Electrode composition, electrode, and battery

A technology of electrode composition and iron compound, which is applied in non-aqueous electrolyte batteries, electrode manufacturing, secondary batteries, etc., can solve the problems of battery performance degradation, insufficient conductivity, safety problems, etc., and achieve good adhesion , good softness, good safety effect

Active Publication Date: 2007-11-14
ZEON CORP
5 Cites 10 Cited by

AI-Extracted Technical Summary

Problems solved by technology

[0005] However, when these binders are used, the conductivity is not sufficient
In addition, since these binders decompose at a volt...
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Method used

Electrode composition of the present invention contains copolymer (P), and described copolymer (P) is by containing at least one monomer and α, β-unsaturated nitrile selected from acrylate and methacrylate The monomer composition of the compound is copolymerized. By using such a copolymer (P) as a binder, an electrode having good adhesion, conductivity, and flexibility can be obtained.
[0045] In addition, the monomer composition may also contain aromatic vinyl compounds such as styrene; conjugated dienes such as 1,3-butadiene or isoprene; and 1-olefins such as ethylene or propylene. The total content of these monomers in the monomer composition is preferably 20% by weight or less, more preferably 10% by weight or less. When the content of these monomers is too large, the heat resistance may be lowered, and the adhesive force or flexibility of the obtained electrode may be lowered.
[0070] The battery of the present invention is a battery comprising the electrode of the present invention described above. The battery of the present invention can generally be produced by using the electrode of the present invention as a positive electrode, combined with conventionally known negative electrodes, electrolytes, diaphragms and other components. As a specific manufacturing method, for example, the negative electrode and the positive electrode (the positive ele...
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Abstract

Disclosed is an electrode composition containing a positive electrode active material including an iron compound and carbon, and a copolymer (P) of an acrylate and/or methacrylate and an a,ss-unsaturated nitrile compound. Also disclosed is an electrode which is composed of an active material layer made of such an electrode composition and a collector. This electrode can be produced by mixing the positive electrode active material, the copolymer (P), a solvent, and if necessary, a thickener using a mixer, thereby forming a slurry electrode composition having a solid content concentration of 40-90% by weight, and then coating the thus-obtained electrode composition over the collector and removing the solvent from the coating. Further disclosed is a battery comprising such an electrode.

Application Domain

Technology Topic

Examples

  • Experimental program(4)
  • Comparison scheme(4)

Example Embodiment

[0097] Example 1
[0098]Under nitrogen ambient atmosphere, 674.9 parts of deionized water, 7.1 parts of 28% sodium lauryl sulfate aqueous solution, and 0.8 parts of sodium tripolyphosphate were supplied to the reactor equipped with a stirrer and a condenser. The contents of the reactor were then heated to 75°C while stirring. Then, 82 parts of 2.44% ammonium persulfate aqueous solution was added to the reactor as an aqueous initiator solution, and then 400 parts of monomer compositions having the composition shown in Table 1 were added to the reactor at a constant rate over 2 hours. After the addition, the reaction temperature was kept at 80°C and the reaction was continued for 3 hours to obtain a copolymer latex. The polymerization conversion rate was 99%, and the composition ratio of the polymer coincided with that of the monomer composition. Ammonia water was added to this latex to adjust the pH to 7, and then concentrated under reduced pressure to remove residual monomers, and the solid content concentration was 40%.
[0099] Then, according to the method described in Japanese Patent Laid-Open No. 2003-36889, an olivine-structured LiFePO containing 1.6% of carbon and having a 50% volume cumulative diameter of 2.9 μm was produced. 4 as a positive electrode active material. That is, put LiH 2 PO 4 and FeC 2 o 4 2H 2 O and acetylene black were mixed with a sand mixer at a molar ratio of Li:Fe:C=1:1:0.4, and the mixture was calcined at 650° C. for 6 hours in an argon flow, and then pulverized to produce the positive electrode active material.
[0100] Add 7.5 parts of latex prepared above (3 parts of copolymer (P) component, 4.5 parts of water), and 75 parts of a 2% aqueous solution of carboxymethylcellulose (Selogen WSC, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) as a thickener , 100 parts of the above-mentioned positive electrode active material, 10 parts of acetylene black as a conductive material and water, so that the solid content is 60%, use a bead mill to mix for 45 minutes at a speed of 750 rpm at room temperature, and obtain an electrode composition slurry material.
[0101] The prepared electrode composition slurry was evenly coated on an aluminum foil with a thickness of 20 μm by a doctor blade method, and dried at 120° C. using a dryer for 15 minutes. Table 1 shows the results of measuring the surface roughness (Ra) of the obtained electrodes. Next, it was compressed using a 2-axis roll press, and then dried under reduced pressure at 0.6 kPa and 250° C. for 10 hours using a vacuum dryer to obtain an electrode for positive electrodes with an active material layer thickness of 110 μm. Table 1 shows the results of evaluating the peel strength and flexibility of the obtained pressurized positive electrode.
[0102] Then, the obtained electrode for a positive electrode was cut into a circle having a diameter of 15 mm. On the active material layer side of the electrode, a separator made of a circular polypropylene porous membrane with a diameter of 18 mm and a thickness of 25 μm, metal lithium used as a negative electrode, and expanded metal were sequentially stacked, and then accommodated in a polypropylene gasket. In a coin-shaped outer container made of stainless steel (diameter 20mm, height 1.8mm, stainless steel thickness 0.25mm). The electrolyte solution was injected into the container so that no air remained, and a stainless steel cover with a thickness of 0.2 mm was fixed on the outer container through a polypropylene gasket, and the battery can was sealed to manufacture a coin-shaped battery with a diameter of 20 mm and a thickness of about 2 mm. As an electrolyte solution, dissolve ethylene carbonate (EC) and diethyl carbonate (DEC) at a concentration of 1 mol/liter in a mixed solvent of EC:DEC=1:2 (volume ratio at 20°C). Make LiPF 6 The solution. Table 1 shows the results of measuring various characteristics of the produced batteries.
[0103] Table 1
[0104] Example
[0105] * 1. Composition of the monomer composition (values ​​in parentheses are % by weight)
[0106] Example 1 2EHA(74)/BA(20)/AN(5)/EDMA(1)

Example Embodiment

[0107] Example 2 2EHA(64)/BA(20)/AN(15)/EDMA(1)

Example Embodiment

[0123] Example 3
[0124] Except using a monomer combination comprising 296 parts of 2-ethylhexyl acrylate (2EHA), 80 parts of butyl acrylate (BA), 20 parts of acrylonitrile (AN) and 4 parts of ethylene glycol dimethacrylate (EDMA) A copolymer latex having a solid content concentration of 40% was obtained in the same manner as in Example 1 except that the monomer composition was used as the monomer composition. Further, a carbon containing 1.6% was produced in the same manner as in Example 1 from this copolymer latex. LiFePO with an olivine structure with a 50% volume cumulative diameter of 2.9 μm 4 as a positive electrode active material.
[0125] Using the obtained positive electrode active material, an electrode having an active material layer thickness of 120 μm was produced in the same manner as in Example 1. Table 2 shows the results of measuring the surface roughness (Ra) of the prepared electrodes.
[0126] In addition, this electrode was compressed and dried under reduced pressure in the same manner as in Example 1 to prepare an electrode for positive electrodes having an active material layer having a thickness of 100 μm. Table 2 shows the results of evaluating the peel strength and flexibility of the obtained compressed positive electrode.
[0127] Next, a battery was produced in the same manner as in Example 1 from the obtained positive electrode. Table 2 shows the results of measuring various characteristics of the produced batteries.
[0128] Table 2
[0129] Example
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PUM

PropertyMeasurementUnit
Diameter20.0mm
Thickness2.0mm
Thickness120.0µm
tensileMPa
Particle sizePa
strength10

Description & Claims & Application Information

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