Negative-electrode active material for sodium-ion secondary battery, method for manufacturing said negative-electrode active material, and sodium-ion secondary battery

Patent metadata

Field	Value
Publication number	US-9755237-B2
Application number	US-201414893027-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	May 22, 2013
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

A negative-electrode active material for a sodium-ion secondary battery contains a porous carbon material which has a plurality of open pores that extend through to the surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material. The distance between (002) planes of carbon in at least a part of the solid portion is 0.36 nm or more. The plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

First claim

The invention claimed is:

1. A negative-electrode active material for a sodium-ion secondary battery, comprising a porous carbon material having a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material, wherein,
a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm; and
the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

2. The negative-electrode active material for a sodium-ion secondary battery of claim 1 , wherein the plurality of open pores account for a volume ratio of 7% or less with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

3. The negative-electrode active material for a sodium-ion secondary battery of claim 1 , wherein the plurality of open pores account for a volume ratio of 3% or less with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

4. A sodium-ion secondary battery comprising:
a negative electrode containing the negative-electrode active material of claim 1 ;
a positive electrode containing a positive-electrode active material capable of occlusion and release of sodium; and
an electrolyte containing sodium ions.

5. A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:
a step of providing an organic material to serve as a carbon source; and
a step of subjecting the organic material to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
the organic material is a cellulose-type resin;
the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm; and
the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

6. The method of producing a negative-electrode active material for a sodium-ion secondary battery of claim 5 , wherein the heat treatment temperature is not less than 1400° C. and not more than 2000° C.

7. The method of producing the negative-electrode active material for a sodium-ion secondary battery of claim 5 , wherein the organic material or carbon material having porosity is not subjected to a pulverization treatment after being subjected to the heat treatment.

8. The method of producing the negative-electrode active material for a sodium-ion secondary battery of claim 5 , further comprising, before the step of subjecting the organic material to the heat treatment:
a step of carburizing the organic material to obtain a carbide; and
a step of pulverizing the carbide,

wherein.
in the step of subjecting the organic material to a heat treatment, the pulverized carbide is heat-treated.

9. A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:
a step of providing an organic material to serve as a carbon source;
a step of pulverizing the organic material in a mortar; and
a step of subjecting the pulverized organic material to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
the organic material is phenolphthalein;
the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm; and
the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

10. The method of producing the negative-electrode active material for a sodium-ion secondary battery of claim 9 , further comprising, before the step of subjecting the organic material to the heat treatment and the step of pulverizing the organic material:
a step of carburizing the organic material to obtain a carbide,

wherein,
in the step of pulverizing the organic material, the carbide is pulverized; and
in the step of heat treatment, the pulverized carbide is heat-treated.

11. The method of producing a negative-electrode active material for a sodium-ion secondary battery of claim 9 , wherein the heat treatment temperature is not less than 1400° C. and not more than 2000° C.

12. The method of producing the negative-electrode active material for a sodium-ion secondary battery of claim 9 , wherein the organic material or carbon material having porosity is not subjected to a pulverization treatment after being subjected to the heat treatment.

13. A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:
a step of providing a carbon material having porosity; and
a step of subjecting the carbon material having porosity to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
the carbon material having porosity is an activated carbon material;
the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm; and
the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a total volume of the plurality of open pores, the plurality of closed pores, and the solid portion.

14. The method of producing a negative-electrode active material for a sodium-ion secondary battery of claim 13 , wherein the heat treatment temperature is not less than 1900° C. and not more than 2300° C.

15. The method of producing the negative-electrode active material for a sodium-ion secondary battery of claim 13 , wherein the organic material or carbon material having porosity is not subjected to a pulverization treatment after being subjected to the heat treatment.

16. A method of producing a negative-electrode active substance for a sodium-ion secondary battery, comprising:
a step of providing a carbon material having porosity; and
a step of subjecting the carbon material having porosity to a heat treatment in an inert atmosphere to obtain a porous carbon material, wherein,
the carbon material having porosity is a template carbon material;
the porous carbon material has a plurality of open pores that extend through to a surface, a plurality of closed pores that do not extend through to the surface, and a solid portion made of carbon material;
a distance between (002) planes of carbon in at least a part of the solid portion is not less than 0.36 nm and not more than 0.41 nm; and
the plurality of closed pores account for a volume ratio of not less than 30% and not more than 90% with respect to a tota

Assignees

• Panasonic Ip Man Co Ltd

Inventors

• Kano Akira
• Hojo Nobuhiko
• Fujimoto Masahisa

Classifications

• H01M4/587 Primary

  for inserting or intercalating light metals · CPC title

• C01B31/00

  Chemistry & Metallurgy · mapped topic

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/133

  Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx · CPC title

• H01M10/054

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