WO2017125680A1

WO2017125680A1 - Titanium oxyhydroxide compound and method for producing same, and electrode and catalyst comprising same

Info

Publication number: WO2017125680A1
Application number: PCT/FR2017/050105
Authority: WO
Inventors: Jiwei MA; Ana-Gabriela PESTY; Damien Dambournet
Original assignee: Centre National De La Recherche Scientifique; Universite Pierre Et Marie Curie (Paris 6)
Priority date: 2016-01-21
Filing date: 2017-01-19
Publication date: 2017-07-27
Also published as: FR3047001B1; FR3047001A1

Abstract

The invention concerns a hydrated titanium oxyhydroxide compound, a composite material comprising same and an electrode and a catalyst comprising said hydrated titanium oxyhydroxide compound and said composite material. The invention also concerns a battery, in particular a lithium battery, comprising said electrode. It further concerns a method for producing said hydrated titanium oxyhydroxide compound and said composite material. The hydrated titanium oxyhydroxide compound according to the invention has the following formula I; TiO_x(OH)_y, nH₂O Formula 1 in which: - 1.15 ≤ x ≤ 1.55, and 0.9 ≤ y ≤ 1.70, and 0.1 ≤ n ≤ 1, preferably 0.3 ≤ n ≤ 0.5, and most preferably n = 0.41, and the compound has an ordered lepidocrocite local structure over a distance of up to 1 nm inclusive, as determined by analysis of the pair-distribution function (PDF) obtained by synchrotron diffraction, but has a disordered structure over a distance of more than 1 nm, revealed by X-ray diffraction. The invention is applicable in the field of energy storage and supply, in particular.

Description

TITANIUM OXY HYBRYXYBE COMPOUND AND MANUFACTURING METHOD THEREOF, ELECTRODE AND CATALYST COMPRISING SAME

The invention relates to a hydrated titanium oxyhydroxide compound, a composite material comprising it and an electrode and a catalyst comprising this hydrated titanium oxyhydroxide compound and this composite material. It also relates to a battery, in particular lithium, comprising this electrode. It also relates to a process for producing this hydrated titanium oxyhydroxide compound and this composite material.

At present, lithium batteries are being used more and more in many devices, in particular. because of their high storage capacity.

In these batteries titanium oxide (TiC ₂ ) has been proposed as a negative electrode material as an alternative to graphite.

Indeed, titanium oxide is a metal oxide which intercalates lithium ions at a potential of about 1 .7-1.8 V vs Li / Li ⁺ , in the stability zone of the éeetrolyte.

The first attempts to use TiO ₂ as anode material have been carried out with rutilate or anatase-rich microcrystalline titanium oxide, or TiO 2. (B),

However, these electrodes have moderate capacities with a maximum lithium intercalation of 0.5 Li / Ti for the anatase structure and Ti (¾ (B) and no activity for the rutile structure.

The research then turned to the use of titanium oxide nanomaterials, these nanomaterials having a higher specific surface area than microcrystalline titanium oxides and thus higher lithium intercalation kinetics.

Thus, Xiong et al., In Seif-improving anode for lithium-ion batteries based on amorphous to cubic phase transition in nanotubes, American Chemical Society, Journal of Physical Chemistry, C2012, 16, 3181-3187. then proposed to use nanotubes of amorphous titanium. However, these amorphous titanium nanotubes have the disadvantage of presenting, during the first discharge cycle, an irreversible phase transition. Indeed, the nanotubes of amorphous titanium then turn into crystalline crystalline titanium oxide nanotubes in the cubic phase,

Above all, the manufacturing process of these nanotubes is very difficult to transpose industrially and the reproducibility of the manufacture of electrodes having the desired properties is also very difficult to industrialize.

Borghols et al. Then proposed in "Lithium, serior in amorphous Ti0 ₂ nanoparticles", Journal of the Electrochemistry Society, 157 (5) A582-A58S (2010), to use nanoparticles, having a size of about 2 to 3 nm, amorphous titanium oxide as anode material for lithium batteries.

The authors recognize, however, the presence of about 5% of small crystalline domains mainly having the anatase structure. They also indicate that when the material they describe is used as anode in a lithium battery, the first discharge cycle shows a fraction of 2.4 Li ions per unit of formula TiC¾ but after this first cycle discharge, 1.9 Li ions per unit TiO _? . remain stored in the Ti <¾ so that in the other charge and discharge cycles, only 0.5 Li ions per Ti € unit are used. This means that this material is not usable industrially

In fact, the cathode is the active lithium reservoir. In the case of the material described in this article, the cathode must supply 2.4 active Li ions per unit of formula TiQz, to compensate for the lithium initially trapped at the anode.

From then on, it would be necessary to increase the mass of the cathode in an unthinking manner which would decrease the volume capacity of the battery.

In addition, there is a loss of performance between the first discharge cycle and subsequent cycles, as shown in Figure 4 (a) of this document.

The invention aims to provide a. titanium-based amorphous material which can be used as anode material for lithium or sodium batteries, having not only high electrochemical performances but also stable over a large number of cycles, without loss of drastic capacity between the first discharge cycle and the following, which, moreover, can be used without destabilize the electrolyte and which is compatible with different electrolytes, particularly aqueous.

In addition, the material of the invention can be synthesized by a simple method and at low temperature, that is to say at a temperature between 20 and 100 ° C.

For this purpose, the invention provides a hydrated titanium oxyhydroxide compound characterized in that it has the following formula 1:

TiO _x (OH) _ys n¾0

Formula I

in which ;

- 1, 15 <x <1.55,

- 0.9 <y <1, 70, and

- 0.1 <n <1, preferably 0.3 <n <0.5 and more preferably n = δ, 4L

and in that it has an orderly structure lepidocrocite over a distance of. up to 1 nxn inclusive as determined by the analysis of the pair distribution function (PDF) obtained by synchrotron diffraction but having a disordered structure at a distance greater than. 1 nm revealed by X-ray diffraction (Ray Cu a, 2 tetha: 10-80 ° C at a scanning speed 0.57min).

Preferably, the hydrated titanium hydroxide hydroxide according to the invention is characterized in that in formula I,

- x = 1, 35,

- y - 1, 30, and

- B = 0.4I.

The invention also proposes a composite material comprising carbon coated with the hydrated titanium oxyhydroxide compound of the invention in all its embodiments,

Preferably, in this composite material, the carbon is in the form of a carbon nanotube.

The invention also provides an electrode characterized in that it comprises a hydrated titanium oxyhydroxide according to the invention or a composite material according to the invention. The invention also proposes a battery characterized in that it comprises an electrode according to the invention.

The invention also provides a photo-catalyst characterized in that ^it comprises a hydrated titanium oxo-hydroxide of the invention is a composite material of the invention.

The invention also proposes a process for producing a hydrated titanium oxyhydroxide of the following formula I:

Formula I

in which ;

- 1, 15 <x <1, 55,

·· 0.9 <y <1.70, and

0.1 <n <0.1, preferably 0.3 <n <0.5, most preferably n ~

0.41

which has an ordered lepidocrocite structure over a distance of up to and including 1 nm as determined by the analysis of the pairwise distribution function (PDF) obtained by synchrotron diffraction but having a disordered structure at a distance greater than 1 nrn revealed by X-ray diffraction,

this method comprising the following steps;

a) dissolving a C¾ to C C alkoxide of titanium in a C₁ to Cs alcohol at a titanium alkoxide concentration of between 0.1 M inclusive and 1.8 M excluding, with stirring, and temperature between 10 and 3G ° C, limits included, b) hydrolysis of the solution obtained in step a) by adding water with stirring, at. temperature between 10 and 30 ° C, with a degree of hydrolysis H ^:::: ΩΗ2θ'ητ _ί between 1.1 1 inclusive el 7 excluded.

e) precipitating a compound of the desired formula, comprising water, at a temperature between 10 and 1.00 ° C inclusive for a period of between 1 hour and 48 hours, preferably a duration of 12 hours,

d) recovering the precipitate formed in step c),

e) washing with a C alcohol; at C _¾ the precipitate obtained in step d), and f) drying the washed precipitate obtained in step e) at 80 ° C for

10 hours, and g) opiionneliement. elimination of physisorbed water by heating at 100 ° C for 2 hours under primary viticum.

By primary vacuum is meant in the present text, a pressure less than 10 ° rnbar.

Preferably ₅ in the process according Γ invention:

in step a) the C 1 to C ₅ alkoxides of titanium / C ₁ to C ₅ alcohol are chosen from titanium / titanium oxide, isopropanol titanium isopropoxide and titanium / butanoic butoxide;

in step e) the alcohol in C; at C ₅ is ethanol.

Finally, the invention provides a method of manufacturing a composite material according to the invention.

This method comprises the following steps:

al) preparing a dispersion of nanotubes and / or nanoparticles of carbon having a concentration of nanotubes and / or carbon nanoparticles between 2.33 and 9.33 gL ^"1 , in a C 1 to C 6 alcohol,

a) introduction of a C -C alkoxide of titanium into the suspension obtained in step a1) and stirring at a temperature of between 10 and 30 ° C., the concentration of alkoxide in the suspension being between 0.1 1M included and 1.8M,

bj hydrolyzing the solution obtained in step a) by adding water with stirring, at a temperature of between 10 and 30 ° C, with a degree of hydrolysis H - »H · o /» Ti of between 1, 11 included and 7 excluded,

c) precipitating a compound of the desired formula, comprising water, at a temperature of between 10 and 100 ° C inclusive for a period of from 1 hour to 48 hours, preferably 12 hours,

d) recovering the precipitate formed in step c),

e) washing with a C ₅ -C ₈ alcohol the precipitate obtained in step d), and 1) drying the washed precipitate obtained in step e) at 80 ° C. for

10 hours, and

g) optional removal of physisorbed water by heating at 100 ° C for 2 hours under primary vacuum. By primary vacuum is meant, in the present text, a pressure less than 1CF ³ œhar.

Preferably, in the process according to the invention:

in step a), the C 1 to C 5 alkoxy pairs of titanium / C 1 to C 5 alcohol are selected from the group consisting of titanium ethoxide / anol, isopropanol / isopropanol and titanium dioxide / hutanol,

in step e) the C 1 to C ₅ alcohol is the hexane

Still preferably, in step a) the C ₅ to C ₅ alcohol is isopropanol.

Most preferably, in the method of manufacturing the composite material of the invention, in step a) the dispersion is a dispersion of carbon nanotubes and the concentration of carbon nanotubes of this suspension is between 5 and 6 g. L ^A.

ί / invention will be better understood and other features and advantages thereof will appear more clearly in the light of the description which follows and which is made with reference to the figures in which:

FIG. 1 shows the curve obtained by analytical thyrotropic analysis (ATD-ATG) of a compound according to the invention of formula 1: TiO SiOH) o, 41H ₂ O,

FIG. 2 shows the X-ray diffraction diagram (Cu.

2tetha = 10-80 ° at 0.5 ° / min.) Of a compound according to the invention of formula I; TiO ₅ (OH) oO, 41H ₂ O,

- Figure 3 shows the curve obtained by affmement data from a synchrotron analysis obtained by pair distribution function (PDF) of the compound according to the invention of formula I: 5 TiO (OH) ₀ _O} 41 H ₂ 0,

FIG. 4 is a schematic representation of the lamellar lepidoeroeite structure in which the compound according to the invention of formula I is ordered over a distance less than or equal to 1 nrn,

FIG. 5 shows the first three charging / discharging curves of a lithium battery comprising as anode an electrode comprising a compound of the invention of formula I: TiOj _, (OB) i _; 3o ^' 0.4i ¾0, and a binder poly (fluoride vinylidene), and as 1M LiPFg electrolyte in a mixture of ethylene carbonate (C) and. dimethyl carbonate (DMC),

· ^■ Figure 6 shows the evolution of the capacity of a lithium battery comprising an anode comprising a compound of the invention of formula I: TiOï. ¾ (OH) i _; 3o ^' 0, 1H ₂ 0 and polyvinylidene fluoride binder), and as 1M LiPFg electrolyte in a mixture of ethylene carbonate (BC) and dimethyl carbonate (DMC), at a ratio, v / v of 1/1,

FIG. 7 shows the first three charging / discharging curves of a lithium battery comprising an anode manufactured with a compound according to the invention of formula I: TiOi _; 35 (OH) i. o ^_"0,41H.? .0 using as binder of sodium alginate in a 1 M électrolyts LiPFg in a solvent which is a mixture of ethylene carbonate (EC) and dimethyl-carbonate (DMC), at a ratio v / v of 1/1,

~ Figure 8 shows the first three curves charging / discharging of a lithium battery comprising an anode made of a compound of the invention of formula I: TiGi s (UH ^jo} 4î¾0 using, as a binder of poly ( vinylidene fluoride) in a 1 M LiCIC electrolyte in a solvent which is a mixture of propylene carbonate (PC) / dimethoxyethane (DM E) / tetrahydroflane (THF), in a proportion v / v / v of 40/15/45,

FIG. 9 shows the first three charging / discharging curves of a lithium battery comprising an anode manufactured with a compound according to the invention of formula 1: TiO 2 (ΟΗ 1) using the binder of poly (FIG. vinylidene acrylate) in a 1 M LiClO 4 electrolyte in a solvent which is a mixture of ethylene caronate / dimethyl carbonate, at a ratio, v / v of 1/1,

· ^■ Figure 10 shows the evolution of the capacity (power test) of a lithium battery comprising an anode made of a compound of the invention of formula I: Tiot jj5 (OH) i, 3o ^* 0,4I% <using as binder of poly (vinylidene fJuorure) consisting of 1M LiClO LiPFg and M * in a solvent which is a mixture of ethylene carbonate (EC) / dimethyl carbonate (DMC) at a v / v ratio of 1/1, and in a solvent which is a mixture of propylene carbonate (PC) / dimethoxyethane (DME) / tetrahydrofuran (THF) in a proportion v / v / v of 40/15/45), o

- Figure 11 shows the evolution of the capacity (test e power) of a battery at. Lithium comprising an anode made with a compound according to the invention of the formula Ti (OH) (## STR2 ## using as binder polyvinylidene fluoride, depending on the number of cycles in charge and discharge in an electrolyte which is a mixture of 1 M LiPF ^' _è and 1 M LICIC _. in a solvent consisting of a mixture EC / DMC in a proportion v / v of 1/1),

FIG. 12 shows the diffractograms of compounds according to the invention of formula I: TiO g (OB) i _; 3o'O, 41 ¾0 depending on their synthesis temperature,

FIG. 13 shows the diffractograms of compounds according to the invention of formula I: TiOu ₅ (OH); _> 30 °, 41 ° C. as a function of the degree of hydrolysis (denoted h in FIG. 13 and H in the present text) used during their synthesis,

FIG. 14 shows the diflraetogrammes of compounds according to the invention of formula 1: TiO - ^ (OH ^ o'O ^ I I0 as a function of the concentration (denoted C) in tide alkoxide used during their synthesis,

FIG. 15 is a photograph taken with a scanning electron microscope, at a magnification of x 60 000, of the composite material obtained in example 6,

FIG. 16 is a photograph taken with a scanning electron microscope, at a magnification of × 100,000, of the composite material obtained in example 6,

FIG. 17 shows the first three charging / discharging curves of a lithium battery comprising, as anode, the composite material of the invention and a polyvinylidene vinyl binder, and as a LiPFδ 1 M electrolyte. in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC), and

FIG. 18 shows the evolution of the charging and discharging capacity, on the one hand, of a lithium battery comprising the compound of example 1 (curves in "-" - "-" ··· _e t & ^■ ^■ <> ^■■ & ^■■ ^■ ø) _s and the other pan, a lithium battery, comprising the composite material of example 6 (curves -AAA ~ ~ and & a) ,

In the invention, the terms "disordered structure" and "amorphous structure" denote the structure of a material or compound whose X-ray diffraction diffractogram (RayCuKa) with a scanning between 10 and 80 ° at a rate of 0.5 ° / H 5 H 3 rse no peaks was distinguishable from the background.

For illustration, examples of difiraetogrammes of material or compounds according to the amorphous invention are shown in Figure 2, Figure 12 (temperature 30 ° C, 50 ° C, 70 ° C and 90 ° C), Figure 13 (rate hydrolysis h = 1.11, 3.33 and 7) and in Figure 14 (aoxide concentration - 0.1 M, 0.22 M, 0.45 M and 0.90 M).

The analysis of the pair distribution function (PDF) was performed as described in Peter L Chupas, Xiangyun Qiu, Jonathan C, Hanson, Peter L, Lee, Clare P. Gray, Simon JL Billinge's "Rapid Acquisition Pair Distribution Punction". (RA-PDF) Analysis, "Journal of Applied Crystallography, 2003, 36, 1342-1347.

The compound of the invention is a hydrated titanium oxyhydroxide having the following formula I:

Ti <OH) _y , n¾Q

in which :

- 1, 15 <x <1.55,

· ^■ 0.9 <y <1.70, and

- 0.1 <n <1, preferably 0.3 <n <0.5, most preferably n = 0 _s 41,

Formula 1 above represents the crude chemical formula of the hydrated titanium oxyhydroxide compound of the invention.

The hydrated titanium oxyhydroxide compound of formula I of the invention has an amorphous structure, that is, it does not exhibit long-range order, i.e. at a distance greater than 1 nm, as determined by X-ray diffraction.

But it has an ordered local structure over a distance of up to 1 nm inclusive as determined by the analysis of the pair distribution function (PDF).

This ordered local structure is that of the epidocrocite.

In addition, the compound of formula I of the invention remains amorphous over a distance greater than 1 nm throughout the charging and discharging cycles when it is ,

used as anode of a lithium battery, in contrast to the titanium oxide compound described by Xiong et al. cited above,

The hydrated titanium oxyhydroxy compound of the invention is preferably used in the form of a composite material with carbon.

In this case, it covers the carbon. The carbon can be graphite, in the form of nanoparticles or plates.

However, most preferably, the carbon is in the form of carbon nanotubes because a percolation layer can thus be formed.

The "nanoparticle (s)" designates, in the invention, particles having a spherical, or rounded, or ovoid shape, or needles, or platelets, having at least one dimension less than 100 nm.

The terms ^! carbon nanotube (s) "designates, in the invention, single-walled carbon nanotubes (SW TC) or multi-walled carbon nanotubes (MWNTC) having a width L less than or equal to 1 μηι and a diameter less than or equal to 100 nm .

The compound and the composite material of the invention do not contain lithium.

The absence of this very expensive and very reactive element represents a real advantage in terms of ease of use and of synthesis costs.

Still due to the absence of lithium, the compound and the composite material of the invention are also more easily recyclable. Indeed, the absence of Lithium makes it possible to use low temperature synthesis methods (that is to say at a temperature of between 10 ° C. and 10 ° C.), thus making it possible to import energy savings.

In addition, the carbon footprint of lithium extraction is avoided.

The recycling of the compound and the composite material of the invention do not require the separation of the titanium and lithium elements.

The hydrated titanium oxyhydroxy compound of the invention is manufactured by a process which is also another object of the invention,

This process consists of solvatively precipitating the compound of the invention using sol-gel precursors. This method of manufacturing ^a titanium oxy-hydroxide hydrate according to the invention which ia following formula I:

TiO _x (OH) _y , nH ₂ 0

Formula I

in which :

■ ^■ 1, 15 <x <1, 55,

~ 0.9 <y <1, 70, and

0.1 <n <1, preferably 0.3 <n <0.5, most preferably n = 0.41,

and which has a lepidocracial ordered local structure over a distance of up to ί ma inclusive as determined by the analysis of the pairwise distribution function (PDF) obtained by synchrotron diffraction but possessing a disordered long-distance structure, it is ie over a distance greater than 1 nm, revealed by the. X-ray (Cu) diffraction with a diffractogram characteristic of an amorphous compound,

characterized in that it comprises the following steps; a) dissolving an alkoxide C> -C ₅ titanium in an alcohol -C € ₅ with stirring and at temperature of between 1.0 and 30 ° C, inclusive, with a titanium alkoxide concentration between 0.1 1 M included and 1, 8 M excluded,

b) hydrolysis of the solution obtained in step a) by adding water with stirring, at a temperature of between 10 and 30 ° C., inclusive, and at a hydrolysis rate H of between 1.1 and 7 excluded. ,

e) precipitation of a desired compound of formula 1 in hydrated form at a temperature between 10 and 100 ° C for a period of between 1 and 48 hours, preferably 12 hours,

d) recovery of. precipitate formed in step c) by filtration or centrifugation, preferably by centrifugation,

e) washing with an alcohol in. VS-. at C ₅ of the precipitate obtained in step d), drying the washed precipitate obtained in step e) at 80 ° C. for

10 hours, g) optionally removing the physisorbed water from the compound obtained in step f) by drying at a temperature between 80 and 150 ° C, preferably at 00 ° C,

In the process of the invention, in step a) the concentration of titanium alkoxide in the alcohol is important.

Indeed, as can be seen in FIG. 14, which represents the evolution of the crystallization of the product obtained by the process of the invention as a function of the concentration of titanium alkoxide, in this case titanium isoxide, as soon as this concentration of titanium alkoxide, denoted C in FIG. 14, is greater than or equal to 1.80 M, the product obtained has a beginning of crystallization, that is to say is no longer an amorphous product as revealed by X-ray diffraction .

In FIG. 14, the top diffraeto gram represents the reference di.ffractogram.me of the titanium oxide of anatase structure,

Also, in the process of the invention, the degree of hydrolysis H of step b) is important.

The degree of hydrolysis H, denoted h in FIG. 13, corresponds to the molar ratio ¾ 0 added / titanium alkoxide.

And as seen in FIG. 13, when this degree of hydrolysis is greater than or equal to 7, the product obtained has a diffractogram with a beginning of appearance of peaks corresponding to the main stripe of the structure of titanium oxide. anatase whose X reference diffraction pattern is shown in the upper part of Figure 13.

The precipitation temperature used in step c) is also important.

Indeed, as seen in Figure 12, which shows the diffrograms of compounds synthesized at different temperatures, when the precipitation temperature of step c) is greater than or equal to 1 .10 ° C, the product obtained is , plus an amorphous product: it presents a distinctive diffraction of a crystallized product, which in this case has the structure Ti0 ₂ anatase.

In step c) the precipitate formed is a compound of formula 1 intended but containing at least 0.3 moles of water more than the desired compound. Preferably, in step a), couples aikoxydes C _$ -C ₅ titanium / alcohol C¾ -C $ - are selected from étlioxyde couples titanium / ethanol, titanium isopropoxide / isopropaool, and butoxide titan e / butanol if at FETAPE e) F alcohol in C _s -C ₅ is ethanol.

The composite material of the invention is, for its part, manufactured by a process, which is still an object of the invention, which comprises, before step a) of the process for producing the titanium oxy-b.hydroxide compound. hydrate according to the invention, described above, a step noted al) for the preparation of a suspension of nanoparticles and / or carbon nanotubes in a Cj to Cs alcohol, this step a1) being followed by the steps noted below. a) to g) of the process for producing the hydrated titanium oxyhydroxide compound of the invention.

However, in the case of the synthesis of the composite material of the invention, step a) of synthesis of the hydrated titanium oxyhydroxide compound is modified in the following way: Titanium isopropoxide is introduced directly into the suspension of nanoparticles and or carbon nanotubes prepared in step al) and stirring at. a temperature of between 10 and. 30 ° C, inclusive terminals, is implemented on this suspension mixture of nanoparticles and / or carbon nanotubes and titanium isopropoxide.

The suspension of nanoparticles and / or carbon nanotubes manufactured in step a1) preferably has a concentration of nanoparticles and / or carbon nanotubes of between 2.33 and 9.33 g × ^-1 more preferably between 4 , 5 and 5.5 g, L ^"! ,

Most preferably, the suspension prepared in step a1) is a suspension of carbon nanotubes, nmitiparois,

The precise chemical composition of the compound of formula I of the invention was determined by thermo-gravimetric analysis.

The curve obtained by thermo-gravimetric analysis (ATD-ATG) of a compound of formula I according to the invention of empirical formula TiO ₃ , 06¾. -2 is shown in Figure 1.

This analysis was carried out using a rise in temperature from 25 ° C. to 600 ° C. with a temperature ramp of 5 ° / min. It was carried out under argon. As seen in Figure 1, this curve has a first? regular mass loss (constant slope) between 20 ° C and 100 ° C, attributable to the loss of physisorbed water. Then this curve shows a new loss of mass, with a slope slightly different from the previous, between 100 ° C and 20 ° C. This loss of weight is attributable to the loss of water present in the structure (structural water). The last loss of mass is attributed to OH groups.

Thus, the compound of the empirical formula TiO 3 H 2 u has the crude chemical formula TiO 3 _{, 3S} (OH); _{, 30} -0, 1 ¾0.

The structural analysis of this compound was first carried out by X-ray diffraction.

The X-ray diffraction pattern obtained is shown in FIG. 2. This diagram is characteristic of an amorphous compound.

Nevertheless, the use of synchrotron radiation makes it possible to obtain the pair distribution function (PDF) which accounts for the local order of the compound irrespective of its crystalline state.

The data obtained were compared to different models and the best agreement is presented in Figure 3,

This agreement shows that the compound according to the invention adopts locally (over a distance less than or equal to 1 nm), the. lamellar structure shown in FIG.

This structure is a Lepidocrocite structure.

In this lepidocrocite structure, the Ti ⁺ cation is surrounded by six Q ^{2 ~} or OH ^' ligands forming an octahedron. These octahedra (Ti (0, OH) $ are linked together by the vertices and edges forming a zig-zag layer, which layers are separated from each other by the presence of structural water.

Sasaki et al., In Chemist y Materials, 1995, 7, 1001-1007 discloses the erisallographic structural formula as H _a Ti ₂ - _c . D "0 ₄ .¾0.

In this formula, □ designates a titanium gap to achieve electron-specificity of the compound: Sasaki describes the lepidroent structure as containing H ₃ O ⁺ ions in F titanium interlayers.

The inventors have discovered that the hydrated titanium oxyhydroxide compound of the invention has, it, a crystallographic structural formula Ti. ₂ -i> Up 0 ₄ .4β (() Η) _. NIH ₂ 0 wherein the formation of gaps is related to the substitution of ions (¾ ^"with OH ^ions", which means that the gap formation mechanism is different from that stated by Sasaki,

This realizes eristailographique structural formula 1 ⁵ structurai arrangement oxy compound ~ titanium hydroxide livdraté while gross chemical formula reports the elemental composition obtained by analyzing tl eïïBogravi etry thereof,

NMR spectroscopy also made it possible to characterize the proton environment in this structure, confirming the presence of titanium and structural water gaps.

The compound of the invention has excellent electrochemical properties when used to make an anode of a lithium battery, as shown by the following examples.

First, the loss of capacity between the first discharge cycle and the next charge cycle is less than 40%. This capacity pearl is represented by the capacity ratio at the first charge / capacity at the first discharge.

For comparison, the loss of capacity obtained with an anode consisting of nanotubes of amorphous titanium oxide described by Borghoîs is between 57 and 63%,

In addition, during the preparation of the anode, various binders may be used, and in particular the water-soluble binders, such as sodium alginate, which reduces the environmental impact during the manufacture of the electrode. .

The compound of the invention is also compatible with many electrolytes comprising various lithium salts and solvents,

Example 1: Synthesis of compound of formula I _U5 TiO (OH) i, ₃₀ -0,41H ₂ O.

The hydrated oxyhydroxy compound (OH) is prepared by solvoalayal precipitation using sol-gel precursors. The protocol comprises dissolving a titanium isopropoxide (13.5 mmol) in its parent alcohol (isopropanol, 25.29 mL) with stirring. Subsequently, a quantity of water (0.81 mL) defined by the rate of hydrolysis H which is the ratio number of moles of kbO / mole number of titanium alkoxide of 3.33, is added to the solution and then stirred for homogenization for 5-15 minutes. The mixture is then placed in the body. Teflon and placed in a steel bomb closed henniquement. The precipitation reaction is. performed by treatment at 90 ° C for 12 hours. After cooling, the solid is recovered and washed with ethanol by centrifugation and then dried at 80 ° C overnight, and the recovered solid is degassed under primary vacuum at 100 ° C for. 2 hours to completely eliminate the physisorbed water to allow the structural characterization and electrochemical tests of this compound.

Although in this example the titanium alkoxide used was titanium isopropoxide other titanium alkoxides, such as ethoxide, isopropoxide or titanium butoxide can also be used in their parent alcohol, ie, ethanol. for titanium ethoxide, isopropanol lice, titanium isopropanol, and butanol for titanium butoxide.

Example 2 Test of the electrocomic properties of the compound obtained in Example 1.

An anode was prepared by mixing 80% by weight of the compound of Example 1, 10% by weight of polyvinylidene fluoride (PVDF) and 10% by mass of Super P * carbon marketed by the company TIMCAL dissolved beforehand. in n-methyl-2-pyrrolidone (NM.P).

Lithium insertion-deinsertion reactions are written as follows:

x.Li + ΤίΟ], 35 (ΟΗ) ι, 30 · 0.4ΪΗ ₂ Ο - U TiO _{} S} (On) ₀ -0AiE ₂ O Based on the redox couple Ti VTi ³ , the theoretical capacity (or quantity of load) that can be stored is 265 mAh.g ^"1 (for x - 1),

The anode obtained in this example was placed in a lithium battery comprising, a lithium metal electrode, and using as 1 M electrolyte LiPF _$ in a mixture by volume of 1/1, ethylene carbonate (EC) and dimethyl carbonate (DMC).

This battery has been operated at a current density of 20 mAfe.g ^-1 and has an average operating potential of 1.55 V vis-à-vis lithium. The first three charging and discharging curves of this battery are shown in FIG. 5,

The shape of these curves indicates a lithium insertion by a solid solution mechanism, that is to say a continuous evolution of the potential as a function of the. capacity. The first discharge capacity is 330 mAh.g ^-1, then charged, it drops to 215 m-h ^-1, indicating that part of the lithium is trapped by the structure or on the surface of the material. stabilizes around 170-180 mAh.g ^{* 1} after 50 cycles, as shown in Figure 6, which shows a good reversibility of the system.

Example 3

This example shows that the PVDF binder can be replaced by a binder dissolved in water during the manufacture of the electrode.

Thus, an electrode comprising 80% by weight of the compound of Example 1 was manufactured with 10% by weight of sodium alginate previously dissolved in water and 10% by mass of Super P ^® type carbon.

The sodium alginate may be replaced by carboxymethylcellulose (CMC), rubber in styrene-butadiene rubber (SBR) or polytetrafluoroethylene (PTFB), and mixtures thereof.

This electrode was tested in the same way as in Example 2.

Figure 7 shows the load and discharge curves for the first three charging and discharging cycles of this battery.

As can be seen, the compound of the invention is compatible with a water-soluble binder.

EXAMPLE 4 Electrochemical Test of the Compound Obtained in Example 1 An electrode was manufactured with the compound obtained in Example 1.

This electrode contains 80% by weight of the compound of Example L 10% by weight of polyvinylidene fluoride (PVDF) and 10% by mass of Super P ^® type carbon dissolved beforehand in n-2-methyl-2 pyrrolidone (NMP),

This electrode was used as anode in the same battery as in Examples 2 and 3 but with different electrolytes.

The first electrolyte used consisted of 1 M 2 O 3 in a solvent which is an EC / DMC mixture at a v / v ratio of 1/1. The charge and discharge curves obtained during the first three cycles with such a battery are shown in FIG.

The second elecirolyte used was an electrolyte consisting of LiC10 ₄ in a PC / DME / THF mixture (v / v / v, 40/15/45).

The charge and discharge curves obtained during the first three cycles of charging and discharging with this battery are shown in. figure 8.

The third electrolyte used was an electrolyte consisting of 1 M LiCR¾ in an EC / DMC mixture (v / v, 1/1).

The charge and discharge curves obtained during the first three charging and discharging cycles with this battery are shown in FIG. 9,

As seen from these figures, the compound obtained in Example 1 is compatible with other lithium salts and solvents.

Example S: Power test of the batteries obtained in Example 4,

Power tests were carried out for the different batteries mentioned in Example 4,

Figure 10 shows the evolution of the capacitance under different current density (power test) as a function of the number of charge and discharge cycles for the batteries using, as 1M LiPF ₆ electrolyte in a mixture EC / DMC (v / v, 1/1) and an elecrolyte ί M Li C1.0 in a PC / DME / THF solvent (v / v / v, 40/15/45) and FIG. the capacity under different current density (power test) as a function of the number of cycles in charge and discharge of a battery using an electrolyte consisting of 1 M LiPF ₆ in a mixture EC / DMC (v / v, 1/1) and using 1M LiC10 ₄ electrolyte in EC / DMC mixture (v / v, 1/1),

It can be seen from FIGS. 10 and 11 that the best power handling is achieved with 1 M LiClC 4 in a PC / DME / THF mixture (v / v / v, 40/15/45).

Example 6; Synthesis of a composite material consisting of the compound of Example i covering carbon nanotubes,

140 mg of carbon nanotubes (multiwall, 0 20mm, Length 1 pm) are dispersed in 25.19 mL of isopropanol in a Teflon ^® container and stirred for 30 minutes. 4 ml of titanium isopropoxycle are then added to this dispersion of carbon nanotubes. The mixture is stirred for 10-30 minutes. Then 0.81 ml of distilled water (1.8.2 cm) is introduced into the mixture and then stirred for 5-15 minutes, which is then placed in an autoclave bomb. The bomb is heated at 90 ° C for 12 hours. After cooling to room temperature, the composite is recovered by centrifugation and washed three times with ethanol and then dried at 80 ° C for one birth. The composite will be degassed again at 100 ° C for 2 h in air before analysis.

Under these conditions of synthesis, the compound described above can grow directly on the carbon nanotubes.

Figure 15 shows a scanning electron micrograph image at x 60,000 magnification showing the growth of nanoparticles of the compound of Example 1 on the carbon fibers.

This growth allowing the coating of the carbon nanotubes with the compound of Example 1 is illustrated in FIG.

Exempt 7 .; Test of the Electrochemical Properties of the Composite Material Obtained in Example 6

An anode was prepared as described in Example 2 but in. replacing the compound obtained in Example 1 with the composite material obtained in Example 6 without the use of Super P ^® carbon.

The anode obtained in this example was placed in a lithium battery comprising a lithium metal electrode, and using as electrolyte 1 M LiPFg in a mixture by volume of 1/1, ethylene carbonate (EC) and dimethyl carbonate (DMC).

This battery has been operated at a current density of 20 mAh.g ^-1 and has an average operating potential of 1.55 V vis-à-vis lithium.

The first three charge and discharge curves for this battery are shown in Figure 17,

The electrochemical properties of the composite material obtained in Example 6, tested in a lithium electrochemical cell, were compared with those of the hydrated titanium oxyhydroxide compound obtained in Example 1, Figure 17 shows the discharge curves (lithium insertion) and charge (désinserho.u) obtained for the first three cycles. It can be seen by comparing FIG. 5 and FIG. 17 that the titanium oxyhydroxide compound of Example I and the composite material of Example 6 have similar electrochemical signatures in terms of capacities and average voltage.

Ers. However, as seen in Figure 1 8 power tests performed on the batteries of Example 2 (curves "-" ^■ - "· -" · and o - "- © e -) and the example 7 (curves AET) demonstrate better power handling of the composite material in particular to high current densities (600 mAh.g ^"J).

These best performances are related to the morphology of the composite which allows a better electronic percolation within the material.

Although the foregoing examples all disclose the use of the compound of the invention for making an anode of a lithium battery, the compound of the invention can also be used in sodium and magnesium batteries. .

In addition, although the foregoing examples all use non-aqueous solvents, the compounds of the invention can be used in aqueous electrolyte batteries.

Also, the compound of the invention can be used as a catalyst, in particular as a photocatalyst because of its band gap at 3.4 eV.

Claims

1, hydroxy hydrated titanium hydroxide characterized. what he has the following formula l

TiO _x (OH) _y , nE ₂ 0

Formula I

in which ;

■ · 1.15 <x <1.55,

- 0.9 <y <1, 70, and

0.1 <rs <1, preferably 0.3 <n <0.5, most preferably n - 0.41,

and in that it has an ordered local structure lepidocroeite over a distance of up to 1 nni inclusive as determined by the analysis of the pair distribution function (PDF) obtained by synchrotron diffraction but having a disordered structure over a distance greater than 1 nm, revealed by X-ray diffraction.

2. Titanium oxyhydroxide according to claim 1, characterized in that in formula I,

- x ^:: ï, 35,

y = 1.30, and

- n - 0.41.

3. Composite material comprising carbon coated with the compound of claim 1 or 2,

4. Composite material according to claim 3 characterized in that the carbon is in the form of nanoparticles and / or carbon nanotubes, preferably in the form of carbon nanotubes.

5. An electrode characterized in that it comprises a titanium oxyhydroxide according to claim 1 or 2 or a composite material according to claim 3 or 4.

6. Battery characterized in that it comprises an electrode according to claim 5,

7. Catalyst characterized in that it comprises a titan oxo-hydroxide according to claim 1 or 2 a composite material according to claim 3 or 4.

8, Process for producing a hydrated titanium oxyhydroxide according to claim 1 or 2 of the following formula I:

TiO _x (OH) _y , n¾0

Formula I

in which :

- I, l5≤x≤ 1, 55,

- 0.9 <y <1, 70, and

^■ 0.1 <n <L preferably 0.3 <n <0.5. most preferably n - 0.41,

and in that it has an ordered lepidocrocite local structure over a distance of up to 1 m inclusive as determined by the analysis of the pair distribution function (PDF) obtained by synchrotron diffraction but having a disordered structure over a distance greater than 1 night revealed by X-ray diffraction,

characterized in that it comprises the following steps; a) dissolving a titanium alkoxide of titanium in a C ₅ to C ₅ alcohol at an alkoxide concentration of between 0.1 M inclusive and. 1, 8 M excluded, with stirring at a temperature of between 10 and 30 ° C., limits included,

b) hydrolysis of the solution obtained in step a) by addition of water under stirring at a temperature between 10 and 30 ° C inclusive, with a degree of hydrolysis ïù¾o¼ikoxy H ^:::: <ie _<k titanium compri .s between 1, 11 included and 7 excluded,

c) precipitation of the desired compound of formula I, hydrated, at a temperature of between 10 and 10. 100 ° C limits included for a period of between 1 and 48 hours, preferably 12 hours,

d) recovering the precipitate formed in step c), by filtration or centrifugation, preferably eentrifdgation,

e) washing with a C 5 to C 5 alcohol of the precipitate obtained in step d), f) drying the washed precipitate obtained in. step e) at 80 ° C for. 10 hours, and g) optionally drying the compound obtained in step i) at a temperature between 80 ° and 150 ° C., preferably at a temperature of 100 ° C., to remove water physisorbed from the compound obtained in step i) .

9. Method according to claim 8 characterized in that:

^■ ■ in step a) alfcoxyâes couples € ¾ titanium Cj / alcohol -C

C5 are selected from the pairs of titanium ethoxide / etharsol, titanium isopropoxide isopropanol, and titanium butoxide / butanol and in that

in step e) the alcohol in d to C ₅ is ethanol.

10. A method of manufacturing a composite material according to the. claim 3 or 4 characterized in that it comprises the following steps:

al) preparing a suspensio of nanotubes and / or nanoparticles of carbon in a C-alcohol; at C5, having a concentration of nanotubes and / or carbon nanoparticles between 2.33 and 9.33

a) introducing a aikoxyde -C € ₅ titanium in the suspension obtained in step al) and stirring at a temperature between 10 and 30 ° C, the aikoxyde concentration in the suspension is between 0.1 1 M included and 1.8 M excluded,

followed by steps b) to g) of the process for producing a hydrated titanium oxyhydroxide according to claim 8,

1. Process according to claim 10, characterized in that in step a1) the suspension is a suspension of carbon nanotubes and the C ₅ to C ₅ alcohol is isopropanol.