PROCESS FOR PREPARING LITHIUM SALTS SUCH AS ANHYDROUS LITHIUM HYDROXIDE AND ANHYDROUS LITHIUM HALIDES

Abstract

The present invention relates to a method for producing lithium salts, such as lithium hydroxide and lithium halides, wherein the lithium salts obtained are substantially free of water and optionally other impurities, such as lithium carbonate and/or lithium oxide. Moreover, the present invention refers to lithium salts, such as lithium hydroxide and lithium halides obtainable by said method, as well as their use for the production of e.g. solid electrolytes, lithium metal or lithium carbonate.

Claims

1. Method for producing a lithium salt which is substantially free of water comprising the steps of: (i) providing lithium hydroxide, hydrates, solvates or mixtures thereof as a starting material in a reactor, wherein the starting material is preferably in solid form, and (ii) subjecting the starting material of step (i) to a stream of carrier gas at room temperature or elevated temperatures, such as at 20-100° C., preferably 20-80° C., more preferably 60-80° C.

2. Method according to claim 1, wherein the starting material in step (i) is LiOH, LiOH.Math.H.sub.2O or a mixture thereof.

3. Method according to claim 1, wherein the carrier gas is an inert gas, including argon, dry air and/or nitrogen.

4. Method according to claim 1, wherein the carrier gas is introduced into the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h and/or exits the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h.

5. Method according to claim 1, wherein the product obtained after step (ii) is substantially free of Li.sub.2CO.sub.3 and/or Li.sub.2O.

6. Method according to claim 1, wherein the method further comprises (iii) contacting the product obtained after step (ii) with a halogen-containing gas, thereby forming lithium halides, wherein step (iii) is preferably carried out at room temperature or elevated temperatures, such as at 20-300° C., preferably 80-200° C., more preferably 80-150° C.

7. Method according to claim 6, wherein the halogen-containing gas is selected from the group consisting of HCl, HBr, HF, HI, and mixtures thereof, preferably HCl, HBr, and mixtures thereof.

8. Method according to claim 6, wherein the halogen-containing gas is introduced into the reactor at a rate of 40-5000 g/h, preferably 50-4500 g/h, more preferably 100-3000 g/h.

9. Method according to claim 6, wherein step (iii) comprises applying a stream of gas comprising the halogen-containing gas, preferably in a volume concentration of 0.001-100 vol.%, more preferably 1.0-10 vol.%, based on the total volume of the gas stream.

10. Method according to claim 6, wherein step (iii) comprises applying a stream of gas comprising a carrier gas.

11. Method according to claim 6, wherein the carrier gas is introduced into the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h and/or exits the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h.

12. Method according to claim 1, wherein the carrier gas and/or the starting material and/or the halogen containing gas acts as a fluid, e.g. in a fluidized bed reactor.

13. Lithium salt product obtainable by a method according to claim 1, which is substantially free of water, Li.sub.2CO.sub.3 and/or Li.sub.2O, preferably free of water, Li.sub.2CO.sub.3 and Li.sub.2O.

14. Lithium salt product obtainable by a method according to claim 6, which is substantially free of water, LiOH and/or Li.sub.2O, preferably free of water, LiOH and Li.sub.2O.

15. Use of the product according to claim 13 for the production of solid electrolytes, lithium metal, lithium carbonate or lithium halides, particularly lithium halides, which are substantially free of water.

Description

[0064] FIG. 1: Powder X-ray diffraction pattern of LiOH obtained according to Example 3 (lower pattern) and comparative Example 2 (upper pattern), measured with CuKα radiation in a 2θ range from 10-90° and displayed as relative intensity I.sub.rel.

[0065] FIG. 2: Raman spectrum of LiCl obtained according to Example 4 (lower spectrum) and comparative Examples 3 (upper spectrum) and 4 (middle spectrum), measured with a laser wavelength of 532 nm from 50-1866 cm.sup.-1 and displayed as relative intensity I.sub.rel.

METHODS

[0066] X-ray powder diffraction analysis was conducted on a Bruker D2 phaser diffractometer with CuK.sub.α radiation in a 2θ range of 10-90° with a step width of 0.040° displayed as relative intensity I.sub.rel. Semiquantitave analysis was conducted by comparing the intensities of the highest reflection of LiOH (2θ=32.5°) and Li.sub.2O (2θ=33.7°).

[0067] Raman spectroscopy analysis was performed on a Thermo Fischer Scientific DXR3 SmartRaman spectrometer with a laser wavelength of 532 nm, an exposure time of 1 s with 32 exposure scans from 50-1866 cm.sup.-1.

[0068] The carbonate content was analyzed by potentiometric acid/base titration utilizing a 1 N and 0.01 N hydrochloric acid, respectively. The measurements had been performed on a Metrohm Titrando 905 system.

[0069] The water content was determined by Karl-Fischer coulometry employing the oven method (T = 150° C.; gas flow = 60 ml/min) using a Metrohm 874 Oven Sample Processor.

Example 1

[0070] 100.0 g of LiOH .Math. H.sub.2O having a total water content of 42 wt.% were heated at 80° C. for 60 min in a fluidized bed reactor while subjected to a stream of nitrogen gas, yielding anhydrous lithium hydroxide salt.

[0071] The water content of the starting material and the product obtained was determined by XRD and Karl-Fischer titration.

[0072] No lithium oxide was detected in the product by XRD.

[0073] No lithium carbonate was detected in the product by XRD and potentiometric titration.

[0074] Example 2

[0075] 58 g of anhydrous lithium hydroxide, obtained as described in Example 1, were heated at 200° C. for 120 min in a fluidized bed reactor while subjected to a stream of gas, comprising 3 vol.% of HCl and 97 vol.% of nitrogen with respect to the total volume of gas stream, yielding anhydrous lithium chloride salt. The stream of gas was introduced into the reactor at a rate of 1 m.sup.3/h.

[0076] The water content of the product obtained was determined by XRD and Karl-Fischer titration.

[0077] No lithium oxide was detected in the product by XRD.

[0078] No lithium carbonate was detected in the product by XRD and potentiometric titration.

[0079] No lithium hydroxide was detected in the product by XRD.

Example 3

[0080] 100.0 g of LiOH .Math. H.sub.2O having a total water content of 43.5 wt.% were heated at 80° C. for 60 min in a fluidized bed reactor while subjected to a stream of nitrogen gas at a rate of 21 m.sup.3/h, yielding anhydrous lithium hydroxide salt.

[0081] The water content of the starting material and the product obtained was determined by Karl-Fischer titration (See table 1).

[0082] The lithium carbonate content was detected in the product by potentiometric titration (See table 1).

[0083] Comparative examples 1 and 2 were conducted as described below.

TABLE-US-00001 Water and carbonate content in LiOH according to Example 3 and Comparative Example 1 H.sub.2O [wt.%] CO.sub.3.sup.2- [wt.%] Example 3 0.04 0.25 Comparative Example 1 1.00 1.41

[0084] No lithium oxide was detected in the product according to Example 3 by XRD (See FIG. 1, lower pattern).

[0085] A lithium oxide content of 2.1 wt.% was detected in the comparative example 2 by XRD (See FIG. 1, upper pattern).

Example 4

[0086] 58 g of anhydrous lithium hydroxide, obtained as described in Example 3, were heated at 200° C. for 120 min in a fluidized bed reactor while subjected to a stream of gas, comprising 3 vol.% of HCl and 97 vol.% of nitrogen with respect to the total volume of gas stream, yielding anhydrous lithium chloride salt. The stream of gas was introduced into the reactor at a rate of 1 m.sup.3/h.

[0087] The water content of the product obtained was determined Karl-Fischer titration (See table 2).

[0088] Comparative examples 3 and 4 were conducted as described below.

TABLE-US-00002 Water content in LiCl according to Example 4 and Comparative Examples 4 and 5 H.sub.2O [wt.%] Example 4 0.03 Comparative Example 3 1.87

[0089] No lithium hydroxide was detected in the product by Raman Spectroscopy at 318 cm.sup.-1 (See FIG. 2, lower spectrum).

[0090] Lithium hydroxide was detected in the Comparative Example 3 by Raman Spectroscopy at 318 cm.sup.-1 (See FIG. 2, upper spectrum).

[0091] No lithium oxide was detected in the product by Raman Spectroscopy at 528 cm.sup.-1 (See FIG. 2, lower spectrum).

[0092] Lithium oxide was detected in the Comparative Example 4 by Raman Spectroscopy (See FIG. 2, middle spectrum).

Comparative Examples

[0093] Comparative examples 1 and 2 were conducted analogous to example 3, while altering the experimental parameters as summarized in table 3 below.

[0094] Comparative examples 3 and 4 were conducted analogous to example 4, while altering the experimental parameters as summarized in table 3 below.

TABLE-US-00003 Experimental parameters for Comparative Examples 1-4 Comparative Example No. Target Product Carrier gas type Carrier gas rate [m.sup.3/h] HCl gas rate [m.sup.3/h] Temperature [°C] 1 LiOH Air (humid) 21 0 80 2 LiOH N.sub.2 21 0 400 3 LiCl N.sub.2 0.05 0.03 200 4 LiCl N.sub.2 0.97 0.03 450

[0095] The present invention covers the following items: [0096] 1. Method for producing a lithium salt which is substantially free of water comprising the steps of: [0097] (i) providing lithium hydroxide, hydrates, solvates or mixtures thereof as a starting material in a reactor, wherein the starting material is preferably in solid form, and [0098] (ii) subjecting the starting material of step (i) to a stream of carrier gas at room temperature or elevated temperatures. [0099] 2. Method according to item 1, wherein the starting material in step (i) is LiOH, LiOH.Math.H.sub.2O or a mixture thereof. [0100] 3. Method according to item 1 or 2, wherein the reactor in step (i) is a heatable reactor. [0101] 4. Method according to any of the preceding items, wherein the reactor in step (i) is a sealable reactor, preferably having a gas inlet tube and a gas outlet tube. [0102] 5. Method according to any of the preceding items, wherein step (ii) is conducted at temperatures of 20-150° C., preferably 60-130° C., more preferably80- 100° C. [0103] 6. Method according to any of the preceding items, wherein the carrier gas is an inert gas, such as argon, dry air and/or nitrogen. [0104] 7. Method according to item 6, wherein the carrier gas acts as a fluid, e.g. in a fluidized bed reactor. [0105] 8. Method according to any of the preceding items, wherein the carrier gas is introduced into the reactor via the gas inlet tube and exits the reactor via the gas outlet tube. [0106] 9. Method according to any of the preceding items, wherein the carrier gas is introduced into the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h. [0107] 10. Method according to any of the preceding items, wherein the carrier gas exits the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h. [0108] 11. Method according to any of the preceding items, wherein step (ii) is conducted under inert gas atmosphere, such as argon, dry air and/or nitrogen gas atmosphere, which is preferably the same as the carrier gas. [0109] 12. Method according to any of the preceding items, wherein the starting material acts as a fluid, e.g. in a fluidized bed reactor. [0110] 13. Method according to any of the preceding items, wherein the product obtained after step (ii) has a water content of less than 1.0 wt.-%, preferably not more than 0.5 wt.-%, preferably 0.001 to 0.5 wt.-% based on the total product weight. [0111] 14. Method according to any of the preceding items, wherein the product obtained after step (ii) is substantially free of Li.sub.2CO.sub.3 and/or Li.sub.2O. [0112] 15. Method according to any of the preceding items, wherein the method further comprises (iii) contacting the product obtained after step (ii) with a halogen-containing gas, thereby forming lithium halides. [0113] 16. Method according to item 15, wherein the halogen-containing gas is selected from the group consisting of HCI, HBr, HF, HI, and mixtures thereof, preferably HCI, HBr, and mixtures thereof. [0114] 17. Method according to item 15 or 16, wherein step (iii) is carried out at room temperature or elevated temperatures such as 20-300° C., preferably 80-200° C., more preferably 80-150° C. [0115] 18. Method according to any of items 15-17, wherein the halogen-containing gas is introduced into the reactor at a rate of 40-5000 g/h, preferably 50-4500 g/h, more preferably 100-3000 g/h. [0116] 19. Method according to any of items 15-18, wherein step (iii) comprises applying a stream of gas comprising the halogen-containing gas, preferably in a volume concentration of 0.001-100 vol.%, more preferably 1.0-10 vol.%, based on the total volume of the gas stream. [0117] 20. Method according to any of items 15-19, wherein step (iii) comprises applying a stream of gas comprising a carrier gas which is preferably the same as the carrier gas of step (ii). [0118] 21. Method according to item 20, wherein the carrier gas acts as a fluid, e.g. in a fluidized bed reactor. [0119] 22. Method according to any of items 15-21, wherein the halogen-containing gas and/or the carrier gas is introduced into the reactor via the gas inlet tube and exits the reactor via the gas outlet tube. [0120] 23. Method according to any of items 20-22, wherein the carrier gas is introduced into the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h. [0121] 24. Method according to any of items 20-23, wherein the carrier gas exits the reactor at a rate of 0.1-1000 m.sup.3/h, preferably 5-500 m.sup.3/h, more preferably 10-50 m.sup.3/h. [0122] 25. Method according to any of items 15-24, wherein the product obtained after step (ii) acts as a fluid, e.g. in a fluidized bed reactor. [0123] 26. Method according to any of items 15-25, wherein step (iii) is conducted under inert gas atmosphere such as argon, dry air and/or nitrogen gas atmosphere, which is preferably the same as the carrier gas. [0124] 27. Method of producing lithium halide comprising the steps (i) and (ii) according to any of items 1-14 and step (iii) according to any of items 15-26. [0125] 28. Lithium salt product obtainable by a method according to any of items 1-14. [0126] 29. Lithium salt product obtainable by a method according to any of items 15-27. [0127] 30. Product according to item 28, which is substantially free of water, Li.sub.2CO.sub.3 and/or Li.sub.2O, preferably free of water, Li.sub.2CO.sub.3 and Li.sub.2O. [0128] 31. Product according to item 29, which is substantially free of water, LiOH and/or Li.sub.2O, preferably free of water, LiOH and Li.sub.2O. [0129] 32. Use of the product according to any of items 28-31 for the production of solid electrolytes, lithium metal, lithium carbonate or lithium halides, particularly lithium halides, which are substantially free of water. [0130] 33. Method according to items 1-27, wherein step (ii) is conducted at temperatures of 20-100° C., preferably 20-80° C., and more preferably 60-80° C.