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Electrode for electrochemical cell, method of manufacturing the same, and electrochemical cell includng the electrode

a technology of electrochemical cells and electrodes, applied in the direction of cell components, final product manufacturing, sustainable manufacturing/processing, etc., can solve the problems of short circuit of electrodes, low electrical capacity, and decreased stability of metal us

Inactive Publication Date: 2006-07-13
SAMSUNG SDI CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when lithium or the like is repeatedly charged and discharged, lithium dendrite grows on the surface of the electrode, short-circuiting the electrode.
As such, use of a metal decreases stability.
However, the use of carbon material results in low electrical capacity.
However, when the electrode is roll-pressed or the like, electrode density increases, but porosity decreases due to a decrease in volume, thus decreasing the impregnating characteristics of the electrolytic solution.
If this happens, the electrolytic solution cannot sufficiently penetrate the inner portion of the electrode, thereby decreasing the contact area between the electrode and the electrolytic solution.
Accordingly, ions are not sufficiently transported to the electrode and sufficient cell capacity cannot be obtained.
When an electrode operates, its temperature increases and the electrode active material expands, thereby decreasing the amount of the electrolytic solution which eventually becomes insufficient.
However, when the porosity of the electrode active material is decreased from roll-pressing or the like, and the contact surface between the electrode and electrolytic solution decreases, it becomes very difficult to improve impregnating characteristics.
Accordingly, even when the inner portion of the electrode is sufficiently porous, the surface of the electrode is less porous and the electrolytic solution cannot sufficiently penetrate the inner portion of the electrode.

Method used

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  • Electrode for electrochemical cell, method of manufacturing the same, and electrochemical cell includng the electrode
  • Electrode for electrochemical cell, method of manufacturing the same, and electrochemical cell includng the electrode
  • Electrode for electrochemical cell, method of manufacturing the same, and electrochemical cell includng the electrode

Examples

Experimental program
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Effect test

example 1

[0059] 150 ml of distilled water was added to a mixture of 97 g of graphite powder, 1.5 g of styrene butadiene rubber (SBR), and 1.5 g of carboxy methyl cellulose (CMC). The mixture was stirred for 30 minutes using a mechanical mixing device, thus forming a first slurry.

[0060] The first slurry was coated on a 10 μm thick Cu current collector to a thickness of about 100 μm and a loading lever of 8 mg / cm2 using a doctor blade. The first slurry was then dried.

[0061] 150 ml of distilled water was then added to a mixture of 5 g of ammonium bicarbonate, 97 g of graphite powder, 1.5 g of SBR, and 1.5 g of CMC and stirred using a mechanical mixing device for 30 minutes to produce a second slurry. The second slurry was coated on the first slurry to a loading level of about 2 mg / cm2.

[0062] The resulting coated Cu current collector was roll-pressed to a density of 1.7 mg / cm3 and dried in a vacuum at 145° C. for 3 hours, thereby forming an anode plate.

example 2

[0063] 150 ml of distilled water was added to a mixture of 97 g of graphite powder, 1.5 g of SBR, and 1.5 g of CMC and stirred for 30 minutes using a mechanical mixing device, thereby forming a slurry.

[0064] The slurry was coated on a 10 μm thick Cu current collector to a loading level of 10 mg / cm2 using a doctor blade. The slurry was then dried.

[0065] The coated Cu current collector was further coated by spraying it with ammonium bicarbonate dissolved in ethanol. The ammonium bicarbonate was coated to a loading level of about 0.1 mg / cm2.

[0066] The coated Cu current collector was roll-pressed to a density of 1.7 g / cm3 and then dried in a vacuum at 145° C. for 3 hours, thereby forming an anode plate.

example 3

[0067] An anode plate was manufactured as in Example 1 except that ammonium oxalate was used instead of ammonium bicarbonate.

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Abstract

An electrode for an electrochemical cell is provided. The electrode comprises an electrode active material coated on a current collector. The surface of the electrode active material has a greater porosity than the portion nearest the current collector. The electrode includes an active material with controlled porosity, where the porosity of the inner portion is equal to or less than the porosity of the surface of the electrode after the electrode is roll-pressed. As a result, the impregnating characteristics of the electrolytic solution are improved and decreases in capacity upon charging and discharging at high rates are prevented. Therefore, excellent charge and discharge characteristics are obtained. In addition, cells including the inventive electrodes exhibit excellent charge and discharge characteristics.

Description

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS [0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0002449, filed on Jan. 11, 2005, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. FIELD OF THE INVENTION [0002] The present invention relates to an electrode having controlled porosity for an electrochemical cell, and to an electrochemical cell having the same. More particularly, the invention is directed to an electrode in which non-uniform porosity of the electrode active material, which occurs during roll-pressing, is prevented, thereby improving the charge and discharge characteristics of the electrochemical cell including the electrode. BACKGROUND OF THE INVENTION [0003] Electrochemical cells, e.g. secondary batteries, are used in portable electronic devices, and the demand for these electrochemical cell has been increasing. As portable devices become smaller and lighter in ...

Claims

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Application Information

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IPC IPC(8): C25B11/02H01M4/02H01M4/13H01M4/139H01M4/36H01M4/62H01M10/05H01M10/0567
CPCH01M4/0404H01M4/0435H01M4/0471H01M4/13H01M4/133H01M4/139H01M4/1393H01M10/0525H01M2004/021Y02E60/122Y02E60/10Y02P70/50A47J36/04A47J27/004
Inventor PARK, JIN-HWANSONG, MI-JEONGIM, DONG-MIN
Owner SAMSUNG SDI CO LTD
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