EP2926392A1

EP2926392A1 - Use of a silica-based powder

Info

Publication number: EP2926392A1
Application number: EP13824015.5A
Authority: EP
Inventors: Caroline Levy; Nabil Nahas; 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: 2012-11-30
Filing date: 2013-11-29
Publication date: 2015-10-07
Also published as: FR2999019A1; WO2014083545A1; JP2016503570A; KR20150091359A; CN104956517A; US20150303430A1

Abstract

The invention relates to the use of a ceramic-oxide powder for the production of a separator element for a lithium-ion battery, said ceramic-oxide powder having the following chemical composition, in percentages on the basis of the weight of the ceramic oxides, making up a total of 100 %: SiO₂ > 85 %, Al₂O₃ < 10 %, ZrO₂ < 10 %, other ceramic oxides < 5 %; said ceramic-oxide powder having a specific surface area of less than 40 m²/g and more than 5 m²/g; said oxide powder having a sphericity index of more than 0.8.

Description

Use of a silica-based powder

Technical area

The invention relates to a new use of a silica-based powder, namely to a use for making a separating element of a lithium-ion battery. The invention also relates to a separation element thus obtained and to a lithium-ion battery incorporating such a separating element.

State of the art

Batteries are commonly used as energy sources, especially in portable electronic devices (phones, computers, cameras and cameras), but also in electric vehicles. Among the batteries, mention may in particular be made of lithium-ion batteries. These batteries are generally composed of an electrolyte, an anode and a cathode, the two electrodes being physically separated from one another in order to avoid any short circuit. The separation barrier of the anode and the cathode is made with one or more separating elements, conventionally a separator, optionally coated with a separator coating, or an electrode coating applied to one or both electrodes. . US 2012/015232, US 2007/117025, US 2012/094184 describe examples of separation barriers.

The separation barrier must have high ion permeability, good mechanical strength, and high stability with respect to the products used in the battery, particularly the electrolyte. The separator is generally composed of one or more polymer layers, the total thickness of which is typically from a few microns to a few tens of microns. One or more of the layers of the separator may also comprise particles of an inorganic material, for example alumina or silica, as described for example in US 6,627,346. These inorganic particles are added either in coating on the surface of the separator or in the form of filler in the polymer constituting one or more layers of the separator, in particular in order to improve the mechanical strength of the separator under conditions of high temperatures (especially in the case of a battery runaway) or shocks, especially in large volume batteries, composed for example of several cells, or requiring high energy densities. However, when the separator comprises silica, its resistance to corrosion by the electrolyte can be reduced, which limits the life of the lithium-ion battery.

There is therefore a need for a lithium-ion battery having a separation element comprising silica and having a longer life. An object of the invention is to satisfy, at least partially, this need. Summary of the invention

According to the invention, this object is achieved by the use, for the manufacture of a separation element of a lithium-ion battery, of a ceramic oxide powder having the following chemical analysis, in percentages on the basis of the mass of ceramic oxides and for a total of 100%:

Si0 ₂ > 85%

A1 ₂ 0 ₃ <10%

Zr0 ₂ <10%

other ceramic oxides <5%. This process is remarkable in that said oxide powder has a specific surface area (preferably measured by the BET method) of less than 40 m ² / g and greater than 5 m ² / g.

As will be seen in more detail in the remainder of the description, the inventors have discovered that such an oxide powder improves the resistance to corrosion by the electrolyte. In addition, they have observed that such an oxide powder improves the dispersibility of the oxides in the starting charge and the shaping of the separating element, and in particular of the separator.

Preferably, the oxide powder also comprises one, and preferably several, of the following optional characteristics:

The powder of oxides preferably has a humidity, measured after drying at 100 ° C. for 4 hours, less than 3%, less than 2%, preferably less than 1.5%, preferably less than 1%, of preferably less than 0.8%, preferably less than

0.5%), preferably less than 0.4%, or even less than 0.3%, or even less than 0.1%. Advantageously, the corrosion resistance is further improved.

The oxide powder has an SiO ₂ + Al ₂ O ₃ + ZrO _{2 content} greater than 90%, preferably greater than 93%, preferably greater than 95%, preferably greater than 97% o, or even greater than 98%, in percentages based on the mass of the oxides.

The oxide powder has an SiO ₂ content greater than 87%, preferably greater than 88%, even greater than 89% and / or less than 99.8%, or even less than 99%, or even less than 98%, or even less than 95%, in percentages based on the mass of the oxides.

The oxide powder has an A1 ₂ 0 _{3 content} greater than 0.05%, or even greater than 0.2%, even greater than 0.5%, or even greater than 1%, or even greater than 2%; , or even greater than 3% and / or less than 8%, preferably less than 6%, or even less than

5% o, in percentages on the basis of the mass of the oxides.

- The oxide powder has a Zr0 ₂ content greater than 0.05% or even greater than 0.5%), or even greater than 1%, or even greater than 2%, or even greater than 3%, or even greater than 4 % and / or less than 8%, preferably less than 6%, in percentages based on the weight of the oxides.

The oxide powder has a content of "other ceramic oxides" of less than 4%, preferably less than 3%, preferably less than 2%, preferably less than 1%, or even less than 0.5%; or even less than 0.1%, in percentages based on the weight of the oxides.

The sum Fe ₂ 0 ₃ + Na ₂ 0 + CaO + P ₂ 0 ₅ represents more than 80% or even more than 90% of the said "other ceramic oxides", in percentages on the basis of the weight of the oxides.

The oxide powder has a Fe ₂ O _{3 content of} less than 0.5%, preferably less than 0.3%, preferably less than 0.2 or less than 0.1%, in percentages on the basis of of the mass of the oxides.

- The oxide powder has a P ₂ 0 ₅ content of less than 0.5%, preferably less than 0.3%, preferably less than 0.2 or even less than 0.1%, in percentages on the basis of the mass of the oxides.

- The oxide powder has a metal iron content of less than 0.1%, or even less than 0.05%, or even less than 0.01%, or even less than 0.001%), in percentages on the basis of mass of the oxide powder.

The oxide powder has a free carbon content of less than 0.5%, preferably less than 0.1%, or even less than 0.05%, in percentages by weight on the basis of the mass of the powder of oxides.

The oxide powder has a silicon carbide content of less than 0.5%, preferably less than 0.1%, or even less than 0.05%, or even less than 0.01%, in percentages by weight on the base of the mass of the oxide powder. The oxide powder has a specific surface area of less than 30 m ² / g, preferably less than 20 m ² / g, preferably less than 15 m ² / g. The oxide powder has a sphericity index greater than 0.8, preferably greater than 0.85, or even greater than 0.9. Advantageously, the implementation of said powder is improved.

- Less than 10%, preferably less than 5%, preferably less than 1%, by weight of the silica of said oxide powder is crystallized, the complement being in an amorphous phase. In one embodiment, the silica of said oxide powder is substantially all in amorphous form.

- The relative density of said oxide powder is greater than 98% of the absolute density, or even greater than 99%, or even greater than 99.5% of the absolute density.

- The oxide powder has a percentile D ₉ 9 _i5 less than 10 μιη, preferably less than 8 μιη, preferably less than 5 μιη, more preferably less than 2μιη.

The oxide powder has a percentile D _{90 of} less than 8 μιη, preferably less than 5 μιη, preferably less than 2 μιη, more preferably less than 1 μιη.

The oxide powder has a percentile D _{50 of} less than 2 μιη, preferably less than 1 μιη, preferably less than 0.8 μιη, preferably less than 0.5 μιη and preferably greater than 0.05 μιη, preferably greater than 0.1 μιη.

- The oxide powder has a ratio (D9o-Dio) / D ₅₀ less than 10, or even less than 5.

- The oxide powder has a loose density greater than 0.2 g / cm ² and / or less than 1 g / cm ² .

In one embodiment, the surface of the oxide powder is functionalized, for example to render said powder hydrophobic, or to improve its dispersion in the polymer, for example by using a graft based on silane or siloxane or on hexamethyldisilazane.

The separating element may be in particular a separator and / or a separator film and / or a separator coating and / or an electrode coating of a device according to the invention, as described below.

The invention also relates to a device selected from a separator, a separator film forming part of a separator consisting of a superposition of several films, a separator coated with one or more separator coatings, an anode coated with a coating. electrode, and a cathode coated with an electrode coating,

- the separator (whether coated or not) or the separator film, and / or

- the separator liner and / or

- the electrode coating (generically "the separating element") having, after calcination at 500 ° C.

2 hours, the following chemical analysis, in percentages based on the mass of the ceramic oxides and for a total of 100%:

Si0 ₂ > 85%

A1 ₂ 0 ₃ <10%

Zr0 ₂ <10%

other ceramic oxides <5%,

and being remarkable in that it comprises particles of these oxides and that the specific surface area of the particles of these ceramic oxides is less than 40 m ² / g and greater than 5 m ² / g.

Such a separating element is described as a separation element "according to the invention".

The invention also relates to a lithium-ion battery comprising an anode and a cathode, generally "the electrodes", and a separation barrier disposed between the anode and the cathode, said separation barrier comprising a separator optionally comprising several separator films. and, optionally, one or more coatings applied on the separator and / or on the anode and / or on the cathode so as to separate the anode and the cathode, at least one separation element selected from the group formed by said separator, said separator film, and the separator and / or electrode coating (s) being a separating element according to the invention.

The invention also relates to a method of manufacturing a lithium-ion battery comprising an anode, a cathode and a separation barrier between the anode and the cathode, the separation barrier comprising a separator, optionally, one or more coatings. separator applied to the separator and optionally one or more coatings applied on the anode and / or on the cathode so as to separate the anode and the cathode, at least one separation element chosen from the group formed by the separator, a film said separator and the separator and / or electrode coating (s) being according to the invention.

Definitions

By "particle size" is meant the size of a particle conventionally given by a particle size distribution characterization performed with a laser granulometer. The laser granulometer used here is a Partica LA-950 from the company HORIBA.

The percentiles or "percentiles" 10 (D ₁₀ ), 50 (D ₅₀ ), 90 (D ₉₀ ) and 99.5 (D ₉ 9 ₁₅ ) are the particle sizes corresponding to the percentages, by weight, of 10%, 50%, 90% and 99.5%, respectively, on the cumulative particle size distribution curve of the powder particle sizes, 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 in mass have a size greater than D ₁₀ . Percentiles can be determined using a particle size distribution using a laser granulometer.

The "maximum particle size of a powder" is the 99.5 percentile (D ₉ 9 ₁₅ ) of said powder.

The sphericity index of a particle powder is the average sphericity index of the particles of said powder (arithmetic mean), the sphericity index of a particle being equal to the ratio between its smaller diameter and its larger diameter. All the known measurement methods can be envisaged, and in particular the laser particle size or an observation of photographic photos of the powder.

The "unpacked density" of an oxide powder can be measured after having filled a defined volume of this powder, without compacting said powder, by dividing the mass poured by said volume.

Unless otherwise indicated, an average is an arithmetic mean.

- Unless otherwise indicated, all percentages relating to the composition of a separating element are percentages by mass on the basis of the ceramic oxides, after calcination at 500 ° C for 2 hours, so as to eliminate the organic constituents.

Brief description of the figures

Other objects, aspects, properties and advantages of the present invention will become apparent in the light of the description and examples which follow and on examining the appended drawing in which FIG. 1 represents, in cross section, a portion of a battery according to the invention equipped with a separation barrier between the electrodes (in this case in the form of a separator).

detailed description

FIG. 1 represents a portion of a battery 2 constituted by a separation barrier 4, an anode 6, a current collector 12 at the anode, a cathode 8 and a current collector 10 at the cathode. The anode 6, the cathode 8 and the separation barrier 4 are immersed in the electrolyte, the current collectors 10 and 12 being in contact with the electrolyte. The anode 6 and the cathode 8 constitute the electrodes.

The material used as anode material is preferably selected from graphite, a titanate, preferably a lithium titanate, or a silicon-based compound selected from, Si, SiO _x , with 0 <x <2, said compound based on silicon which may optionally be mixed with a carbon compound, such as for example graphite. The material used as cathode material is preferably selected from LiCoO ₂ , LiMnO ₂ ,

LiMn ₂ 0 _4, LiFeP0 _4, LiNi0 _2, these materials may optionally contain one or more dopants, such as LiMnO ^ PC ^ Feo or Li i / ₃ Mni / ₃ Coi / ₂ 0 _3.

The electrolyte is preferably a solution comprising an organic solvent based on carbonates, esters and / or ethers, the solvent preferably being chosen from ethylene carbonate, propylene carbonate and butylene carbonate, and diethyl carbonate, solvent in which is dissolved a compound preferably selected from LiFP ₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , Li (SO ₂ CF ₃ ) ₂ , Li (SO ₂ C ₂ F ₅ ) ₂ , LiAlCl ₄ , LiBOB, and mixtures thereof.

The separation barrier 4 consists of a separator and, optionally,

- a separator coating extending over one or both large faces of the separator, preferably in (the) covering completely, and / or

an electrode coating extending over one or both of the electrodes, preferably the fully covering one or both of them.

According to the invention, at least one separating element, that is to say one element chosen from the separator (or a separator film), the separator coatings and the electrode coatings, preferably all the elements of the separator. separation constituting the barrier of separation, present (s), after calcination:

a composition such that, in percentages on the basis of the weight of the ceramic oxides and for a total of 100%:

Si0 ₂ > 85%

A1 ₂ 0 ₃ <10%

Zr0 ₂ <10%

Other ceramic oxides <5%,

a specific surface area of the particles of these oxides of less than 40 m ² / g and greater than 5 m ² / g. The specific surface area of the particles of these oxides can be easily evaluated by measuring, according to the BET method (Brunauer Emmet Teller) as described in Journal of American Chemical Society 60 (1938), pages 309 to 316, the specific surface area of the powder used. as raw material. The known methods for producing said separating element do not substantially modify the shape of the oxide particles when they are assembled to form said element.

The vast majority of commercially available powders having a chemical analysis in accordance with that of the powder used according to the invention and having a specific surface area of less than 40 m ² / g and greater than 5 m ² / g have a moisture content of less than 3% after drying. at 100 ° C for 4 hours. Moreover, the person skilled in the art knows how to reduce this humidity, in particular to a value of less than 3%. A heat treatment under air at a temperature of between 400 ° C. and 500 ° C., with a holding time at this temperature greater than 2 hours, is one of the means making it possible to reduce the humidity of the oxide powder. Another means consists in subjecting the oxide powder to a heat treatment in a vacuum, at a pressure of less than 10 ^-1 Pa, at a temperature of between 110 ° C. and 300 ° C., for a period of typically 5 hours. .

Moisture can be measured as described in the examples.

The open porosity of the separating element, in particular when the separating element is a separator, is preferably greater than 20%, preferably greater than 30%, preferably greater than 40%, preferably greater than 50%. %> and less than 90%>, preferably less than 80%), preferably less than 70%> of the volume of said separating element.

In general, a separating element according to the invention may in particular be manufactured according to a process according to which

A) a feedstock is prepared by adding an oxide powder as defined above,

B) said starting charge is shaped to form said separating member.

The starting charge preferably comprises more than 0.1%, preferably more than 1%, preferably more than 5%, preferably more than 10%, preferably more than 20%, and more than 40%. and less than 90%, or even less than 80%, or even less than 70%, of said oxide powder, in weight percent based on said feedstock.

The oxide powder may be agglomerated, for example in the form of granules, to promote its introduction into the feedstock.

The feedstock, in particular the feedstock used in the manufacture of a separator and / or a separator film, preferably comprises a polymer. The polymer is preferably selected from the group consisting of polyacrylonitriles, polyamides, polyesters, celluloses, and mixtures thereof, preferably selected from the group consisting of polyethylene terephthalate, fluoropolymers and polyolefins and mixtures thereof, preferably selected from the group consisting of polyethylene terephthalates, polytetrafluoroethylenes (or PTFE), polyvinylidene fluorides (or PVDF), polypropylenes, polyethylenes, polyoxypropylenes, and mixtures thereof

A separator can be manufactured according to any known technique of the state of the art, for example as described in US 6,627,346 or JP2000208123. In particular, the separator can be manufactured using a method comprising the following steps:

a) preparing a suspension by mixing polymers, optionally additives for generating the porosity, such as an oil and an oxide powder;

b) extruding the slurry to form a film at a temperature above the melting temperature of the polymer, generally greater than 20 ° C to 60 ° C at said temperature;

c) preferably, heat treating the extruded film so as to increase the crystallinity and orientation of the polymer;

d) creating the porosity in said extruded film, and optionally heat treatment; e) optionally, drying the porous film obtained.

In step c), the heat treatment temperature is a function of the nature of the polymer used. For example, for a polypropylene film, heat treatment at a temperature between 110 ° C and 160 ° C and applied for a time of between 3 seconds and 200 seconds is well suited.

In step d), the porosity may result, for example, from an extraction or removal of the additive. Other methods, for example a stretching method ("film stretching method" in English) are also possible.

The separator may consist of several superimposed porous films thus manufactured. These films can be prepared independently and hot-pressed. The number of films may typically be between 1 and 5. For example it may comprise three superimposed films.

Preferably, the separator comprises a separator film according to the invention which extends substantially in the center of said separator, in particular along a median plane of said separator.

The separator preferably has a thickness greater than 5 μιη and less than 100 μιη, or even less than 50 μιη, or even less than 30 μιη, or even less than 20 μιη.

In a preferred embodiment, the silica is distributed substantially uniformly in the volume of said separator.

A separator coating may be manufactured and applied to the separator according to any known prior art technique. In particular, a separator coating may be manufactured using a method comprising the following steps:

i- preparation of a slurry comprising the oxide powder, a solvent and a binder, ii- depositing said slip on the surface of the separator, according to all techniques known to those skilled in the art, for example screen printing, the "Doctor Blade" process, the strip casting, or slip casting, in English "slip" casting ", with a deposit thickness generally between 1 and 560 μιη, preferably between 2 and 10 μιη, iiii- drying.

In step i, the binder used may be in particular a resin, an ester, such as a polyethyl acrylate ester, a polyvinyl acetate, a polyethylene, a polypropylene, or a fluoropolymer such as polyfluoride. vinylidene (PVDF).

The solvent may be, for example, water, N-methyl-2-pyrrolidone (or NMP), acetone, xylene, or chloroform.

The slip may also contain agents for adjusting the viscosity, depending on the deposition process used. In one embodiment, the slip does not contain such agents.

The separator coating preferably has a thickness greater than Ι μιη, or even greater than or equal to 3μιη or even greater than or equal to 5μιη and less than 15μιη, or even less than ΙΟμιη, or even less than 8μιη.

In one embodiment, the separator, preferably according to the invention, comprises first and second major faces covered by first and second separator coatings according to the invention, respectively. A method identical to that described above for the manufacture of a separator coating may be used to fabricate and coat one or both electrodes with an electrode coating.

The electrode coating has a thickness greater than Ι μιη, or even greater than 3μιη, or even greater than 5μιη and preferably less than 15μιη, or even less than ΙΟμιη, or even less than 8μιη.

According to the invention, the oxide powder, consisting for the most part of silica particles, has a specific surface area of less than 40 m ² / g and greater than 5 m ² / g

Such powders are for example marketed by Saint-Gobain under the name of NS-950 and NS-980. Other silica powders can be adapted, for example silica powders from the silicon industry.

Examples

The following examples are provided for illustrative purposes and do not limit the invention. The chemical analysis was carried out on a powder calcined for 4 hours at 1000 ° C., by X-ray fluorescence with regard to the constituents whose content is greater than 0.5%, the content of the constituents present in an amount of less than 0, 5% was determined by AES-ICP ("Atomic Emission Spectoscopy-Inductively Coupled Plasma").

Measurement of the particle size of the powders and the 10, 50, 90 and 99.5 percentiles was carried out using a Partica LA-950 laser particle size analyzer from the company HORIBA.

The specific surface of a powder was calculated by the BET method (Brunauer Emmet Teller) as described in Journal of American Chemical Society 60 (1938), pages 309 to 316. The moisture of a powder was determined by the following method: we weigh a mass of sample and placed in a cup for 4 hours in the oven. After this time, the cup is removed from the oven and placed in a desiccator, containing for example a silica gel, so that the temperature of the powder contained in the cup decreases. The mass m ₂ of the sample after drying is determined, at the latest within 30 minutes after leaving the oven. The moisture content of the powder is then calculated to be 100. (mi-m ₂ ) / mi.

The corrosion resistance was measured by the following method: The powder to be tested is pre-dried in an oven for 2 days at 110 ° C. 3 grams of said powder are then introduced into a Teflon container.

Under an argon glove box, the preparation of the electrolyte which will be used to corrode the powder is carried out as follows:

25 g of lithium hexafluorophosphate LiFP ₆ ("> 99.99% Battery grade, marketed by Sigma-Aldrich) (LiFP ₆ is an electrolyte commonly used in lithium-ion batteries),

109 g of ethylene carbonate and

- 88.2 g of dimethyl carbonate

are introduced into an aluminum flask with a capacity of 300 ml. This mixture is stirred for 12 hours.

Always in a glove box, 15g of said mixture is introduced into the Teflon container containing the powder to be tested. The Teflon container is closed and placed in an oven at 75 ° C for 14 days to simulate the extreme conditions of a battery.

At the end of these 14 days, the sample is recovered and the liquid phase is separated from the solid phase by simple transfer. Then, the liquid phase is filtered through a 0.45 μιη filter to remove the fine powders from the electrolyte. 2mL of this filtrate is then recovered which is placed in a 50ml flask with also 2ml of hydrochloric acid (in solution at 30% by mass) for the ICP assay. The electrolyte is also passed in ICP measurement to serve as blank to the measurement.

The calibration range of the ICP is between 0 and 200ppm. The Si element is dosed for each of the powders tested. The smaller the amount of silicon found in the electrolyte, the more resistance the test powder has to the electrolyte.

The sphericity index was determined from powder images obtained using a scanning electron microscope. The sphericity indices of at least 500 particles were determined, then the arithmetic mean of said indices was calculated to determine the sphericity index of the powder.

The following powders were tested:

The powder of Comparative Example 1 is a powder used in the separators of the state of the art. It is an Aerosil 200 powder manufactured by the company Dégussa.

The powder of Comparative Example 2 is a powder used in the separators of the state of the art. This is a Cabosil CT-1111G powder manufactured by Cabot.

The powder of Example 3, intended to be used in a separating element according to the invention, is an NS-950 powder, sold by Saint-Gobain,

The powder of Example 4, intended to be used in a separating element according to the invention, is a NS-980 powder, sold by Saint-Gobain.

The following Table 1 summarizes the properties of the powders tested:

Table 1 The amounts of silicon element measured in the electrolyte after the corrosion resistance tests by the electrolyte are shown in Table 2 below:

Table 2

As shown by the results in Table 2, the silica powders of Examples 3 and 4, used in the separating elements according to the invention, surprisingly exhibit a corrosion resistance in the LiFP ₆ electrolyte which is much greater than that of the silica powders of Examples 1 and 2 used in the separation elements of the state of the art. The silica powder according to Example 3 is the most preferred powder of all.

As is now clear, the invention thus provides a means for improving the resistance of a separation member of a lithium-ion battery to corrosion by the electrolyte, thereby improving stability over time. and the performance of the battery. The oxide powders according to the invention used also have a lower rehydration capacity compared to that of the silica powders of the state of the art (fumed silica, precipitated silica). This ability to lower rehydration thus limits the degradation of the electrolyte, the formation of hydrofluoric acid and the generation of gas in the battery, and thus contributes to increasing the battery life. The ability to rehydrate is the opposite of the difference in moisture between a powder of oxides dried at 100 ° C for 4 hours and the same oxide powder after treatment for 96 hours in air at 35 ° C and 80 ° C. % humidity.

The ability to rehydrate the powders of the examples is shown in Table 3 below:

Table 3 Furthermore, the oxide powders according to the invention used have a greater flowability than the silica powders of the state of the art (fumed silica, precipitated silica). This superior flowability improves the handling and dispersibility, and by the same the implementation of these powders. Finally, surprisingly, the use of powders according to the invention having a sphericity index greater than 0.8 advantageously leads to a more homogeneous distribution of the particles of said powders in the polymer of the separator.

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

Claims

Use, for the manufacture of a separating element of a lithium-ion battery, of a ceramic oxide powder having the following chemical analysis, in percentages on the basis of the mass of the ceramic oxides and for a total of 100%:

Si0 ₂ > 85%

A1 ₂ 0 ₃ <10%

Zr0 ₂ <10%

other ceramic oxides <5%,

said ceramic oxide powder having a specific surface area of less than 40 m ² / g and greater than 5 m ² / g,

said oxide powder having a sphericity index greater than 0.8.

Use according to the preceding claim, wherein said specific surface area is less than 30 m ² / g.

Use according to the preceding claim, wherein said specific surface area is less than 15 m ² / g.

Use according to any one of the preceding claims, wherein said oxide powder has a humidity, measured after drying at 100 ° C for 4 hours, of less than 3%.

Use according to the preceding claim, wherein said moisture is less than 2%.

Use according to the preceding claim, wherein said moisture is less than 1%.

Use according to the preceding claim, wherein said moisture is less than 0.1%.

Use according to any one of the preceding claims, wherein the oxide powder has

a content of SiO ₂ + Al ₂ O ₃ + ZrO ₂ greater than 90%>, and / or

an Si0 ₂ content greater than 87%, and / or an AI ₂ O _{3 content} greater than 0.2% and less than 8%, and / or

- a Zr0 ₂ content greater than 1% and less than 8%, and / or

- a content of "other ceramic oxides" of less than 4%.

9. Use according to the preceding claim, wherein the oxide powder has

a content of SiO ₂ + Al ₂ O ₃ + ZrO ₂ greater than 95%, and / or

an Si0 ₂ content greater than 89%, and / or

- an AI ₂ O _{3 content} greater than 2% and less than 6%, and / or

- a Zr0 ₂ content greater than 3% and less than 6%, and / or

- a content of "other ceramic oxides" of less than 2%.

10

Use according to any one of the preceding claims, wherein less than 10% by weight of the silica of said oxide powder is crystallized.

12. Use according to any one of the preceding claims, wherein the oxide powder has a particle size distribution such that

- D ₉₀ <8 μιη, and / or

- D ₅₀ <2 μιη, and / or

- (D ₉ oD ₁₀ ) / D ₅ o <10.

Use according to the preceding claim, in which the oxide powder has a particle size distribution such that

- D ₉₀ <2 μιη, and / or

- D ₅₀ <0.5 μιη, and / or

- (D ₉ OD ₁₀ ) / D ₅ o 5. Lithium ion battery comprising a separation element obtained by a manufacturing method implementing a use according to any one of the preceding claims.

15. Battery according to the preceding claim, wherein the separating element is chosen from a separator, a separator film forming part of a separator consisting of a superposition of several films, a separator coated with one or more coatings. separator, and an electrode coating.