Lithium ion secondary battery

A secondary battery and lithium-ion technology, applied in the direction of secondary batteries, secondary battery manufacturing, battery electrodes, etc., can solve the problems of inability to improve conductivity, inability to seek capacity, condensation of conductive materials, etc., and achieve excellent output characteristics, high Potential cycle characteristics, effect of high active material density

Active Publication Date: 2015-03-04
ZEON CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when fluorine-containing polymers are used alone as a binder, the finely granulated conductive material may aggregate, resulting in insufficient dispersibility, and the conductivity cannot be improved, and the capacity cannot be improved.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0241] Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. It should be noted that the parts and % in this example are based on mass unless otherwise specified. In Examples and Comparative Examples, various physical properties were evaluated as follows.

[0242] (Measurement of swelling degree of non-aqueous electrolyte solution)

[0243] An 8% N-methylpyrrolidone (NMP) solution of a nitrile group-containing acrylic polymer was poured into a Teflon petri dish so that the thickness after drying might be 100 μm to prepare a polymer film. The obtained film was punched to 16 mmφ, and the weight was measured (the weight was set to "A"). 5% fluoroethylene carbonate was mixed in a mixture of ethylene carbonate and ethyl methyl carbonate in a weight ratio of 3:7, and lithium hexafluorophosphate (LiPF 6 ) to prepare a non-aqueous electrolyte. A film punched to 16 mmφ was immersed in 20 g of the...

preparation example 1

[0288] Production of nitrile group-containing acrylic polymer (B1-1)

[0289] 164 parts of ion-exchanged water, 59.5 parts of 2-ethylhexyl acrylate (2EHA), 20 parts of methacrylic acid (MAA), 20 parts of acrylonitrile (AN), and 2-acrylamide-2 were added to an autoclave equipped with a stirrer. -0.5 parts of methylpropanesulfonic acid (AMPS), 0.3 parts of potassium persulfate as a polymerization initiator, and 1.6 parts of sodium lauryl sulfate as an emulsifier, after stirring well, heated at 70° C. for 3 hours, and heated at 80° C. Polymerization was performed by heating for 2 hours to obtain an aqueous dispersion of the nitrile group-containing acrylic polymer (B1-1). In addition, the polymerization conversion rate calculated|required from solid content concentration was 96%. Separately, 500 parts of N-methylpyrrolidone was added to 100 parts of the aqueous dispersion, and after all water and residual monomers were evaporated under reduced pressure, 81 parts of N-methylpyrro...

preparation example 2～11

[0291] Production of nitrile group-containing acrylic polymers (B1-2) to (B1-11)

[0292] The same procedure as in Preparation Example 1 was carried out, except that the feeding amount and the type of the monomers were changed as shown in Table 1. In addition, in Table 1, AN means acrylonitrile, 2EHA means 2-ethylhexyl acrylate, MAA means methacrylic acid, AA means acrylic acid, and AMPS means 2-acrylamido-2-methyl acrylate Propanesulfonic acid, St means styrene and AMA means allyl methacrylate. Table 1 shows the non-aqueous electrolyte swelling degree and THF insoluble content of the obtained polymers (B1-1) to (B1-11).

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Abstract

[Problem] To provide a high-capacity lithium ion secondary battery which is flexible and has excellent high potential cycle characteristics, while being prevented from the occurrence of cracks in an electrode layer when bent. [Solution] A lithium ion secondary battery of the present invention is characterized by comprising a negative electrode, a positive electrode and a nonaqueous electrolyte solution, and is also characterized in that: the negative electrode contains an alloy-based active material; the positive electrode contains a positive electrode active material, a binder for positive electrodes, and a conductive material; the binder for positive electrodes contains a nitrile group-containing acrylic polymer and a fluorine-containing polymer; the nitrile group-containing acrylic polymer has a swelling degree of three times or less with respect to the nonaqueous electrolyte solution and a THF insoluble fraction of 30% by mass or less; and the conductive material has particle diameters of 5-40 nm.

Description

Background technique [0001] The present invention relates to a lithium ion secondary battery, and more specifically, to a lithium ion secondary battery capable of realizing high capacity. [0002] Background technique [0003] In recent years, the popularity of portable terminals such as notebook computers, mobile phones, and PDAs (Personal Digital Assiatants) has been remarkable. A nickel-hydrogen secondary battery, a lithium-ion secondary battery, or the like is often used as a secondary battery that can be used as a power source for these portable terminals. Portable terminals are required to have more comfortable portability, and their miniaturization, thickness reduction, weight reduction, and performance enhancement have been rapidly advanced. As a result, portable terminals have been used in various applications. [0004] In addition, similarly to the portable terminal, reduction in size, thickness, weight, and performance are also required for batteries. In additio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36B82Y40/00H01G11/22H01M4/13H01M4/62
CPCY02E60/122H01G11/38H01M4/36H01M4/62B82Y30/00H01M4/13H01M4/133H01M4/134H01M4/364H01M4/386H01M4/405H01M4/587H01M4/622H01M4/623H01M10/0431H01M10/0525Y02E60/10Y02P70/50
Inventor 杉本拓己召田郁哉
Owner ZEON CORP
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