Electrode including current collector with nano-scale coating and method of making the same

• US 8,802,288 B2
• Filed: 04/12/2012
• Issued: 08/12/2014
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Divigalpitiya, Ranjith, Buckett, Mary I.
• Primary Examiner(s): HARRIS, GARY D
• Application Number:
  US13/444,991
• Publication Number:
  US 20120231331A1
• Time in Patent Office: 852 Days
• Field of Search: 429/231.4, 429/211, 429/209, 977/755
• US Class Current: 429/209
• 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 10/0565 Polymeric materials, e.g. gel-type or solid-type
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/0404 by coating on electrode collectors
• CPC Class Codes: H01M 4/0416 involving impregnation with a solution, dispersion, paste or dry powder H01M4/0438 takes precedence
• CPC Class Codes: H01M 4/36 Selection of substances as active materials, active masses, active liquids
• CPC Class Codes: H01M 4/48 of inorganic oxides or hydroxides
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/623 fluorinated polymers
• CPC Class Codes: H01M 4/661 Metal or alloys, e.g. alloy coatings H01M4/669 take precedence
• CPC Class Codes: H01M 4/663 containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• CPC Class Codes: H01M 4/667 in the form of layers, e.g. coatings
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 977/755 Nanosheet or quantum barrier/well, i.e. layer structure having one dimension or thickness of 100 nm or less

Abstract

Current collectors and methods are provided that relate to electrodes that are useful in lithium polymer electrochemical cells. The provided current collectors include a metallic substrate, a substantially uniform nano-scale carbon coating, and an active electrode material. The coating has a maximum thickness of less than about 200 nanometers.

Claims

1. An electrode for an electrochemical cell comprising:

a current collector comprising;

a metallic substrate; and

a substantially uniform nano-scale coating comprising graphite; and

an active electrode material,

wherein the nano-scale coating has a maximum thickness of less than about 200 nanometers;

wherein the nano-scale coating is disposed between the active electrode material and the metallic substrate; and

wherein the nano-scale coating is substantially free of a binder.

2. An electrode according to claim 1 wherein the metallic substrate is selected from aluminum, copper;

magnesium, nickel, tin, and alloys thereof.

3. An electrode according to claim 1 wherein the coating has a maximum thickness of less than about 50 nanometers.

4. An electrode according to claim 1 wherein the coating has a sheet resistance of less than about 100 ohms/square.

5. An electrode according to claim 1 wherein the active material is selected from LiFePO₄, VO₂, and combinations thereof.

6. An electrode according to claim 1 wherein the carbon coating consists essentially of graphite.

7. A battery comprising at least one electrode according to claim 1.

14. An electrode according to claim 1, wherein a Raman Spectrum of said graphite coating has:

at least one peak between wave numbers of 1500 and 1630 cm<sup>−

1</sup>,

at least two peaks between wave numbers 800 and 1900 cm<sup>−

1</sup>, and

substantially no peak between wave numbers 1400 and 1500 cm<sup>−

1</sup>;

wherein each of said peaks has a full width at half maximum value of 90 cm<sup>−

1</sup> or less.

8. A method of making a current collector comprising:

providing a metallic substrate; and

applying to the substrate without a solvent present, a dry composition including graphite particles;

buffing an effective amount of said particles on said substrate at a pressure normal to the surface of greater than 0 and less than about 30 g/cm² using an applicator pad, said applicator pad moving in a plane parallel to said surface in a plurality of directions relative to a point on the surface such that a substantially uniform coating of said particles is provided, and

providing an active electrode material,

wherein said particles have a Mohs'"'"' hardness between 0.4 and 3 and a largest dimension of less than about 100 microns,

wherein the substantially uniform coating has a maximum average thickness of less than about 100 nanometers with a variation in thickness of no more than 10%, ;

and

wherein the metallic substrate is selected from aluminum, copper, magnesium, nickel, tin, and alloys thereof,

wherein the substantially uniform coating is disposed between the active electrode material and the metallic substrate; and

wherein the substantially uniform coating is substantially free of a binder.

9. A method according to claim 8 wherein the substantially uniform coating has a maximum average thickness of less than about 50 nanometers.

10. A method according to claim 8 further comprising heating the coated substrate to a temperature of at least 175°

C. for a period of at least 5 minutes.

11. A method according to claim 8 wherein the coated substrate has a surface resistance of less than about 1000 ohms/square.

12. A lithium polymer battery comprising at least one electrode wherein the current collector is made by the method according to claim 8.

13. A battery according to claim 12 wherein the at least one electrode comprises an active material selected from LiFePO₄, VO₂, and combinations thereof.