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US-20260128296-A1 - SYNTHESIS OF DISORDERED ROCK SALT (DRX) CATHODE MATERIALS FOR LI-ION BATTERIES

US20260128296A1US 20260128296 A1US20260128296 A1US 20260128296A1US-20260128296-A1

Abstract

A method of making a disordered rock salt cathode material for lithium-ion batteries includes performing combustion synthesis with an aqueous solution of metal-containing compounds. The method may include a two-stage process having a first stage followed by a second stage. The first stage includes performing combustion synthesis to obtain a metal oxide precursor. The second stage includes one or more of lithiating, fluorinating, and annealing the metal oxide precursor to obtain a disordered rock salt (DRX) oxide or oxyfluoride. The obtained disordered rock salt (DRX) may have a chemical composition Li 1+x Mn y TM 1-x-y O 2-z F z wherein 0≤x≤0.3, 0.4≤y≤1, 0≤z≤0.3, and TM is one or more transition metals selected from a group of Ti, Zr, Mo, Nb, and V. A lithium-ion battery cathode including a disordered rock salt cathode material and a lithium-ion battery including the lithium-ion battery cathode are also provided.

Inventors

  • Ethan C. Self
  • Beth L. Armstrong
  • Matthew S. Chambers

Assignees

  • UT-BATTELLE, LLC

Dates

Publication Date
20260507
Application Date
20251030

Claims (19)

  1. 1 . A method of making a disordered rock salt cathode material for lithium-ion batteries, the method comprising: performing combustion synthesis with an aqueous solution of metal-containing compounds to obtain a disordered rock salt (DRX) oxide or a disordered rock salt (DRX) oxyfluoride.
  2. 2 . The method of claim 1 , wherein the method comprises: a two-stage process including a first stage followed by a second stage; wherein the first stage includes the performing of combustion synthesis to obtain a metal oxide precursor; wherein the second stage includes one or more of lithiating, fluorinating, and annealing the metal oxide precursor to obtain the disordered rock salt (DRX) oxide or the disordered rock salt (DRX) oxyfluoride.
  3. 3 . The method of claim 2 , wherein performing combustion synthesis in the first stage includes preparing a first mixture that is the aqueous solution of metal-containing compounds, adding a fuel to the first mixture to obtain a second mixture, and heating the second mixture to at least an auto-ignition temperature of the second mixture.
  4. 4 . The method of claim 3 , wherein the metal-containing compounds include water-soluble metal compounds.
  5. 5 . The method of claim 4 , wherein the metal-containing compounds include a metal nitrate.
  6. 6 . The method of claim 3 , wherein the metal-containing compounds include one or both of: i) a lithium-containing compound; and ii) one or more transition metal-containing compound.
  7. 7 . The method of claim 3 , wherein the metal-containing compounds include a lithium-containing compound, a manganese-containing compound, and a titanium-containing compound.
  8. 8 . The method of claim 1 , wherein the obtained disordered rock salt (DRX) has a chemical composition according to the chemical formula Li 1+x Mn y TM 1-x-y O 2-z F z wherein 0≤x≤0.3, 0.4≤y≤1, 0≤z≤0.3, and TM is one or more transition metals selected from a group of Ti, Zr, Mo, Nb, and V.
  9. 9 . The method of claim 3 , wherein the fuel is glycine, sucrose, malic acid, citric acid, cellulose, ethylene glycol, urea, carbohydrazide, or a combination thereof.
  10. 10 . The method of claim 2 , wherein prior to the second stage, the metal oxide precursor is heat treated in air at a temperature in a range of from 100 to 300° C. for a time period in a range of from 0.5 to 4 hours.
  11. 11 . The method of claim 2 , wherein fluorinating the metal oxide precursor in the second stage includes combining the metal oxide precursor with lithium fluoride to obtain a third mixture, and heating the third mixture up to a predetermined temperature.
  12. 12 . The method of claim 11 , wherein the predetermined temperature is in a range of from 700 to 1,100° C.
  13. 13 . The method of claim 11 , wherein combining the metal oxide precursor with lithium fluoride includes grinding the metal oxide precursor and lithium fluoride.
  14. 14 . The method of claim 2 , wherein lithiating the metal oxide precursor in the second stage includes combining the metal oxide precursor with a lithium-containing agent to obtain a fourth mixture, and heating the fourth mixture up to a predetermined temperature.
  15. 15 . The method of claim 2 , wherein annealing the metal oxide precursor in the second stage includes heating the metal oxide precursor up to a predetermined temperature.
  16. 16 . The method of claim 1 , wherein the obtained DRX oxyfluoride is a Mn/Ti-based DRX oxyfluoride.
  17. 17 . The method of claim 16 , wherein the Mn/Ti-based DRX oxyfluoride has a nominal composition of: i) Li 1.25 Mn 0.5 Ti 0.3 O 1.95 F 0.05 ; ii) Li 1.35 Mn 0.7 Ti 0.1 O 1.85 F 0.15 ; or iii) Li 1.1 Mn 0.8 Ti 0.1 O 1.9 F 0.1 .
  18. 18 . A lithium-ion battery cathode including a disordered rock salt cathode material made by the method of claim 1 .
  19. 19 . A lithium-ion battery including the lithium-ion battery cathode of claim 18 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 63/715,138, filed Nov. 1, 2025, the disclosure of which is incorporated by reference in its entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT This invention was made with government support under Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of Energy. The government has certain rights in the invention. FIELD OF THE INVENTION The present invention relates to a method of synthesizing disordered rock salt (DRX) materials for battery cathodes and other applications. BACKGROUND OF THE INVENTION Lithium-ion (Li-ion) batteries are widely utilized in a range of applications including portable electronics, electric vehicles, and grid storage. The cost and energy density of Li-ion batteries are largely influenced by the cathode material selection. State-of-the-art layered oxides (e.g., LiNixMnyCo1-x-yO2 (NMC) and LiNixCoyAl1-x-yO2 (NCA)) exhibit high operating voltages (greater than 3.8 V vs. Li/Li+) and reversible capacities (up to 220 mA h g−1), but their over-reliance on critical resources, namely nickel (Ni) and cobalt (Co), presents considerable problems in developing sustainable supply chains. Co/Ni-free alternatives, including olivine LiFePO4 and spinel LiMn2O4, have been commercialized, but these materials have significantly lower energy density, highlighting the need for new cathode chemistries based on earth-abundant transition metals. Li-excess disordered rock salt (DRX) oxides represent a promising class of materials for next-generation Li-ion cathodes. DRX materials adopt the cubic Fm-3m rock salt structure, where Li+ and transition metals occupy the cation site, and O2− anions occupy the anion site. Typically, these materials contain both redox-active transition metal(s) (e.g., manganese (Mn) and nickel (Ni)) and d0 transition metal(s) (e.g., Ti4+, Zr4+, and Nb5+), the latter stabilizing the DRX structure. Compared to conventional Li-ion cathodes, DRX materials exhibit broad compositional flexibility, and their disordered nature may provide other advantages such as smaller volume changes during cycling. They have been reported with impressive performance including specific capacities greater than or equal to 300 mA h g−1 and specific energies of approximately 1000 W h kg−1. Their electrochemical performance can be further improved by partially substituting O2− with F−, which has been widely investigated for Mn/Ti-based compositions (e.g., Li1+xMnyTi1-x-yO2-zFz). In addition to improving oxidative stability, F-substitution has been shown to increase Lit mobility via formation of percolating 0-TM channels in Li1.2Ti0.35Ni0.35Nb0.1O1.8F0.2. On the other hand, it has been demonstrated that fluorination levels of greater than 10% (i.e. 0.2 mol F per DRX formula unit) hinder Li+ percolation compared to the pure oxide DRX, but Li+ mobility increases at higher fluorination levels (greater than 15%). It has also been demonstrated for Mn-rich DRX (e.g., Li1+xMnyTi1-x-yO2-zFz, y≥0.5), the capacity and cycling stability mostly depend on the Mn content, while fluorination plays a secondary role. Despite their promising attributes, a significant limitation of DRX cathodes is the lack of flexible synthesis platforms, which are needed to fine tune the material's structure and performance. DRX powders are typically prepared using solid-state methods, which utilize ball milling to mix inorganic precursors followed by high-temperature reactions for an appreciable amount of time (e.g., 12 hours at 1000° C. or greater than 9 hours at greater than or equal to 900° C.). These methods are difficult to scale and provide little control over the particle morphology. For oxyfluoride compositions, this lack of control is compounded by uncertainty in the product's stoichiometry due to LiF evaporation at high temperature and/or the presence residual amorphous LiF in the final product, which cannot be detected using standard scattering tools. Furthermore, preparing Mn-rich compositions (Li1+xMnyTi1-x-yO2-zFz wherein y≥0.5) is challenging due to the high energy of Mn—F bonds compared to Li—F and Ti—F bonds. For example, difficulty has been shown in simultaneously incorporating Mn3+ and F− into a DRX lattice when using Li3TiO3F and MnO precursors. Considering these challenges, alternative methods have been explored to produce DRX cathodes including mechanochemical, sol-gel, molten salt, and microwave synthesis routes. However, a need continues to exist for suitable, scalable methods of synthesizing DRX cathode materials for use in applications such as Li-ion batteries. SUMMARY OF THE INVENTION A method of making a disordered rock salt cathode material for lithium-ion batteries is provided. The method includes performing combustion synthesis with an aqueous solution of metal-containing compounds to obtain a disordered rock salt (DRX) oxide or a disordered rock salt (DRX) oxyfluoride. In