Positive electrode active material for sodium battery, and method of producing the same

Patent metadata

Field	Value
Publication number	US-9660253-B2
Application number	US-201214241188-A
Country	US
Kind code	B2
Filing date	Jun 13, 2012
Priority date	Aug 29, 2011
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

The invention provides a positive electrode active material for sodium batteries which has a high working potential and can be charged and discharged at a high potential. The invention also provides a method of producing such a positive electrode active material, with this positive electrode active material for sodium batteries being represented by general formula (1) below:

Na x M y (AO 4 ) z (P 2 O 7 ) w   (1)

(wherein M is at least one selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc; A is at least one selected from the group consisting of aluminum, silicon, phosphorus, sulfur, titanium, vanadium and tungsten; x satisfies the condition 4≧x≧2; y satisfies the condition 4≧y≧1, z satisfies the condition 4≧z≧0; w satisfies the condition 1≧w≧0; and one or both of z and w is 1 or more).

First claim

The invention claimed is:

1. A positive electrode active material for a sodium battery, represented by general formula (1) or general formula (2) below:
Na 4 Co (3-a) Mn a (PO 4 ) 2 (P 2 O 7 )  (1)

Na 4 Co (3-b-c) Mn b Ni c (PO 4 ) 2 (P 2 O 7 )  (2)

where:
“a” satisfies a condition 0.3 ≦a≦0.8;
“b” satisfies a condition 0.3 ≦b≦1.0; and
“c” satisfies a condition 0.3 ≦c≦1.0;

wherein the positive electrode active material has a crystal structure belonging to a space group Pn2 1 a.

2. A positive electrode active material for a sodium battery, represented by formula (1) or formula (2):
Na 4 Co (3-a) Mn a (PO 4 ) 2 (P 2 O 7 )  (1)

Na 4 Co 2.4 Mn 0.3 Ni 0.3 (PO 4 ) 2 (P 2 O 7 )  (2)

where “a” satisfies a condition 0.3≦a≦0.8.

3. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a formula: Na 4 Co 2.7 Mn 0.3 (PO 4 ) 2 (P 2 O 7 ).

4. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a formula: Na 4 Co 2.4 Mn 0.6 (PO 4 ) 2 (P 2 O 7 ).

5. The positive electrode active material according to claim 1 , wherein the positive electrode active material has a formula: Na 4 Co 2.2 Mn 0.8 (PO 4 ) 2 (P 2 O 7 ).

6. A method of producing the positive electrode active material for a sodium battery according to claim 1 , the method comprising:
a pre-firing step of firing a starting material mixture that includes at least an Na-containing compound, a Co-containing compound, a Mn-containing compound, and a P-containing compound in an open-air atmosphere at a temperature of from 150 to 500° C.; and
a main firing step of firing the thus-obtained pre-fired material in an open-air atmosphere at a temperature of from 500 to 800° C. after implementing the pre-firing step.

7. The method of producing a positive electrode active material for the sodium battery according to claim 6 , further comprising, prior to the pre-firing step, size-reducing the Na-containing compound, the Co-containing compound, the Mn-containing compound, and the P-containing compound.

Assignees

• Nose Masafumi
• Toyota Motor Co Ltd

Inventors

• Nose Masafumi

Classifications

• H01M10/054

  Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium · CPC title

• H01M4/5825 Primary

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M4/0471 Primary

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title

• C01B25/45 Primary

  containing plural metal, or metal and ammonium · CPC title

• H01M4/58 Primary

  of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates · CPC title