Pore orientation using magnetic fields

• US 10,569,480 B2
• Filed: 10/02/2015
• Issued: 02/25/2020
• Est. Priority Date: 10/03/2014
• Status: Active Grant

• Current Assignee: Massachusetts Institute of Technology, Northeastern University
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Sander, Jonathan Samuel, Chiang, Yet-Ming, Erb, Randall Morgan
• Primary Examiner(s): Thrower, Larry W
• Application Number:
  US14/874,253
• Publication Number:
  US 20160096334A1
• Time in Patent Office: 1,607 Days
• CPC Class Codes: B29C 67/202 comprising elimination of a solid or a liquid ingredient
• CPC Class Codes: B29L 2031/3468 Batteries, accumulators or fuel cells battery cases B29L2031/7146
• CPC Class Codes: H01F 1/447 characterised by magnetoviscosity, e.g. magnetorheological, magnetothixotropic, magnetodilatant liquids electrorheological fluids C10M171/001
• CPC Class Codes: H01M 2004/021 Physical characteristics, e.g. porosity, surface area
• CPC Class Codes: H01M 4/04 Processes of manufacture in general
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The use of magnetic fields in the production of porous articles is generally described. Certain embodiments comprise exposing a matrix to a magnetic field such that particles within the matrix form one or more elongated regions (e.g., one or more regions in which the particles chain). In some embodiments, after the magnetic field has been applied, the particles and/or a liquid within the matrix can be at least partially removed. Removal of the particles and/or the liquid can leave behind anisotropic pores within the remainder of the matrix material.

Claims

1. A method, comprising:

exposing a matrix comprising a liquid and emulsion droplets to a magnetic field such that the magnetic field causes at least a portion of the emulsion droplets to chain; and

at least partially removing the emulsion droplets from the matrix to form anisotropic pores within the matrix.

2. The method of claim 1, wherein at least partially removing the emulsion droplets from the matrix is performed without sintering particles within the matrix.

3. The method of claim 1, wherein exposing the matrix to the magnetic field comprises exposing the matrix to a magnetic field having a gradient of at least about 100 Oe/cm.

4. The method of claim 1, wherein the emulsion droplets are magnetic emulsion droplets.

5. The method of claim 1, wherein the emulsion droplets comprise a magnetic fluid.

6. The method of claim 1, wherein the matrix comprises magnetic particles, and the emulsion droplets are non-magnetic emulsion droplets.

7. The method of claim 6, wherein the matrix comprises the non-magnetic emulsion droplets within a magnetic fluid.

8. The method of claim 7, wherein the magnetic fluid is a ferrofluid.

9. The method of claim 6, wherein the non-magnetic emulsion droplets are at least one order of magnitude larger than the magnetic particles.

10. The method of claim 1, wherein the matrix comprises electrode material.

11. The method of claim 10, wherein the electrode material comprises Li(Ni,Co,Al)O₂, an LiMnO₃—

LiMO₂ alloy, and/or graphite.

12. The method of claim 1, wherein exposing the matrix to the magnetic field causes emulsion droplets in the matrix to form multiple chains.

13. The method of claim 12, wherein longitudinal axes of the multiple chains are substantially aligned with each other.

14. The method of claim 1, wherein at least partially removing the emulsion droplets from the matrix comprises washing the emulsion droplets with a solvent.

15. The method of claim 1, wherein at least partially removing the emulsion droplets from the matrix comprises evaporating emulsion droplet material from the matrix.

16. The method of claim 1, comprising, prior to at least partially removing the emulsion droplets from the matrix, consolidating the matrix.

17. The method of claim 16, wherein consolidating the matrix comprises polymerizing the matrix.