Cyclic process for wet-chemically producing lithium metal phosphates

Patent metadata

Field	Value
Publication number	US-9242864-B2
Application number	US-90883206-A
Country	US
Kind code	B2
Filing date	Mar 17, 2006
Priority date	Mar 18, 2005
Publication date	Jan 26, 2016
Grant date	Jan 26, 2016

Abstract

The invention relates to a method for producing lithium metal phosphates of a formula LiMPO 4 , wherein M is at least one type of bivalent metal, preferably selected from the first transition metal range. The inventive method consists in reacting a lithium phosphate with a metal salt and an acid phosphate source in a polar solvent for converting into a corresponding M-containing phosphate, in adding a basic lithium source for obtaining a precursor mixture for a desired lithium metal phosphate, in converting and separating the thus obtained mixture, preferably in hydrothermal conditions, in such a way that a desired final product is obtained, thereby receiving a lithium-containing filtrate. The addition of the basic lithium source initiates a lithium ion precipitation in the form of a lithium phosphate. The thus obtainable lithium phosphate can be reused in the form of a raw material, whereby said cycle enables lithium to be highly reusable.

First claim

The invention claimed is:

1. A process for preparing a lithium metal phosphate of the formula LiMPO 4 , where M is at least one divalent metal, which comprises:
a) reacting a Li 3 PO 4 (lithium phosphate) with at least one metal salt MX n and an acid phosphate source in a solution containing the at least one metal salt MX n and the acid metal phosphate source and a polar solvent, wherein M is at least one transition metal and X is an anion other than phosphate which together with the metal M forms a salt which is soluble in the solvent and n is the quotient of the valency of the metal M and the valency of the anion X, giving a suspension of particles of at least one M-containing phosphate in the solvent;
b) adding a basic lithium source to the suspension of M-containing phosphate in the solvent obtained in (a), giving a precipitation product;
c) converting the precipitation product obtained in (b) into a lithium metal phosphate of the formula LiMPO 4 , giving a residual solution containing lithium ions;
d) adding a basic phosphate source to the residual solution so that lithium phosphate is precipitated from the residual solution; and
e) separating the lithium phosphate from the residual solution.

2. A process according to claim 1 , wherein the lithium phosphate obtained in (e) is recirculated to (a).

3. A process according to claim 1 , wherein M is selected from the group consisting of Fe, Mn, Co and Ni.

4. A process according to claim 1 , wherein M is Fe.

5. A process according to claim 1 , wherein X is selected from the group consisting of chloride, nitrate and sulphate.

6. A process according to claim 1 , wherein the pH of the solution containing the at least one metal salt MX n , the acid phosphate source and the polar solvent is less than 2, the pH of the suspension of M-containing phosphate in the solvent is in the range of 2 to 6, and the pH of the suspension containing the precipitated product in (b) is in the range from 6 to 8.

7. A process according to claim 1 , wherein a reducing agent is added in (a) or (b) or in (a) and (b).

8. A process according to claim 1 , wherein the polar solvent is water.

9. A process according to claim 1 , wherein the acid phosphate source in (a) is a phosphoric acid compound.

10. A process according to claim 1 , wherein the basic lithium source in (b) is lithium hydroxide or lithium oxide or is lithium hydroxide and lithium oxide.

11. A process according to claim 1 , wherein the basic phosphate source in (d) is an alkali metal phosphate.

12. A process according to claim 1 , wherein the reacting in (a) and adding in (b) are carried out at a temperature of 5° to 80° C.

13. A process according to claim 1 , wherein (a) or (b), or (a) and (b) comprises forming particle aggregates and (a) or (b), or (a) and (b), further comprises carrying out deagglomerating or comminuting, or deagglomerating and comminuting, particle aggregates in the suspension until the D 90 of the particles present in the suspension is less than 50 μm.

14. A process according to claim 13 , wherein the D 90 of the particles present in the suspension is less than 25 μm.

15. A process according to claim 13 , wherein the dispersing or milling treatment is carried out in (a) or (b) or in (a) and (b).

16. A process according to claim 13 , wherein
(I) the deagglomerating or comminuting, or deagglomerating and comminuting, particle aggregates commences before addition of the metal salt MX n in (a) and is continued during (a) or
(II) the deagglomerating or comminuting, or deagglomerating and comminuting, particle aggregates commences before addition of the metal salt MX n in (a) and is continued during (a) and (b) or
(III) the deagglomerating or comminuting, or deagglomerating and comminuting, particle aggregates in (b) commences before addition of the basic lithium source and is continued during (b).

17. A process according to claim 1 , further comprising adding
(A) a carbon-containing or electron-conducting substance or a precursor compound of an electron-conducting substance, or
(B) a carbon-containing and electron-conducting substance, or
(C) an electron-conducting substance and a precursor compound of an electron-conducting substance, or
(D) a carbon-containing and a precursor compound of an electron-conducting substance, or
(E) a carbon-containing and electron-conducting substance and a precursor compound of an electron-conducting substance, in
(I) (a) or (b) or (c), or
(II) (a) and (b), or
(III) (b) and (c), or
(IV) (a) and (c), or
(V) (a) and (b) and (c).

18. A process according to claim 17 , wherein the electron-conducting substance is carbon.

19. A process according to claim 17 , wherein the precursor compound of an electron-conducting substance is a carbon-containing compound.

20. A process according to claim 9 , wherein the phosphoric acid compound is H 3 PO 4 and the ratio of Li 3 PO 4 :MX n :H 3 PO 4 is about 8:12:4.

21. A process according to claim 1 , wherein
(I) (a) or (b) or (c), or
(II) (a) and (b), or
(III) (b) and (c), or
(IV) (a) and (c), or
(V) (a) and (b) and (c),

are carried out under an inert gas atmosphere.

22. A process according to claim 13 , wherein the deagglomerating or comminuting, or deagglomerating and comminuting, particle aggregates of the suspension is carried out by a disperser, a mill, an intensive mixer, a centrifugal pump, an in-line mixer, a mixing nozzle or an ultrasonic instrument.

23. A process according to claim 1 , wherein the precipitation product from (b) is, in (c), separated off, optionally washed and dried, and then converted by calcination under an inert or reducing condition into lithium metal phosphate.

24. A process according to claim 1 , wherein the precipitation product from (b) is converted directly into lithium metal phosphate under a hydrothermal condition in (c).

25. A process according to claim 24 , wherein the precipitation product from (b) is converted directly into lithium metal phosphate under a hydrothermal condition in (c) which is carried out at a temperature of 100 to 250° C. and a pressure of 1 bar to 40 bar of steam pressure.

26. A process according to claim 1 , wherein the precipitation product in (b) which has been separated off and optionally washed or lithium metal phosphate in (c), optionally before a drying, is mixed with a carbon-containing precursor compound and dried at a temperature of 50° to 500° C. and calcined at a temperature of 500° to 1000° C. under an inert or reducing condition.

27. A process for preparing a lithium metal phosphate of the formula LiMPO 4 , where M is at least one divalent metal, which comprises:
f) reacting at a temperature of 5 to 80° C. a Li 3 PO 4 (lithium phosphate) with at least one metal salt MX n and an acid phosphate source in a solution containing the at least one metal salt MX n and the acid metal phosphate source and a polar solvent, wherein M is at least one transition metal and X is an anion other than phosphate which together with the metal M forms a salt which is soluble in the solvent and n is the quotient of the valency of the metal M and the valency of the anion X, giving a suspension of particles of at least one M-containing phosphate in the solvent;
g) adding a basic lithium source to the suspension of M-containing phosphate in the solvent obtained in (a), giving a precipitation product;
h) converting the

Assignees

• Nuspl Gerhard
• Vogler Christian
• Zuber Josefine
• Johnson Matthey Plc

Inventors

• Nuspl Gerhard
• Vogler Christian
• Zuber Josefine

Classifications

• C01B25/45 Primary

  containing plural metal, or metal and ammonium · CPC title

• C01B25/37

  Phosphates of heavy metals · CPC title

• C01B25/00 Primary

  Phosphorus; Compounds thereof ({C01B6/00} , C01B21/00, C01B23/00 take precedence; perphosphates C01B15/16) · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title