Controlled porosity in electrodes

• US 10,164,242 B2
• Filed: 05/19/2015
• Issued: 12/25/2018
• Est. Priority Date: 04/07/2011
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology, Regents of the University of California (University of California)
• Original Assignee: Massachusetts Institute of Technology, Regents of the University of California (University of California), Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Chiang, Yet-Ming, Bae, Chang-Jun, Halloran, John William, Fu, Qiang, Tomsia, Antoni P., Erdonmez, Can K.
• Primary Examiner(s): Ruddock, Ula C
• Assistant Examiner(s): Van Oudenaren, Matthew W
• Application Number:
  US14/716,501
• Publication Number:
  US 20150364753A1
• Time in Patent Office: 1,316 Days
• CPC Class Codes: H01M 10/052 Li-accumulators
• 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 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/0411 by extrusion
• 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 4/139 Processes of manufacture
• CPC Class Codes: H01M 4/1391 of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• 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: Y10T 29/4911 including sealing

Abstract

Porous electrodes in which the porosity has a low tortuosity are generally provided. In some embodiments, the porous electrodes can be designed to be filled with electrolyte and used in batteries, and can include low tortuosity in the primary direction of ion transport during charge and discharge of the battery. In some embodiments, the electrodes can have a high volume fraction of electrode active material (i.e., low porosity). The attributes outlined above can allow the electrodes to be fabricated with a higher energy density, higher capacity per unit area of electrode (mAh/cm²), and greater thickness than comparable electrodes while still providing high utilization of the active material in the battery during use. Accordingly, the electrodes can be used to produce batteries with high energy densities, high power, or both compared to batteries using electrodes of conventional design with relatively highly tortuous pores.

Claims

1. A method of forming an electrode, comprising:

providing a primary structure comprising;

a first constituent; and

a second constituent associated with the first constituent, the second constituent including a plurality of substantially aligned elongated regions, each elongated region having an aspect ratio of at least about 3;

1;

separating a first portion of the primary structure from a second portion of the primary structure; and

removing at least a portion of the second constituent from the primary structure prior to the separating and/or removing at least a portion of the second constituent from the first portion of the primary structure after the separating, such that the first portion of the primary structure comprises elongated pores,

wherein;

the elongated pores within the first portion of the primary structure have longitudinal axes that are surrounded by the first constituent, and

the second constituent and/or pores left behind from removal of the second constituent establish a plurality of elongated regions within the second portion of the primary structure, the elongated regions within the second portion of the primary structure having longitudinal axes that are surrounded by the first constituent.

2. A method as in claim 1, wherein the first portion of the primary structure and the second portion of the primary structure are separated along a plane that is substantially perpendicular to the longitudinal axes of the elongated regions of the second constituent and/or pores corresponding to the elongated regions of the second constituent.

3. A method as in claim 1, wherein providing the primary structure comprises co-extruding at least the first constituent and the second constituent.

4. A method as in claim 3, wherein the first constituent comprises a ceramic.

5. A method as in claim 3, wherein the second constituent comprises a carbon-based material.

6. A method as in claim 1, wherein removing at least a portion of the second constituent comprises heating the second constituent.

7. A method as in claim 1, wherein providing the primary structure comprises solidifying a precursor of the primary structure to produce the first constituent and the second constituent.

8. A method as in claim 7, wherein the precursor comprises a fluid in which solid particles are suspended.

9. A method as in claim 8, wherein the fluid comprises naphthalene.

10. A method as in claim 8, wherein the fluid comprises water.

11. A method as in claim 8, wherein the fluid comprises an additive, and the additive comprises an alcohol and/or a sugar.

12. A method as in claim 8, wherein the solid particles comprise electrode active material.

13. A method as in claim 8, wherein, upon cooling the precursor, the particles agglomerate to form the first constituent, and the fluid solidifies to form the second constituent.

14. A method as in claim 1, wherein removing the second constituent comprises at least partially sublimating the second constituent.

15. A method as in claim 1, further comprising sintering at least a portion of the primary structure.

16. A method as in claim 1, wherein at least about 50% of the second constituent is removed from the primary structure.

17. The method of claim 1, wherein the first portion of the primary structure comprising the elongated pores therein is used as a battery electrode.

18. The method of claim 1, wherein the first portion of the primary structure comprising the elongated pores therein is used as a battery electrode within a battery.