Electrode compsn. and lithium secondary battery

A lithium secondary battery and electrode composition technology, applied in secondary batteries, primary batteries, lithium batteries, etc., can solve problems such as low-temperature performance difficulties, and achieve the effects of reduction, stable diffusion, and improved expansion capacity

Inactive Publication Date: 2003-02-19
TDK CORPARATION
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the main purpose of these is to improve the electrolyte composition; while using γ-butyrolactone to prevent battery swelling, it is still very difficult to improve low temperature performance

Method used

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Examples

Experimental program
Comparison scheme
Effect test

no. 1 approach

[0040] According to a first embodiment of the present invention, there is provided an electrode composition comprising a lithium fluoroborate-based salt in an electrolyte, poly(vinylidene fluoride) homopolymer at least as a binder, and Contains γ-butyrolactone as an electrolyte solvent. The poly(vinylidene fluoride) homopolymer is obtained by emulsion polymerization.

[0041] According to the first embodiment of the present invention, there is also provided a lithium secondary battery including the above electrode composition.

[0042] According to the present invention, only when poly(vinylidene fluoride) homopolymer (abbreviated as PVDF hereinafter) is used as a binder, the capacity reduction of the lithium fluoroborate-based system (abbreviated as BF system) can be reduced. This effect was not found at all when using PVDF obtained by other methods. Therefore, the use of PVDF provides a very efficient means of making electrodes energy dense. Although the mechanism is not ...

no. 2 approach

[0084]According to a second embodiment of the present invention, there is provided a lithium secondary battery including a case, and a cathode, an anode, and an electrolyte contained therein, wherein the cathode active material contains a lithium-containing composite oxide including lithium cobalt oxide and auxiliary Component element M, wherein M represents a transition metal or a typical metal element other than Li and Co, and its content is 0.001 to 2 at% relative to the cobalt in lithium cobalt oxide, and a solvent for electrolyte, which contains 60 to 95% by volume of γ-butyrolactone, the thickness of the above shell is 0.3 mm or less.

[0085] According to the present embodiment, it is possible to provide a lithium secondary battery that has satisfactory low-temperature performance and does not emit gas even at high temperatures. Even when using a casing made of a film, any expansion of the casing is prevented.

[0086] In the lithium secondary battery according to the ...

Embodiment A-1

[0106] Lithium cobalt oxide is used as an electrode active material. For the preparation of the electrodes, various methods such as those mentioned above can be employed. In this case, the following PVDF polymers were used as binders.

[0107] PVDF Elf Atochem Co., Ltd. (Atofina Co., Ltd.) Kynar 741

[0108] The PVDF is produced by emulsion polymerization. Electrodes were prepared using this binder. In this embodiment, a gel solid electrolyte is used as an electrolyte. This gel solid electrolyte was synthesized and prepared according to the description in JP-A 11-276298.

[0109] More specifically, LiCoO 2 Used as a cathode active material, acetylene black was used as a conductive aid, and PVDF Kynar 741 was used as a binder.

[0110] These supplies are weighed according to a certain method in order to obtain the following ratio: LiCoO 2 : Acetylene black: PVDF=83:6:11 by mass. Then, add acetone in a certain way to make acetone:PVDF=9:1 mass. These were mixed together...

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Abstract

One object of the invention is to provide an electrode composition that prevents capacity decreases that occurs when BF-based salts are used and a lithium secondary battery, and another object is to provide a lithium secondary battery having high discharge capacity even at low temperature with no risk of swelling even during storage. These objects are attained by the provision of an electrode composition containing a lithium fluoroborate-based salt in an electrolyte, wherein a poly(vinylidene fluoride) homopolymer is contained at least as a binder and a lactone is contained as an electrolyte solvent while the poly(vinylidene fluoride) homopolymer has been obtained by a emulsion polymerization process, and a lithium secondary battery using the same.

Description

technical field [0001] The invention relates to an electrode composition for secondary battery materials used in lithium secondary batteries, an improvement to an electrolytic solution using a non-aqueous solvent, and a secondary battery using the composition. Background technique [0002] The recent astonishing advancements in mobile devices and equipment have resulted in an increased demand for batteries, particularly lithium-ion batteries, as power sources for mobile devices and equipment. As the functions of mobile devices and equipment diversify, obtaining higher energy and improving the performance of accompanying batteries are new goals of technological development. Important technical challenges include: [0003] (1) Improved safety (prevention of overcharging, etc.), [0004] (2) Enhance high temperature storage, and [0005] (3) Improve cycle performance. [0006] Improved high-temperature storage performance has been achieved in certain battery systems, for ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/48H01M4/485H01M4/52H01M4/525H01M4/62H01M6/16H01M6/18H01M6/40H01M10/052H01M10/0525H01M10/0565H01M10/0568H01M10/36H01M50/403H01M50/417H01M50/426H01M50/449
CPCH01M2/1653H01M2/1686H01M6/164H01M2/145H01M4/525H01M10/052H01M6/40H01M4/485H01M10/0525H01M4/623H01M2300/0037Y02E60/122H01M4/621H01M2/0287H01M4/625H01M10/0565H01M2/1673H01M10/0568H01M2300/0085H01M6/188H01M2/0292H01M2/168H01M6/166Y02E60/10H01M50/124H01M50/1245H01M50/46H01M50/461H01M50/403H01M50/449H01M50/417H01M50/426
Inventor 丸山哲长山森小须田敦子
Owner TDK CORPARATION
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