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Vinylidene fluoride based core-shell type polymer and use thereof in nonaqueous electrochemical device

一种二氟乙烯、聚合物的技术，应用在非水系电化学元件领域，能够解决电池寿命特性恶化、集电体破裂、难以制作均一涂布的电极等问题

Inactive Publication Date: 2008-01-16
KUREHA KAGAKU KOGYO KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

1,1-Difluoroethylene-based resin is mainly used as the binder (binder) of the electrode material, but it is obtained by coating the electrode mixture on the metal foil (collector) and drying it when making the electrode. The electrode plates are tightly packed into the battery container, so for example, for a cylindrical battery, when the electrode plate is wound around an axis with a small radius of curvature, or for an angular battery, when the electrode plate is bent, sometimes the electrode mixture Layer rupture, detachment from current collector, or current collector itself rupture
[0003] For the purpose of imparting flexibility to the electrode mixture, rubber-like polymers such as styrene-butadiene rubber are sometimes used in the binder, but even if the electrode mixture layer is pressed, it is difficult to increase the density due to rubber elasticity.
When using, for example, 1,1-difluoroethylene-chlorotrifluoroethylene (CTFE) copolymer and 1,1-difluoroethylene-hexafluoropropylene (HFP) copolymer in fluorine-based resins, 1,1-difluoroethylene can be reduced. The crystallinity of vinyl fluoride makes it a soft binder, but it is known that if the content of CTFE and HFP is high, the electrode mixture layer will swell or dissolve in the electrolyte, and the battery life characteristics will deteriorate
[0004] has also proposed the use of a rubber-like binder (Patent Document 1 below), but when using it alone to prepare an electrode, the powdery active material is in the electrode. Separation and sedimentation in the slurry, it is difficult to form a stable electrode mixture layer
It has also been proposed to mix 1,1-vinylidene fluoride resin and rubber polymer (Patent Document 2 below), but this is dissolved in an organic solvent such as NMP, and when it is used as an adhesive, it is difficult to Phase separation occurs in the mixture solution. Even if it is further mixed with electrode substances such as active materials to prepare electrode mixture slurry, the active material and solution components are easy to separate, and it is difficult to make uniformly coated electrodes.
[0005] has proposed the use of a core / shell adhesive (Patent Document 3 below), but since the core is PTFE, it has a high modulus of elasticity and cannot Making Soft Electrodes

Method used

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  • Vinylidene fluoride based core-shell type polymer and use thereof in nonaqueous electrochemical device
  • Vinylidene fluoride based core-shell type polymer and use thereof in nonaqueous electrochemical device

Examples

Experimental program
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Effect test

Embodiment

[0070] Hereinafter, the present invention will be described in more detail through examples of preparation of polymers, examples as binders, and comparative examples. In addition, in the following description, unless otherwise specified, "part" and "%" which show a composition or a ratio are based on weight.

[0071] Including the description below, the characteristic values ​​described in this specification are based on the measured values ​​obtained by the following methods.

[0072] (Determination of latex particle size)

[0073] The particle size of the polymer in the latex prepared by emulsion polymerization was measured with a particle size distribution measuring device (“N4 PLUS” manufactured by Beckman Coulter, Inc.). The measurement is based on the particle size distribution measured by the photon correlation method at a scattering angle of 90 degrees in a monodisperse mode, and the average particle size of each particle size by the scattering intensity is taken as t...

preparation example

[0108] Polymers A-1 to A-5 corresponding to Examples of the core / shell polymer (A) of the present invention were prepared as follows.

[0109] (Polymer A-1)

[0110] Polymerization of the core: Add 1000g of ion-exchanged water, 4g of ammonium perfluorooctanoate, and 0.8g of sodium pyrophosphate into an autoclave with an inner capacity of 2 liters, pressurize to 5 MPa, perform nitrogen replacement 3 times, and then raise the temperature to 80°C. Weigh 120g of 1,1-difluoroethylene (VDF), 80g of chlorotrifluoroethylene (CTFE), 2g of perfluorodivinyl ether (CL) represented by the following formula:

[0111] CF 2 =CFO(CF 2 ) 2 OCF (CF 3 ) CF 2 OCF=CF 2 ,

[0112] And the ethyl acetate of 1g, mix in the tank that adorns monomer, form the monomer mixture of 203g, add this monomer mixture of a part of 82g together in the above-mentioned autoclave, when the pressure in the kettle reaches 2.6MPa , 20 g of an aqueous solution of 1% by weight of ammonium persulfate was added to ca...

Embodiment 1、5 and 6

[0152] Polymers A-1, A-4 and A-5 corresponding to examples of the core / shell polymer (A) of the present invention were used alone as binders.

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Abstract

Disclosed is a core-shell type polymer (A) having a rubbery core portion composed of a crosslinked vinylidene fluoride copolymer (a) wherein the vinylidene fluoride content is 30-90% by weight, and a shell portion composed of a vinylidene fluoride polymer (b) wherein the vinylidene fluoride content is more than that of the crosslinked vinylidene fluoride copolymer (a) and not less than 80% by weight. In this core-shell type polymer (A), the weight ratio (a) / (b) is from 30 / 70 to 90 / 10. This vinylidene fluoride based core-shell type polymer (A) is excellent in mechanical characteristics including flexibility and nonaqueous electrolyte solution resistance characteristics, and suitably used as a binder for nonaqueous electrochemical devices which enables, in combination with an active material powder, to form an electrode mix layer which exhibits excellent flexibility and excellent adhesion to an electrode collector.

Description

technical field [0001] The present invention relates to new 1,1-difluoroethylene core / shell type polymer and its application in the non-aqueous electrochemical element, that is, the present invention relates to the use of the non-aqueous electrochemical element containing the core / shell type polymer A binder composition, an electrode mixture composition, an electrode, and a nonaqueous electrochemical element. Background technique [0002] In order to increase the capacity of non-aqueous electrochemical elements such as lithium-ion secondary batteries and electric double-layer capacitors, studies are underway to increase the density of electrodes and increase the amount of active material per unit volume. 1,1-Difluoroethylene-based resin is mainly used as the binder (binder) of the electrode material, but it is obtained by coating the electrode mixture on the metal foil (collector) and drying it when making the electrode. The electrode plates are tightly packed into the batt...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08F259/08C08L27/16C08L51/08H01G9/058H01M4/02H01M4/62H01M10/40H01G11/38H01G11/48H01M4/13H01M10/0525H01M10/36
CPCY02E60/12H01G11/48H01G11/38H01M10/0525H01M4/623Y02E60/13H01G9/155H01M4/13C08L51/04C08L51/003C08L27/16H01M4/621C08F259/08H01G9/058Y10T428/2985Y10T428/2991Y10T428/3154Y02E60/10C08L2666/24C08L2666/02H01M10/05
Inventor 佐久间充康五十岚民人永井爱作阿彦信男菅原檀
Owner KUREHA KAGAKU KOGYO KK