Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G33/00—Compounds of niobium
  • C01G33/006—Compounds containing niobium, with or without oxygen or hydrogen, and containing two or more other elements
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
  • C01G41/00—Compounds of tungsten
  • C01G41/006—Compounds containing tungsten, with or without oxygen or hydrogen, and containing two or more other elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/51—Particles with a specific particle size distribution
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer

Definitions

• TITLE Active material in mixed niobium titanium oxide substituted with tungsten
• the present invention relates to the field of active materials intended to form an electrode for lithium accumulators.
• the invention relates to an active material formed of particles of mixed oxide of niobium and titanium, part of the niobium of which is substituted by tungsten and titanium.
• the invention proposes a process for manufacturing such an active material.
• the invention proposes an electrode formed from said active material and an electrochemical generator, in particular of the battery type, which comprises a negative electrode in said active material.
• Ni-MH accumulators peak at 100-1 10 Wh/kg and Ni-Cd accumulators have an energy density of around 50-70 Wh/kg, this, associated with the drop in costs, explains that lithium batteries are now the most sold.
• New generations of more efficient lithium batteries are being developed for ever more diversified applications (hybrid or all-electric automobiles, photovoltaic cell energy storage, etc.).
• power demands per unit of mass and/or volume
• new, even more efficient Li-ion battery electrode materials are essential.
• the Li4TisOi 2 compound finds its place on the market thanks to its high work potential, around 1.6V vs Li+/Li, which makes it very safe and thanks to very good cyclability at high speeds, which makes it the negative electrode material of choice for power applications.
• the most interesting compounds are the oxides TiNb2O7 and Ti2NbioC>29. They have very high theoretical capacities (388mAh/g and 396mAh/g, respectively) compared to Li4TisOi2 (175mAh/g) and present a working potential close to that of Li 4 Ti 5 0i2, which allows them to retain the advantages of the latter in terms of security. They are therefore very interesting candidates with a view to replacing it for applications requiring more energy.
• the TiNb2 ⁇ 7 material more attractive in terms of cost due to the higher Ti/Nb ratio than in the Ti2NbioC>29 material, presents limitations in terms of power performance and cyclability.
• the present invention aims to remedy the drawbacks mentioned above.
• the present invention proposes an active material intended for the manufacture of an electrode, the active material comprising a monoclinic mixed oxide of substituted niobium titanium, capable of allowing the insertion and extraction of Li-i- ions, the active material having the following crude formula (I): Ti(1 + x)Nb(2-2x)WxO7 (I) in which the value x is chosen in the range from 0.05 to 0.2.
• This active material requires the substitution of part of the niobium in the mixed oxide of TiNb2O7 with tungsten and titanium while preserving the initial crystal structure. As will be seen later in Figure 2, only the volume of the mesh increases with the tungsten content. The niobium content decreases at the same time as the tungsten content increases as well as the titanium content to maintain the initial stoichiometry.
• the active material consists of a single monoclinic mixed oxide of substituted niobium titanium of the following crude formula (I):
• titanium has an oxidation degree +IV and niobium has an oxidation degree +V.
• the oxidation states of the metals in Ti(i +X )Nb(2-2x)WxO7 are identical to those of the unsubstituted compound TiNb2O7. This is advantageous because a reduction in the degrees of oxidation, from Ti4+ to Ti3+ or from Nb5+ to Nb4+, would de facto limit the number of electrons available during the first lithiation (reduction of metals) and therefore reduce the capacity of the material.
• the active material may comprise particles having an average diameter Di greater than 100 nm and less than or equal to 0.5 mm. These average diameter Di values meet the density/compactness needs of the active material to provide a satisfactory energy density.
• the active material consists solely of said particles.
• the active material consists of a mixed oxide of Ti(1 +x)Nb(2-2x)WxO7.
• the active material is intended for the manufacture of an electrode for Li-ion accumulators.
• the particles can be divided into three populations of average diameters Di, a first population having an average diameter D1 with 0.1 pm ⁇ D1 ⁇ 0.8 pm, a second population having an average diameter D2 with 1 pm ⁇ D2 ⁇ 10 pm, and a third population presenting an average diameter D3 with 10 pm ⁇ D3 ⁇ 0.5 mm.
• the particles are divided into two populations of average diameters Di, a first population having an average diameter D1 with D1 ⁇ 0.8 pm, and a second population having an average diameter D2 with D2 > 1 pm.
• the invention proposes a process for manufacturing the active material as previously described, which comprises solid-state synthesis.
• the synthesis by solid route is intended to lead to particles of active material.
• the synthesis by solid route is carried out from precursor reagents, in particular solid precursor reagents.
• the precursor reagents are TiOa, Nb20s and WO3.
• the precursor reagents are used in stoichiometric proportions.
• the process comprises after step b) carrying out a step c) of low energy grinding of the active material so as to reduce any agglomerates and obtain a homogeneous powder having particles of an average diameter Di greater than 100 nm and less than or equal to 0.5 mm.
• low energy grinding is manual grinding, particularly using a mortar and pestle.
• the invention proposes an electrode comprising the active material as previously described.
• the invention proposes an electrochemical generator, in particular of the battery type, which comprises a positive electrode and a negative electrode comprising the active material as previously described and a non-aqueous electrolyte comprising lithium.
• the active materials proposed by the invention can be adapted to high power requirements (rapid charge/rapid discharge, associated with very good cyclability), and maintaining an energy density at a high level (>100Wh/kg).
• FIG. 1 represents a laser particle size analysis of different compositions of active materials according to one embodiment of the invention.
• FIG. 2 represents an X-ray diffraction (XRD) pattern of the different compositions of active materials.
• the present invention proposes an active material intended for the manufacture of electrodes for lithium accumulators based on a mixed niobium titanium oxide substituted by tungsten:
• the recovered active material is manually ground in an agate mortar. Five minutes of grinding are enough to obtain a homogeneous powder in the form of particles having an average diameter Di greater than 100 nm and less than or equal to 0.5 mm. As shown in Figure 1 illustrating the laser particle size distribution diagram (left column), the average diameter Di is divided into three populations similar to those of the mixed niobium titanium oxide devoid of tungsten (device used MALVERN MASTERSIZER).
• These three populations include a first population having an average diameter D1 with 0.4 micrometer ⁇ D1 ⁇ 0.8 micrometer, a second population having an average diameter D2 with 1 micrometer ⁇ D2 ⁇ 10 micrometers, and a third population having an average diameter D3 with 10 micrometers ⁇ D3 ⁇ 0.5 mm.
• the particles are divided into two populations of average diameters Di, a first population having an average diameter D1 with D1 ⁇ 0.8 pm, and a second population having an average diameter D2 with D2 > 1 pm.
• the particles of active material subjected to ultrasonic treatment lead to the same particle size distribution, which shows that the particles obtained at the end of step c) are devoid of agglomerate.
• an X-ray diffraction analysis of the particles obtained at the end of step c) makes it possible to verify that the crystal structure of Ti2NbsO? is identical to that of the active material Ti(i +X )Nb(2-2x)WxO7 for all W substitution rates (x from 0.05 to 0.2).
• Electrodes and button cells were designed using the traditional method in order to observe the properties obtained by the active material as a function of different values of x and Ti2NbsC>7.
• the active material Ti(i+x)Nb(2-2x)WxC>7 (with x between 0.05 and 0.25) and a carbon additive (Carbon Black SUPER C65 from TIMCAL) are mixed and crushed manually in a agate mortar in cyclohexane (Purity >99.5%, Merck ENSURE) for 5 minutes.
• PVDF polyvinylidene fluoride
• NMP N-methyl-2-pyrrolidone
• the electrodes are then assembled in a glove box to form CR2032 type button cells.
• the counter electrode is Lithium metal
• one of the separators is made of polypropylene felt (Viledon, Freudenberg) and the other separator is made of polypropylene (CG2500, Celgard).
• the electrolyte consists of a mixture of ethylene carbonate (EC) / propylene carbonate (PC) / dimethyl carbonate (DMC) (1:1:3 vol) with lithium hexafluorophosphate (LiPF6) (1 M) (LP100, UBE Industries).
• the right part of Figure 3 illustrates the evolution of the Lithiation capacity of the same compounds with cycling at the C/10 regime from the 31st cycle.
• the power handling (on the left respectively with cycling at C/10; C, 2C, 3C, 5C and 10C for ease of comparison) is 120mAh/g at 10C. Although correct, this hold remains lower than the optimum obtained which is greater than 130.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Inorganic Compounds Of Heavy Metals (AREA)
• Battery Electrode And Active Subsutance (AREA)

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• 2022
  • 2022-08-31 FR FR2208740A patent/FR3139132A1/fr active Pending
• 2023
  • 2023-09-01 WO PCT/IB2023/000493 patent/WO2024047396A1/fr not_active Ceased
  • 2023-09-01 EP EP23773329.0A patent/EP4580996A1/de active Pending

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