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Coating liquid for formation of positive electrode for lithium rechargeable battery, positive electrode for lithium rechargeable battery, and lithium rechargeable battery

A lithium secondary battery, coating liquid technology, applied in secondary batteries, battery electrodes, lithium storage batteries, etc., can solve the problem of incapable of high-density filling, and achieve high practicability, excellent coating properties, and high energy density. the effect of

Inactive Publication Date: 2009-12-23
PANASONIC CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is not possible to fill the active material particles at a sufficiently high density only by spheroidizing the active material particles.

Method used

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  • Coating liquid for formation of positive electrode for lithium rechargeable battery, positive electrode for lithium rechargeable battery, and lithium rechargeable battery
  • Coating liquid for formation of positive electrode for lithium rechargeable battery, positive electrode for lithium rechargeable battery, and lithium rechargeable battery
  • Coating liquid for formation of positive electrode for lithium rechargeable battery, positive electrode for lithium rechargeable battery, and lithium rechargeable battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0108] (1) Preparation of coating solution for positive electrode formation

[0109] As the large particle size active material, lithium cobaltate having an average particle size of 7 μm was used. As the small particle size active material, lithium cobaltate with an average particle size of 70 nm was used. In addition, the compounding ratio (active material with large particle diameter:active material with small particle diameter)=70:30 (weight ratio). In addition, since both the active material with a large particle size and the active material with a small particle size are lithium cobaltate, the compounding ratio (volume ratio=volume ratio) is replaced by a weight ratio. Hereinafter, even when the active material with a large particle size and the active material with a small particle size are the same compound, the compounding ratio will be replaced by a weight ratio.

[0110] Dissolve 3 parts by weight of polyvinylidene fluoride (binder, weight-average molecular weight:...

Embodiment 2

[0129] In addition to using lithium cobalt oxide with an average particle size of 20 μm as the large particle size active material, using lithium cobalt oxide with an average particle size of 100 nm as the small particle size active material, and setting the compounding ratio (weight ratio) as the large particle size active material The coating liquid for forming a positive electrode and the positive electrode of the present invention were produced in the same manner as in Example 1 except for the small particle size active material = 50:50. Even when the obtained coating liquid of the present invention was stored for 3 weeks, no sedimentation, aggregation, separation of the dispersion medium, etc. were observed. In addition, the coating liquid of the present invention maintained its initial liquid properties even after being stored for 3 weeks, and deterioration in film-forming properties, leveling properties, and the like was not observed.

Embodiment 3

[0131] In addition to using lithium cobalt oxide with an average particle size of 20 μm as the large particle size active material, using lithium cobalt oxide with an average particle size of 100 nm as the small particle size active material, and setting the compounding ratio (weight ratio) as the large particle size active material The coating liquid for forming a positive electrode and the positive electrode of the present invention were produced in the same manner as in Example 1 except that the active material with small particle diameter was 90:10. Even when the obtained coating liquid of the present invention was stored for 3 weeks, no sedimentation, aggregation, separation of the dispersion medium, etc. were observed. In addition, the coating liquid of the present invention maintained its initial liquid properties even after being stored for 3 weeks, and deterioration in film-forming properties, leveling properties, and the like was not observed.

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Abstract

This invention provides a coating liquid for the formation of a positive electrode for a lithium rechargeable battery. This coating liquid contains a large particle diameter active material having an average particle diameter of 1 to 20 [mu]m and a small particle diameter active material having an average particle diameter of 5 to 100 nm. The mixing ratio between the large particle diameter active material and the small particle diameter active material is 90 : 10 to 50 : 50 on a volume basis, and the average particle diameter ratio (the average particle diameter of the large particle diameter active material / the average particle diameter of the small particle diameter active material) is 50 to 500. The coating liquid has an excellent long-term storage stability and can realize high-density filling of the active material in the coating liquid. Accordingly, the preparation of a positive electrode using the coating liquid can realize the provision of a lithium rechargeable battery with a high energy density and a high capacity.

Description

technical field [0001] The present invention relates to a coating solution for forming a positive electrode for a lithium secondary battery, a positive electrode for a lithium secondary battery, and a lithium secondary battery. More specifically, this invention mainly relates to the improvement of the coating liquid for positive electrode formation for lithium secondary batteries. Background technique [0002] A nonaqueous electrolyte secondary battery using a positive electrode active material capable of reversibly repeating intercalation and deintercalation of lithium ions by charging and discharging has been proposed and put into practical use. A positive electrode used in such a nonaqueous electrolyte secondary battery is generally produced by a production method including a kneading process, a coating process, a rolling process, and a cutting process. In the kneading process, the positive electrode active material, the conductive material, and the binder are mixed and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/04H01M4/02H01M4/36B82Y99/00H01M4/13H01M4/131H01M4/139H01M4/1391H01M10/052H01M10/36
CPCY02E60/122H01M2004/028H01M4/13H01M4/0404H01M4/1391H01M10/052H01M4/139H01M4/364H01M4/131Y02E60/10
Inventor 南野哲郎松井彻芳泽浩司
Owner PANASONIC CORP
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