WO2008141422A1

WO2008141422A1 - Processes for preparing inorganic phosphates

Info

Publication number: WO2008141422A1
Application number: PCT/CA2008/000812
Authority: WO
Inventors: Amer Hammami; Benoit Marsan; Alexandre Ndedi Ntepe
Original assignee: Transfert Plus SC
Current assignee: Transfert Plus SC
Priority date: 2007-05-21
Filing date: 2008-04-29
Publication date: 2008-11-27
Anticipated expiration: 2009-11-21

Abstract

There are provided processes for preparing compounds of formula (I) AMPO4. The processes comprise reacting a compound or formula (II) AH2PO4 and a compound of formula (III) MXn, in the presence of an acid scavenger adapted to at least substantially solubilize the compound of formula (II) and the compound of formula (III), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation. A, M, and X can be various chemical entities and n can be 1 or 2. A process for preparing electrodes is also provided.

Description

PROCESSES FOR PREPARING INORGANIC PHOSPHATES

TECHNICAL FIELD

[0001] The present document relates to improvements in the field of preparation of inorganic compounds. In particular, it relates to the preparation of inorganic phosphates such as phospho-olivine type compounds.

BACKGROUND OF THE INVENTION

[0002] So far, several attempts have been made so as to provide an efficient process for preparing inorganic phosphates such as phospho-olives compounds which are used in lithium batteries. These processes often required costly reagents or comprised several steps. Moreover, the processes that have been proposed so far are often very costly since they imply a high energy consumption.

[0003] It would therefore be highly desirable to be provided with a process that would overcome the above-mentioned drawbacks.

SUMMARY OF THE INVENTION

[0004] According to one aspect, there is provided a process for preparing a compound of formula (I):

AMPO₄ (I)

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺; and

M is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺;

the process comprising reacting a compound of formula (II) with a compound of formula (III): AH₂PO₄ (II)

MX_n (HI)

wherein

A is as previously defined;

M is as previously defined;

X is chosen from F^", Cf, Br, I^", CN^", CH₃COO-, CF₃SO₃ ^", NO₃-, OCN-, SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and

n is 1 or 2,

in the presence of an acid scavenger adapted to at least substantially solubilize the compound of formula (II) and the compound of formula (III), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation.

[0005] According to another embodiment, there is provided a process for preparing an electrode comprising:

reacting a compound of formula (II) with a compound of formula (III):

AH₂PO₄ (II)

MX_n (III)

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺; and M is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺;

X is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO^", CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2" , S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and

n is 1 or 2,

in the presence of an acid scavenger adapted to at least substantially solubilize the compound of formula (II) and the compound of formula (III), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation, thereby obtaining a composition comprising a compound of formula (I) AMPO₄ in which A and M are as previously defined, the protonated acid scavenger, and optionally the unprotonated acid scavenger;

depositing the composition on a substrate; annealing the composition deposited on the substrate so as to obtain the electrode.

[0006] For example, the acid scavenger can be liquid at room temperature. It can also be liquid at a temperature of about O to about 35 ⁰C. For example, the compound of formula (II) can be reacted with the compound of formula (III) at a temperature lower than 200 ⁰C, lower than 150 ⁰C, lower than 100 ⁰C, or lower than 60 ⁰C. According to another example, they can be reacted together at room temperature, at a temperature of about 15 ⁰C to about 60 ⁰C, or at a temperature of about 20 ⁰C to about 35 ⁰C.

[0007] For example, the acid scavenger can be a compound of formula

(IV) :

(IV)

wherein

R is chosen from hydrogen atom, C1-C12 alkyl, C₃-Ci₂ cycloalkyl, C₁-C₁₂ heterocyclyl, C2-C12 alkenyl, C₂-Ci₂ alkynyl, C6-Ci₂ aryl, Ce- C20 aralkyl, C₆-C₂O alkylaryl, and C1-C12 heteroaryl.

[0008] For example, R can be a polymerizable moiety. The polymerizable moiety can comprise at least one polymerizable entity chosen from a double bond, a triple bond, a carbonyl, a free radical acceptor, and a polymerizable cyclic compound. For example, the polymerizable cyclic compound can be an epoxide, an aziridine, a cyclopropene, or a thiophene. For example, the polymerizable moiety can be chosen from a cyclopropenyl, a C₄-C_2O alkylcyclopropenyl, a C₄-C₂O cyclopropenylalkyl, an epoxide, a C3-C20 alkyloxirane, a C3-C20 oxiranealkyl, C2-C20 alkenyl, and C₂-C₂O alkynyl. The polymerizable moiety can also be a C₂-Ci₂ alkenyl, or a C₂-Ci₂ alkynyl.

[0009] For example, the compound of formula (I) can be chosen from

LiFePO₄, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

[0010] For example, the compound of formula (III) can be chosen from

FeCI₂, FeBr₂, FeI₂, FeF₂, Fe(CN)₂, Fe(SCN)₂, FeSO₄, Fe(CH₃COO)₂, and FeC₂O₄. [0011] For example, a super valent metal salt chosen from Nb⁵⁺, Al³⁺,

Ti⁴⁺, Mg²⁺, W⁶⁺, and Zr⁴⁺ can be added to the compound of formula (II), the compound of formula (III), and the acid scavenger. A carbon source can also be optionally added to the compound of formula (II), the compound of formula (III), and the acid scavenger. The carbon source can be carbon black or a polymer or rich carbon organic compound which is soluble in the acid scavenger. The carbon source can also be nanoparticles of carbon black or carbon nanotubes (multi-wall carbon nanotubes or single-wall carbon nanotubes). An organic solvent can also be further added to the compound of formula (II), the compound of formula (III), and the acid scavenger. The organic solvent can be chosen from acetonitrile, dimethylformamide, tetrahydrofuran, dimethoxymethane, and mixtures thereof.

[0012] According to another aspect, there is provided a method of scavenging protons, the method comprising contacting the protons with a compound of formula (IV) :

R

HN S^' /<^N'N

(IV)

wherein

R is chosen from hydrogen atom, C1-C1₂ alkyl, C₃-Ci₂ cycloalkyl, C1-C12 heterocyclyl, C₂-Ci₂ alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, C₆- C₂₀ aralkyl, C₆-C₂O alkylaryl, and CrCi₂ heteroaryl.

[0013] According to another aspect, there is provided the use of a compound of formula (IV) :

(IV)

wherein

R is chosen from hydrogen atom, C1-C12 alkyl, C₃-Ci₂ cycloalkyl, C₁-C₁₂ heterocyclyl, C2-C12 alkenyl, C2-C12 alkynyl, C6-C12 aryl, Ce- C2₀ aralkyl, C6-C20 alkylaryl, and C1-C12 heteroaryl.

as an acid scavenger in the preparation of a phospho-olivine type compound.

[0014] According to another aspect, there is provided a method of using a compound of formula (IV)

(IV)

wherein

R is chosen from hydrogen atom, C₁-C1₂ alkyl, C₃-C12 cycloalkyl, C1-C12 heterocyclyl, C₂-Ci₂ alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, C₆- C20 aralkyl, C6-C20 alkylaryl, and C1-C12 heteroaryl,

the method comprising using the compound of formula (IV) as an acid scavenger in the preparation of a phospho-olivine type compound.

[0015] For example, the compound of formula (IV) can be contacted with protons generated during preparation of a phospho-olivine type compound. The compound of formula (IV) can further be used as a solvent during preparation of the phospho-olivine type compound. For example, the phospho-olivine type compound can be chosen from LiFePO4, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

[0016] According to another aspect, there is provided a method for preparing LiFePO₄ comprising reacting together a lithium source, an iron source, and a phosphorus source, the improvement wherein the lithium source and the phosphorous source is LiH₂PO₄, and the iron source is FeX_n in which X is chosen from F₁ Cl^", Br^", l\ CN^", CH₃COO-, CF₃SO₃ ^", NO₃-, OCN-, SCN^", (CN)₂N^", CO₃ ^2", CIO₃-, CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and n is 1 or 2. For example, LiH₂PO₄ can be reacted with FeX_n at a temperature lower than 200 ⁰C, lower than 150 ⁰C, lower than 100 ⁰C, or lower than 60 ⁰C. According to another example, LiH₂PO₄ can be reacted with FeX_n at room temperature, at a temperature of about 15 ⁰C to about 60 ⁰C, or at a temperature of about 20 ⁰C to about 35 ⁰C. For example, in such a method a compound of formula (IV), as previously defined, can be used as a proton scavenger. The compound of formula (IV) can also used as a solvent.

[0017] According to another example, the compound of formula (IV) can be

R N ^ N

[0018] According to another example, the compound of formula (IV) can be

[0019] According to another example, the compound of formula (IV) can be

[0020] According to another aspect, there is provided a process for preparing a compound of formula (Ia):

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺; and

M¹ is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺;

M² is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺; and

T has a value of 0 to 1 ,

the process comprising reacting a compound of formula (II) with a compound of formula (Ilia) and a compound of formula (HIb) :

AH₂PO₄ (H)

M¹(X¹) π1 (Ilia)

M²(X²) n2 (nib)

wherein A is as previously defined;

M¹ and M² are as previously defined;

X¹ is chosen from P₁ Cl^", Br^", I^", CN^", CH₃COO-, CF₃SO₃ ^", NO₃-, OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2" , S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S²-, CIO^", and C₂O₄ ^2";

X² is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO^", CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2', S₂O₄ ^2", S₄O₆ ^2" , S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2', CIO^", and C₂O₄ ^2";

n¹ is 1 or 2; and

n² is 1 or 2,

in the presence of an acid scavenger adapted to at least substantially solubilize the compound of formula (II), the compound of formula (Ilia), and the compound of formula (IHb)₁ at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation.

[0021] Alternatively, T can have a value comprised between O and 1.

[0022] The person skilled in the art would clearly recognize that the process for preparing compounds of formula (Ia) is similar to the process for preparing compounds of formula (I). In fact, the particular embodiments and examples previously mentioned concerning the process for preparing compounds of formula (I), when possible, can all be applied to the process for preparing compounds of formula (Ia).

[0023] The term "alkyl" as used herein means straight and/or branched chain, saturated alkyl radicals and can include, for example, methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, 2,2-dimethylbutyl, n-pentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, n-hexyl and the like. [0024] The term "heteroaryl" has used herein refers to an aromatic cyclic or fused polycyclic ring system having at least one heteroatom selected from N, O₁ and S. For example, the heteroaryl group can be furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, thiazolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzoxazolyl, pyrimidinyl, benzimidazolyl, quinoxalinyl, benzothiazolyl, naphthyridinyl, isoxazolyl, isothiazolyl, purinyl, quinazolinyl, and so on.

[0025] The term "heterocyclyl" includes non-aromatic rings or ring systems that contain at least one ring having at least one hetero atom (such as nitrogen, oxygen or sulfur). For example, this term can include all of the fully saturated and partially unsaturated derivatives of the above mentioned heteroaryl groups. Exemplary heterocyclic groups include pyrrolidinyl, tetrahydrofuranyl, morpholinyl, thiomorpholinyl, piperidinyl, piperazinyl, thiazolidinyl, isothiazolidinyl, and imidazolidinyl.

[0026] The term "cycloalkyl" has used herein refers to a hydrocarbon ring which may contain or not double bonds. BRIEF DESCRIPTION OF DRAWINGS

[0027] In the following drawings, which represent by way of example only, various embodiments of the invention :

Fig. 1 shows a X-ray diffraction (XRD) pattern of a LiFePO₄ sample prepared in accordance with a process as previously defined;

Fig. 2 shows a Scanning Electron Microscope (SEM) image of the sample analyzed in Fig. 1 , wherein the scale is 500 nm; and

Fig. 3 shows an Energy Dispersive X-ray Spectroscopy (EDX) graph of the sample analyzed in Fig. 1.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS [0028] Further features and advantages will become more readily apparent from the following non-limiting examples.

Examples

Example 1 : Synthesis of LiFePO₄

[0029] Fe(CH₃COO)₂ (1.73 g, 10 mmol) was dissolved in 50 mL of anhydrous N-methylimidazole (NMI) in a 250 mL two-neck flask under argon at room temperature. LiH₂PO₄ (1.03 g, 10 mmol, 1 equiv) was dissolved in 50 mL of NMI at room temperature and was added dropwise to the solution of Fe(CH₃COO)₂ over a period of 15 minutes under argon. The resulting solution was stable against aggregation. The mixture was then heated during 2 hours at 6O⁰C. Then, the grey particles obtained were filtered and dried at room temperature under vacuum overnight. The LiFePO₄ particles can eventually be annealed. The sample obtained in Example 1 was analyzed by XRD, SEM, and EDX (see Figs. 1 to 3) after being annealed at 500 ⁰C during 1 hour.

[0030] The lattice constants were experimentally calculated by using the distances d_hki between the reticular plans (101), (211) and (311) according to an equation appropriate for an orthorhombic system.

Table 1. Experimental and theoretical lattice constants, a/b and c/b ratios, and unit cell volume of the LiFePO₄Of Example 1 :

* : values taken from ICSD datasheet

[0031] By comparing the experimental results and the theoretical values taken from the ICSD data sheet, it can be seen that such values are very similar. The experimental cristallinity diameter is 33.0 nm. [0032] It was calculated by using the Debye-Scherrer equation :

K λ diameter =

Bcosθ

K = 0.9 ; λ is the wavelength of the radiation source ((λ = 1 ,7890 A); B is the width at 50 % of the height of the peak(rad) of the (101) plan.

[0033] As it can be seen from the SEM image of Fig. 2, spherical nanoparticles having a diameter of about 50 nm have been prepared. [0034] The results shown in Fig. 3 and in Table 2 clearly demonstrate that the stoechiometry of the LiFePO₄ particles obtained in Example 1. In fact, the observed ratio Fe : P was 1 : 1.1

Table 2. EDX Spectrometry of LiFePO₄ (coupled to SEM via an X-Ray detector).

Ratio Fe : P 1 : 1.1

Example 2 : Synthesis of LiMnPO₄

[0035] Mn(CH₃COO)₂ (1.73 g, 10 mmol) was dissolved in 50 mL of anhydrous N-methylimidazole (NMI) in a 250 mL two-neck flask under argon at room temperature. LiH₂PO4 (1.03 g, 10 mmol, 1 equiv) was dissolved in 50 mL NMI at room temperature and was added dropwise to the solution of Mn(CH₃COO)₂ over a period of 15 minutes under argon. The resulting solution was stable against aggregation. The mixture was then heated during 2 hours at a temperature of 60⁰C. Then, the grey particles were filtered and dried at room temperature under vacuum overnight. The LiMnPO₄ particles can eventually be annealed. The sample obtained in Example 2 was analyzed by XRD and XPS.

[0036] When the process is used for preparing LiFePO₄, the reaction scheme can be as follows :

LiH₂PO₄ + FeX₂ + N ^ N *. LiFePO₄ + 2 N ^ N H

\=/ _χΘ

(2 equivalents)

[0037] The reaction scheme can also be as follows :

LiH₂PO₄ + FeX₂ + N ^ N *. LiFePO₄ + 2 N ^N H x^Θ

(more than 2 equivalents)

[0038] It was found that such processes for preparing various inorganic phosphates comprise several advantages over the prior art processes. In fact, such processes can be carried out at low temperature as opposed to processes of the prior art (for example those used for preparing LiFePO₄) which require high temperatures generally greater than 800 ⁰C (such as processes involving the use of UCO3 (lithium carbonate), NH₄PO4 (ammonium phosphate) and Fe(CH₃COO)₂ (ferrous acetate). Moreover, the processes can be carried out in an organic solvent which is also an acid scavenger. For example, they permit to keep the obtained compound (for example LiFePO₄) under anhydrous conditions and to substantially avoid the presence of Fe(III) ions, which are contaminants detrimental for lithium batteries. [0039] When the reaction is completed, the composition obtained which comprises the desired compound, the protonated acid scavenger, and optionally the unprotonated acid scavenger, can then readily be annealed, thereby using the scavenger as a source of carbon. Depending on the fact that an excess of acid scavenger was used or not at the beginning of the reaction, the obtained composition will be more or less viscous and easily deposited onto a desired substrate so as to prepare an electrode having such a coating thereon.

[0040] While a description was made with particular reference to the illustrated embodiments, it will be understood that numerous modifications thereto will appear to those skilled in the art. Accordingly, the above description should be taken as specific examples and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A process for preparing a compound of formula (I):

AMPO₄ (I)

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺; and

M is chosen from B _Jte,2²+⁺, K MΛ~g2²+⁺, Q Ba_2²+⁺, _n Ca_n2²+⁺, S _C-r2²+⁺, F ce~2²+⁺, p C_Λo2²+⁺,

said process comprising reacting a compound of formula (II) with a compound of formula (III):

AH₂PO₄ (II) MX_n (III) wherein

A is as previously defined;

M is as previously defined;

X is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO^", CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2" , S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and

n is 1 or 2,

in the presence of an acid scavenger adapted to at least substantially solubilize said compound of formula (II) and said compound of formula (III), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation.

2. The process of claim 1 , wherein said acid scavenger is a compound of formula (IV):

(IV)

wherein

R is chosen from hydrogen atom, C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl, C₁-C₁₂ heterocyclyl, C₂-C₁₂ alkenyl, C₂-C₁₂ alkynyl, C₆-C₁₂ aryl, C6-C20 aralkyl, C₆-C₂O alkylaryl, and C1-C12 heteroaryl.

3. The process of claim 2, wherein said acid scavenger is

R N ^ N

4. The process of claim 1 , wherein said acid scavenger is

5. The process of claim 1 , wherein said acid scavenger is

6. The process of any one of claims 1 to 5, wherein said compound of formula (I) is chosen from LiFePO₄, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

7. The process of any one of claims 1 to 5, wherein said compound of formula (I) is LiFePO₄.

8. The process of claim 7, wherein said compound of formula (III) is chosen from FeCI₂, FeBr₂, FeI₂, FeF₂, Fe(CN)₂, Fe(SCN)₂, FeSO₄, Fe(CH₃COO)₂, and FeC₂O₄.

9. A process for preparing an electrode comprising:

reacting a compound of formula (II) with a compound of formula (III):

AH₂PO₄ (II)

MX_n (III)

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺;

M is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺; X is chosen from F^', Cl^", Br^", I^", CN^', CH₃COO^', CF₃SO₃ ^', NO₃ ^', OCN^', SCN^", (CN)₂N^", CO₃ ^2', CIO₃ ^', CrO₄ ^2", BrO₃ ^', Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2', SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and

n is 1 or 2,

in the presence of an acid scavenger adapted to at least substantially solubilize said compound of formula (II) and said compound of formula (III), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation, thereby obtaining a composition comprising a compound of formula (I) AMPO₄ in which A and M are as previously defined, said protonated acid scavenger, and optionally said unprotonated acid scavenger;

depositing said composition on a substrate; and

annealing said composition deposited on said substrate so as to obtain said electrode.

10. The process of claim 9, further comprising adding a super valent metal salt chosen from Nb⁵⁺, Al³⁺, Ti⁴⁺, Mg²⁺, W⁶⁺, and Zr⁴⁺ to said compound of formula (II), said compound of formula (III), and said acid scavenger.

11. The process of claim 9 or 10, further comprising adding a carbon source to said compound of formula (II), said compound of formula (III), and said acid scavenger.

12. The process of claim 11 , wherein said carbon source comprises carbon black, a polymer, or a carbon-rich organic compound which is soluble in said acid scavenger.

13. The process of claim 11 , wherein said carbon source comprises nanoparticles of carbon black, carbon nanotubes or a mixture thereof.

14. The process of claim 11 , wherein said carbon source comprises multi- wall carbon nanotubes or single-wall carbon nanotubes.

15. The process of any one claims 9 to 14, further comprising adding an organic solvent to said compound of formula (II), said compound of formula (III), and said acid scavenger.

16. The process of claim 15, wherein said organic solvent is chosen from acetonitrile, dimethylformamide, tetrahydrofuran, dimethoxymethane, and mixtures thereof.

17. The process of any one of claims 9 to 16, wherein said acid scavenger is a compound of formula (IV):

(IV)

wherein

R is chosen from hydrogen atom, C₁-C₁₂ alkyl, C₃-C₁₂ cycloalkyl, C1-C12 heterocyclyl, C₂-Ci₂ alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, Ce-C₂₀ aralkyl, C₆-C₂₀ alkylaryl, and CrCi₂ heteroaryl.

18. The process of claim 17, wherein said acid scavenger is

R N ^ N

19. The process of claim 17 or 18, wherein said acid scavenger is liquid at room temperature.

20. The process of any one of claims 17 to 19, wherein R comprises a polymerizable moiety.

21. The process of any one of claims 9 to 18, wherein said acid scavenger is

22. The process of any one of claims 9 to 18, wherein said acid scavenger is

23. The process of any one of claims 9 to 22, wherein said compound of formula (I) is chosen from LiFePO₄, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

24. The process of any one of claims 9 to 23, wherein said compound of formula (I) is LiFePO₄.

25. The process of claim 24, wherein said compound of formula (III) is chosen from FeCI₂, FeBr₂, FeI₂, FeF₂, Fe(CN)₂, Fe(SCN)₂, FeSO₄, Fe(CH₃COO)₂, and FeC₂O₄.

26. The process of any one of claims 1 to 25, wherein said compound of formula (I) is annealed after being prepared.

27. The process of any one of claims 1 to 26, wherein the compound of formula (I) is in the form of nanoparticles.

28. The process of any one of claims 1 to 27, wherein said predetermined temperature is lower than 200 ⁰C.

29. The process of any one of claims 1 to 27, wherein said predetermined temperature is lower than 150 ⁰C.

30. The process of any one of claims 1 to 27, wherein said predetermined temperature is lower than 100 ⁰C.

31. The process of any one of claims 1 to 27, wherein said predetermined temperature is about 15 ⁰C to about 60 ⁰C.

32. The process of any one of claims 1 to 27, wherein said predetermined temperature is about 20 ⁰C to about 35 ⁰C.

33. Use of a compound of formula (IV):

(IV)

wherein R is chosen from hydrogen atom, C1-C12 alkyl, C3-C12 cycloalkyl, C₁-C₁₂ heterocyclyl, C₂-Ci₂ alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, C₆-C₂₀ aralkyl, C₆-C_2O alkylaryl, and CrCi₂ heteroaryl,

as an acid scavenger in the preparation of a phospho-olivine type compound.

34. The use of claim 33, wherein said compound of formula (IV) is

R N ^ N

\=/

35. The use of claim 33 or 34, wherein said phospho-olivine type compound is chosen from LiFePO₄, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

36. The use of claim 35, wherein said phospho-olivine type compound is LiFePO₄.

37. The use of any one of claims 33 to 36, wherein said compound of formula (IV) is

38. The use of any one of claims 33 to 36, wherein said compound of formula (IV) is

\ N N

39. A method of using a compound of formula (IV)

(IV)

wherein

R is chosen from hydrogen atom, d-C-₁₂ alkyl, C₃-Ci₂ cycloalkyl, C1-C12 heterocyclyl, C2-C12 alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, C6-C₂o aralkyl, C6-C20 alkylaryl, and C1-C12 heteroaryl,

said method comprising using said compound of formula (IV) as an acid scavenger in the preparation of a phospho-olivine type compound.

40. The method of claim 39, wherein said compound of formula (IV) is contacted with protons generated during the synthesis of said phospho-olivine type compound.

41. A method of scavenging protons, said method comprising contacting said protons with a compound of formula (IV):

(IV)

wherein R is chosen from hydrogen atom, C1-C12 alkyl, C3-C12 cycloalkyl, C₁-C₁₂ heterocyclyl, C₂-Ci₂ alkenyl, C₂-Ci₂ alkynyl, C₆-Ci₂ aryl, C₆-C₂O aralkyl, C₆-C_2O alkylaryl, and Ci-Ci₂ heteroaryl.

42. The method of claim 42, wherein said compound of formula (IV) is contacted with protons generated during preparation of a phospho- olivine type compound.

43. The method of claim 42, wherein said compound of formula (IV) is further used as a solvent during preparation of said phospho-olivine type compound.

44. The method of claim 39, 40, 42, or 43, wherein said phospho-olivine type compound is chosen from LiFePO₄, LiBePO₄, LiMgPO₄, LiBaPO₄, LiCaPO₄, LiSrPO₄, LiCoPO₄, LiNiPO₄, LiMnPO₄, LiZnPO₄, LiCuPO₄, and LiMoPO₄.

45. The method of claim 44, wherein said phospho-olivine type compound is LiFePO₄.

46. In a method for preparing LiFePO₄ comprising reacting together a lithium source, an iron source, and a phosphorus source, the improvement wherein said lithium source and said phosphorous source is LiH₂PO₄, and said iron source is FeX_n in which X is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO^", CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃-, CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2"; and n is 1 or 2.

47. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature lower than 200 ⁰C.

48. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature lower than 150 ⁰C.

49. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature lower than 100 ⁰C.

50. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature lower than 60 ⁰C.

51. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at room temperature.

52. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature of about 15 ⁰C to about 60 ⁰C.

53. The method of claim 46, wherein LiH₂PO₄ is reacted with FeX_n at a temperature of about 20 ⁰C to about 35 ⁰C.

54. The method of any one of claims 46 to 53, said method being characterized in that a compound of formula (IV):

(IV)

wherein

R is chosen from hydrogen atom, C₁-C₁₂ alkyl, C₃-Ci₂ cycloalkyl, C₁- C₁₂ heterocyclyl, C₂-C₁₂ alkenyl, C₂-Ci₂ alkynyl, Ce-C₁₂ aryl, Ce-C_2O aralkyl, C6-C₂o alkylaryl, and C₁-C₁₂ heteroaryl,

is used as a proton scavenger.

55. The method of claim 54, wherein said compound of formula (IV) is also used as a solvent.

56. The method of any one of claims 39 to 45 and 54, wherein said compound of formula (IV) is

57. The method of any one of claims 39 to 45 and 54, wherein said compound of formula (IV) is

58. The method of any one of claims 39 to 45 and 54, wherein said compound of formula (IV) is

\_ S N % N

59. A process for preparing a compound of formula (Ia):

AM¹τM² _1-τPO₄ (Ia)

wherein

A is chosen from H⁺, Li⁺, Na⁺, K⁺, and Cs⁺; and

M¹ is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺; M² is chosen from Be²⁺, Mg²⁺, Ba²⁺, Ca²⁺, Sr²⁺, Fe²⁺, Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, Cu²⁺, and Mo²⁺; and

T has a value of 0 to 1 ,

said process comprising reacting a compound of formula (II) with a compound of formula (Ilia) and a compound of formula (IUb) :

AH₂PO₄ (II)

M²(X²) _n2 (HIb)

wherein

A is as previously defined;

M¹ and M² are as previously defined;

X¹ is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO-, CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2";

X² is chosen from F^", Cl^", Br^", I^", CN^", CH₃COO^", CF₃SO₃ ^", NO₃ ^", OCN^", SCN^", (CN)₂N^", CO₃ ^2", CIO₃ ^", CrO₄ ^2", BrO₃ ^", Cr₂O₇ ^2", S₂O₄ ^2", S₄O₆ ^2", S₂O₃ ^2", SO₄ ^2", MnO₄ ^", S^2", CIO^", and C₂O₄ ^2";

n¹ is 1 or 2;

n² is 1 or 2;

in the presence of an acid scavenger adapted to at least substantially solubilize said compound of formula (II), said compound of formula (Ilia), and said compound of formula (HIb), at a predetermined temperature, and adapted to be converted into a protic ionic liquid upon protonation.

60. The process of claim 59, wherein T has a value comprised between 0 and 1.

61. The process of claim 59 or 60, wherein said compound of formula (Ia) is annealed after being prepared.

62. The process of any one of claims 59 to 61 , wherein the compound of formula (Ia) is in the form of nanoparticles.

63. The process of any one of claims 59 to 62, wherein said predetermined temperature is lower than 200 ⁰C.

64. The process of any one of claims 59 to 62, wherein said predetermined temperature is lower than 150 ⁰C.

65. The process of any one of claims 59 to 62, wherein said predetermined temperature is lower than 100 ⁰C.

66. The process of any one of claims 59 to 62, wherein said predetermined temperature is about 15 ⁰C to about 60 ⁰C.

67. The process of any one of claims 59 to 62, wherein said predetermined temperature is about 20 ⁰C to about 35 ⁰C.