Substituted lithium phosphates and solid electrolytes therefrom

• US 4,009,092 A
• Filed: 02/27/1976
• Issued: 02/22/1977
• Est. Priority Date: 02/27/1976
• Status: Expired due to Term

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Taylor, Barry Edward
• Primary Examiner(s): Walton, Donald L.
• Application Number:
  US05/662,003
• Time in Patent Office: 361 Days
• Field of Search: 136/6 FS, 136/83 R, 136/153, 423/306, 252/62.2, 204/1 S, 204/195 S, 204/242
• US Class Current: 204/242
• CPC Class Codes: C01B 25/45 containing plural metal, or metal and ammonium
• CPC Class Codes: C01B 33/00 Silicon; Compounds thereof C01B6/00, C01B21/00, C01B23/00 take precedence; persilicates C01B15/14; carbides C01B32/956
• CPC Class Codes: C25C 3/02 of alkali or alkaline earth metals
• CPC Class Codes: H01M 6/185 with oxides, hydroxides or oxysalts as solid electrolytes

Abstract

Lithium phosphates are provided which have the formula:

Li.sub.1.sub.-2x.sub.-y.sub.+z Mg.sub.x M.sub.2.sub.-y.sup.4.sup.+

M_y⁵⁺ (P_1-z/3 Si_z/3 O₄)₃.q(Li₂ O)

wherein

M⁴⁺ is at least one of zirconium and hafnium;

M⁵⁺ is at least one of niobium and tantalum;

x is 0 to about 0.15;

y is 0 to about 0.5;

z is 0 to about 0.3;

q is 0 to about 0.2; and

2x+y-z is at least -0.1.

These substituted lithium phosphates are useful as solid electrolytes in electrochemical cells such as galvanic cells and electrolytic cells.

Claims

1. A lithium phosphate of the formula:

space="preserve" listing-type="equation">Li.sub.1.sub.-2x.sub.-4.sub.+z Mg.sub.x M.sub.2.sub.-y.sup.4.sup.+ M.sub.y.sup.5.sup.+ (P.sub.1.sub.-2/3 Si.sub.2/3 O.sub.4).sub.3.sup.. q(Li.sub.2 O)

wherein

M⁴⁺ is at least one of zirconium and hafnium;

M⁵⁺ is at least one of niobium and tantalum;

x is 0 to about 0.15;

y is 0 to about 0.5;

z is 0 to about 0.3;

q is 0 to about 0.2; and

2x+y=z is at least -0.1 and at least one of x, y and z is not equal to 0.

2. The lithium phosphate of claim 1 wherein 2x+y-z is at least -0.1 and no greater than about 0.5.

3. The lithium phosphate of claim 1

4. The lithium phosphate of claim 1

5. The lithium phosphate of claim 4 wherein M⁵⁺ is tantalum.

6. The lithium phosphate of claim 5 wherein M⁴⁺ is zironcium.

7. The lithium phosphate of claim 5 wherein M⁴⁺ is hafnium.

8. The lithium phosphate of claim 1

9. The lithium phosphate of claim 8 wherein M⁴⁺ is zirconium.

10. In an electrochemical device having:

a. two electrodes, one of which is lithium, LiA1 or LiHg amalgam;

b. a solid electrolyte separating the two electrodes; and

c. connecting electrical conductor to complete an electrical circuit between the two electrodes;

the improvement wherein the solid electrolyte consists essentially of a lithium phosphate of the formula;

space="preserve" listing-type="equation">Li.sub.1.sub.-2x.sub.-y.sub.+z Mg.sub.x M.sub.2.sub.-y.sup.4.sup.+ M.sub.y.sup.5.sup.+ (P.sub.1.sub.-z/3 Si.sub.z/3 O.sub.4).sub.3.sup.. q(Li.sub.2 O)

wherein

M⁴⁺ is at least one of zirconium and hafnium;

M⁵⁺ is at least one of niobium and tantalum;

x is 0 to about 0.15;

y is 0 to about 0.5;

z is 0 to about 0.3;

q is 0 to about 0.2; and

2x+y-z is at least -0.1.

11. The device of claim 10 wherein it is an electrolytic cell.

12. The device of claim 10 wherein it is a galvanic cell.

13. The device of claim 11 wherein the solid electrolyte consists essentially of the lithium phosphate of claim 8 or Li_1-y M_2-y⁴⁺ M_y⁵⁺ (PO₄)₃ wherein y is 0 to about 0.5.

14. The device of claim 12 wherein the solid electrolyte consists essentially of the lithium phosphate of claim 8 or Li_1-y M_2-y⁴⁺ M_y⁵⁺ (PO₄)₃ wherein y is 0 to about 0.5.

15. The device of claim 12 wherein the solid electrolyte consists essentially of Li_1-y Zr_2-y Ta_y (PO₄)₃ where y is from about 0.05-0.5;

Li_1-y Hf_2-y Ta_y (PO₄)₃ where y is 0 to about 0.5 and Li_1-2x Mg_x Zr₂ (PO₄)₃ where x is about 0.05-0.15.

16. The device of claim 11 wherein the solid electrolyte consists essentially of Li_1-y Zr_2-y Ta_y (PO₄)₃ where y is from about 0.05-0.5;

Li_1-y Hf_2-y Ta_y (PO₄)₃ where y is 0 to about 0.5 and Li_1-2x Mg_x Zr₂ (PO₄)₃ where x is about 0.05-0.15.