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 ≤ 0.08M1 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 abstract: [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 to anode materials comprising these oxides.

[0002] The invention also relates to anodes comprising these anode materials and to 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: telephones and portable computers, portable tools, autonomous sensors) or for the traction of electric vehicles would have a long lifespan, would be capable of storing both large quantities of energy and power, could operate in a very wide temperature range and would not present risks of overheating or explosion.

[0005] Currently, these electrical devices are powered primarily by lithium-ion batteries, which have the best energy density among the various storage technologies available. There are different electrode architectures and chemical compositions for producing lithium-ion batteries. The manufacturing processes for lithium-ion batteries are presented 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 / Plénum 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 capacity of the electrodes in Ah or mAh multiplied by the operating voltage of the cell. This operating voltage is the difference between the insertion potentials of lithium in the anodes and cathodes.

[0007] Among the anode materials frequently used in such devices are mixed oxides of lithium and titanium (Li4Ti50i2) or mixed oxides of titanium and niobium, such as for example the mixed oxide of formula TiNb2O7 called TNO. As illustrated for example in application EP3379613, mixed oxides of niobium and Titanium are particularly interesting because they have a very high theoretical capacity per unit mass. Thus, the mixed composite of monoclinic structure TiNb2O7 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 having 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 which is as small as possible.

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

[0010] - high mass 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) for avoid the formation of lithium dendrites, particularly during rapid recharge phases;

[0012] - a loss of capacity depending on the number of charge / discharge cycles which is as small as possible to ensure prolonged performance over time Statement 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 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.

[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 of between 2 nm and 100 nm, preferably between 2 nm and 60 nm.

[0020] Advantageously, the aggregates of primary nanoparticles of the 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 oxide of titanium, niobium and lanthanum has a specific surface area of ​​between 10 m2 / g and 80 m2 / g, preferably between 25 m2 / g and 50 m2 / g.

[0022] The invention also relates to an anode active 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 a device for storing or producing electrical energy comprising at least one anode as described above, the device for storing or producing electrical energy preferably being 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 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.

[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 FIGURES

[0030] [Fig.l] represents scanning electron microscope images of the powders according to: - example A (a - top): TiNb2O7 - TNO - example B (b - bottom): Ti0j95La0j05Nb2O7 'TNO 0.05 La'

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

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

[0033] [Fig.4] represents the cycling curves (charge and discharge) E(V) vs Li+ / Li as a function of the specific capacity Cs (mA.h / g) at different C-Rates (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 curves (charge and discharge) E(V) vs Li+ / Li as a function of the specific capacity Cs (mA.h / g) at different C-Rates (C and C / 5) of the electrodes obtained with the Ti0j95La0j05Nb2O7 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 capacity Cs (mA.h / g) at C / 5:

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

[0037] - for the anode of the half-battery facing lithium with TNO doped with Cerium ('TNO X Ce') as a function of the dopant fraction 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 with respect to the first cycle for the half-cells with TNO and TNO doped at 5% (x=0.05) with lanthanum, at 10% (x=0.1) with germanium and at 5% (x=0.05) with cerium according to the examples AD 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. The term "nanoparticle" means any particle or object of nanometric size having at least one of its dimensions less than or equal to 400 nm.

[0040] By "ionic liquid" is meant any liquid salt, differing from all molten salts by a melting temperature 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 "ionic liquids at room temperature".

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

[0042] By “mesoporous” materials is meant any solid which has within its structure pores called “mesopores” having 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 that adopted by IUP AC (International Union for Pure and Applied Chemistry), which is a reference for those skilled in the art. The term "nanopore" is therefore not used here, even if the mesopores as defined above have nanometric dimensions within the meaning of the definition of nanoparticles, knowing that pores smaller than mesopores are called "micropores" by those skilled in the art.

[0043] A presentation of the concepts of porosity (and the terminology just 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”, treatise Analysis and Characterization, booklet P 1050; this article also describes the techniques for characterizing porosity, in particular the BET method.

[0044] For the purposes of the present invention, the term "porous layer" means a layer which has pores. The term "mesoporous layer" means a layer which has mesopores. In these layers, the pores and mesopores contribute significantly to the total pore volume; this fact is translated by the expression "Porous / mesoporous layer with porosity greater than X% by volume" used in the present 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 which can be determined by transmission electron microscopy. An aggregate of aggregated primary nanoparticles can normally be destroyed (i.e. reduced to primary particles) in suspension in a liquid phase by any suitable means, in particular under the effect of 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 when charging the battery. When discharging, the same electrode no longer has an anode function.

[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 in mol%. Thus if x = 0.05, this means that the titanium in the compound of formula (I) is substituted at 5 mol% by lanthanum. Mixed oxide of titanium, niobium and lanthanum

[0048] A first subject 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 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.

[0051] When 0.03 < x < 0.08, the mixed oxide of titanium, niobium and lanthanum 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 performance in terms of charge and discharge capacity similar to that of the material not doped with lanthanum but has better resistance to aging than the material not doped with lanthanum.

[0052] When x < 0.03, the doping rate of Lanthanum is not sufficient and the aging performance of the mixed oxide of titanium, niobium and lanthanum 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 material not doped with lanthanum.

[0053] When x > 0.08, the performance in terms of charge and discharge capacity of the mixed oxide of titanium, niobium and lanthanum 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 material not doped with lanthanum.

[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 embodiments, the mixed oxide of titanium, niobium and lanthanum can be preloaded with lithium in order 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 oxide of titanium, niobium and lanthanum of formula (I) may not comprise element M2. This is the oxide of formula (I) in which z=0.

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

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

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

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

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

[0062] Thus, at a degree of substitution x of Ti equal to 0.03 < x < 0.08, the aging performance of the mixed oxide of titanium, niobium and lanthanum 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 an aging resistance similar to the undoped material (TNO).

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

[0066] By aging performance or aging resistance, it is understood the evaluation of the capacity retention as a function of the number of cycles of the oxide of formula (I) when it is 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 compared to another oxide is improved, this means that the capacity retention as a function of the number of cycles decreases more quickly for the reference oxide than for the oxide of formula (I).

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

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

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

[0070] Generally speaking, TNO (TiNb2O7) type compositions have 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 in size.

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

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

[0073] To best optimize the volumetric energy density of lithium ion batteries produced with these conventional manufacturing processes, it can be very useful to reduce the porosity of the electrodes. This reduction in porosity, in other words the increase in 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 size distribution of the particles, it is possible to achieve a density of approximately 70%. An electrode having 30% porosity, containing conductive fillers and impregnated with an electrolyte conducting lithium ions will have a volumetric energy density approximately 35% higher than the same electrode with 50% porosity consisting of particles monodisperse in size.

[0075] Although it makes it possible to increase the energy density of the electrodes, this size distribution of the particles of active material is not without problems. Particles of different sizes in an electrode will have different capacities 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 under current demand, the local charge states between particles will be balanced again, but during these transient phases, the local imbalances can lead to particles being locally stressed outside their stable voltage ranges. These imbalances in local charge states will be all the more pronounced as the current densities are high.These imbalances therefore induce losses in cycling performance, safety risks and a limitation of the power of the battery cell.

[0076] These effects of the size distribution of active material particles 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 particle 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 generally have a size between 5 pm and 15 pm. The contact between two neighboring particles is essentially point-like, the particles being linked 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 anode active material can be implemented from an ink as described above.

[0081] The active anode material may also be implemented as described above but by additionally carrying out a heat treatment step making it possible to eliminate any organic residue in order to obtain a porous, preferably mesoporous, anode having high porosity, free of binder, where appropriate free of any additional electronic conductor, whether additional conductive fillers or a conductive material deposited on and inside 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 aggregates of primary nanoparticles having an average diameter D50 of 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 of 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 may have an average diameter D50 of between 10 nm and 20 pm, preferably between 20 nm and 10 pm.

[0086] Particle size 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 multiplies the exchange surfaces, and consequently, the power of the battery. Thus, it may be useful to have a mixed oxide of titanium, niobium and lanthanum having 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 oxide of titanium, niobium and lanthanum of formula fl)

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

[0092] It is known that TNO (TiNb2O7) type particles can be synthesized by hydrothermal means, with a dispersed size between about 50 nm and about 300 nm; however, it is difficult to control this size, and the dispersion is wide. This synthesis leads to amorphous particles which must then be crystallized by a high-temperature heat treatment, for example around 1000 °C for about 30 minutes. During this crystallization, the particles can grow in an uncontrolled manner, which widens the size dispersion. 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, it is preferred to use 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. Such nanoparticles can be obtained by different methods.

[0094] According to one method, salts, complexes or alcoholates (such as ethanolates) of the cations of metallic elements entering into the composition of the desired phase are mixed to obtain a perfectly homogenized distribution at the atomic scale, and polymers are used to fix this distribution of the molecules, ions or complexes comprising the metallic element. These polymers are then eliminated by heat treatment and leave only the inorganic constituents at the atomic scale for which a simple calcination at relatively low temperature will make it possible to obtain the desired phase, crystallized, at the nanoparticle scale. Organic materials capable of degassing strongly during the heat treatment phases can be added, which will contribute to obtaining mesoporous agglomerates.

[0095] An example for 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 by an organic molecule (such as citric acid or EDTA (ethylene diamine tetra acetate)) 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 diluted cations. Subsequently, the polymer and the complexing organic molecule are removed by pyrolysis, leading to the formation of the targeted inorganic oxides. Calcination at about 800 °C makes it possible to obtain crystallized nanoparticles. The process makes it possible to adjust the particle size, which decreases when the concentration of cations in the polymer matrix decreases. Active anode material

[0096] A second subject 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 those 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 incorporated into inks as described above.

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

[0102] The method for obtaining the anode can make it possible to obtain an anode devoid 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 A1, a layer of an electronically conductive material may be deposited on the surface of the particles of the anode active 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 may 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 provide a current collector. Any substrate capable of collecting electric current may be used, such as a metal substrate. The anode current collector may be: Mo, Cu, Ni, alloys based on the aforementioned elements, 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 device for storing or producing electrical energy may be a capacitor, supercapacitor, lithium-ion hybrid supercapacitor, photovoltaic cell, photoelectrochemical cell, lithium-ion cell or 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 produced with very different powers. In particular, the batteries can be lithium ion microbatteries, which excel in their high power, which opens up numerous uses for them on electronic cards, in electronic devices, and in particular 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 may be lithium ion batteries. They are of particular interest in the form of high-power batteries, particularly for use in electric vehicles.

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

[0113] The cathode material may be any material known to those skilled in the art. For example, LiCoPO4; LiMnij5Nio,504; LiFexCoi XPO4 (where 0 < x < 1); LiNii / XCoi / y Mni / Z02 with x+y+z = 10; Liij2Nio,i3Mnoj54Cooji302; 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; LiNio,8Co0,i5Alo,o502; 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] As an 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 have 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 comprise a separator, an electrical insulator. Oxides of the type A12O3, ZrO2, SiO2, or even phosphates or borates may be used.

[0119] The electrolyte is preferably a lithium ion-carrying phase selected 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-methyl-pyrrolidinium 4,5-dicyano-2-(trifluoromethyl)imidazole (Pyrl4TDI) and containing lithium salts of the LiTDI type,

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

[0128] The lithium ion carrier phase may be as described in application WO2021 / 220174 A1 or WO 2023 / 275779 A1

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

[0130] Another subject 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 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.

[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 oxide of titanium, niobium and lanthanum, the active anode 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 X-ray diffraction:

[0137] The powders resulting from the heat treatment at 800°C are analyzed by X-ray diffraction. The indexed peaks are compared to the indexed peaks of the 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 particles are determined by scanning electron microscope and transmission electron microscope.

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

[0141] A formulation of TiNb2O7 nanoparticle agglomerates was 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 mixture of ethoxides 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 mixture of alkoxides was introduced with vigorous stirring into the citric acid / ethylene glycol solution at room temperature. The reaction mixture is stirred for one hour at 90°C then at 110°C overnight, which results in the solution gelling (obtaining a very viscous resin).

[0144] The gel is then extracted to be placed in an alumina crucible. The crucibles are placed in a heating chamber at 250°C for 12 hours. This heating step will eliminate the excess ethylene glycol and activate the esterification reactions. The product is then calcined at 600°C for 1 hour to eliminate a large part of the organics.

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

[0146] The powder is in the form of micrometric-sized aggregates made up of nanoparticles (elementary size of 20 nm) - see [Fig.l](a) (SEM observations) and [Fig.2](a) (MET observations).

[0147] The nanoparticles are crystallized in the space group I2 / m JCPDS: 39-1407 in the form of 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 TiNb207 nanoparticle agglomerates was synthesized from the following precursors: Ti(OC2H5)4, Nb(OC2H5)4 and La(NO3)3, 6H20.

[0150] The procedure is identical to that of example A with the exception of the preparation of the mixture of precursors respecting the stoichiometry of the targeted 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 (elementary size of 20 nm) - see [Fig.l](b) (SEM observations) and [Fig.2](b) (MET observations).

[0152] A size distribution was calculated from TEM observations on a total of 63 particles ([Fig.3]): the average 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 in the form of 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') - outside the 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 targeted 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 rate, a single crystalline phase corresponding to TNO crystallized according to the monoclinic phase described above is obtained.

[0159] Examples D - Cerium-doped TNO ('TNO X Ce') - outside the 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 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 targeted 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 the doping rates of 1% (x=0.01) and 5% (x=0.05). For the rate of doping of 50% (x=0.5), a different crystalline phase is obtained.

[0163] 3. Electrochemical characterization of materials:

[0164] 3.1. Preparation of button 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 conduction electronics

[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 on 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 at least 20 min to evaporate the solvent. It is then calendered under a pressure of 3 MPa and then cut into 14 mm diameter discs.

[0171] The electrodes obtained are left to dry overnight at 80°C under vacuum before being cycled at room temperature against a lithium metal disc with a polypropylene polymer membrane (Celgard®3501 from CELGARD) as a separator and LiPF6 as 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 rates for the anodes of the cell with TNO and the cell with Tio^Lao^MhOv (x=0.05) are shown respectively in Figures 4 and 5.

[0174] The charge and discharge curves have similar shapes.

[0175] Figures 6 and 7 respectively represent the cycling curves at C / 5: - for the anode of the half-cell facing lithium with TNO doped with Germanium ('TNO X Ge') depending on the fraction of dopant x; - for the anode of the half-cell facing lithium with TNO doped with Cerium ('TNO X Ce') depending on the fraction of dopant 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] [Tableauxl] 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, TNO doped with 10% Germanium, with 5% Cerium, and with 5% Lanthanum are cycled at IC for 146, 98, 98 and 159 cycles respectively.

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

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

[0183] The Ti0j95La0j05Nb2O7 powder has physicochemical characteristics very close to the undoped material.

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

[0185] - does not significantly change the mass capacity

[0186] - does not influence 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

Claims

1. Mixed oxide of titanium, niobium and lanthanum of formula (I): LiwTi, ^asNb2 yM'yO- ZM-Z (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<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 in which y=0

4. Mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims of formula Tii xLaxNb2O7 (Ia) 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 aggregates of primary nanoparticles have an average diameter D50 of 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. An anode active material comprising a mixed oxide of titanium, niobium and lanthanum according to any one of the preceding claims.

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

10. Device for storing or producing electrical energy comprising at least one anode according to claim 9, the device for storing or producing electrical energy preferably being 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 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. to improve the aging resistance of said oxide used as an active anode material in an energy storage or production device.

Images