CARBON MATERIAL-CONTAINING DISPERSION LIQUID, SLURRY FOR ELECTRODE FORMATION, AND METHOD FOR PRODUCING ELECTRODE FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERIES

• US 20200136143A1
• Filed: 06/04/2018
• Published: 04/30/2020
• Est. Priority Date: 06/05/2017
• Status: Active Application

• Current Assignee: Sekisui Chemical Company Limited (Sekisui)
• Original Assignee: Sekisui Chemical Company Limited (Sekisui)
• Inventors: Masuda, Hiroki, Sawada, Yuuki, Nakasuga, Akira, Fujiwara, Akihiko
• Application Number:
  US16/616,256
• Publication Number:
  US 20200136143A1
• Time in Patent Office: Days
• CPC Class Codes: C01B 32/182 Graphene
• CPC Class Codes: C01B 32/198 Graphene oxide
• CPC Class Codes: C01B 32/21 After-treatment
• CPC Class Codes: C01B 32/225 Expansion; Exfoliation
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/22 Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/60 Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0471 involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• CPC Class Codes: H01M 4/13 Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/139 Processes of manufacture
• CPC Class Codes: H01M 4/1393 of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/62 Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries

Abstract

Provided is a carbon material-containing dispersion liquid that is excellent in dispersibility when used as a slurry for electrode formation of a secondary battery, and is capable of enhancing the battery characteristics such as output characteristics of the secondary battery. A carbon material-containing dispersion liquid includes a carbon material and a dispersion medium for the carbon material. In the carbon material-containing dispersion liquid, a concentration of the carbon material in the carbon material-containing dispersion liquid is 0.01% by weight or more and 20% by weight or less, and a light transmittance at a wavelength of 650 nm of a supernatant of the carbon material-containing dispersion liquid when the carbon material-containing dispersion liquid is left to stand at 25° C. for 24 hours after preparation is 1% or more and 60% or less.

Claims

1. A carbon material-containing dispersion liquid comprising a carbon material and a dispersion medium for the carbon material,

wherein a concentration of the carbon material in the carbon material-containing dispersion liquid is 0.01% by weight or more and 20% by weight or less, and

a light transmittance at a wavelength of 650 nm of a supernatant of the carbon material-containing dispersion liquid when the carbon material-containing dispersion liquid is left to stand at 25°

C. for 24 hours after preparation is 1% or more and 60% or less.

2. The carbon material-containing dispersion liquid according to claim 1, wherein the dispersion medium has a viscosity at 25°

C. of 0.89 mPa·

s or more and 1.89 mPa·

s or less.

3. The carbon material-containing dispersion liquid according to claim 1, wherein the dispersion medium is water or N-methyl-2-pyrrolidone.

4. The carbon material-containing dispersion liquid according to claim 1, wherein the carbon material has a graphite structure, and has a structure in which graphite is partially exfoliated.

5. The carbon material-containing dispersion liquid according to claim 1, wherein the carbon material has a mean particle diameter of 1 μ

m or more and 40 μ

m or less.

6. The carbon material-containing dispersion liquid according to claim 1, wherein a ratio y/x of a methylene blue adsorption y (μ

mol/g) per 1 g of the carbon material that is determined based on a difference between an absorbance of a 10 mg/L methylene blue solution in methanol and an absorbance of a supernatant obtained by introduction of the carbon material into the methylene blue solution in methanol, followed by centrifugal separation, and a BET specific surface area x (m²/g) of the carbon material is 0.15 or more.

7. The carbon material-containing dispersion liquid according to claim 1, wherein a peak intensity ratio D/G of a D band and G band in a Raman spectrum of the carbon material falls within a range of 0.05 or more and 0.8 or less.

8. The carbon material-containing dispersion liquid according to claim 1, wherein a particle concentration of the carbon material when a 20 ppm solution of the carbon material in N-methyl-2-pyrrolidone is measured by a flow-type particle image analyzer is 10,000 particles/μ

L or more and 200,000 particles/μ

L or less.

9. The carbon material-containing dispersion liquid according to claim 1, further comprising a dispersibility imparting agent composed of a polyvinyl acetal resin and/or a polyvinylidene fluoride resin.

10. The carbon material-containing dispersion liquid according to claim 9, wherein a ratio B/(A+B) where A represents a weight of the carbon material and B represents a weight of the dispersibility imparting agent falls within a range of 0.001 or more and 0.15 or less.

11. A slurry for electrode formation for use in forming an electrode of a nonaqueous electrolyte secondary battery, the slurry for electrode formation comprising:

the carbon material-containing dispersion liquid according to claim 1;

an active material; and

a binder.

12. The slurry for electrode formation according to claim 11, further comprising a second carbon material, the second carbon material being a different carbon material from a first carbon material when the carbon material contained in the carbon material-containing dispersion liquid is set as the first carbon material, and lacking a structure in which graphite is partially exfoliated.

13. The slurry for electrode formation according to claim 11, wherein the second carbon material is at least one selected from the group consisting of graphene oxide, a particulate graphite compound, a fibrous graphite compound, and carbon black.

14. A method for producing an electrode for nonaqueous electrolyte secondary batteries, the method comprising:

a step of preparing the slurry for electrode formation according to claim 11; and

a step of forming an electrode by applying the slurry for electrode formation on a collector foil substrate, and drying the slurry for electrode formation.