EP2655259A1

EP2655259A1 - Method for the production of an lmo product

Info

Publication number: EP2655259A1
Application number: EP11810691.3A
Authority: EP
Inventors: Caroline Levy; Samuel Marlin; Yves Boussant-Roux
Original assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Current assignee: Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Priority date: 2010-12-23
Filing date: 2011-12-22
Publication date: 2013-10-30
Also published as: WO2012085874A1; FR2969595A1; CN103402921B; US9695060B2; KR20130132530A; US20130323597A1; CN103402921A

Abstract

The present invention relates to a molten product comprising lithium-manganese spinel, optionally doped, with a spinel structure AB₂O₄, in which site A is occupied by lithium, site B is occupied by manganese, site B is optionally doped with an element B' and site A is optionally substoichiometric or superstoichiometric relative to site B, such that the product complies with formula Li_(1+x)Mn_(2-y)B'_yO₄ with -0.2 ≤ x ≤ 0.4 and 0 ≤ y ≤ 1, element B' being selected from aluminium, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc, gallium, calcium, niobium, yttrium, barium, silicon, boron, zirconium and mixtures thereof.

Description

Method of manufacturing an LMO product

Technical area

The invention relates to a novel product comprising lithium-manganese spinel, referred to as "LMO product" and a novel process for producing such a product.

State of the art

Classically known as "lithium manganese spinel", or "LMO", a material having an AB ₂ 0 ₄ spinel structure, where the site A is occupied by lithium, the site B by manganese, the site B being able to be doped with a B 'element, and the site A may have a sub-stoichiometry or an over-stoichiometry with respect to the site B so that the product respects the formula Li _{(1 + X)} Mn ₍₂ -y ₎ B'y0 ₄ with -0.20 <x <0.4 and 0 <y <1, the element B 'being chosen from aluminum, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc, gallium, calcium, niobium, yttrium, barium, silicon, boron, zirconium and mixtures thereof. The electroneutrality of said spinel structure product of formula Li _{(1 + X)} Mn _(2- y ₎ B'y0 ₄ is ensured by the oxygen content. LiMn ₂ 0 ₄ is a particular example of LMO.

The LMO is used in particular for the manufacture of cathodes of lithium-ion batteries. It is generally manufactured by the following methods:

co-precipitation / sol-gel,

- synthesis by solid-state sintering, or

- synthesis from precursors and pyrolysis.

These complex processes lead to a high cost.

There is therefore a need for a new process for manufacturing at low cost and in industrial quantities of LMO. The object of the invention is to satisfy this need.

Summary of the invention

According to the invention, this object is achieved by means of a product comprising or even consisting of LMO, called "LMO product", which is remarkable in that it is melted, that is to say that it is obtained by melting then solidification. Although the manufacture of fusion-solidification products is well known, it is the merit of the inventors to have discovered that, contrary to a prejudice, this technique makes it possible to manufacture LMO.

Advantageously, the product according to the invention can therefore be manufactured at reduced costs and in industrial quantities.

The product according to the invention is preferably an annealed product, that is to say having undergone a heat treatment after its solidification.

The content and nature of the LMO obtained depend in particular on the composition of the feedstock. A product according to the invention is however still polycrystalline.

In one embodiment of the invention, the molten product comprises an LMO content greater than 50%, excluding impurities, said LMO having molar contents li, b 'and m in lithium, dopant element and manganese respectively, such that, by putting x = (2.N / (m + b ')) -1 and y = 2.b' / (m + b '),

- x≥ -0.20, preferably x≥ -0.15, preferably x≥ -0.1, preferably x≥0 and x <0.4, preferably x <0.33, preferably x < 0.2, or even x <0.1, and

- 0 <y <1, preferably y <0.8, preferably y <0.6, preferably y <0.4, preferably y <0.3.

The variables x and y correspond to the atomic proportions x and y of the Li _{(1 + X)} Mn ₍ 2-y ₎ B'yO 4 structure of the lithium-manganese spinel, optionally doped with the product according to the invention.

The definition of the LMO rate of a product is given later in this description.

Preferably, a product according to the invention also comprises one, and preferably several, of the following optional characteristics:

The level of LMO, excluding impurities, is greater than 60%, preferably greater than 70%, preferably greater than 90%, preferably greater than 99%, more preferably greater than 99.9% or even 100%; ;

The complement to 100% of the LMO and impurities is preferably constituted, for more than 60%, more than 80%, more than 90%, more than 95%, more than 98%, more than 99%, even substantially 100 % by mass, constituents of LMO in other forms; Element B 'is a dopant of manganese chosen from the group formed by aluminum, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc, gallium and their mixtures. These dopants significantly improve the number of charge / discharge cycles that an electrode made from a product according to the invention can undergo and / or the electrical capacitance of said electrode;

The element B 'used is chosen from the group formed by aluminum, cobalt, nickel, chromium, iron and their mixtures;

- Preferably, the total mass content of impurities, expressed as oxides, is less than 1%, preferably less than 0.7%, preferably less than 0.4%, preferably less than 0.1% ;

In the preferred embodiment, the impurities are all elements other than lithium, element B ', manganese and combinations of these elements. In particular, the elements Na, K or even Al, Co, Ni, Cr, Fe, Mg, Ti, V, Cu, Zn, Ga, Ca, Nb, Y, Ba, Si can be found as impurities. B or Zr when the element B 'does not comprise, respectively, aluminum, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc, gallium, calcium, niobium, yttrium, barium, silicon, boron or zirconium;

- Preferably,

Na ₂ 0 <0.1%, preferably Na ₂ 0 <0.07%, preferably Na ₂ 0 <0.05%, and / or

- K ₂ 0 <0, 1%, preferably K ₂ 0 <0.07%, preferably K ₂ 0 <0.05%. Advantageously, these optional characteristics improve the electrical conductivity properties, making the products particularly suitable, after optional grinding, for the manufacture of cathodes for lithium-ion batteries.

In a particular embodiment, lithium-manganese spinel is not doped, and has the formula Li _{(1 + X)} Mn ₂ 0 ₄ . Preferably, the ratio (1 + x) / 2 is greater than 0.45, preferably greater than 0.48, preferably greater than 0.50, preferably greater than 0.51 and / or preferably less than 0, 57, preferably less than 0.56, preferably less than 0.54. Advantageously, the amount of energy stored in the battery is increased.

A product according to the invention may in particular be in the form of a particle. The particle size may in particular be greater than 0.01 μηη, or even greater than 0.1 μηη, or even greater than 0.5 μηη, or even greater than 1 μηη, or even greater than 10 μηη or 0.25 mm and / or less than 5 mm, or even less than 4 mm, or even less than 3 mm.

A particle according to the invention may in particular comprise more than 50%, more than 60%, more than 70%, more than 80%, more than 90%, or even substantially 100% by weight of melted product. The invention also relates to a powder comprising more than 90% by weight, or even more than 95% or even substantially 100% of particles according to the invention.

The median size of the powder is preferably greater than 0.4 μηη and / or less than 4 mm.

In a first particular embodiment, the median size of the powder is between 0.5 μηη and 5 μηη, preferably between 2 μηη and 4 μηη. In a second particular embodiment, the median size of the powder is between 5 μηη and 15 μηη, preferably between 7 μηη and 12 μηη. In a third particular embodiment, the median size of the powder is between 15 μηη and 35 μηη, preferably between 20 μηη and 30 μηη.

A product according to the invention may also be in the form of a block of which all the dimensions are preferably greater than 1 mm, preferably greater than 2 mm, preferably greater than 5 cm, more preferably greater than 15 cm. . Preferably a block has a mass greater than 200 g.

The invention also relates to a manufacturing method comprising the following steps:

a) mixture of raw materials so as to form a suitable starting charge to obtain, at the end of step c), a product comprising LMO, b) melting of the feedstock until obtaining a liquid mass, c) cooling until complete solidification of said liquid mass, so as to obtain a molten product,

d) optionally grinding said molten product,

e) preferably, heat treatment of the molten product at a bearing temperature between 500 ° C and 1540 ° C, and during a hold time greater than 30 minutes.

By simple adaptation of the composition of the feedstock, fusion-solidification processes followed by a heat treatment, thus make it possible to manufacture LMO products of different sizes and having a level of LMO, excluding impurities, greater than 50% preferably greater than 70%, preferably greater than 90%, more preferably greater than 99%, more preferably greater than 99.9% or even substantially 100%. Preferably, a manufacturing method according to the invention also comprises one, and preferably several, of the following optional characteristics:

In step b), the temperature at which the feedstock is melted is preferably greater than 1450.degree. C., preferably greater than 1480.degree. C., and / or preferably less than 1800.degree. 1700 ° C, and preferably below 1600 ° C, preferably below 1550 ° C,

- The method is adapted to lead to a product according to the invention;

At least one or all of the lithium, B 'and manganese elements are introduced in oxide form;

The compounds providing the elements lithium, B 'and manganese together represent more than 90%, preferably more than 99%, in percentages by weight, of the constituents of the feedstock. Preferably, these compounds, together with the impurities, represent 100% of the constituents of the feedstock;

The compounds providing the elements lithium, B 'and manganese are chosen from Li ₂ CO ₃ , Li ₂ O, MnO ₂ , MnO, Mn ₃ 0 ₄ , the carbonates of element B', the hydroxides of element B ', and the oxides of element B';

In a particular embodiment, oxide powders are used to supply the elements B 'and manganese, and a carbonate powder to provide the lithium element;

- In step b), we do not use a plasma torch nor a heat gun. In particular, an arc furnace or induction furnace is used. Advantageously, the productivity is improved. In addition, processes using a plasma torch or a heat gun generally do not allow the manufacture of melted particles, if there is fusion in the plasma torch or in the heat gun, larger than 200 microns, and at least greater than 500 microns.

In step b), melting is carried out in a crucible in a heat treatment furnace, preferably in an electric furnace, preferably in an oxygenated environment, for example in air.

The melted product according to the invention may be at the end of step c) in the form of particles smaller than 100 μηη. The grinding of said particles is then not necessary.

In a first embodiment, step c) comprises the following steps:

Ci) dispersion of the liquid mass in the form of liquid droplets, c ₂ ) solidification of these liquid droplets by contact with an oxygenated fluid, so as to obtain molten particles.

By simple adaptation of the composition of the feedstock, conventional dispersion processes, in particular by blowing or atomization, thus make it possible to manufacture, from a molten liquid mass, particles having an LMO content, excluding impurities. greater than 50%, preferably greater than 60%, more preferably greater than 70%, more preferably greater than 90%, more preferably greater than 99%, more preferably greater than 99.9%, even more preferably greater than 100%; %.

In the first embodiment, preferably, the manufacturing method further comprises one, and preferably more than one, of the optional features listed above and / or the following particular features:

- In step Ci) and / or in step c ₂ ), said liquid mass is brought into contact with an oxygenated fluid, preferably identical.

The oxygenated fluid is preferably a gas.

The oxygenated fluid preferably has an oxygen content of greater than 20% by volume.

- The dispersion and solidification steps are simultaneous.

- It maintains a contact between the droplets and an oxygenated fluid until complete solidification of said droplets.

In a second embodiment, step c) comprises the following steps:

Ci ') pouring the liquid mass into a mold;

c ₂ ') cooling solidification of the liquid mass cast in the mold until a block at least partially solidified;

c ₃ ') demolding the block.

In the second embodiment, preferably, the manufacturing method according to the invention also comprises one, and preferably several, of the optional characteristics listed above and / or the following particular characteristics:

In the step Ci ') and / or in the step c ₂ ') and / or after the step c ₃ '), the said liquid mass being solidified is brought into contact, directly or indirectly, with a fluid oxygenated, preferably having at least 20% oxygen, preferably a gas.

- One starts said contact immediately after demolding the block. - The said contact is maintained until complete solidification of the block.

The molten product according to the invention may be at the end of step c) in the form of a block or particles larger than 100 μηη. The molten product is then preferably milled so as to obtain a powder having a maximum size D _{99.5 of} less than 10 μηη, preferably less than 100 μηη, preferably less than 80 μηη, preferably less than 53 μηη, of preferably less than 30 μηη, preferably less than 10 μηη.

In optional step d), the melt is ground.

In step e), the molten particles are preferably annealed at a bearing temperature of between 500 ° C. and 1540 ° C. and during a holding time of greater than 30 minutes. Preferably, the bearing temperature is greater than 550 ° C, preferably greater than 600 ° C, preferably greater than 650 ° C, preferably greater than 700 ° C and / or preferably less than 1200 ° C, preferably lower at 1100 ° C, preferably below 1000 ° C, preferably below 900 ° C. A bearing temperature of 800 ° C is well suited.

Preferably, the dwell time is greater than 2 hours and / or less than 24 hours, preferably less than 15 hours, preferably less than 10 hours. A bearing temperature of 800 ° C, maintained for 4 hours is well suited.

More preferably, the melted particles are annealed under an atmosphere containing at least 20% by volume of oxygen, preferably in air, preferably at ambient pressure of about 1 bar.

The annealed melted particles can be crushed and / or undergo a granulometric selection operation depending on the intended applications, for example by sieving, in particular so that the particles obtained have a size greater than 1 μηη, or even greater than 10 μηη and / or less than 5 mm.

The annealed melted particles may also undergo an additional granulation or atomization step to form aggregates or agglomerates.

Whatever the embodiment considered, other phases than the LMO may be present, as well as impurities from the raw materials.

The invention also relates to a product that can be obtained by a process according to the invention. The invention also relates to the use of molten products according to the invention or manufactured or capable of being manufactured by a method according to the invention in the manufacture of cathodes for lithium-ion battery.

The invention finally relates to a cathode for lithium-ion battery and a battery comprising such a cathode comprising a melted product according to the invention or manufactured or likely to have been manufactured by a method according to the invention. The cathode may in particular be obtained by shaping a powder according to the invention.

Definitions

For a given LMO, there is generally an International Center for Diffraction Data (ICDD) sheet for identifying the angular domains of the diffraction peaks corresponding to said LMO. For example, ICDD sheet 00-054-0258 is that of LiMn ₂ 0 ₄ lithium-manganese spinel phase _. The main angular domain is one which, among these angular domains, corresponds to the peak or multiplet of higher intensity. If the ICDD record of an LMO does not exist, the LiMn ₂ 0 ₄ lithium-manganese ICDD record will be considered as the ICDD record of the LMO.

When attempting to evaluate the rate of an LMO from an X-ray diffraction pattern, the term "main peak" or "main multiplet" is conventionally referred to as the peak or multiplet that extends into the main angular domain of said LMO or in close proximity to said main angular domain.

The level of LMO excluding impurities, in%, is defined in a product according to formula (1) below:

T = 100 ^* (Α | _Μθ) / (A | _MO ⁺ secondary phase) (1)

OR

ALMO is the sum of the areas of the LMO phases, measured on an X-ray diffraction diagram of said product, for example obtained from a BRUKER D5000 diffractometer type apparatus provided with a copper DX tube, without deconvolution treatment. . The area of an LMO phase is that of its main diffraction peak or main diffraction multiplet;

- Secondary Aphases is the sum of the areas of the secondary phases, measured on the same diagram, without deconvolution treatment. The area of a secondary phase is that of its diffraction peak of higher non-superimposed intensity or diffraction multiplet of higher non-superimposed intensity. The secondary phases are the phases detectable by X-ray diffraction other than the LMO phases. Enter other, Li ₀ , ₄ Mn ₀ , 6O, or LiMnO ₂ , or Mn ₃ 0 ₄ , or MnO, or Mn ₂ 0 ₃ may be secondary phases identified on the X-ray diffraction pattern, particularly when the LMO is not not doped, that is to say when it does not contain element B '. A "non-superimposed" diffraction peak is a diffraction peak corresponding to a single phase (no overlap of two peaks corresponding to two different phases). Similarly, a diffraction multiplet "not superimposed" is a diffraction byte corresponding to a single phase.

"Particle" means a solid object whose size is less than 10 mm, preferably between 0.01 μηη and 5 mm. The "size" of a particle is the average of its largest dimension dM and its smallest dimension dm: (dM + dm) / 2. The size of a particle is classically evaluated by a particle size distribution characterization performed with a laser granulometer. The laser granulometer may be, for example, a Partica LA-950 from the company HORIBA.

The "sphericity" of the particle may be greater than 0.5, preferably 0.6, sphericity being defined as the ratio between its smallest dimension and its largest dimension.

By "block" is meant a solid object that is not a particle.

"Melted product" means a product obtained by solidification by cooling of a molten material.

A "molten material" is a liquid mass that may contain some solid particles, but not enough to structure the mass. To maintain its shape, a molten material must be contained in a container.

The percentiles or "percentiles" 10 (D ₁₀ ), 50 (D ₅₀ ), 90 (D ₉₀ ) are the particle sizes corresponding to the percentages, by weight, of 10%, 50% and 90%, respectively, on the cumulative particle size distribution of the powder particles, the particle sizes being ranked in ascending order. For example, 10% by weight of the particles of the powder have a size less than D ₁₀ and 90% of the particles by mass have a size greater than D ₁₀ . Percentiles can be determined using a particle size distribution using a laser granulometer.

The "minimum size of a powder" is the percentile (D ₁₀ ) of said powder.

The "50th percentile" (D ₅₀ ) of said powder is called the "median size of a powder". By "impurities" is meant the inevitable constituents introduced involuntarily and necessarily with the raw materials or resulting from reactions with these constituents. Impurities are not necessary constituents, but only tolerated.

Unless otherwise indicated, all the oxide contents of the products according to the invention are mass percentages expressed on the basis of the oxides.

"Containing a", "comprising a" or "containing a" means "having at least one", unless otherwise indicated.

detailed description

An exemplary method according to the invention is now described in detail.

In step a), a feedstock for producing a molten product according to the invention is formed from lithium compounds, optionally element B 'and manganese, especially in the form of oxides or carbonates or hydroxides or oxalates or nitrates, or precursors of the elements lithium, B 'and manganese. The composition of the feedstock can be adjusted by the addition of pure oxides or mixtures of oxides and / or precursors, in particular Li ₂ O, Li ₂ CO ₃ , oxide (s) of the element B ', carbonate (s) of the element B', hydroxide (s) of the element B ', Mn0 ₂ , MnO or Mn ₃ 0 ₄ . The use of oxides and / or carbonates and / or hydroxides and / or nitrates and / or oxalates improves the availability of oxygen necessary for the formation of LMO and its electroneutrality, and is therefore preferred .

The amounts of lithium, element B 'and manganese of the feedstock are found essentially in the manufactured melted product. Some of the constituents, for example manganese and / or lithium, vary depending on the melting conditions, can volatilize during the melting step. By his general knowledge, or by simple routine tests, a person skilled in the art knows how to adapt the quantity of these constituents in the starting charge according to the content he wishes to find in the melted products and the melting conditions. implemented.

The granulometries of the powders used can be those commonly encountered in the melting processes.

Preferably, no compound other than those providing the elements lithium, B 'and manganese, or any compound other than Li ₂ 0, Li ₂ CO ₃ , oxide (s) of the element B', carbonate (s) of the element B ', hydroxide (s) of element B', Mn0 ₂ , MnO or Mn ₃ 0 ₄ is deliberately introduced into the feedstock, the other elements present being thus impurities. In one embodiment, the sum of Li ₂ 0, Li ₂ CO ₃ , oxide (s) of element B ', carbonate (s) of element B', hydroxide (s) of element B ' , MnO ₂ , MnO or Mn ₃ 0 ₄ and their precursors represents more than 99% by weight of the feedstock.

To increase the content of LMO possibly doped in the molten product, it is preferable that the molar proportions of the elements lithium, B 'and manganese in the starting charge are close to those of the spinel LMO, possibly doped, which one wishes to manufacture .

Thus, it is preferable, in the starting charge, that the molar contents CM, C _B 'and C _M of the elements lithium, B' and manganese, respectively, in molar percentages on the basis of the sum of the contents d ,, C _B 'and C _M , respect the following conditions:

• kL (1 + x) / (2-y) <C, i / C _m <k ₂ . (1 + x) / (2-y) (2), and / or

• ki. (1 + x) / y <C _B 7 C _m <k ₂ . (1 + x) / y (3)

or

x and y can take the values defined above, in particular -0.20 <x <0.4 and

0 <y <1, and

ki is 0.8, preferably 0.9, and

k ₂ is 1, 2, preferably 1, 1.

Of course, these values of k-ι and k ₂ are those to be adopted under established operating conditions, that is to say outside of the transition phases between different compositions and outside the startup phases. Indeed, if the desired product involves a change in the composition of the feedstock relative to that used to manufacture the previous product, it is necessary to take into account the residues of the previous product in the oven. Those skilled in the art, however, know how to adapt the starting load accordingly.

Intimate mixing of the raw materials can be done in a mixer. This mixture is then poured into a melting furnace.

In step b), the feedstock is melted, preferably in an electric arc furnace. Electrofusion makes it possible to manufacture large quantities of melted product with interesting yields.

One can for example use a Herault type arc furnace comprising two electrodes and whose vessel has a diameter of about 0.8 m and can contain about 180 kg of molten liquid. Preferably, the energy is between 1300 and 1500 kWh / T. The voltage is for example close to 1 15 volts and the power of the order of 250 kW. But all known furnaces are conceivable, such as an induction furnace, a plasma furnace or other types of Heroult furnace, provided they allow to completely melt the starting charge. A melting furnace in electric furnace is also possible.

At the end of step b), the feedstock is in the form of a liquid mass, which may optionally contain some solid particles, but in an amount insufficient for them to structure said mass. By definition, to maintain its shape, a liquid mass must be contained in a container.

In a first embodiment, step c) consists of steps Ci) and c ₂ ) described above.

In step Ci), a stream of molten liquid, at a temperature preferably greater than 1450 ° C., preferably greater than 1480 ° C. and preferably less than 1800 ° C., preferably less than 1700 ° C., is dispersed in liquid droplets.

When the initial charge is adjusted to obtain an undoped LMO product, a stream of molten liquid, at a temperature preferably above 1450 ° C, preferably above 1480 ° C and preferably below 1600 ° C, preferably below 1550 ° C, is dispersed in liquid droplets. When the feedstock is adjusted to obtain a cobalt-containing LMO product as element B ', the temperature of the melt stream is preferably greater than 1580 ° C, preferably greater than 1590 ° C and less than 1590 ° C. 1650 ° C, preferably below 1630 ° C. When the feedstock is adjusted to produce an aluminum-containing LMO product as element B ', the temperature of the melt stream is preferably greater than 1580 ° C, and lower than 1630 ° C, preferably below 1620 ° C.

The dispersion can result from blowing through the net of the liquid mass. But any other method of atomizing a liquid mass, known to those skilled in the art, is possible.

In step c ₂ ), the liquid droplets are converted into solid particles by contact with an oxygenated fluid, preferably a gas, more preferably with air and / or steam. The oxygenated fluid preferably comprises at least 20% by volume of oxygen.

Preferably, the process is adapted so that, as soon as formed, the droplet of molten liquid is in contact with the oxygenated fluid. More preferably, the dispersion (step Ci)) and the solidification (step c ₂ )) are substantially simultaneous, the liquid mass being dispersed by an oxygenated fluid, preferably gaseous, able to cool and solidify this liquid.

Preferably, the contact with the oxygenated fluid is maintained at least until complete solidification of the particles.

Air blowing at room temperature is possible.

At the end of step c ₂ ), solid particles are obtained which have a size of between 0.01 μηη and 3 mm, or even between 0.01 μηη and 5 mm, depending on the dispersion conditions.

In a second embodiment, step c) consists of the steps Ci '), c ₂ ' and c ₃ ') described above.

In step Ci '), the liquid mass is cast in a mold capable of withstanding the bath of molten liquid. Preferably, graphite, cast iron, or as defined in US 3.993.1.19 molds will be used. In the case of an induction furnace, the turn is considered to constitute a mold. Casting is preferably carried out under air.

In step c ₂ '), the liquid mass cast in the mold is cooled until an at least partially solidified block is obtained.

Preferably, during solidification, the liquid mass is brought into contact with an oxygenated fluid, preferably gaseous, preferably with air. This contacting can be performed as soon as casting. However, it is preferable to start this contacting only after casting. For practical reasons, the contact with the oxygenated fluid preferably begins after demolding, preferably as soon as possible after demolding.

The oxygenated fluid preferably comprises at least 20% by volume of oxygen.

Preferably, the contact with the oxygenated fluid is maintained until complete solidification of the block.

In step c ₃ '), the block is demolded. To facilitate contacting the liquid mass with an oxygenated fluid, it is preferable to unmold the block as quickly as possible, if possible before complete solidification. The solidification then continues at step <¾ '). Preferably, the block is demolded as soon as it has sufficient rigidity to substantially retain its shape. Preferably, the block is removed as quickly as possible and the contact with the oxygenated fluid is then immediately begun.

Preferably, the demolding is carried out less than 20 minutes after the beginning of the solidification.

After complete solidification, a block capable of giving after steps d) and optionally e) a particle powder according to the invention is obtained.

In step d), the melted product obtained is crushed and / or ground so as to reduce the size of the pieces to be heat treated during the following step e). The powder of melted particles obtained at the end of step d) preferably has a maximum size D99 less than 1 μηη, preferably less than 100 μηη, preferably less than 80 μηη, preferably less than 53 μηη, preferably less than at 30 μηη, preferably less than 10 μηη.

All types of crushers and grinders can be used to reduce the size of pieces to be heat treated. Preferably, an air jet mill or a ball mill will be used.

In step e), the pieces obtained at the end of step c) and / or at the end of step d) are preferably introduced into an oven to undergo a heat treatment annealing. Advantageously, such annealing increases the level of LMO. It is possible to obtain LMO levels that are substantially equal to 100%, excluding impurities.

Preferably, the product intended to be heat-treated is in the form of a powder having a maximum size D _{99.5 of} less than 10 μηη, preferably less than 100 μηη, preferably less than 80 μηη, preferably less than 100 μηη. 53 μηη, preferably less than 30 μηη, preferably less than 10 μηη. The efficiency of the annealing heat treatment is advantageously improved.

The bearing temperature of the annealing treatment is preferably greater than 550 ° C., preferably greater than 600 ° C., preferably greater than 650 ° C., preferably greater than 700 ° C. and / or preferably less than 1200 ° C. preferably below 1100 ° C, preferably below 1000 ° C, preferably below 900 ° C. This temperature is preferably maintained for a period greater than 2 hours and / or less than 24 hours, preferably less than 15 hours, preferably less than 10 hours. An annealing treatment at a bearing temperature of 800 ° C, maintained for 4 hours is well suited. Preferably, the heat treatment of annealing is carried out under an atmosphere containing at least 20% by volume of oxygen, preferably in air, preferably at ambient pressure of about 1 bar.

The melted particles can be crushed after annealing. If necessary, a granulometric selection is then carried out, depending on the intended application.

The melted particles of LMO can undergo a granulation or atomization step, facilitating their implementation.

The melted LMO particles and / or the aggregates of said particles and / or the agglomerates of said particles may also be surface-coated, at least partially or completely, so as in particular to limit the dissolution of the manganese, in particular when they are used in a cathode for lithium-ion batteries. In an "aggregate", the association between the particles is stronger than in the case of an association in the form of agglomerates. For example, the particles may be chemically bonded to one another. The breakage of agglomerates into smaller agglomerates or particles is therefore easier than breaking aggregates into smaller aggregates or particles.

The coating materials used to coat the LMO particles and / or the aggregates of said particles and / or the agglomerates of said particles may in particular be chosen from the group consisting of Si0 ₂ , MgO, ZnO, CeO ₂ , ZrO ₂ , Al ₂ O ₃ , solid solutions Co ₃ O ₄ -Al ₂ O ₃ , and oxides comprising lithium, in particular optionally doped lithium phosphates such as LiFePO ₄ , optionally mixed oxides such as LiCoO ₂ or LiNi _0.8 Co _{0, 2} O _2, lithium titanates optionally doped as Li ₄ Ti ₅ 0i2, and LMO as _LiNi o ₅ Mn _{1 95} 0 _4. Preferably said coating material is selected from the group consisting of Zr0 ₂ , Al ₂ 0 ₃ , solid solutions Co ₃ 0 ₄ -Al ₂ O ₃ , and oxides comprising lithium.

The coating layer may have a thickness greater than 1 μηη, or even greater than 2 μηη, or even greater than 3 m and / or less than 10 μηη, or even less than 6 μηη.

The coating of the LMO particles can be carried out according to techniques known to those skilled in the art, for example by precipitation, impregnation and evaporation, or by sol-gel.

In one embodiment, an aggregate or an agglomerate of melted LMO particles has, between said LMO particles, from its core to its surface, a concentration gradient of a compound, in particular chosen from the group consisting of SiO ₂ , MgO, ZnO, Ce0 _2, Zr0 _2, Al ₂ 0 ₃ solid solutions C03O4-Al2O3, and the oxides containing lithium, such as lithium phosphate optionally doped as LiFeP0 _4, mixed oxides optionally doped as LiCo0 _2, or LiNi ₀ , 8Coo, 20 ₂ , lithium titanates possibly doped as Li ₄ Ti ₅ 0i ₂ , and LMOs such as LiNi ₅ O ₅ Mn ₁ , 9 ₅ 0 ₄ ,.

Such agglomerates and aggregates, generally called "core-shell", can be obtained by atomization ("spray drying" in English) of melted LMO particles and a solvent containing said compound or a precursor of said compound in solution and / or in suspension.

The melted product particles according to the invention may advantageously have various dimensions, the manufacturing process is not limited to obtaining submicron LMO powders. It is therefore perfectly suited to industrial manufacturing. In addition, the particles obtained can advantageously be used to manufacture a cathode for lithium-ion batteries.

Remarkably, the LMO products according to the invention behave differently from the LMO products manufactured by prior art, in particular as regards the evolution of the mesh parameter of the face-centered cubic crystal structure of said product as a function of the ratio (1 + x) / (2-y), especially when said ratio is between 0.45 and 0.6. The mesh parameter of a face-centered cubic crystal structure is equal to the length of the cube edge.

The mesh parameter can be determined by X-ray powder diffraction s with a maximum size of less than 40 μηη, by the Rietveld refinement technique with PANalytical's High Score Plus software. Acquisitions can be made with X'Pert Pro (Xcelerator copper-detector anticathode) from 10 ° to 125 ° in 2 °, a step of 0.017 ° and 100 seconds / step.

Examples

The following examples are provided for illustrative purposes and do not limit the invention. The melted products were manufactured in the following manner.

The following starting raw materials were first intimately mixed in a blender: - lithium carbonate powder Li ₂ C0 ₃ , the purity is greater than 99% by weight and the median size is less than 420 μηη;

- Powder Mn0 ₂ , whose purity is greater than 91% by weight and whose median size is about 45 μηη;

for Examples 6 and 7, a Co ₃ 0 ₄ powder whose purity is greater than 99% by weight and whose median size is between 5 and 7 μηη;

for example 8, an Al ₂ O ₃ alumina powder whose purity is greater than 99.7% by mass and whose median size is approximately 60 μηη.

For Examples 1 to 7, each of the starting feeds obtained, which has a mass of 4 kg, was poured into a Herault type arc melting furnace. It was then melted following a fusion with a voltage of 40 volts, a power of 16 kW, and an applied energy substantially equal to 1400 kWh / T, in order to melt the entire mixture completely and homogeneously.

For the product according to Example 1, when the melting was complete, the molten liquid was cast in air, in cast iron molds as defined in US Pat. No. 3,993,19 and such as the thickness of the casting equal to 5 mm. The temperature of the molten liquid measured during casting was 1495 ° C.

For the products according to Examples 2 to 7, when the melting was complete, the molten liquid was cast to form a net. The temperature of the molten liquid measured during casting was between 1490 ° C. and 1550 ° C. for the fusions of Examples 2 to 5 and between 1598 ° C. and 1630 ° C. for the fusions of Examples 6 and 7. Compressed dry air, at room temperature and at a pressure of 8 bar, breaks the net and disperses the molten liquid into droplets.

Blowing cools these droplets and freezes them in the form of melted particles. Depending on the blowing conditions, the melted particles may be spherical or not, hollow or solid. They have a size between 0.005 mm and 5 mm.

For Example 8, the starting charge of a mass of 75 grams was poured into an alumina crucible. The crucible was placed in a Nabertherm HT 16/17 electric furnace, and was then heated in the open air for 1 hour at 1540 ° C, the rate of rise in temperature being 300 ° C / h and the speed falling in temperature being 300 ° C / h. After cooling, a molten product is recovered in the crucible.

The melted product of Example 1 was then broken with the aid of a hammer so as to obtain a piece having the dimensions 10 × ¹⁰ × 4.8 mm ³ . The melted particles of Example 2 were then milled in an RS100 vibro-disc mill marketed by the Retsch company, and then sieved so as to recover the pass through the 106 μηη opening sieve.

The melted particles of Example 3 were then sieved so as to recover the pass on the sieve of opening 106 μηη, the between sieve 250 μηη - 500 μηη and the between sieve 2 mm - 5 mm.

The melted particles of Example 5 were then milled in a RS100 vibro-disc mill marketed by the Retsch company, and then sieved so as to recover the pass through the 53 μηη opening sieve.

The melted particles of Examples 4, 6 and 7 were then sieved so as to recover the pass through the sieve 53 μηη.

The melts of Examples 1 to 7 were heat-treated in an electric oven as follows: for each example, between 5 and 20 grams of product are placed in a Nabertherm HT 16/17 electric furnace in an alumina crucible. The oven is then heated to a temperature T with a rise speed of 300 ° C / h. The holding time at the temperature T is equal to t. The descent rate is 300 ° C / h. The heat treatment was carried out under an atmosphere of air at atmospheric pressure.

The chemical and phase determination analyzes of lithium-manganese spinel, possibly doped, were carried out on samples which, after grinding, had a median size of less than 40 μηη.

Chemical analysis was performed by X-ray fluorescence and Inductively Coupled Plasma or ICP for lithium oxide and manganese oxide.

The determination of the LMO content was carried out on the basis of the X-ray diffraction diagrams, acquired with a BRUKER D5000 diffractometer provided with a copper DX tube.

Using the EVA software (marketed by BRUKER) and after performing a continuous background subtraction (background 0.8), it is possible to measure the area A _L MO (without deconvolution treatment) of the main peak or main diffraction multiplier of the LMO and, for each of the secondary phases, the area A _ps (without deconvolution treatment) of the peak of greater non-superimposed intensity or the multiplet of higher intensity not superimposed. We can then calculate the total area A _pha ses secondary by the sum of the areas A _ps . The LMO rate is then calculated according to formula (1). Thus, if the LMO phase is the only phase present in the X-ray diffraction pattern, the LMO level is equal to 100%.

Thus, the product of Example 7, after undergoing annealing heat treatment at 800 ° C. for 4 hours, exhibits an X-ray diffraction pattern showing a principal peak of LiMn ₂ 0 ₄ in the angular range 2Θ between 17 , 5 ° and 19.5 ° and a peak of higher intensity for the secondary phase at Mn0 ₂ in the angular range 2Θ between 20.5 ° and 21.6 °. The LMO rate is 99.5%.

Tables 1 and 2 summarize the results obtained:

Table 1

These examples make it possible to demonstrate the effectiveness of the process according to the invention.

A comparison of the results of the annealing treatments of the product of Example 3 also shows that the heat treatment is more effective than the dimensions of the treated products are low.

As it is now clear, the process according to the invention makes it possible to manufacture in a simple and economical manner, in industrial quantities, products comprising large quantities of molten lithium-manganese spinel Li _{(1 + X)} Mn _(2- ₎ B ' _y 0 ₄ with -0.20 <x <0.4 and 0 <y <1, the element B' being selected from aluminum, cobalt, nickel, chromium, iron, magnesium , titanium, vanadium, copper, zinc, gallium, calcium, niobium, yttrium, barium, silicon, boron, zirconium and mixtures thereof.

In particular, this process makes it possible to manufacture particles whose lithium-manganese Li _{(1 + X)} Mn ₂ 0 ₄ spinel content with -0.20 <x <0.4, excluding impurities, is greater than 99%, greater than 99.9%, or even 100%. This process allows the manufacture of products containing lithium-manganese spinel including:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 7.60%, preferably greater than 8.04%, preferably greater than 8.47%, preferably greater than 9.32%, and or less than 12.82%, preferably less than 12.26%, preferably less than 1 1, 20%, or even less than 10.36%, and / or

the mass content of "Manganese expressed as MnO" is greater than 85.43%, preferably greater than 85.98%, preferably greater than 87.03%, or even greater than 87.95% and / or lower; at 92.25%, preferably less than 91.80%, preferably less than 91.36%, preferably less than 90.49%, and / or

the mass content of impurities is less than 2%, preferably less than 1%, preferably less than 0.7%, preferably less than 0.4%, preferably less than 0.1%.

In the case where element B 'is aluminum, this process makes it possible in particular to manufacture products containing aluminum-doped lithium-manganese spinel, of which:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 8.73%, preferably greater than 9.69%, preferably greater than 10.67% and / or less than 13.31%; and or

the mass content of "aluminum expressed as A1 ₂ 0 ₃ " is greater than 9.57% and / or less than 38.1%, preferably less than 29.61%, preferably less than 21.58%, preferably less than 14.00%, or even less than 10.36%, and / or

the mass content of "Manganese expressed as MnO" is greater than 48.67%, preferably greater than 51.92%, preferably greater than 60.51%, preferably greater than 68.61%, preferably greater than 75.38% or more than 76.27% and / or less than 81.58% and / or

In the case where the element B 'is cobalt, this process makes it possible in particular to manufacture products containing cobalt-doped lithium-manganese spinel, including:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 7.41%, preferably greater than 9.09%, preferably greater than 9.25% and / or less than 12.73%, and or

the mass content of "cobalt expressed as CoO" is greater than 13.44% and / or less than 47.49%, preferably less than 38.19%, preferably less than 28.79%, preferably less than 19,29%, or even less than 14,50%, and / or

the mass content of "Manganese expressed as MnO" is greater than 41.69%, preferably greater than 44.05%, preferably greater than 53.13%, preferably greater than 62.31%, preferably greater than 71, 58% or more than 72.09% and / or less than 77,80%, and / or

In the case where element B 'is nickel, this process makes it possible in particular to manufacture products containing nickel-doped lithium-manganese spinel, including:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 7.42%, preferably greater than 9.10%, preferably greater than 9.25% and / or less than 12.74%, and or

the mass content of "nickel expressed as NiO" is greater than 13.41% and / or less than 47.42%, preferably less than 38.12%, preferably less than 28.73%, preferably less than 19,25%, or even less than 14,47%, and / or the mass content of "Manganese expressed as MnO" is greater than 41.74%, preferably greater than 44.1%, preferably greater than 53.19%, preferably greater than 62.36%, preferably greater than 71, 61%, or even greater than 72, 11% and / or less than 77.83%, and / or

In the case where the element B 'is chromium, this process makes it possible in particular to manufacture products containing chromium-doped lithium-manganese spinel, of which:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 7.36%, preferably greater than 9.02%, preferably greater than 9.23% and / or less than 12.70%, and or

the mass content of "chromium expressed as Cr ₂ 0 ₃ " is greater than 13.61% and / or less than 47.85%, preferably less than 38.53%, preferably less than 29.09%; , preferably less than 19.52%, or even less than 14.69%, and / or

the mass content of "Manganese expressed as MnO" is greater than 41.42%, preferably greater than 43.75%, preferably greater than 52.84%, preferably greater than 62.05%, preferably greater than 71, 37% or more than 77,94% and / or less than 77,64%, and / or

In the case where element B 'is iron, this process makes it possible in particular to manufacture products containing iron-doped lithium-manganese spinel, of which:

the mass content of "Lithium expressed as Li ₂ 0" is greater than 7.18%, preferably greater than 8.82%, preferably greater than 9.16% and / or less than 12.62%; and or

the mass content of "iron expressed as Fe ₂ O ₃ " is greater than 14, 19% and / or less than 49.07%, preferably less than 39.69%, preferably less than 30.10%; , preferably less than 20.30%, or even less than 15.31%, and / or the mass content of "Manganese expressed as MnO" is greater than 40.50%, preferably greater than 42.73%, preferably greater than 51.84%, preferably greater than 61.16%, preferably greater than 70.68% or more than 71, 44% and / or less than 77.07%, and / or

The dimensions of these products can then be reduced, for example by grinding in the form of powders if their use requires it. These products can also be obtained directly in the form of particles.

Of course, the present invention is not limited to the described embodiments provided by way of illustrative and non-limiting examples.

In particular, the products according to the invention are not limited to particular shapes or dimensions.

Claims

1. A molten product comprising lithium-manganese spinel, optionally doped, of AB ₂ 0 ₄ spinel structure, in which the A site is occupied by lithium, the B site by manganese, the B site being dopable with a B 'element, and the site A may have sub-stoichiometry or superstoichiometry with respect to the B site so that the product is of the formula Li _{(1 + X)} Mn ₍ 2-y ₎ B'y0 ₄ with -0.20 < x <0.4 and 0 <y <1, the element B 'being chosen from aluminum, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc , gallium, calcium, niobium, yttrium, barium, silicon, boron, zirconium and their mixtures.

2. Melted product according to the preceding claim, wherein the element B 'is selected from aluminum, cobalt, nickel, chromium, iron, magnesium, titanium, vanadium, copper, zinc, gallium and their mixtures

3. Melted product according to the preceding claim, wherein the element B 'is selected from aluminum, cobalt, nickel, chromium, iron and mixtures thereof.

A molten product according to any one of the preceding claims, wherein

- x≥ -0.20 and x <0.4, and

- 0 <y <1.

5. Melted product according to the preceding claim, wherein x≥ -0,15 and / or x <0.33

6. The molten product according to the preceding claim, wherein x≥ -0.1 and / or x <0.2.

7. Melted product according to the preceding claim, wherein x≥ 0.

A molten product according to any one of the preceding claims, wherein y <0.8.

9. Melted product according to the preceding claim, wherein y <0.6

10. Melted product according to the preceding claim, wherein y <0.4.

1 1. Melted product according to the preceding claim, wherein y <0.2.

12. A molten product according to any one of the preceding claims, comprising an optionally doped lithium-manganese spinel content greater than 50%, excluding impurities.

13. Melted product according to the preceding claim, wherein the level of spinel lithium-manganese optionally doped, excluding impurities, is greater than 70%.

14. The molten product according to the preceding claim, wherein the level of lithium-manganese spinel optionally doped, excluding impurities, is greater than 90%.

15. Melted product according to the preceding claim, wherein the level of spinel of lithium-manganese optionally doped, excluding impurities, is greater than 99%.

16. The molten product according to the preceding claim, wherein the level of lithium-manganese spinel optionally doped, excluding impurities, is greater than 99.9%.

17. A molten product according to any one of the preceding claims, having the following chemical composition, in percentages by weight and for a total of 100%:

7.60% <lithium expressed as Li ₂ 0 <12.82%,

- 85.43% <manganese expressed as MnO <92.25%,

- impurities <2%.

18. A molten product according to any one of claims 1 to 16, having the following chemical composition, in percentages by weight and for a total of 100%:

- 8.73% <lithium expressed as Li ₂ 0 <13.31%,

48.67% <manganese expressed as MnO <81.58%,

9.57% <aluminum expressed as Al ₂ O ₃ <38.1 1%,

- impurities <2%.

19. A molten product according to any one of claims 1 to 16, having the following chemical composition, in percentages by weight and for a total of 100%:

7.41% <lithium expressed as Li ₂ 0 <12.73%,

41, 69% <manganese expressed as MnO <77.80%,

13.44% <cobalt expressed as CoO <47.49%,

- impurities <2%.

20. The molten product according to any one of claims 1 to 16, having the following chemical composition, in percentages by weight and for a total of 100%:

7.42% <lithium expressed as Li ₂ 0 <12.74%,

41, 74% <manganese expressed as MnO <77.83%,

13.41% <nickel expressed as NiO <47.42%,

- impurities <2%.

21. A molten product according to any one of claims 1 to 16, having the following chemical composition, in percentages by weight and for a total of 100%:

7.36% <lithium expressed as Li ₂ 0 <12.70%,

41, 42% <manganese expressed as MnO <77.64%,

13.61% <chromium expressed as Cr ₂ 0 ₃ <47.85%,

- impurities <2%.

22. A molten product according to any one of claims 1 to 16, having the following chemical composition, in percentages by weight and for a total of 100%:

7.18% <lithium expressed as Li ₂ 0 <12.62%,

- 40.50% <manganese expressed as MnO <77.07%,

14.19% <iron expressed as Fe ₂ O ₃ <49.07%,

- impurities <2%.

23. Particle powder in a melted product according to any one of the preceding claims, having a median size greater than 0.4 μηη and / or less than 4 mm.

24. Powder according to the preceding claim, having a median size between 0.5 μηη and 5 μηη.

25. Powder according to claim 23, having a median size of between 5 μηη and 15 μηη.

26. Powder according to claim 23, having a median size of between 15 μηη and 35 μηη.

27. Manufacturing process comprising the following steps: a) mixing raw materials so as to form a suitable starting feedstock to obtain, at the end of step c), a product according to any one of claims 1 to 22,

b) melting the feedstock to a liquid mass,

c) cooling until complete solidification of said liquid mass, so as to obtain a molten product,

d) optionally, grinding said molten product,

e) optionally, heat treatment of the molten product at a bearing temperature of between 500 ° C. and 1540 ° C., and during a hold time of greater than 30 minutes.

28. Method according to the preceding claim, comprising said step e).

29. Method according to the preceding claim, wherein the molten product is in the form of a powder having a maximum size of less than 53 μηη.

30. A method according to any one of the three immediately preceding claims, wherein in step e), the heat treatment is carried out at a plateau temperature of between 700 ° C and 900 ° C for a time of temperature plateau included between 2 and 10 o'clock.

31. A process according to the immediately preceding claim, wherein the heat treatment is carried out under an atmosphere containing at least 20% by volume of oxygen.

32. The method according to any of the five immediately preceding claims, wherein step c) comprises the following steps:

Ci) dispersion of the liquid mass in the form of liquid droplets,

c ₂ ) solidification of these liquid droplets by contact with an oxygenated fluid, so as to obtain molten particles,

or the following steps:

Ci ') pouring the liquid mass into a mold;

c ₃ ') demolding the block. Process according to the preceding claim, in which, in step Ci) and / or in step c ₂ ) and / or in step Ci ') and / or in step c ₂ ') and / or after step c ₃ '), said liquid mass is brought into contact with an oxygenated fluid.

34. Method according to the preceding claim, wherein said contact is maintained until complete solidification.

35. Process according to any one of the two immediately preceding claims, in which the dispersion stages Ci) and solidification stages c ₂ ) are simultaneous.

36. Process according to any one of claims 27 to 35, in which the compounds providing the elements lithium, B 'and manganese together represent more than 90%, in percentages by weight, of the constituents of the feedstock.

37. Process according to the preceding claim, the compounds providing the elements lithium, B 'and manganese together representing more than 99%, in percentages by weight, of the constituents of the feedstock.

38. Process according to the preceding claim, the compounds providing the elements lithium, B 'and manganese representing, together with the impurities, 100% of the constituents of the feedstock.

39. Process according to any one of claims 27 to 38, the compounds providing the elements lithium, B 'and manganese being selected from Li ₂ CO ₃ , Li ₂ O, MnO ₂ , MnO, Mn ₃ 0 ₄ , the carbonates of the element B ', the hydroxides of the element B', and the oxides of the element B '.

40. Process according to any one of claims 27 to 39, the molar contents d ,, C _b 'and C _m of the elements lithium, B' and manganese, respectively, in the starting charge in molar percentages on the basis of sum of the contents d ,, C _b 'and C _m , respecting the following conditions:

• kL (1 + x) / (2-y) <C, i / C _m <k ₂ . (1 + x) / (2-y) (2), and / or

• ki. (1 + x) / y <C _b C _m <k ₂ . (1 + x) / y (3)

where -0.20 <x <0.4 and 0 <y <1, where ki is 0.8, and k ₂ is equal to 1, 2.

Method according to the preceding claim, k-ι being equal to 0.9, and k ₂ being equal to 1, 1.

42. Product obtainable by a process according to any one of claims 27 to 41.

43. Cathode for lithium-ion batteries comprising a melted product according to any one of claims 1 to 22 or of a melted product obtained or obtainable by a process according to any one of claims 27 to 41, or manufactured to from a powder according to any one of claims 23 to 26.

44. Battery comprising a cathode according to the preceding claim.