Adhesive for lithium-ion electrode, electrode for lithium-ion battery and method for manufacturing electrode for lithium-ion battery

Patent metadata

Field	Value
Publication number	US-11430973-B2
Application number	US-201816605639-A
Country	US
Kind code	B2
Filing date	Apr 20, 2018
Priority date	Apr 21, 2017
Publication date	Aug 30, 2022
Grant date	Aug 30, 2022

Abstract

The present invention provides a viscous adhesive capable of retaining the shape of an electrode and allowing for production of an electrode for a lithium-ion battery having a structure in which the energy density of the electrode does not decrease. The present invention relates to a viscous adhesive for a lithium-ion electrode which allows active materials to adhere to each other in a lithium-ion electrode, the viscous adhesive having a glass transition temperature of 60° C. or lower, a solubility parameter of 8 to 13 (cal/cm3)1/2, and a storage shear modulus and a loss shear modulus of 2.0×103 to 5.0×107 Pa as measured in a frequency range of 10−1 to 101 Hz at 20° C., wherein the viscous adhesive is an acrylic polymer essentially containing a constituent unit derived from a (meth)acrylic acid alkyl ester monomer, the proportion of the (meth)acrylic acid alkyl ester monomer in monomers constituting the viscous adhesive is 50 wt % or more based on the total monomer weight, and the proportion of a fluorine-containing monomer is less than 3 wt % based on the total monomer weight.

First claim

The invention claimed is:

1. A viscous adhesive for a lithium-ion electrode
which allows active materials to adhere to each other in the lithium-ion electrode,
the viscous adhesive having a glass transition temperature of 60° C. or lower, a solubility parameter of 8 to 13 (cal/cm 3 ) 1/2 , and a storage shear modulus of 2.0×10 3 to 5.0×10 7 Pa and a loss shear modulus of 2.0×10 3 to 5.0×10 7 Pa as measured in a frequency range of 10 −1 to 10 1 Hz at 20° C.,
wherein the viscous adhesive is an acrylic polymer essentially containing a constituent unit derived from a (meth)acrylic acid alkyl ester monomer, a proportion of the (meth)acrylic acid alkyl ester monomer in monomers constituting the viscous adhesive is 50 wt % or more based on a total monomer weight, the (meth)acrylic acid alkyl ester monomer contains 1,6-hexanediol di(meth)acrylate, and a proportion of a fluorine-containing monomer is less than 3 wt % based on the total monomer weight.

2. The viscous adhesive for the lithium-ion electrode according to claim 1 ,
wherein the viscous adhesive contains two or more (meth)acrylic acid alkyl ester monomers as constituent monomers, and a total content of the two or more (meth)acrylic acid alkyl ester monomers is 50 wt % or more based on the total monomer weight.

3. The viscous adhesive for s-the lithium-ion electrode according to claim 1 ,
wherein the viscous adhesive contains, as a constituent monomer, a monovinyl monomer copolymerizable with the (meth)acrylic acid alkyl ester monomer.

4. The viscous adhesive for the lithium-ion electrode according to claim 1 ,
wherein the viscous adhesive contains a (meth)acrylic acid monomer as a constituent monomer.

5. An electrode for a lithium-ion battery comprising:
an unbound product between the viscous adhesive according to claim 1 and a coated electrode active material including an electrode active material that occludes and releases lithium ions and a coating layer containing a coating resin on at least a portion of a surface of the electrode active material, with the proviso that starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinylpyrrolidone, tetrafluoroethylene, styrene-butadiene rubber, polyethylene, polypropylene, and styrene-butadiene copolymer are each excluded from the electrode.

6. The electrode for the lithium-ion battery according to claim 5 ,
wherein a weight ratio of the coated electrode active material to the viscous adhesive (coated electrode active material/ viscous adhesive) is 90/10 to 99.99/0.01.

7. The electrode for the lithium-ion battery according to claim 5 ,
wherein an electrode active material layer constituting the electrode has a thickness of 150 μm or more.

8. A method of producing an electrode for a lithium-ion battery, comprising:
compressing a mixture of a coated electrode active material and a viscous adhesive for a lithium-ion electrode so as to form an electrode active material layer formed from an unbound product of the mixture containing the coated electrode active material and the viscous adhesive,
the coated electrode active material including an electrode active material that occludes and releases lithium ions and a coating layer containing a coating resin on at least a portion of a surface of the electrode active material,
the viscous adhesive for the lithium-ion electrode allowing active materials to adhere to each other in the lithium-ion electrode,
the viscous adhesive having a glass transition temperature of 60° C. or lower, a solubility parameter of 8 to 13 (cal/cm 3 ) 1/2 , and a storage shear modulus of 2.0×10 3 to 5.0×10 7 Pa and a loss shear modulus of 2.0×10 3 to 5.0×10 7 Pa as measured in a frequency range of 10 −1 to 10 1 Hz at 20° C.,
wherein the viscous adhesive is an acrylic polymer essentially containing a constituent unit derived from a (meth)acrylic acid alkyl ester monomer, a proportion of the (meth)acrylic acid alkyl ester monomer in monomers constituting the viscous adhesive is 50 wt % or more based on a total monomer weight, the (meth)acrylic acid alkyl ester monomer contains 1,6-hexanediol di(meth)acrylate, and a proportion of a fluorine-containing monomer is less than 3 wt % based on the total monomer weight.

9. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein the viscous adhesive contains two or more (meth)acrylic acid alkyl ester monomers as constituent monomers, and a total content of the two or more (meth)acrylic acid alkyl ester monomers is 50 wt % or more based on the total monomer weight.

10. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein the viscous adhesive contains, as a constituent monomer, a monovinyl monomer copolymerizable with the (meth)acrylic acid alkyl ester monomer.

11. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein the viscous adhesive contains a (meth)acrylic acid monomer as a constituent monomer.

12. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein a weight ratio of the coated electrode active material to the viscous adhesive (coated electrode active material/viscous adhesive) in the mixture is 90/10 to 99.99/0.01.

13. The method of producing the electrode for a-the lithium-ion battery according to claim 8 ,
wherein the mixture is an electrolyte solution-containing mixture further containing an electrolyte solution, and
the electrode active material layer is formed by compressing the electrolyte solution- containing mixture.

14. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein the electrode active material layer has a thickness of 150 μm or more.

15. The viscous adhesive for the lithium-ion electrode according to claim 1 ,
wherein the (meth)acrylic acid alkyl ester monomer contains n-butyl (meth)acrylate.

16. The method of producing the electrode for the lithium-ion battery according to claim 8 ,
wherein the (meth)acrylic acid alkyl ester monomer contains n-butyl (meth)acrylate.

Assignees

• Sanyo Chemical Ind Ltd

Inventors

• Ohta Tomoya
• Nasu Kotaro
• Kawakita Kenichi
• Suenaga Takuya
• Mori Yusuke
• Ohsawa Yasuhiko
• Kusachi Yuki
• Satou Hajime
• Akama Hiroshi
• Horie Hideaki

Classifications

• H01M4/139

  Processes of manufacture · CPC title

• H01M4/043

  involving compressing or compaction · CPC title

• H01M4/366

  as layered products · CPC title

• H01M4/622 Primary

  being polymers · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title