Lithium-ion secondary battery and manufacturing method thereof

• US 20070003837A1
• Filed: 04/06/2006
• Published: 01/04/2007
• Est. Priority Date: 04/07/2005
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Nishijima, Motoaki, Nishimura, Naoto, Kobayashi, Shinsuke
• Granted Patent: US 8,465,874 B2
• Time in Patent Office: Days
• US Class Current: 429/232
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0416 involving impregnation with a solution, dispersion, paste or dry powder H01M4/0438 takes precedence
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: H01M 4/806 Nonwoven fibrous fabric containing only fibres
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y10T 29/49108 Electric battery cell making

Abstract

In a lithium-ion secondary battery of the present invention, the electrical resistivity of the mixture of a positive electrode active material, an electrically conductive member, and a binder is 0.1 Ωcm or more but 1 Ωcm or less. The positive and negative electrodes each have an electrical capacity of 10 mAh or more but 50 mAh or less per volume of a rectangular parallelepiped that has a 1 cm² square base on a face of the electrode of one polarity facing the electrode of the other polarity and that has a height equal to the thickness of the electrode of the one polarity at the square base. Used as the negative electrode thereof is a negative electrode formed by sintering graphite powder, non-graphitizing carbon, and fibrous powder retained in the pores of a porous metal structure in an inert gas atmosphere at a temperature of between 600 and 1000° C.

Claims

1. A lithium-ion secondary battery having a battery capacity of 5 Ah or more, the lithium-ion secondary battery comprising:

a positive electrode comprising a positive electrode active material, an electrically conductive member, a binder, and a charge collecting member;

a negative electrode comprising a negative electrode active material, an electrically conductive member, a binder, and a charge collecting member; and

an electrolyte containing an electrolytic salt,

wherein

an electrical resistivity of a mixture of the positive electrode active material, the electrically conductive member, and the binder is 0.1 Ω

cm or more but 1 Ω

cm or less,

the positive and negative electrodes each have an electrical capacity of 10 mAh or more but 50 mAh or less per volume of a rectangular parallelepiped that has a 1 cm² square base on a face of the electrode of one polarity facing the electrode of the other polarity and that has a height equal to a thickness of the electrode of the one polarity at the square base, and

the negative electrode is formed by sintering negative electrode ingredients including graphite powder, non-graphitizing carbon, and fibrous powder in pores of a porous metal structure used as the charge collecting member.

2. The lithium-ion secondary battery of claim 1,

wherein a porosity of the porous metal structure is 75% or more but 98% or less.

3. The lithium-ion secondary battery of claim 1,

wherein the porous metal structure is formed of a material selected from the group consisting of iron, cobalt, nickel, and an alloy thereof.

4. The lithium-ion secondary battery of claim 3,

wherein the porous metal structure is nickel foam.

5. The lithium-ion secondary battery of claim 1,

wherein the non-graphitizing carbon is a carboxymethylcellulose polymer or a polymer of carboxymethylcellulose derivative.

6. The lithium-ion secondary battery of claim 1,

wherein the fibrous powder is powder of highly graphitized carbon fiber.

7. The lithium-ion secondary battery of claim 1,

wherein a fiber diameter of the fibrous powder is between 0.1 and 80 μ

m.

8. The lithium-ion secondary battery of claim 1,

wherein the graphite powder exhibits, when subjected to wide-angle X-ray diffractometry, an average interplanar spacing of (002) plane of between 0.335 and 0.340 nm, a crystallite thickness in (002) plane direction of 10 nm or more, and a crystallite thickness in (110) plane direction of 10 nm or more.

9. The lithium-ion secondary battery of claim 1,

wherein a particle size of the graphite powder is 80 μ

m or less.

10. The lithium-ion secondary battery of claim 1,

wherein a sintering temperature of the negative electrode is between 600 and 1000°

C.

11. A method of manufacturing a lithium-ion secondary battery, the method comprising the steps of:

forming a negative electrode by mixing together negative electrode ingredients including graphite powder, non-graphitizing carbon, and fibrous powder, adding thereto a solvent so as to obtain a paste, rubbing the paste thus obtained into pores of a porous metal structure, and sintering a product thus obtained at a temperature of between 600 and 1000°

C.;

forming a positive electrode by mixing together positive electrode ingredients including a positive electrode active material, an electrically conductive member, and a binder, dissolving the mixture thus obtained in a solvent so as to prepare slurry, injecting the slurry thus prepared into a charge collecting member, and drying a product thus obtained; and

assembling a battery by inserting, into a covering material, the positive electrode and the negative electrode stacked with a separator interposed therebetween so as not to make electrical contact with each other, injecting an electrolytic solution thereinto, and then sealing the covering material.