Method of making an anode structure containing a porous region

Patent metadata

Field	Value
Publication number	US-10833311-B2
Application number	US-201816026426-A
Country	US
Kind code	B2
Filing date	Jul 3, 2018
Priority date	Jul 3, 2018
Publication date	Nov 10, 2020
Grant date	Nov 10, 2020

Abstract

An anode structure for rechargeable lithium-ion batteries that have a high-capacity are provided. The anode structure, which is made utilizing an anodic etching process, is of unitary construction and includes a non-porous region and a porous region including a top porous layer (Porous Region 1 ) having a first thickness and a first porosity, and a bottom porous layer (Porous Region 2 ) located beneath the top porous layer and forming an interface with the non-porous region. At least an upper portion of the non-porous region and the entirety of the porous region are composed of silicon, and the bottom porous layer has a second thickness that is greater than the first thickness, and a second porosity that is greater than the first porosity.

First claim

What is claimed is:

1. A method of making a lithium battery anode structure, the method comprising:
immersing a substrate including at least an upper portion that is composed of p-doped silicon in concentrated hydrogen fluoride while utilizing an anodization setup;
applying an electrical current to the anodization setup; and
anodizing the substrate electrochemically, wherein the anodizing provides a structure composed entirely of at least one semiconductor material and of unitary construction, wherein the structure includes a non-porous region and a porous region comprising a top porous layer having a first thickness and a first porosity, and a bottom porous layer located beneath the top porous layer and forming an interface with the non-porous region, wherein at least an upper portion of the non-porous region and an entirety of the porous region are composed of silicon, and wherein the bottom porous layer has a second thickness that is greater than the first thickness, and a second porosity that is greater than the first porosity, and wherein the upper porous region represents a topmost portion of the structure.

2. The method of claim 1 , further comprising cleaning the substrate prior to the immersing.

3. The method of claim 1 , further comprising rinsing the structure with deionized water and drying, after the anodizing.

4. The method of claim 1 , wherein an entirety of the substrate is composed of p-doped silicon.

5. The method of claim 4 , wherein the p-doped silicon is single crystalline.

6. The method of claim 2 , wherein the cleaning is performed by using a mixture of deionized water, ammonium hydroxide, and hydrogen peroxide, 5:1:1 by volume, at a temperature from 60° C. to 80° C., for a period in the range of five to thirty minutes, followed by rinsing in deionized water.

7. The method of claim 1 , wherein the concentrated hydrogen fluoride is a 49% hydrofluoric acid solution.

8. The method of claim 1 , wherein the electrical current is a constant current in a range of 1 mA/cm 2 to 10 mA/cm 2 .

9. The method of claim 1 , wherein the anodizing of the substrate is performed at a temperature from 20° C. to 30° C.

10. The method of claim 9 , wherein the anodizing of the substrate is performed at an electrical current that is less than or equal to 5 mA/cm 2 for 10 seconds to 2000 seconds.

11. The method of claim 1 , wherein the top porous layer, the bottom porous layer, and the non-porous region are entirely composed of silicon.

12. The method of claim 11 , wherein the silicon is single crystalline.

13. The method of claim 1 , wherein a lower portion of the non-porous layer is composed of doped silicon or a doped silicon germanium alloy having a germanium content of less than 10 atomic percent.

14. The method of claim 1 , wherein the first porosity of the upper porous layer has an average pore opening of less than 3 nm, and wherein the second porosity of the bottom porous layer has an average pore opening of greater than 3 nm.

15. The method of claim 1 , wherein the first thickness of the top porous layer is 50 nm or less.

16. The method of claim 1 , wherein the second thickness of the bottom porous layer is between 0.1 μm to 20 μm.

17. The method of claim 1 , wherein the non-porous region is composed of p-doped silicon that is single crystalline.

18. The method of claim 1 , wherein the non-porous region and the porous regions are entirely comprised of p-type doped silicon.

19. The method of claim 1 , wherein the silicon is p-doped silicon having a p-type dopant concentration in a range of 10 19 cm −3 .

20. The method of claim 1 , wherein the silicon is boron-doped silicon.

21. The method of claim 1 , further comprising patterning the porous region including the top and bottom porous layers.

22. The method of claim 1 , wherein the porous region is formed at the top, bottom or side of any three-dimensional structure.

Assignees

• IBM

Inventors

• De Souza Joel P
• Collins John
• Sadana Devendra K
• Ott John A
• Hopstaken Marinus J P
• Bedell Stephen W

Classifications

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title

• H01M10/0562

  Solid materials · CPC title

• C25D11/32

  of semiconducting materials · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title