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Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same

A technology of lithium secondary battery and manufacturing method, which is applied to secondary batteries, electrode manufacturing, battery electrodes, etc., can solve the problems of not being able to find high-capacity lithium secondary batteries, and failing to fully satisfy high-capacity and cycle characteristics.

Inactive Publication Date: 2007-09-19
HITACHI MAXELL ENERGY LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, according to the study of the present inventors, it is known that these technologies cannot sufficiently satisfy high capacity and cycle characteristics.
[0008] In this way, in the prior art, it is almost impossible to find a lithium secondary battery with high capacity and high cycle characteristics.

Method used

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  • Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same
  • Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same
  • Negative electrode for lithium secondary battery, method for producing same, and lithium secondary battery using same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] As graphite A, the crystallite size in the c-axis direction is 88.5nm, and the interplanar distance d of the (002) plane is used. 002 =0.3357nm, the average particle size of the primary particles by SEM is 17μm, the R value of the Raman spectrum is 1.670, and the tap density is 1.19g / cm 3 , specific surface area is 3.12m 2 / g. Graphite A1 whose surface is covered with 3 to 4% by weight of non-graphitic carbon formed by sintering pitch. Figure 1 shows the appearance of the graphite A1 by SEM. As shown in FIG. 1 , graphite A1 contains at least substantially elliptical primary particles.

[0049] As graphite B, the crystallite size in the c-axis direction is 116nm, and the interplanar distance d of the (002) plane is used. 002 =0.3362nm, the average particle size of secondary particles by SEM is 19μm, the average particle size of flat primary particles is 1-9μm, and the tap density is 0.59g / cm 3 , specific surface area is 4.40m 2 / g of graphite. Figure 2 shows the ap...

Embodiment 2

[0058] A prismatic lithium secondary battery was produced in the same manner as in Example 1, except that a mixture of 70% by weight of graphite A1 and 30% by weight of graphite B was used as the negative electrode active material. The density of the negative coating film is 1.50g / cm 3 .

Embodiment 3

[0060] A prismatic lithium secondary battery was produced in the same manner as in Example 1, except that a mixture of 50% by weight of graphite A1 and 50% by weight of graphite B was used as the negative electrode active material. The density of the negative electrode coating film is 1.51g / cm 3 .

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Abstract

A lithium secondary battery comprises a positive electrode (1), a negative electrode (2) and a nonaqueous electrolyte. The negative electrode (2) contains a negative electrode active material and a binder; and the negative electrode active material contains graphite (A) and graphite (B). Primary particles of the graphite (A) have a spherical or oval-spherical shape with an average particle diameter of 10-30 mum. The graphite (A) has a crystallite size along the c-axis of less than 100 nm, and a tap density of 1.0 g / cm<3> or more. Primary particles of the graphite (B) have a flat shape with an average particle diameter of 1-10 mum. The graphite (B) has a crystallite size along the c-axis of 100 nm or more. Consequently, the lithium secondary battery has a large capacity and excellent cycle characteristics.

Description

technical field [0001] The present invention relates to a negative electrode for a lithium secondary battery, and more specifically relates to an inexpensive negative electrode for a lithium secondary battery that has a high capacity and is excellent in cycle characteristics. Background technique [0002] In recent years, the need for high-capacity secondary batteries that can be repeatedly charged and discharged has increased due to the development of portable electronic devices such as mobile phones and notebook personal computers, as well as environmental concerns and resource conservation. Lithium secondary batteries are widely used as power sources for these portable electronic devices due to their high energy density, light weight, small size, and excellent charge-discharge cycle characteristics. As the power consumption of portable electronic devices increases, further improvements are required. high capacity and cycle characteristics improvement technology. [0003]...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/02H01M4/04H01M4/58H01M4/62H01M10/40H01M4/133H01M4/1393H01M4/587H01M10/0525
CPCY02E60/122Y02E60/10
Inventor 阪越治雄大西益弘东彪石泽政嗣户川文夫和田秀一
Owner HITACHI MAXELL ENERGY LTD