Mixed oxide of titanium, niobium and lanthanum, anode material, anode comprising this material and battery comprising this anode

Abstract

The present invention relates to a mixed oxide of titanium, niobium, and lanthanum of formula (I): LiwTi1-xLaxNb2-yM1yO7-zM2z (I) in which: 0.03 ≤ x ≤ 0.08; M1 and M2 are at least one element selected from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn; 0 ≤ w ≤ 5, 0 ≤ y < 2, and 0 ≤ z ≤ 0.3. Figure for abbreviation: [Fig. 8]

Description

Title of the invention: Mixed oxide of titanium, niobium and lanthanum, anode material, anode comprising this material and battery comprising this anode. FIELD OF THE INVENTION

[0001] The invention relates to mixed oxides of titanium, niobium and lanthanum, as well as anode materials comprising these oxides.

[0002] The invention also relates to anodes comprising these anode materials and batteries using such anodes. STATE OF THE ART

[0003] The invention relates to the field of electrochemistry, and more particularly to electrochemical systems.

[0004] Ideal batteries for powering autonomous electrical devices (such as: mobile phones and laptops, handheld tools, autonomous sensors) or for traction of electric vehicles would have a long lifespan, be capable of storing large amounts of energy and power, could operate in a very wide temperature range and would not present any risk of overheating or explosion.

[0005] Currently, these electrical devices are primarily powered by lithium-ion batteries, which offer the highest energy density among the various storage technologies available. Different architectures and electrode chemical compositions exist for manufacturing lithium-ion batteries. The manufacturing processes for lithium-ion batteries are described in numerous articles and patents, and the books "Advances in Lithium-Ion Batteries" (ed. W. van Schalkwijk and B. Scrosati), published in 2002 (Kluever Academie / Plenum Publishers), and "Lithium Batteries: Science and Technology" by C. Julien, A. Mauger, A. Vijh, and K. Zaghib (Springer, Heidelberg 2016) provide a good overview.

[0006] In addition to the architecture and manufacturing processes of battery cells, the choice of electrode materials is also fundamental. The energy stored in batteries is the product of the electrode capacity in Ah or mAh multiplied by the cell's operating voltage. This operating voltage is the difference between the insertion potentials of the lithium in the anodes and cathodes.

[0007] Among the anode materials frequently used in such devices are mixed lithium-titanium oxides (Li4Ti50i2) or mixed titanium-nobium oxides, such as the mixed oxide with the formula TiNb2O7, known as TNO. As illustrated, for example, in application EP3379613, mixed nobium and Titanium compounds are particularly interesting because they possess a very high theoretical capacity per unit mass. For example, the monoclinic TiNb2O7 composite would have a theoretical capacity of 387 mAh / g compared to 175 mAh / g for the Li4Ti50i2 compound.

[0008] While it is particularly advantageous to use an anode material with a high theoretical capacity, it is crucial that this material has good resistance to aging, i.e. a loss of capacity as a function of the number of charge / discharge cycles that is as reduced as possible.

[0009] From an industrial point of view, a need remains for the provision of anode materials combining the following characteristics:

[0010] - high specific capacity in order to compensate for energy losses by reducing the operating voltage by increasing their capacity;

[0011] - insertion of lithium at a relatively high voltage (greater than 0.5V / Li) to avoid the formation of lithium dendrites, especially during rapid charging phases;

[0012] - a loss of capacity depending on the number of charge / discharge cycles which is as reduced as possible to ensure sustained performance over time Description of the invention

[0013] The present invention relates to a mixed oxide of titanium, niobium and lanthanum of formula (I):

[0014] LiwTi1.xLaxNb2.yM1yO7.zM2z (I)

[0015] in which: • 0.03 < x < 0.08 • M1 and M2 are at least one element chosen from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs and Sn; • 0 <w<5, 0<y<2et0<z< 0,3.

[0016] Advantageously, the mixed oxide of titanium, niobium and lanthanum is such that z=0.

[0017] Advantageously, the mixed oxide of titanium, niobium and lanthanum is such that y=0.

[0018] Advantageously, the mixed oxide of titanium, niobium and lanthanum has the formula Tibx LaxNb2O7 (la) or LiwTii xLaxNb2O7(Ib), x and w being as defined above.

[0019] Advantageously, the mixed oxide of titanium, niobium and lanthanum is in the form of aggregates of primary nanoparticles of said oxide and the primary nanoparticles have an average primary diameter D50 between 2 nm and 100 nm, preferably between 2 nm and 60 nm.

[0020] Advantageously, the aggregates of primary nanoparticles of mixed oxide of titanium, niobium and lanthanum have an average diameter D50 between 10 nm and 20 pm, preferably between 20 nm and 10 pm.

[0021] Advantageously, the mixed titanium, niobium and lanthanum oxide has a specific surface area between 10 m2 / g and 80 m2 / g, preferably between 25 m2 / g and 50 m2 / g.

[0022] The invention also relates to an active anode material comprising a mixed oxide of titanium, niobium and lanthanum as described above.

[0023] The invention also relates to an anode comprising the active material as described above or obtained from the active material as described above.

[0024] The invention also relates to an electrical energy storage or production device comprising at least one anode as described above, the electrical energy storage or production device being, preferably, a capacitor, a supercapacitor, a lithium-ion hybrid supercapacitor, a photovoltaic cell, a photoelectrochemical cell or a battery, preferably a lithium-ion battery.

[0025] The invention also relates to the use of lanthanum in a mixed oxide of titanium, niobium and lanthanum of formula (I):

[0026] LiwTil xLaxNb2_yM1yO7_zM2z (I)

[0027] in which: • 0.03 < x < 0.08 • M1 and M2 are at least one element chosen from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs and Sn; • 0 <w<5, 0<y<2et0<z< 0,3.

[0028] to improve the aging resistance of said oxide used as an active anode material in an energy storage or production device.

[0029] Other aspects of the invention are as described below. DESCRIPTION OF THE FIGURES

[0030] Figure 1 shows scanning electron microscope images of powders according to: - Example A (a - top): TiNb2O7 - TNO - example B (b - bottom): Ti0j95La0j05Nb2O7 'TNO 0.05 La'

[0031] Figure [Fig. 2] shows transmission electron microscopy images of powders according to: - Example A (a - top): TiNb2O7 - TNO - example B (b - bottom): Ti0j95La0j05Nb2O7 'TNO 0.05 La'

[0032] Figure 3 shows the size distribution of the nanoparticles (N = number of nanoparticles of diameter D in nm) from the TEM images of a total of 63 nanoparticles. particles for the Tio^Lao^MhOv 'TNO 0.05 La' powder according to example B.

[0033] Fig. 4 represents the cycling (charge and discharge) curves E(V) vs Li+ / Li as a function of the specific capacitance Cs (mA.h / g) at different C-Rate (C and C / 5) of the electrodes obtained with the TiNb2O7 particles according to example A at 2.44 mg / cm2.

[0034] Fig. 5 represents the cycling (charge and discharge) curves E(V) vs Li+ / Li as a function of the specific capacitance Cs (mA.h / g) at different C-Rate (C and C / 5) of the electrodes obtained with the TiO₂₅LaO₂₅Nb₂O₇ particles according to example B at 2.9 mg / cm².

[0035] Figures 6 and 7 respectively represent the cycling curves E(V) vs Li+ / Li as a function of the specific capacitance Cs (mA.h / g) at C / 5:

[0036] - for the anode of the half-cell facing the lithium with Germanium-doped TNO ('TNO X Ge') as a function of the fraction of dopant x (x=0 / 0.1 or 10% / 0.5 or 50%) according to examples C;

[0037] - for the anode of the half-cell facing the lithium with cerium-doped TNO ('TNO X Ce') depending on the fraction of dopant x (x=0 / 0.01 or 1% / 0.05 or 5%) according to examples D.

[0038] Fig. 8 illustrates the percentage of capacity retention R relative to the first cycle for half-cells with TNO and TNO doped with 5% (x=0.05) lanthanum, 10% (x=0.1) germanium and 5% (x=0.05) cerium according to the AD examples as a function of the number of cycles N. DETAILED DESCRIPTION OF THE INVENTION Definitions

[0039] For the purposes of this document, the size of a particle is defined by its largest dimension. "Nanoparticle" means any particle or object of nanometric size having at least one of its dimensions less than or equal to 400 nm.

[0040] The term "ionic liquid" refers to any liquid salt that differs from all molten salts by having a melting point below 100°C. Some of these salts remain liquid at room temperature and do not solidify, even at very low temperatures. Such salts are called "room-temperature ionic liquids."

[0041] The term "electrolyte" means any ionically conductive substance due to the presence of mobile ions; it may be solid without a liquid phase or liquid. These ions are preferably Li+. A liquid electrolyte may be in gel form. To galvanically separate the electrodes, the electrolytes are electronic insulators.

[0042] By "mesoporous" materials, we mean any solid that has pores within its structure called "mesopores" with a size intermediate between that of micropores (width less than 2 nm) and that of macropores (width greater than 50 nm), namely a size between 2 nm and 50 nm. This terminology corresponds to The definition adopted by IUP AC (International Union for Pure and Applied Chemistry) is the one used by those skilled in the art. Therefore, the term "nanopore" is not used here, even though mesopores as defined above have nanometric dimensions in the sense of the definition of nanoparticles, given that pores smaller than mesopores are called "micropores" by those skilled in the art.

[0043] A presentation of the concepts of porosity (and of the terminology which has just been set out above) is given in the article "Texture of powdery or porous materials" by F. Rouquerol et al., published in the collection "Techniques de l'Ingénieur", Analyse et Caractérisation treatise, fascicle P 1050; this article also describes the techniques for characterizing porosity, in particular the BET method.

[0044] For the purposes of the present invention, a "porous layer" means a layer that has pores. A "mesoporous layer" means a layer that has mesopores. In these layers, the pores and mesopores contribute significantly to the total pore volume; this is reflected in the expression "Porous / mesoporous layer with porosity greater than X% by volume" used in this description.

[0045] The term “aggregate” means, according to the IUPAC definitions, a loosely bound assembly of primary particles. In this case, these primary particles are particles having a diameter that can be determined by transmission electron microscopy. An aggregate of primary nanoparticles can normally be destroyed (i.e., reduced to primary particles) in suspension in a liquid phase by any suitable means, in particular by ultrasound or by grinding, according to a technique known to those skilled in the art.

[0046] The anode function refers to the function of the electrode during battery charging. During discharge, the same electrode no longer functions as an anode.

[0047] In the present application, the lanthanum doping in the compound of formula (I) is expressed as the molar ratio La / (La + Ti) = x. This ratio can also be expressed as a molar percentage. Thus, if x = 0.05, this means that the titanium in the compound of formula (I) is substituted at a rate of 5 molar percent by lanthanum. Mixed oxide of titanium, niobium and lanthanum

[0048] A first object of the invention relates to a mixed oxide of titanium, niobium and lanthanum of formula (I):

[0049] LiwTil xLaxNb2_yM>yO7 zM2z (I)

[0050] in which: • 0.03 < x < 0.08 • M1 and M2 are at least one element chosen from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs and Sn; • 0 < w < 5, 0 <y<2et0<z< 0,3.

[0051] When 0.03 < x < 0.08, the mixed titanium, niobium and lanthanum oxide according to formula (I) used as an active electrode material in an energy storage or production device, such as in a cell or battery, retains similar charge and discharge capacity performance to the un-lanthanum-doped material but has better aging resistance than the un-lanthanum-doped material.

[0052] When x < 0.03, the Lanthanum doping rate is not sufficient and the aging performance of the mixed titanium, niobium and lanthanum oxide according to formula (I) used as an active electrode material in an energy storage or production device, such as in a cell or battery, is not improved compared to that of the un-lanthanum-doped material.

[0053] When x > 0.08, the performance in terms of charge and discharge capacity of the mixed titanium, niobium and lanthanum oxide according to formula (I) used as an active electrode material in an energy storage or production device, such as in a cell or battery, is degraded compared to that of the non-lanthanum-doped material.

[0054] Thus, surprisingly, the value of x such that 0.03 < x < 0.08 in the mixed oxide of formula (I) makes it possible to obtain an oxide whose performance in terms of charge / discharge capacity is preserved and which has improved resistance to aging.

[0055] According to some embodiments, the mixed titanium, niobium, and lanthanum oxide can be pre-charged with lithium to increase its electronic conductivity. Thus, w can be equal to 0, preferably greater than 0 and less than or equal to 5.

[0056] The mixed titanium, niobium and lanthanum oxide of formula (I) may not include an M2 element. It is the oxide of formula (I) in which z=0.

[0057] The mixed titanium, niobium and lanthanum oxide of formula (I) may not comprise any element ML II is the oxide of formula (I) in which y=0.

[0058] The mixed titanium, niobium and lanthanum oxide of formula (I) may not include the element M1 or the element M2. It is the oxide of formula (I) in which y=0 and z=0.

[0059] Preferably, the mixed titanium, niobium and lanthanum oxide of formula (I) is Tii xLaxNb2O7 of formula (la) or LiwTii xLaxNb2O7 of formula (Ib), x and w being as defined above.

[0060] Preferably, the mixed titanium, niobium and lanthanum oxide of formula (I) is the Ti|XLaxNb2O7 of formula (la), x and w being as defined above.

[0061] Surprisingly, the applicant also discovered that mixed titanium, niobium and lanthanum oxides of formula (I) have better performance in aging than equivalent mixed oxides for which titanium is partially substituted by another metallic element.

[0062] Thus, at degree of substitution x of Ti equal with 0.03 < x < 0.08, the aging performance of the mixed titanium, niobium and lanthanum oxide according to formula (I) used as an active electrode material in an energy storage or production device, such as in a cell or battery, is improved compared to that of the material doped with Germanium or Cerium.

[0063] The lanthanum-doped material has better resistance to aging than the undoped material (TNO).

[0064] The Cerium-doped material has a similar resistance to aging to the undoped material (TNO).

[0065] The Germanium-doped material has a lower resistance to aging than the undoped material (TNO).

[0066] Aging performance or aging resistance refers to the evaluation of the capacity retention as a function of the number of cycles of the oxide of formula (I) when used as an active electrode material in an energy storage or production device, such as in a cell or battery. Thus, if the aging resistance is improved compared to another oxide, this means that the capacity retention as a function of the number of cycles decreases more rapidly for the reference oxide than for the oxide of formula (I).

[0067] Characteristics of the mixed titanium, niobium and lanthanum oxide of formula (I)

[0068] The mixed oxide of titanium, niobium and lanthanum can be in the form of particles of any shape and size suitable for use as an active anode material.

[0069] A person skilled in the art knows how to adapt the particle size of the mixed titanium, niobium and lanthanum oxide according to characteristics such as the power of the battery, the composition of the anode (presence or absence of binder, electronic conductive material), the desired porosity of the anode and / or the desired size of the pores of the anode.

[0070] In general, TNO (TiNb2O7) type compositions exhibit very low electronic conductivity. In a battery, to be able to deliver high power, it is therefore advantageous for the oxide particles to be small.

[0071] The active materials used to make the electrodes are typically used in the form of powder suspensions with an average particle size between 5 pm and 15 pm in diameter.

[0072] These particles are incorporated into an ink which is made up of these particles, organic binders, and a filler of a powder of an electronically conductive material (also called a conductive filler), typically of Carbon black. This ink is deposited on the surface of a metallic substrate, then dried to eliminate the organic solvents it contains and leave on the surface of the metallic substrate only a porous deposit consisting of particles of active materials mechanically linked together by organic binders and electrically connected by the conductive charge.

[0073] To optimize the volumetric energy density of lithium-ion batteries produced using these conventional manufacturing processes, reducing electrode porosity can be very beneficial. This reduction in porosity, in other words, increasing the amount of active material per unit volume of electrode, can be achieved in several ways.

[0074] With conventional inking techniques, it is thus possible to increase the volumetric energy density by optimizing the size distribution of the deposited particles. Indeed, as shown, for example, in the article by J. Ma and LC Lim, "Effect of particle size distribution on sintering of agglomerate-free submicron alumina powder compacts," published in 2002 in the journal J. European Ceramic Society 22 (2002), pp. 2197-2208, by optimizing the particle size distribution, it is possible to achieve a density of approximately 70%. An electrode with 30% porosity, containing conductive fillers and impregnated with a lithium-ion conductive electrolyte, will have a volumetric energy density approximately 35% higher than the same electrode with 50% porosity made of particles of uniform size dispersion.

[0075] Although this size distribution of the active material particles increases the energy density of the electrodes, it is not without its problems. Particles of different sizes within an electrode will have different capacitances and, under the effect of identical charge and / or discharge currents, will be locally more or less charged and / or discharged depending on their size. When the battery is no longer subjected to current, the local charge states between particles will be rebalanced, but during these transient phases, local imbalances can lead to particles being subjected to voltage outside their stable ranges. These local charge state imbalances will be more pronounced as the current densities increase.These imbalances consequently lead to performance losses during cycling, safety risks, and a limitation of battery cell power.

[0076] These effects of the particle size distribution of active materials on the current / voltage relationships of the electrodes were studied and simulated by ST Taleghani et al. in the publication “A study on the effect of porosity and particles size distribution on Li-ion battery performance”, published in the journal J. Electrochemical Society, 164 (11) 2017, p. E3179-E3189.

[0077] With the electrode inking techniques as described above, the Active material particles are generally between 5 pm and 15 pm in size. The contact between two neighboring particles is essentially point contact, the particles being bonded together by an organic binder which is most often PVDF.

[0078] According to embodiments, the mixed oxide of titanium, niobium and lanthanum is in the form of particles having a micron size, as described above.

[0079] According to other embodiments, it may be advantageous for the anode active material to comprise nanoparticles.

[0080] The active anode material can be implemented from an ink as described above.

[0081] The active anode material can also be implemented as described above, but with the additional step of heat treatment to remove any organic residue in order to obtain a porous, preferably mesoporous, anode with high porosity, free of binder, and optionally free of any additional electronic conductors, whether additional conductive fillers or conductive material deposited on and within the pores. An example of such an anode is described in application WO 2019 / 215 407 AL

[0082] Advantageously, the use of an anode active material powder in the form of primary nanoparticle aggregates having an average diameter D50 less than 100 nm makes it possible to obtain high electronic conductivity and promotes sintering (necking) between the primary particles during a subsequent consolidation step.

[0083] Thus, according to embodiments, the mixed oxide of titanium, niobium and lanthanum can be in the form of aggregates of primary nanoparticles of said oxide.

[0084] Advantageously, the primary nanoparticles have an average primary diameter D50 between 2 nm and 100 nm, preferably between 2 nm and 60 nm, more preferably between 2 nm and 40 nm.

[0085] The aggregates or agglomerates of primary nanoparticles can have an average diameter D50 between 10 nm and 20 pm, preferably between 20 nm and 10 pm.

[0086] The size of the particles can be measured by observation using scanning electron microscopy and transmission electron microscopy.

[0087] The size of the nanoparticles is measured using a transmission electron microscope.

[0088] The specific surface area of ​​the active anode material increases the exchange surfaces and, consequently, the battery power. Thus, it may be useful to have a mixed oxide of titanium, niobium, and lanthanum with a high specific surface area. Advantageously, its specific surface area is between 10 m² / g and 80 m² / g, preferably between 25 m² / g and 50 m² / g.

[0089] The specific surface area can be measured by BET.

[0090] Preparation of the mixed titanium, niobium and lanthanum oxide of formula fl)

[0091] The mixed titanium, niobium and lanthanum oxide particles of formula (I) can be manufactured by any method known to a person skilled in the art.

[0092] It is known that TNO (TiNb2O7) type particles can be synthesized hydrothermally, with a size range between approximately 50 nm and approximately 300 nm; however, controlling this size is difficult, and the size range is wide. This synthesis leads to amorphous particles that must then be crystallized by high-temperature heat treatment, for example, at around 1000 °C for about 30 minutes. During this crystallization, the particles can grow uncontrollably, which further widens the size range. Alternatively, there are solid-state synthesis methods, which also require high-temperature treatment to homogenize the chemical composition.

[0093] In the context of the present invention, primary nanoparticles, agglomerated or not, with a size of less than 100 nm, preferably less than 60 nm, and even more preferably less than 40 nm, are preferred to be used. Such nanoparticles can be obtained by various processes.

[0094] According to one method, salts, complexes, or alkoxides (such as ethoxides) of cations of metallic elements comprising the desired phase are mixed to obtain a perfectly homogenized distribution at the atomic scale. Polymers are then used to fix this distribution of molecules, ions, or complexes containing the metallic element. These polymers are subsequently removed by heat treatment, leaving only the atomic-scale inorganic constituents, which can then be obtained by simple calcination at a relatively low temperature, resulting in the desired phase, crystalline, at the nanoparticle scale. Organic materials capable of significant outgassing during the heat treatment phases can be added, which will contribute to the formation of mesoporous agglomerates.

[0095] An example of such a synthesis is the "Pechini method," a process in which the cations of the desired phase (in our case, for example, Nb, Ti, and La) are complexed with an organic molecule (such as citric acid or EDTA (ethylenediaminetetraacetate)) and introduced into a polymer matrix (for example, a polyalcohol such as polyethylene glycol or polyvinyl alcohol). This results in a very homogeneous distribution of complexed and dilute cations. Subsequently, the polymer and the complexing organic molecule are removed by pyrolysis, leading to the formation of the desired inorganic oxides. Calcination at approximately 800 °C yields crystallized nanoparticles. The process allows for adjusting the particle size, which decreases as the concentration of cations in the polymer matrix decreases. Anode active material

[0096] A second object of the invention relates to an active anode material comprising a mixed oxide of titanium, niobium and lanthanum as described above. Anode

[0097] Another object of the invention relates to an anode comprising the active material as described above or obtained from the active material as described above.

[0098] The mixed oxide of titanium, niobium and lanthanum can be shaped, as an anode active material, to obtain an anode by any technique known to the person skilled in the art.

[0099] The anode according to the invention can be manufactured using known coating techniques (in particular by coating techniques, such as roll coating, curtain coating, slot die coating, doctor blade, tape casting).

[0100] The particles of the anode active material are typically integrated into inks as described above.

[0101] Ink compositions are well known to those skilled in the art.

[0102] The process for obtaining the anode can make it possible to obtain an anode free or not of any organic matter and, where appropriate, of any additional electronic conductor, whether it be additional conductive charges or a conductive material deposited on and inside the pores.

[0103] As described in application WO 2021 / 220 176 Al, a layer of an electronically conductive material can be deposited on the surface of the particles of the active anode material in order to increase the electronic conductivity of the anode material; a thin layer of carbon or a thin layer of an electronically conductive oxide material can be used for this purpose.

[0104] The anode may have a porous or mesoporous structure. When the anode is mesoporous, this means that it comprises mesopores according to the definition given above.

[0105] The anode may include a current collector. Any substrate capable of collecting electric current may be used, such as a metallic substrate. The anodic current collector may be: Mo, Cu, Ni, alloys based on the aforementioned elements, or stainless steel.

[0106] Device for storing or producing electrical energy

[0107] Another object of the invention relates to a device for storing or producing electrical energy comprising a cathode, an anode as described above and an electrolyte.

[0108] The electrical energy storage or production device may be a capacitor, a supercapacitor, a hybrid lithium-ion supercapacitor, a photovoltaic cell, a photoelectrochemical cell, a lithium-ion cell or a lithium-ion battery.

[0109] Advantageously, the device is a lithium ion battery comprising a cathode, an anode as described above and an electrolyte.

[0110] The batteries according to the invention can be made with very different power ratings. In particular, the batteries can be lithium-ion microbatteries, which excel in their high power, thus opening them up to numerous applications on electronic boards, in electronic devices, and especially in medical devices. These batteries can operate in a very wide temperature range and can be recharged in less than 15 minutes.

[0111] Conversely, the batteries can be lithium-ion batteries. They are of particular interest in the form of high-power batteries, especially for use in electric vehicles.

[0112] With intermediate power ratings, the batteries can be used in various portable electronic devices such as mobile phones, laptops, and portable reading devices.

[0113] The cathode material can be any material known to those skilled in the art. By way of example, LiCoPO4; LiMnij5Nio,5O4; LiFexCoi XPO4 (where 0 < x < 1); LiNii / XCoi / y Mni / ZO2 with x+y+z = 10; Liij2Nio,i3Mnoj54Cooji3O2; LiMni,5Ni0,5-xXxO4 where X is selected from Al, Fe, Cr, Co, Rh, Nd, Sc, Y, Lu, La, Ce, Pr, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and where 0 < x < 0.1; LiNi,8Co0,i5Alo,o5O2; Li2MPO4F (with M = Fe, Co, Ni or a mixture of these different elements); LiMPO4F (with M = V, Fe, Ti or a mixture of these different elements); LiMSO4F (with M = Fe, Co, Ni, Mn, Zn, Mg), LiNii / xMni / yCoi / zO2 with x+y+z = 10; LiCoO2.

[0114] For high capacity cathodes, LiNii / xMni / yCoi / zO2 with x+y+z = 10, LiNioj8Cooji5Alojo502, and LiCoO2 are particularly preferred.

[0115] By way of example, LiNixMnyCozO2 (also known by the acronym "NMC") can be used, preferably with x + y + z= 1, and even more preferably with x:y:z = 0,8:0,1:0,1 (material known by the acronym "NMC811").

[0116] The cathode may possess all the characteristics of the anode as described above except for the active material.

[0117] The cathode current collector is made of a material selected from the group formed by: Mo, Ti, W, Ta, Cr, Al, alloys based on the aforementioned elements, stainless steel.

[0118] The battery may further include a separator, an electrical insulator. Oxides of the type Al2O3, ZrO2, SiO2, or even phosphates or borates may be used.

[0119] The electrolyte is preferably a selected lithium ion carrier phase in the group formed by:

[0120] • an electrolyte composed of at least one aprotic solvent and at least one salt of lithium;

[0121] • an electrolyte composed of at least one ionic liquid and at least one salt of lithium;

[0122] • a mixture of at least one aprotic solvent and at least one ionic liquid and of at least one lithium salt;

[0123] • a polymer made ionically conductive by the addition of at least one lithium salt; and

[0124] • a polymer made ionically conductive by the addition of a liquid electrolyte, either in the polymer phase, either in the mesoporous structure,

[0125] and even more preferably, by an electrolyte selected from the group formed by:

[0126] • an electrolyte comprising N-butyl-N-methylpyrrolidinium 4,5-dicyano-2-(trifluoromethyl)imidazole (Pyrl4TDI) and containing LiTDI-type lithium salts,

[0127] • an electrolyte comprising l-Methyl-3-propylimidazolium 4,5-dicyano-2-(trifluoro-methyl)imidazolide (PMIM-TDI) and lithium 4,5-dicyano-2-(trifluoro-methyl)imidazolide (LiTDI).

[0128] The lithium ion carrier phase may be as described in application WO2021 / 220174 Al or WO 2023 / 275779 AL

[0129] Use of lanthanum to improve the aging resistance of the mixed titanium, niobium and lanthanum oxide

[0130] Another object of the invention relates to the use of lanthanum in a mixed oxide of titanium, niobium and lanthanum of formula (I):

[0131] LiwTilxLaxNb2.yM*yO7.zM2z (I)

[0132] in which: • 0.03 < x < 0.08 • M1 and M2 are at least one element chosen from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs and Sn; • 0 <w<5, 0<y<2et0<z< 0,3.

[0133] to improve the aging resistance of said oxide used as an active anode material in an energy storage or production device.

[0134] The mixed titanium, niobium and lanthanum oxide, the anode active material and the energy storage or production device are as described above in the preceding sections. EXAMPLES

[0135] The following examples of implementation of a method according to the invention are given by way of illustration and should not be interpreted as limiting the scope of the invention.

[0136] 1. Methods for characterizing mixed oxide powders Diffraction X:

[0137] The powders obtained from the heat treatment at 800°C are analyzed by X-ray diffraction. The indexed peaks are compared to the indexed peaks of crystallized TNO without the monoclinic phase according to the ICDD reference sheet 00-39-1407.

[0138] Specific surface area: measured by gas adsorption using the BET method.

[0139] Measurement of the size of elementary nanoparticles and aggregates: the size of Powder particle size is determined by scanning electron microscopy and transmission electron microscopy.

[0140] 2. Synthesis of mixed oxides Example A - Undoped TNO (outside the scope of the invention):

[0141] A formulation of TiNb2O7 nanoparticle agglomerates has been synthesized from the alkoxides Ti(OC2H5)4, and Nb(OC2H5)4.

[0142] In a first step, citric acid (72.9g) was dissolved in 223.4g of ethylene glycol by magnetic stirring and heating to 80°C. In parallel, the ethoxide mixture was prepared in a glove box under an inert atmosphere, respecting the stoichiometry of the target component (i.e., 38.2g - 0.12 mol of Nb(OC2H5)4 and 13.69g - 0.06 mol of Ti(OC2H5)4).

[0143] In a second step, the alkoxide mixture was introduced under vigorous stirring into the citric acid / ethylene glycol solution at room temperature. The reaction mixture was stirred for one hour at 90°C and then at 110°C overnight, resulting in the gelling of the solution (obtaining a highly viscous resin).

[0144] The gel is then extracted and placed in an alumina crucible. The crucibles are placed in a heating chamber at 250°C for 12 hours. This heating step eliminates excess ethylene glycol and activates the esterification reactions. The product is then calcined at 600°C for 1 hour to remove a large portion of the organic matter.

[0145] Then a second heat treatment is carried out for 1 hour at 800°C. A white and finely divided powder is obtained.

[0146] The powder is in the form of micrometric-sized aggregates made up of nanoparticles (with an elementary size of 20 nm) - cf [Fig.1](a) (SEM observations) and [Fig.2](a) (TEM observations).

[0147] The nanoparticles are crystallized in the space group I2 / m JCPDS: 39-1407 as pure monoclinic crystals.

[0148] The powder obtained has a specific surface area of ​​36 m2 / g. Example B - Lanthanum-doped TNO ('TNO 0.05 La')

[0149] A formulation of lanthanum-doped TiNb2O7 nanoparticle agglomerates was synthesized from the following precursors: Ti(OC2H5)4, Nb(OC2H5)4 and La(NO3)3, 6H2O.

[0150] The operating procedure is identical to that of example A except for the preparation of the precursor mixture respecting the stoichiometry of the target component (38.2g - 0.12 mol of Nb(OC2H5)4 and 13g - 0.057 mol of Ti(OC2H5)4 and 1.3g - 0.003 mol of La(NO3)3, 6H20 dissolved in 30 mL of anhydrous ethanol).

[0151] The powder is in the form of micrometric-sized aggregates made up of nanoparticles (with an elementary size of 20 nm) - cf [Fig.1](b) (SEM observations) and [Fig.2](b) (TEM observations).

[0152] A size distribution was calculated from TEM observations on a total of 63 particles ([Fig.3]): the mean physical diameter is 23.7 nm with a standard deviation of 6.4 nm.

[0153] The nanoparticles are crystallized in the space group I2 / m JCPDS: 39-1407 as pure monoclinic crystals.

[0154] The powder obtained has a specific surface area of ​​35 m2 / g.

[0155] Examples C - Germanium-doped TNO ('TNO X Ge') - not an invention

[0156] A formulation of nanoparticle agglomerates of formula Tii xGexNb207 (x=0.1 - 'TNO 0.1 Ge' and x=0.5 - 'TNO 0.5 Ge') was synthesized according to the procedure described above from the alkoxides Ge(OC2H5)4, Ti(OC2H5)4 and Nb(OC2H5)4.

[0157] The quantity of precursors is adapted to respect the stoichiometry of the target component.

[0158] A powder having similar characteristics in terms of size and specific surface area to that obtained in Example B is obtained. Furthermore, regardless of the doping level, only one crystalline phase corresponding to TNO crystallized according to the monoclinic phase described above is obtained.

[0159] Examples D - Cerium-doped TNO ('TNO X Ce') - not an invention

[0160] A formulation of nanoparticle agglomerates of formula Tii.xCexNb207 (with x=0.01 - 'TNO 0.01 Ce', x=0.05 - 'TNO 0.05 Ce' and x=0.5 - 'TNO 0.5 Ce') was synthesized according to the operating procedure of Example B from the following precursors: ammonium cerium (iV) nitrate, Ti(OC2H5)4 and Nb(OC2H5)4.

[0161] The quantity of precursors is adapted to respect the stoichiometry of the target component.

[0162] A powder having similar characteristics in terms of size and specific surface area to that obtained in Example B is obtained. A single crystalline phase corresponding to TNO crystallized according to the monoclinic phase described above is obtained for doping levels of 1% (x=0.01) and 5% (x=0.05). For the level of A 50% doping (x=0.5) results in a different crystalline phase.

[0163] 3. Electrochemical characterization of materials:

[0164] 3.1. Preparation of button cell batteries

[0165] The ink is formulated at 21% by mass in N-methyl-2-pyrrolidone (NMP). The dry matter consists of:

[0166] - 80% by mass of one of the powders according to the examples above

[0167] - 10% by mass of Super P Carbon Black, to ensure electrical conductivity tronics

[0168] - 10% by mass of polyvinylidene fluoride (PVDF) HSV 1800 which serves as a binder

[0169] The homogenization of the ink is ensured by 2 cycles of 2 min at 2000 rpm in the planetary mixer (Thinky Mixer).

[0170] The ink is then deposited onto a 19 µm thick aluminum strip using a manual doctor blade set at 200 µm. The deposit is then placed in an oven at 120°C for a minimum of 20 minutes to evaporate the solvent. It is then calendered under a pressure of 3 MPa and cut into 14 mm diameter discs.

[0171] The electrodes obtained are dried overnight at 80°C under vacuum before being cycled at room temperature in front of a lithium metal disk with a polypropylene polymer membrane (CELGARD's Celgard®3501) as a separator and LiPF6 as an electrolyte in Ethylene Carbonate (EC) / Dimethyl carbonate (DMC) (1:1 by volume).

[0172] 3.2. Characterization in cvclage

[0173] The charge and discharge curves obtained at different speeds for the anodes of the cell with TNO and of the cell with Tio^Lao^MhOv (x=0.05) are shown respectively in Figures 4 and 5.

[0174] The charging and discharging curves have similar shapes.

[0175] Figures 6 and 7 respectively represent the C / 5 cycling curves: - for the anode of the half-cell facing lithium with Germanium-doped TNO ('TNO X Ge') as a function of the dopant fraction x; - for the anode of the half-cell facing lithium with Cerium-doped TNO ('TNO X Ce') depending on the dopant fraction x.

[0176] The capacity decreases significantly when x is greater than or equal to 0.1.

[0177] The table below compares the electrochemical characteristics of the different anodes.

[0178] [Tables] Dopant Germanium Cerium Lanthanum X 0% 10% 50% 1% 5% 50% 5% Max capacity (mAh / g) at C / 5 264 235 200 265 256 100 262 e1 / 2(V) 1.56 1.61 1.61 1.57 1.57 — 1.55

[0179] 3.3. Characterization of aging

[0180] The half-cells made respectively from TNO, from TNO doped with 10% Germanium, with 5% Cerium, and with 5% Lanthanum are cycled at IC on respectively 146, 98, 98 and 159 cycles.

[0181] Fig. 8 illustrates the percentage of capacity retention R relative to the first cycle for these half-stacks.

[0182] Over the first 98 cycles, the half-cell with TiNb2O7 exhibits an aging rate of 0.085% per cycle, whereas the capacity loss for the half-cell with TiO₂₂MhO₂ is 0.050% per cycle. TiNb2O7 doped with 10% Germanium or with 5% Cerium exhibits greater aging than undoped TiNb2O7.

[0183] The Ti0j95La0j05Nb2O7 powder exhibits physico-chemical characteristics very close to the undoped material.

[0184] In terms of electrochemical properties, doping with 5% lanthanum:

[0185] - does not substantially alter the specific capacity

[0186] - does not affect the value of the potential / 2

[0187] - improves the material's resistance to aging (capacity loss of 0.050% / cycle) instead of 0.085% / cycle for the undoped product.

[0188] Conversely, doping with 5% Cerium or with 10% Germanium leads to a degradation of the resistance to aging compared to the undoped material.

Claims

Demands

1. Mixed titanium, niobium, and lanthanum oxide of formula (I): LiwTi, ^asNb2 yM'yO- ZM-Z (I) wherein: • 0.03 < x < 0.08 • M1 and M2 are at least one element selected from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs, and Sn; • 0 <w<5, 0<y<2et0<z< 0,3.

2. Mixed oxide of titanium, niobium and lanthanum according to claim 1 in which z=0.

3. Mixed oxide of titanium, niobium and lanthanum according to claim 1 or claim 2 wherein y=0

4. Mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims of formula Tii xLaxNb2O7 (la) or LiwTibxLax Nb2O7(Ib), x and w being as defined in any one of the preceding claims.

5. Mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims characterized in that it is in the form of aggregates of primary nanoparticles of said oxide and that the primary nanoparticles have an average primary diameter D50 of between 2 nm and 100 nm, preferably between 2 nm and 60 nm.

6. Mixed oxide of titanium, niobium and lanthanum according to claim 5 characterized in that the primary nanoparticle aggregates have an average diameter D50 between 10 nm and 20 pm, preferably between 20 nm and 10 pm.

7. Mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims characterized in that its specific surface area is between 10 m2 / g and 80 m2 / g, preferably between 25 m2 / g and 50 m2 / g.

8. Anode active material comprising a mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims.

9. Anode comprising the active material according to claim 8 or obtained from the active material according to claim 8.

10. Electrical energy storage or production device comprising at least one anode according to claim 9, the electrical energy storage or production device being, preferably, a capacitor, a supercapacitor, a lithium-ion hybrid supercapacitor, a photovoltaic cell, a photoelectrochemical cell or a battery, preferably a lithium-ion battery.

11. Use of lanthanum in a mixed oxide of titanium, niobium and lanthanum of formula (I): Li Jh, sLasNb2 yM'yO- ZM2Z (I) in which: • 0.03 < x < 0.08 • M1 and M2 are at least one element chosen from the group consisting of V, Ta, Fe, Co, Ti, Bi, Sb, As, P, Cr, Mo, W, B, Na, Mg, Ca, Ba, Pb, Al, Zr, Si, Sr, K, Cs and Sn; • 0 <w<5, 0<y<2et0<z< 0,3. to improve the aging resistance of said oxide used as an active anode material in an energy storage or production device.

Images