COMBINED ELECTROCHEMICAL AND CHEMICAL ETCHING PROCESSES FOR GENERATION OF POROUS SILICON PARTICULATES

• US 20160293935A1
• Filed: 05/05/2016
• Published: 10/06/2016
• Est. Priority Date: 01/07/2013
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), Rice University
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation), Rice University
• Inventors: Biswal, Sibani Lisa, Wong, Michael S., Thakur, Madhuri, Sinsabaugh, Steven L.
• Granted Patent: US 9,947,918 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C01B 33/02 Silicon forming single crystals or homogeneous polycrystalline material with defined structure C30B
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/16 Pore diameter
• CPC Class Codes: C25F 3/12 of semiconducting materials
• 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 2004/027 Negative electrodes
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/621 Binders
• CPC Class Codes: H01M 4/622 being polymers
• CPC Class Codes: H01M 4/626 Metals
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 20/133 Renewable energy sources, e.g. sunlight

Abstract

Embodiments of the present disclosure pertain to methods of preparing porous silicon particulates by: (a) electrochemically etching a silicon substrate, where electrochemical etching comprises exposure of the silicon substrate to an electric current density, and where electrochemical etching produces a porous silicon film over the silicon substrate; (b) separating the porous silicon film from the silicon substrate, where the separating comprises a gradual increase of the electric current density in sequential increments; (c) repeating steps (a) and (b) a plurality of times; (d) electrochemically etching the silicon substrate in accordance with step (a) to produce a porous silicon film over the silicon substrate; (e) chemically etching the porous silicon film and the silicon substrate; and (f) splitting the porous silicon film and the silicon substrate to form porous silicon particulates. Further embodiments of the present disclosure pertain to the formed porous silicon particulates and anode materials that contain them.

Claims

1. An anode material comprising:

porous silicon particulates,

wherein the porous silicon particulates comprise a plurality of pores, wherein the plurality of pores comprise diameters between about 1 nanometer to about 5 micrometers;

a coating associated with the porous silicon particulates; and

a binding material associated with the porous silicon particulates, wherein the binding material is selected from the group consisting of binders, carbon materials, polymers, metals, additives, carbohydrates, and combinations thereof.

2. The anode material of claim 1, wherein the coating comprises a metal coating.

3. The anode material of claim 2, wherein the metal is selected from the group consisting of silver, copper, chromium, gold, aluminum, tantalum, lead, zinc, silicon, and combinations thereof.

4. The anode material of claim 2, wherein the metal is silver.

5. The anode material of claim 1, wherein the binding material comprises a polymer selected from the group consisting of polyacrylonitrile (PAN), pyrolyzed polyacrylonitrile (PPAN), polyvinylidene difluoride (PVDF), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), and combinations thereof.

6. The anode material of claim 1, wherein the binding material comprises carbonized polyacrylonitrile.

7. The anode material of claim 1, wherein the plurality of pores comprise diameters of at least about 50 nm, less than about 50 nm, less than about 2 nm, and combinations thereof.

8. The anode material of claim 1, wherein the plurality of pores comprise hierarchical pores.

9. The anode material of claim 1, wherein the hierarchical pores comprise micropores and mesopores within macropores.

10. The anode material of claim 1, wherein the porous silicon particulates have thicknesses ranging from about 10 micrometers to about 200 micrometers.

11. The anode material of claim 1, wherein the porous silicon particulates comprise pores that span at least 50% of a thickness of the porous silicon particulates.

12. The anode material of claim 1, wherein the porous silicon particulates comprise pores that span an entire thickness of the porous silicon particulates.

13. The anode material of claim 1, wherein the porous silicon particulates comprise diameters from about 1 μ

m to about 50 μ

m.

14. The anode material of claim 1, wherein the anode material has a discharge capacity of at least about 600 mAh/g over at least 50 cycles.

15. The anode material of claim 1, wherein the anode material has a discharge capacity of at least about 1000 mAh/g over at least 50 cycles.

16. The anode material of claim 1, wherein the anode material has a Coulombic efficiency of at least about 90% over at least 50 cycles.

17. The anode material of claim 1, wherein the anode material is utilized as part of a lithium ion battery.