (WO 2022021231 A1).
    • Positive electrode: NMC811 with conductive carbon (2 mass%) and PVDF binder (2 mass%) on aluminum current collector (WO 2022021231 A1).
    • Design: prismatic stacked multilayer cells with favorable deformation resistance (WO 2024243875 A1).
    • Process:
      1. Supramolecular ionic liquid synthesis via Williamson reaction and FeCl3 cyclization (WO 2022021231 A1).
      2. Sequential or parallel (such as with multi-slurry feeder) injection gradient crosslinking film formation (WO 2024243875 A1).
      3. Hot pressing (1-20 MPa, 50-100°C) with spatially controlled crosslinking density.
      4. Vacuum annealing (60-80°C, 1-8 h).
      5. Electrode and electrolyte layer lamination through cold-pressing (250 MPa, 25 °C, 2 min) to obtain multi-layer cells.
      6. Prismatic cell encapsulation.

    Supporting inventions listed in Figure CA-2 (bottom) might additionally be employed in this context.

  • Key Sulfide Electrolyte Product Development Concepts

    This information is included in the full version.

  • Highly Relevant Inventions Covered in Recent Triweekly Patent Updates

    The full version includes a summary and discussion of 3 additional highly relevant all-solid / semi-solid Li-ion battery electrolyte patents that have been identified during our triweekly patent screening process.

  • AI-based Patent Summaries

    The adjacent Excel file contains AI-based patent summaries for all patents mentioned in this chapter, classified in terms of electrolyte type (Figure CA-1) and level 1 (electrode / electrolyte patents) to level 3D (manufacturing patents).


  • Table of Contents (351 pages, see PDF)

    • Focus of this Review
    • Solid-state / Semi-solid Li-ion Battery Components
    • The Solid-state / Semi-solid Li-ion Battery Market Today
    • (Projected) Market Launches – Solid-state / Semi-solid Li-ion Battery EVs
    • Number of Commercially Relevant Patent Families / Utility Models Since 2022
    • Solid Electrolytes – Types – Launched or Close to Market Launch
    • Solid Electrolytes – Types – Based on Patent Filings
    • Solid Electrolytes – Concepts
    • Solid Electrolytes – Oxides That Do Not Contain Phosphorus – (Probably) Crystalline
    • Solid Electrolytes – Phosphates / P-containing Oxides – (Probably) Crystalline
    • Solid Electrolytes – Oxide / Phosphates – (Probably) Glasses
    • Solid Electrolytes – Hydroxides
    • Solid Electrolytes – Sulfides
    • Solid Electrolytes – Mitigation of Hydrogen Sulfide Emissions
    • Solid Electrolytes – Polymers
    • Solid Electrolytes – Halides / Oxohalides
    • Solid Electrolytes for Thin-film Batteries
    • Solid Electrolytes – Boranes
    • Lithium (Sodium) Salts
    • Plasticizers
    • Liquid Electrolyte Components / Liquid Additives
    • Solid Electrolyte Additives / Support & Filler Materials That Do Not Contain Li
    • Solid Electrolyte Binders
    • Negative Electrode Active Materials
    • Positive Electrode Active Materials
    • Negative Electrode Additives
    • Positive Electrode Additives
    • Negative Electrode Binders
    • Positive Electrode Binders
    • Cell Design
    • Cell Design – Concepts
    • Pack Engineering
    • Reliability
    • Applications
    • Electrolyte Film Deposition Processes
    • Inherent Safety – Key Risk Factors
    • Energy Density – Positive & Negative Electrode Active Material Selections
    • Power Density – Ion Conductivity of Solid / Semi-solid Electrolytes
    • Longevity – Risk of Crack Formation & Chemical Instability
    • Cell Size
    • Raw Materials & Manufacturing Processes
    • Predictions
    • Assessment of Companies
    • Ampcera
    • BASF
    • Blue Current
    • Blue Solutions
    • BrightVolt
    • BYD
    • Contemporary Amperex Technology Ltd. (CATL)
    • Corning
    • Enpower Greentech
    • Factorial Energy
    • FDK / Fujitsu
    • Foxconn (Hon Hai Precision Industry) / SolidEdge Solution
    • Ganfeng Lithium / Zhejiang Fengli / Zhejiang Funlithium
    • GM
    • Hydro Québec
    • Idemitsu Kosan
    • Ilika Technologies
    • ION Storage Systems
    • JX Nippon Mining and Metals / Eneos
    • LG Energy Solution / LG Chemical
    • Maxell
    • Mitsui Mining and Smelting / Mitsui Kinzoku
    • Murata Manufacturing
    • NGK Insulators
    • Ohara
    • Panasonic
    • Piersica
    • PolyPlus
    • ProLogium Technology
    • Qingtao Kunshan New Energy Materials / Suzhou Qingtao New Energy Technology / Yichung Qingtao Energy Technology
    • QuantumScape
    • Sakuú
    • Samsung
    • SES Holdings
    • Soelect
    • Solid Power
    • SVOLT Energy Technology / Fengchao Energy Technology / Honeycomb Technology
    • Taiyo Yuden
    • TDK
    • TeraWatt Technology
    • Toshiba
    • Toyota
    • WeLion
    • Introduction
    • Halides with Ion Conductivities Identified in the Patent Literature (Table with 70 Entries)
    • Halides in Prospective Next-generation Solid-state Li-ion Battery Cells for Microscale Electronics Applications
    • Halide Catholytes in Prospective Next-generation Sulfide Solid-state Li-ion Battery EV Cells
    • Further Examples of Conceptually Unique Halides
    • Trade-offs When Selecting Halides (Incl. Decision Sequence)
    • Conclusion
    • Introduction
    • Ion-conductive Polymers – Estimate of the Current State of the Art
    • Reducing the Need for Electrochemical Stability of Polymer Electrolytes
    • Incorporation of Non-conducting Porous Polymer Films
    • A Four-track Product Development Approach
    • Cell Failure Root Causes That Cannot Easily Be Identified at Lab Scale
    • Conclusion
    • Introduction
    • All-solid vs. Semi-solid vs. Liquid Catholytes & Anolytes – General Considerations
    • Summary – Catholyte Component Options & Trade-offs
    • Estimate of Current State of the Art
    • Under-explored Materials & Chemicals
    • Introduction
    • 'Decision Maze' Towards Product Launch
    • Academic Findings on Si-sulfide Interface Reactions
    • Parasitic Reactions of Carbon Additives in Si-based Negative Electrodes
    • Electronic Conductivity of Si and Si-Li Alloys in Carbon-free Negative Electrodes
    • Role of Porosity and Tortuosity in Si-based Negative Electrodes
    • Active Material Optimization for Dry Processing
    • Reconsidering the ‘Decision Maze’ – Under-explored Approaches
    • Role of Si Coatings
    • Role of Si Doping
    • Impact of Doped Sulfide Electrolytes on Interface
    • Control of Metallurgical Si Nano- & Microcrystallinity
    • Conclusion
    • Summaries of Patent Families Discussed in ‘Decision Maze’
    • Introduction
    • ‘Semi-solid’ Electrolytes & Si-based Active Materials – A Pair of ‘Imperfect’ Materials That Enabled Above-average Progress to Market Launches
    • Estimate of Current State of the Art
    • ‘Decision Maze’ Towards Product Launch
    • Hypothesis- and Data-driven Interface Design
    • Impact of the Negative Electrode / Electrolyte Interface on Cell Performance
    • Feasibility of Data-driven Screening Approaches
    • Which Si-based Active Materials Have Been ‘Under-explored’ in Combination with Oxide and / or Polymer-based Electrolytes?
    • The Lowest-Cost Solution Wins if Performance & Safety Are Almost Equal
    • Introduction
    • ‘Decision Maze’ Towards Oxide Electrolyte-containing Li-ion Battery Cells
    • At Which Temperature Should Electrolyte Film Formation Occur?
    • Crystalline vs. Glassy / Amorphous Electrolytes
    • Dopant Selection / Defect Density / Defect Filling
    • Modifications of Particle Surface Chemical Composition
    • Combination with Other Electrolyte Classes

  • About the Author

  • Pirmin Ulmann obtained a diploma in chemistry from ETH Zurich (Switzerland) in 2004 and a PhD from Northwestern University (USA) in 2009. Thereafter, he was a JSPS Foreign Fellow in an ERATO academic-industrial project at the University of Tokyo (Japan). From 2010 to 2016, while working at a major battery materials manufacturer in Switzerland, he was a co-inventor of 7 patent families related to lithium-ion batteries. He was also in charge of a collaboration with the Paul Scherrer Institute, evaluated outside technologies for corporate strategy, and made customer visits to battery manufacturers in East Asia, North America & Europe. He holds the credential Stanford Certified Project Manager (SCPM) and has co-authored scientific articles with more than 2,000 citations.

  • AI Patent Analysis Methodology

  • The patent information source for this review is the European Patent Office (EPO), which covers patent filings from more than 100 patent offices around the world. >3M patent documents are included in the b-science.net database that were published since 1980, which either contain the words 'battery' or 'batteries' in the title or abstract, or were assigned to one of the energy storage-related CPC (cooperative patent classification) or IPC (international patent classification) codes: H01M (batteries & fuel cells) or H01G (capacitors). An AI model was defined for commercially relevant Li-ion battery solid / semi-solid / gel electrolytes. Patent documents were grouped into patent families and scored with the AI model. An AI relevancy score cutoff value of 40 was applied (100: very relevant, 0: not relevant). For companies covered with a chapter, AI scores between 35 and 45 were checked manually and false-positives / false-negatives were corrected if necessary.

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