METHOD FOR PRODUCING A LITHIUM-CONTAINING METAL OXIDE THAT CAN BE USED AS AN ACTIVE MATERIAL FOR A POSITIVE ELECTRODE

Abstract

A method for producing a lithium-containing oxide comprising one or more metal elements, which can be used as an active material for an electrode, for example a positive electrode for a lithium battery, the method comprising the following successive steps: a) a step of bringing at least one coordination polymer into contact with a lithium source, the coordination polymer comprising the other metal element(s) interconnected by organic ligands; b) a step of calcining the mixture resulting from step a).

Claims

1.-17. (canceled)

18. Method for producing a lithium-containing oxide comprising one or more other metal elements comprising the following successive steps: a) a step of contacting at least one coordination polymer comprising the metal element or other metal elements bonded to one another by organic ligands with a lithium source; b) a step of calcination of the mixture produced from step a).

19. Method according to claim 18, wherein the metal element or other metal elements are selected from transition metal elements, post-transition metal elements and mixtures of the latter.

20. Method according to claim 18, wherein the metal element or other metal elements are selected from manganese, cobalt, nickel and mixtures thereof.

21. Method according to claim 18, wherein the organic ligands comprise at least two groups establishing coordination bonds with the metal element or other metal elements.

22. Method according to claim 18, wherein the organic ligands are: organic ligands comprising at least two groups selected from —COOR groups, —OH groups and combinations thereof, with R representing a hydrogen atom or a monovalent cation; organic ligands consisting of aromatic compounds comprising at least one ring comprising at least two nitrogen atoms; or mixtures thereof.

23. Method according to claim 18, wherein the organic ligands are aromatic compounds comprising at least one ring comprising at least two groups selected from —COOR groups, OH groups and combinations thereof, with R representing a hydrogen atom or a monovalent cation.

24. Method according to claim 23, wherein the organic ligands are ligands from the family of hydroxyterephthalic acids.

25. Method according to claim 23, wherein the coordination polymer is a coordination polymer comprising at least one metal element selected from cobalt, nickel, manganese and mixtures thereof, the metal elements being bonded to one another by organic ligand, wherein the organic ligand is: an organic ligand comprising at least two groups selected from —COOR groups, —OH groups and combinations thereof, with R representing a hydrogen atom or a monovalent cation; an organic ligand consisting of aromatic compounds comprising at least one ring comprising at least two nitrogen atoms; an aromatic compound comprising at least one ring comprising at least two groups selected from —COOR groups, OH groups and combinations thereof, with R representing a hydrogen atom or a monovalent cation; or mixtures thereof.

26. Method according to claim 18, wherein the organic ligands are: monocyclic aromatic compounds with five members comprising two nitrogen atoms; bicyclic aromatic compounds, where one ring is a ring with five members comprising two nitrogen atoms; monocyclic aromatic compounds with six members comprising two nitrogen atoms or three nitrogen atoms; or mixtures of the latter.

27. Method according to claim 26, wherein the organic ligands are imidazole compounds corresponding to at least of the following formulae (II) to (V): ##STR00006##

28. Method according to claim 26, wherein the organic ligands are benzimidazole compounds.

29. Method according to claim 26, wherein the organic ligands are compounds corresponding to one of the formulae (VII) to (IX): ##STR00007##

30. Method according to claim 26, wherein the organic ligands are compounds according to one of the following formulae (X) to (XII): ##STR00008##

31. Method according to claim 26, wherein the coordination polymer is a coordination polymer comprising cobalt and organic ligands, wherein the organic ligands are: monocyclic aromatic compounds with five members comprising two nitrogen atoms; bicyclic aromatic compounds, where one ring is a ring with five members comprising two nitrogen atoms; monocyclic aromatic compounds with six members comprising two nitrogen atoms or three nitrogen atoms; or mixtures of the latter.

32. Method according to claim 18, wherein the source of lithium is lithium carbonate, lithium hydroxide or lithium acetate.

33. Method according to claim 18, wherein the calcination step is performed at a temperature ranging from 700° C. to 1000° C. for a duration ranging from 12 hours to 24 hours.

34. Method according to claim 18, also comprising a step of preparing the coordination polymer or polymers used in step a).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present invention will be better understood by referring to the following description and the accompanying figures in which:

[0068] FIGS. 1A, 2A, 3A and 4A are schematic representations of different coordination polymers, according to different embodiments of the invention;

[0069] FIGS. 1B, 2B, 3B and 4B are schematic representations of different oxides obtained after calcination of the coordination polymers represented respectively in FIGS. 1A, 2A, 3A and 4A, according to different embodiments of the invention;

[0070] FIGS. 1C, 2C, 3C and 4C show X-ray diffraction spectra of the coordination polymers represented respectively in FIGS. 1A, 2A, 3A and 4A;

[0071] FIGS. 1D, 2D, 3D and 4D show X-ray diffraction spectra of the oxides represented respectively in FIGS. 1B, 2B, 3B and 4B;

[0072] FIGS. 1E, 2E, 3E and 4E are graphs representing the capacity C (in mAh/g) as a function of the ring number N at C/10 of the oxides represented respectively in FIGS. 1B, 2B, 3B and 4B; and

[0073] FIG. 1F is a graph representing the capacity C (in mAh/g) as a function of the ring number at 1C of metal oxide represented in FIG. 1B.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

Example 1

[0074] The present example relates to the synthesis of a lamellar oxide of type Li(Ni.sub.1/3Mn.sub.1/3Co.sub.1/3)O.sub.2 from a coordination polymer with a base of 2,5-dihydroxyterephthalic acid and metal elements cobalt, nickel and manganese (this coordination polymer can be denoted MOF-74) which is reacted with lithium carbonate to form the aforementioned lithium-containing oxide.

[0075] The reaction scheme is illustrated symbolically in FIGS. 1A and 1B by representation of the coordination polymer MOF-74 and the lithium-containing oxide having different octahedral sheets 1 comprising cobalt, manganese and nickel between which infill sheets 3 of lithium ions are arranged.

[0076] To achieve this, a mixture of 0.43 g cobalt nitrate Co(NO.sub.3).sub.2*6H.sub.2O, 0.37 g manganese nitrate Mn(NO.sub.3).sub.2*4H.sub.2O and 0.43 g nickel nitrate Ni(NO.sub.3).sub.2*6H.sub.2O is dissolved in a solution comprising a mixture of 51 mL dimethylformamide, 3 mL ethanol and 3 mL water.

[0077] 2,5-dihydroxyterephthalic (2,5-dhtp) acid (0.10 g) is introduced into the mixture. The solution is then decanted into an autoclave and heated to 160° C. for 24 hours. A black powder is obtained. An X-ray diffraction analysis (XRD) confirms that it is a MOF-74 (Ni.sub.xMn.sub.yCo.sub.z).sub.2(2,5-dhtp), the result of this analysis being illustrated in FIG. 1C.

[0078] This material is then mixed with 0.23 g lithium carbonate (excess of 3.3% in stoichiometric ratio relative to 7.24 mmol recovered MOF-74) then is calcined at 900° C. for 24 hours.

[0079] The X-ray diffraction analysis (XRD) of the powder obtained shows lithium-containing metal oxide obtained in lamellar form Li(Ni.sub.1/3Mn.sub.1/3Co.sub.1/3)O.sub.2, the result of this analysis being illustrated in FIG. 1D.

[0080] The lithium-containing oxide obtained in this way is subjected to electrochemical tests to determine the evolution of its specific capacity as a function of the number of cycles, the results being shown in FIG. 1E (for a C/10 regime) and FIG. 1F (for a 1C regime). This indicates, for a C/10 regime, a capacity ranging between 150 and 120 mAh/g between 0 and 100 cycles and, for a 1C regime, a capacity ranging between 120 and 100 mAh/g between 0 and 100 cycles. These results are the level of those obtained with a NMC type lithium-containing oxide already used in lithium batteries.

EXAMPLE 2

[0081] The present example relates to the synthesis of a lamellar oxide LiCoO.sub.2 from a coordination polymer based on 2-methylimidazole and cobalt (this coordination polymer can be denoted ZIF-8) which is reacted with lithium carbonate to form the aforementioned lamellar oxide.

[0082] The reaction scheme is illustrated symbolically in FIGS. 2A and 2B by representation of the coordination polymer ZIF 8 in FIG. 2A and, in FIG. 2B, of lithium-containing oxide having different octahedral sheets 5 comprising cobalt between which infill sheets 7 of lithium ions are arranged.

[0083] To achieve this, a mixture of 2.8 g cobalt nitrate Co(NO.sub.3).sub.2*6H.sub.2O and 5.9 g 2-methylimidazole is mixed with 60 mL methanol. After dissolving cobalt nitrate, the mixture is then placed into an autoclave which is heated at 100° C. for 16 hours. A violet powder is produced. An X-ray diffraction analysis (XRD) confirms that it is a type ZIF-8 coordination polymer, the result of this analysis being illustrated in FIG. 2C.

[0084] 300 mg of this material is then mixed with 52.6 g Li.sub.2CO.sub.3 (excess of 3.3% in stoichiometric ratio) then is calcined at 850° C. for 24 hours.

[0085] The X-ray diffraction analysis (XRD) of the powder obtained shows the production of a lithium-containing metal oxide in the form of lamellar LiCoO.sub.2, the result of this analysis being illustrated in FIG. 2D.

[0086] The lithium-containing oxide obtained in this way is subjected to electrochemical tests, so as to determine its specific capacity, the results being presented in FIG. 2E (for a C/10 regime). This indicates an initial specific capacity of 120 mAh/g.

EXAMPLE 3

[0087] The present example relates to the synthesis of a lamellar oxide of type LiMn.sub.2O.sub.4 from a coordination polymer based on 2,5-dihydroxyterephthalic acid and manganese (this coordination polymer can be denoted MOF-74) which is reacted with lithium carbonate to form the aforementioned lithium-containing oxide.

[0088] The reaction scheme is illustrated symbolically in FIGS. 3A and 3B by representation of the coordination polymer MOF-74 and the spinel structure lithium-containing oxide.

[0089] To achieve this, 1.37 g Mn(NO.sub.3).sub.2*4H.sub.2O is dissolved in a solution comprising 55 mL dimethylformamide and 2.5 mL water. To that, 2,5-dihydroxyterephthalic acid (0.56 g in 2.5 mL water) is introduced into the mixture. The solution is then decanted into an autoclave then heated to 160° C. for 24 hours. An X-ray diffraction analysis (XRD) confirms that it is a MOF-74 type coordination polymer, the result of this analysis being illustrated in FIG. 3C.

[0090] 300 mg of this material is then mixed with 19.1 mg lithium carbonate (excess of 3.3% in stoichiometric ratio) then is calcined at 800° C. for 12 hours.

[0091] X-ray diffraction analysis of the powder obtained shows obtaining a spinel phase of LiMn.sub.2O.sub.4, as shown in FIG. 3D.

[0092] The lithium-containing oxide obtained in this way is subjected to electrochemical tests, so as to determine its specific capacity, the results being presented in FIG. 3E (for a C/10 regime). This results in an initial specific capacity of 100 mAh/g.

EXAMPLE 4

[0093] The present example relates to the synthesis of a lamellar oxide LiCoO.sub.2 from a coordination polymer based on 2,5-dihydroxyterephthalic acid and cobalt (this coordination polymer can be denoted MOF-74) which is reacted with lithium carbonate for forming the aforementioned lithium-containing oxide.

[0094] The reaction scheme is illustrated symbolically in FIGS. 4A and 4B by representation of the coordination polymer MOF-74 and lamellar lithium-containing oxide having different octahedral sheets 9 comprising cobalt between which infill sheets 11 of lithium ions are arranged.

[0095] To achieve this, 1.62 g cobalt nitrate Co(NO.sub.3).sub.2*6H.sub.2O is dissolved in a solution comprising 55 mL dimethylformamide and 2.5 mL water. To that, 2,5-dihydroxyterephthalic acid (0.56 g in 2.5 mL water) is introduced into the mixture. The solution is then decanted into an autoclave then heated at 160° C. for 24 hours. An X-ray diffraction analysis (XRD) confirms that it is a MOF-74 type coordination polymer, the result of this analysis being illustrated in FIG. 4C.

[0096] 300 mg of this material is then mixed with 37.3 mg lithium carbonate (excess of 3.3% in stoichiometric ratio) then is calcined at 800° C. for 12 hours.

[0097] The X-ray diffraction analysis (XRD) of the powder obtained shows the formation of a lithium-containing metal oxide in the form of lamellar LiCoO.sub.2, the result of this analysis being illustrated in FIG. 4D.

[0098] The lithium-containing oxide obtained in this way is subjected to electrochemical tests, so as to determine the evolution of its specific capacity as a function of the number of cycles, the results being presented in FIG. 4E (for a C/10 regime). This indicates an initial specific capacity of 105 mAh/g, which remains stable for at least 50 cycles.