Design criteria for crystal structures of zero-strain cathode materials for lithium ion batteries

• Applicants: Dr. Joachim Rudolf Binder; Professor Dr. Christian Elsässer
• Subject Area: Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials ; Synthesis and Properties of Functional Materials
• Term: from 2020 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 424815519

• Final Report Year: 2025

Final Report Abstract

In zero-strain (ZS) materials, only small volume changes occur in the active material when charging and discharging with lithium ions. The lower mechanical stresses improve the service life of the batteries, but only a few ZS materials are known to date. In addition, no common criteria for the occurrence of ZS behavior have been identified to date. The aim of this project is to investigate whether general design criteria for such materials can be established by combining experimental measurements and theoretical calculations. For this purpose, two families of materials were investigated: colquiriites and tungsten bronzes. The atomistic investigations of the colquiriite structure for various transition metals reveal one factor influencing the global volume change. The fluor octahedra, which coordinate the transition metals, exhibit different degrees of volume expansion depending on the transition metal. Experimentally, the compound CaTiF6 was synthesized. The compound showed ZS behavior regarding the intercalation of lithium. The comparison of theoretical and experimental methods showed that the low measured volume expansions in representatives of this material class cannot be explained exclusively by a single-crystal mechanism. The compound LixK0.6FeF3 in the tetragonal tungsten bronze structure was produced using a novel synthesis route, which was realized as part of a collaboration with the University of Le Mans. The material was also extensively characterized and a ZS behavior, which was already known in the literature for sodium, was also experimentally proven for lithium. The ZS behavior in this compound could be explained with the help of atomistic simulations; local structural changes take place in the material that compensate each other. This possibility of the compensation mechanism was investigated in other representatives of the tungsten bronze family and qualitative criteria for low volume expansions could be derived. The deviation between experimentally measured volume changes and theoretical predictions for representatives of colquiriites could be the subject of further investigations, in particular the investigation of effects that take place on larger scales (interfaces, amorphous phases, structural (point) defects due to processing). The agreement between the experimental and theoretical results shows the potential of combining these two research methods to lead to a deeper understanding of material properties. Based on the systematic variations in the theoretical calculations, a machine learning-based model could be created to accelerate the search for new ZS materials.

Publications

• Designkriterien zum Aufbau der Kristallstruktur von Zero-Strain- Kathodenmaterialien für Lithiumionenbatterien, Beitrag im FMF Jahresbericht 2020
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Bestimmung lokaler Strukturänderungen in LixCaFeF6 durch variierende Li-Konzentration anhand von DFT-Berechnungen, Beitrag im FMF Jahresbericht 2021
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Design von zero-strain Kathodenmaterialien des Colquiriit-Typs LixCa(M,M‘)F6, Beitrag im FMF Jahresbericht 2022
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Investigation of volume changes in the colquiriite structure due to Li insertion from first principles, DPG (Spring)Meeting SKM 2022, Regensburg, Vortrag
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Synthesis and electrochemical characterization of the potential zero strain material Li1-xCaTiF6, IMLB 2022 Sydney, 26.6.-1.7.2022, Poster
  A. Vogt, H. Geßwein, J. & R. Binder
  
• Atomistic analysis of volume changes in tungsten-bronze-type compounds AxFeF3 during intercalation of A cations (A=Li, Na, K), FEMS Euromat 2023, Frankfurt, 4.9.2023, Vortrag
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Design of zero strain cathode materials based on colquiriite-type LixCa(M,M’)F6, DPG Spring meeting SKM 2023, Dresden, Vortrag
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Designkriterien für zero-strain Kathoden Materialien der Wolframbronzen-Verbindungen AFeF3 (A=Li, Na, K) aus first-principles Rechnungen, Beitrag im FMF Jahresbericht 2023
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• First-principles analysis of the interplay between electronic structure and volume change in colquiriite compounds during Li intercalation. Physical Review B, 108(16).
  Baumann, A. F.; Mutter, D.; Urban, D. F. & Elsässer, C.
  
• K0.6FeF3 as a new zero-strain cathode material for lithium-ion batteries, ECS Meeting 2023, Göteborg, Poster
  A. Vogt, H. Gesswein, J. Chable, A.F. Baumann, D. Mutter, D. F. Urban, C. Elsässer, J. Lhoste & J. R. Binder
  
• K0.6FeF3 as a new zero-strain cathode material for lithium-ion batteries, FEMS Euromat 2023, Frankfurt, 4.9.2023, Vortrag
  A. Vogt, H. Gesswein, J. Chable, A. F. Baumann, D. Mutter, D. F. Urban, C. Elsässer, J. Lhoste & J. R. Binder
  
• Design Criteria for Zero-Strain Behavior in Colquiriite-Type and Tungsten-Bronze-Type Inorganic 3d-Transition-Metal-Fluoride Compounds for Alkali-Metal-Ion Batteries – A First-Principles Study, MRS Fall 2024, Boston, Poster
  C. Elsässer, A. F. Baumann, D. Mutter & D. F. Urban
  
• Design criteria for zero-strain cathode materials of the tungsten bronze type compounds AxFeF3 (A=Li, Na, K) by first-principles, DPG Spring meeting SKM 2024, Berlin, Vortrag
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• Design criteria for zero-strain cathode materials of the tungsten bronze type compounds AxFeF3 (A=Li, Na, K) by first-principles, MMM11, Prag, 25.09.2024, Vortrag
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer
  
• First-principles study of strain behavior in iron-based fluorides of tungsten bronze type as cathode materials for alkaliion batteries. Physical Review Materials, 8(9).
  Baumann, A. F.; Mutter, D.; Urban, D. F. & Elsässer, C.
  
• Vorhersage von Volumenänderungen in Kristallstrukturen durch Einlagerung von (Erd-)Alkali-Metallionen, Beitrag im FMF Jahresbericht 2024
  A. F. Baumann, D. Mutter, D. F. Urban & C. Elsässer