Binder for lithium cell, composition for producing electrode, and electrode

Patent metadata

Field	Value
Publication number	US-2018138508-A1
Application number	US-201715819452-A
Country	US
Kind code	A1
Filing date	Nov 21, 2017
Priority date	Oct 26, 2012
Publication date	May 17, 2018
Grant date	—

Abstract

It is an object of the present invention to provide an electrode capable of maintaining superior capacity retention without destruction of an electrode structure, even in the case of using an active material including silicon.
The present invention relates to “a binder for a lithium cell, the binder comprising polyacrylic acid cross-linked by a cross-linking agent selected from the compounds described in the general formulae [1] to [13] and the polymer described in the general formula [14] (provided that the one which includes a functional group-containing vinylidene fluoride-based polymer is excluded)”; a “composition for producing an electrode of a lithium cell, the composition comprising 1) an active material containing silicon, 2) a conductive assistant and 3) a cross-linked-type polyacrylic acid (provided that the one containing a functional group-containing vinylidene fluoride-based polymer is excluded)”; and an “electrode for a lithium cell, the electrode comprising 1) an active material containing silicon, 2) a conductive assistant, 3) a cross-linked-type polyacrylic acid, and 4) a current collector (provided that the one containing a functional group-containing vinylidene fluoride-based polymer is excluded)”.

First claim

1 . A binder for a lithium cell comprising polyacrylic acid cross-linked by a cross-linking agent selected from the compounds described in the following general formulae [1] to [11], provided that the one which includes a functional group-containing vinylidene fluoride-based polymer is excluded, wherein viscosity of the cross-linked polyacrylic acid is 30 to 10000 mPa·S under 60 rpm of a rotational viscometer, or 10000 to 400000 mPa·S under 0.6 rpm of a rotational viscometer, provided that as viscosity measured in a dispersed solution of the cross-linked polyacrylic acid in water in a concentration of 1% by weight;

wherein k represents an integer of 1 to 6,

wherein R 25 and R 26 each independently represent a hydrogen atom or a methyl group, R 20 represents an alkylene group having 1 to 20 carbon atoms, a group represented by the following general formula [2-1],
R 17 —O r   [2-1]

wherein R 17 represents an alkylene group having 1 to 6 carbon atoms, r represents an integer of 1 to 6, or the group represented by the following general formula [2-2]
R 18 —O t R 19 —  [2-2]

wherein R 18 and R 19 each independently represent an alkylene group having 1 to 6 carbon atoms, t represents an integer of 1 to 12,

wherein R 1 to R 6 and R 61 each independently represent an alkylene group having 1 to 3 carbon atoms,

wherein R 7 to R 10 each independently represent an alkylene group having 1 to 6 carbon atoms, 1 represents an integer of 1 to 6, m represents an integer of 0 to 6, v1 and v2 each independently represent an integer of 0 or 1,

wherein R 31 to R 38 each independently represent a hydrogen atom, a vinyl group or a vinylketone group, and at least two or more groups thereof are a vinyl group or a vinylketone group,

wherein R 12 to R 14 each independently represent an alkylene group having carbon 1 to 6 atoms,

wherein Ar 1 represents an aryl group having 6 to 10 carbon atoms, R 15 represents an alkylene group having 1 to 6 carbon atoms, q represents an integer of 2 to 4,

wherein Ar 2 and Ar 3 each independently represent an arylene group having 6 to 10 carbon atoms, R 16 represents an alkylene group having 1 to 6 carbon atoms,

wherein Ar 4 represents an arylene group having 6 to 10 carbon atoms,

wherein, R 11 represents an alkylene group having 1 to 6 carbon atoms.

2 . The binder according to claim 1 , wherein viscosity of the cross-linked polyacrylic acid is 30 to 10000 mPa·S under 60 rpm of a rotational viscometer, provided that as viscosity measured in a dispersed solution of the cross-linked polyacrylic acid in water in a concentration of 1% by weight.

3 . The binder according to claim 1 , wherein the cross-linked polyacrylic acid is the neutralized one.

4 . The binder according to claim 1 , wherein the cross-linked polyacrylic acid is the neutralized one with sodium hydroxide.

5 . The binder according to claim 1 , wherein a cross-linking agent is a compound represented by the general formula [2], the general formula [3], the general formula [4], the general formula [9], the formulae [10-1] to [10-4], or the general formula [11].

6 . The binder according to claim 1 , wherein a cross-linking agent is a compound described in the general formula [2], the general formula [3], the general formula [4], or the formulae [10-1] to [10-4].

7 . The binder according to claim 1 , wherein amount of the cross-linking agent is 0.007 to 0.5% by mol, to 1 mol of acrylic acid.

8 . The binder according to claim 1 , wherein amount of the cross-linking agent is 0.1 to 0.3% by mol, to 1 mol of acrylic acid.

9 . A binder for a lithium cell comprising polyacrylic acid cross-linked by a cross-linking agent selected from the compounds described in the following general formulae [1] to [11], provided that the one which includes a functional group-containing vinylidene fluoride-based polymer is excluded, wherein an amount of the cross-linking agent is 0.007 to 0.5% by mol, to 1 mol of acrylic acid;

wherein k represents an integer of 1 to 6,

wherein R 25 and R 26 each independently represent a hydrogen atom or a methyl group, R 20 represents an alkylene group having 1 to 20 carbon atoms, a group represented by the following general formula [2-1],
R 17 —O r   [2-1]

wherein R 17 represents an alkylene group having 1 to 6 carbon atoms, r represents an integer of 1 to 6, or the group represented by the following general formula [2-2]
R 18 —O t R 19 —  [2-2]

wherein R 18 and R 19 each independently represent an alkylene group having 1 to 6 carbon atoms, t represents an integer of 1 to 12,

wherein R 1 to R 6 and R 61 each independently represent an alkylene group having 1 to 3 carbon atoms,

wherein R 7 to R 10 each independently represent an alkylene group having 1 to 6 carbon atoms, 1 represents an integer of 1 to 6, m represents an integer of 0 to 6, v1 and v2 each independently represent an integer of 0 or 1,

wherein R 31 to R 38 each independently represent a hydrogen atom, a vinyl group or a vinylketone group, and at least two or more groups thereof are a vinyl group or a vinylketone group,

wherein R 12 to R 14 each independently represent an alkylene group having carbon 1 to 6 atoms,

wherein Ar 1 represents an aryl group having 6 to 10 carbon atoms, R 15 represents an alkylene group having 1 to 6 carbon atoms, q represents an integer of 2 to 4,

wherein Ar 2 and Ar a each independently represent an arylene group having 6 to 10 carbon atoms, R 16 represents an alkylene group having 1 to 6 carbon atoms,

wherein Ar 4 represents an arylene group having 6 to 10 carbon atoms,

Assignees

• Wako Pure Chem Ind Ltd
• Univ Tokyo Science Found

Inventors

• Komaba Shinichi
• Yabuuchi Naoaki
• HAN Zhen-Ji
• Sasaki Takeo
• Hashimoto Shota
• Okamoto Kuniaki
• Maesawa Tsuneaki

Classifications

• C08G59/40 Primary

  characterised by the curing agents used · CPC title

• H01M4/622 Primary

  being polymers · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• C08L33/02

  Homopolymers or copolymers of acids; Metal or ammonium salts thereof · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title