Electrode for secondary battery and production process for the same and secondary battery

Patent metadata

Field	Value
Publication number	US-9537150-B2
Application number	US-59751308-A
Country	US
Kind code	B2
Filing date	Apr 24, 2008
Priority date	Apr 27, 2007
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

To provide an electrode for secondary battery, electrode which can materialize secondary batteries that are adapted into producing high output and additionally whose durability is high.
It is characterized in possessing an electrode material that has an active-material powder 11 , a conductive material 12 being formed of a carbonaceous material, and being adhered to a surface of said active-material powder 11 , and fibrous conductive materials 13 being bonded to said conductive material 12 . First of all, it becomes feasible to maintain the electric connection between the active-material powder and the conductive material stably by adhering the conductive material to a surface of the active-material powder. Further, the fibrous conductive materials are bonded to the conductive material that is adhered to a surface of the active-material powder. It is feasible to maintain the electric connection by getting the fibrous conductive materials entangled to each other. That is, it is feasible to keep the electric connection even when strains occur in the electrode material, because the fibrous conductive materials absorb the strains to keep the mutual contacts; even if large strains occur, it is possible to maintain the electric connection, because it is not disconnected compared with that in conventional conductive materials.

First claim

The invention claimed is:

1. An electrode for secondary battery, wherein the electrode includes an electrode material having:
an active-material powder for positive electrode;
a conductive material being formed of a carbonaceous material, and being adhered to a surface of said active-material powder; and
fibrous conductive materials being bonded to said active-material powder and said conductive material;
wherein a specific surface area of said active-material powder, to whose surface said conductive material is adhered, is 1 m 2 /g or more; and
wherein said conductive material has at least one covalent bond with said active material powder, and/or with said fibrous conductive materials.

2. The electrode for secondary battery as set forth in claim 1 , wherein said conductive material is at least one that is selected from the group consisting of amorphous carbonaceous materials, turbostratic carbonaceous materials and activated carbon.

3. The electrode for secondary battery as set forth in claim 1 , wherein at least a part of said fibrous conductive materials are bonded to a plurality of said conductive materials.

4. The electrode for secondary battery as set forth in claim 3 , wherein the at least a part of said fibrous conductive materials are disposed so as to span independently between a first conductive material adhered to a surface of a first active-material powder and a second conductive material adhered to a surface of a second active-material powder.

5. The electrode for secondary battery as set forth in claim 1 , wherein said fibrous conductive materials contain at least one member that is selected from the group consisting of carbon fibers, graphite fibers, vapor-phase-growth carbonaceous fibers, nano carbon fibers and nano carbon tubes.

6. The electrode for secondary battery as set forth in claim 1 , wherein said fibrous conductive materials exhibit a fibrous diameter of 5 nm-200 nm.

7. The electrode for secondary battery as set forth in claim 1 , wherein said fibrous conductive materials exhibit a fibrous length of 100 nm-50 μm.

8. The electrode for secondary battery as set forth in claim 1 , wherein a content of said fibrous conductive materials is 1-10% by mass when a sum of a mass of said active-material powder and a mass of said conductive material is taken as the standard.

9. A production process for electrode for secondary battery, wherein the production process includes:
an adhering/bonding step of mixing a conductive material, which is formed of a carbonaceous material, with an active-material powder for positive electrode and fibrous conductive materials, forming the mixture as a conductive-material-adhered active-material powder being in such a state that it is adhered to a surface of said active-material powder, and bonding the mixture between said active-material powder and said fibrous conductive materials, thereby obtaining an electrode material; and
a step of forming an electrode of said electrode material being obtained;
wherein a specific surface area of said active-material powder, to whose surface said conductive material is adhered, is 1 m 2 /g or more; and
wherein said conductive material has at least one covalent bond with said active material powder, and/or with said fibrous conductive materials.

10. The production process for electrode for secondary battery as set forth in claim 9 , wherein said adhering/bonding step is a step of mixing an active-material raw material, which generates an active-material powder by means of doing calcination, with a conductive-material raw material, which comprises a carbonaceous material that generates a conductive material by doing calcination, and then calcining them.

11. The production process for electrode for secondary battery as set forth in claim 9 , wherein said adhering/bonding step is a step of mixing said active-material powder with a conductive-material raw material, which comprises a carbonaceous material that generates a conductive material by doing calcination.

12. The production process for electrode for secondary battery as set forth in claim 9 , wherein a step of adhering/bonding said conductive material onto a surface of said active-material powder at said adhering step, and/or a step of forming a chemical bond between said fibrous conductive materials and said conductive material is a step of calcining both of them at 1,500° C. or less in an inert atmosphere after mixing them.

13. The production process for electrode for secondary battery as set forth in claim 9 , wherein said conductive material is at least one that is selected from the group consisting of amorphous carbonaceous materials, turbostratic carbonaceous materials and activated carbon.

14. A secondary battery including: a positive electrode; a negative electrode; a separator being interposed between said positive electrode and said negative electrode; and a nonaqueous electrolyte;
wherein said positive electrode is:
an electrode for secondary battery, the electrode including an electrode material that has: an active-material powder for positive electrode; a conductive material being formed of a carbonaceous material, and being adhered to a surface of said active-material powder; and fibrous conductive materials being bonded to said conductive material; or
an electrode for secondary battery, the electrode being produced by a production process for electrode for secondary battery, the production process including: an adhering/bonding step of mixing a conductive material, which is formed of a carbonaceous material, with an active-material powder for positive electrode and fibrous conductive materials, forming the mixture as a conductive-material-adhered active-material powder being in such a state that it is adhered to a surface of said active-material powder, and bonding the mixture between said active-material powder and said fibrous conductive materials, thereby obtaining an electrode material; and a step of forming an electrode of said electrode material being obtained; and
wherein a specific surface area of said active-material powder, to whose surface said conductive material is adhered, is 1 m 2 /g or more; and
wherein said conductive material has at least one covalent bond with said active material powder, and/or said conductive material and with said fibrous conductive materials.

Assignees

• Yano Tsuyoshi
• Ishikawa Tetsuhiro
• Saito Shinji
• Sawai Takehiko
• Toyota Motor Co Ltd
• Sei Corp

Inventors

• Yano Tsuyoshi
• Ishikawa Tetsuhiro
• Saito Shinji
• Sawai Takehiko

Classifications

• Y02E60/122

  Cross-Sectional Technologies · mapped topic

• H01M4/625 Primary

  Carbon or graphite · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M4/139

  Processes of manufacture · CPC title

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title