Carbonaceous electrode material for secondary battery and process for production thereof

• US 5,616,436 A
• Filed: 08/23/1995
• Issued: 04/01/1997
• Est. Priority Date: 08/23/1994
• Status: Expired due to Term

• Current Assignee: Kureha Corporation
• Original Assignee: Kureha Kagaku Kogyo Kabushiki Kaisha
• Inventors: Ishikawa, Minoru, Iwasaki, Takao, Sonobe, Naohiro
• Primary Examiner(s): Kalafut, Stephen
• Assistant Examiner(s): LILLEY, RICHARD
• Application Number:
  US08/518,306
• Time in Patent Office: 587 Days
• Field of Search: 429/194, 429/197, 429/218, 429/232, 423/421, 423/445, 423/447.1, 423/447.9
• US Class Current: 429/231.8
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 6/10 with wound or folded electrodes
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A carbonaceous electrode having improved capacities for doping and dedoping of a cell active substance, such as lithium, and suitable for a non-aqueous solvent-type secondary battery, is constituted by a carbonaceous material having a specific microtexture. The carbonaceous material is characterized by it'"'"'s ability to provide an electrochemically lithium-doped product showing a main resonance peak which is shifted by 80-200 ppm to a lower magnetic field side from a resonance line of LiCl as a reference substance when subjected to ⁷ Li-NMR spectroscopy analysis.

Claims

1. A carbonaceous electrode material for a secondary battery, using a non-aqueous electrolyte solution comprising a carbonaceous material characterized by providing an electrochemically lithium-doped product showing a main resonance peak which is shifted by 80-200 ppm to a lower magnetic field side from a resonance line of LiCl as a reference substance when subjected to ⁷ Li-NMR spectroscopy analysis.

2. A carbonaceous electrode material according to claim 1, wherein the carbonaceous material further shows a hydrogen/carbon ratio H/C of at most 0.10.

3. A carbonaceous electrode material according to claim 2, wherein the ratio H/C is at most 0.08.

4. A carbonaceous electrode material according to claim 1, wherein the main resonance peak is shifted by at least 90 ppm to a lower magnetic field side from the resonance line of LiCl.

7. An electrode structure for a secondary battery, using a non-aqueous electrolytic solution comprising:

an electroconductive substrate and a composite electrode layer disposed on at least one surface of the electroconductive substrate;

said composite electrode layer comprising a carbonaceous electrode material according to any one of claims 1-4 in a particulate form, and a binder.

8. A secondary battery, using a non-aqueous electrolytic solution comprising, a positive electrode, a negative electrode, and a separator and a non-aqueous electrolytic solution disposed between the positive and negative electrodes;

at least one of said positive and negative electrodes comprising an electrode structure according to claim 7.

9. A secondary battery according to claim 8, wherein the electrode structure constitutes the negative electrode.

5. A process for producing a carbonaceous electrode material for a secondary battery using a non-aqueous electrolytic solution, comprising the steps of:

crosslinking a tar or pitch of a petroleum or coal origin with a polyfunctional vinyl polymer in the presence of a radical initiator, and

carbonizing the crosslinked tar or pitch at a temperature of 900°

-1500°

C. under a reduced pressure of at most 10 kPa, so as to provide a carbonaceous material characterized by providing an electrochemically lithium-doped product showing a main resonance peak which is shifted by 80-200 ppm to a lower magnetic field side from a resonance line of LiCl as a reference substance when subjected to ⁷ Li-NMR spectroscopy.

6. A process for producing a carbonaceous electrode material for a secondary battery, using a non-aqueous electrolyte solution comprising:

carbonizing coconut shell at a temperature of 900°

-1500°

C. under a reduced pressure of at most 10 kPa, so as to provide a carbonaceous material characterized by providing an electrochemically lithium-doped product showing a main resonance peak which is shifted by 80-200 ppm to a lower magnetic field side from a resonance line of LiCl as a reference substance when subjected to ⁷ Li-NMR spectroscopy.

10. A process for producing a carbonaceous electrode material for a secondary battery, using a non-aqueous electrolyte solution comprising the steps of:

crosslinking a tar or pitch of a petroleum or coal origin, and

carbonizing the crosslinked tar or pitch at a temperature of 900°

-1500°

C. under a reduced pressure of at most 10 kPa, so as to provide a carbonaceous material characterized by providing an electrochemically lithium-doped product showing a main resonance peak which is shifted by 80-200 ppm to a lower magnetic field side from a resonance line of LiCl as a reference substance when subjected to ⁷ Li-NMR spectroscopy;

said crosslinking being carried out through the steps of;

mixing the pitch with an additive comprising an aromatic compound having two or three aromatic rings and a boiling point of at least 200°

C. to form a shaped pitch product,

extracting the additive from the shaped pitch product with a solvent showing a low dissolving power to the pitch and a high dissolving power to the additive, thereby leaving a porous pitch product, and

oxidizing the porous pitch product.