Safe and low temperature thermite reaction systems and method to form porous silicon

Patent metadata

Field	Value
Publication number	US-10246337-B2
Application number	US-201715436027-A
Country	US
Kind code	B2
Filing date	Feb 17, 2017
Priority date	Feb 17, 2017
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

Embodiments of a safe, low-temperature reaction system and method for preparing porous silicon are disclosed. The porous silicon is prepared from porous silica, a low-melting metal halide, and a metal comprising aluminum, magnesium, or a combination thereof. Advantageously, embodiments of the disclosed methods can be performed at temperatures ≤400° C. Silicon produced by the disclosed methods has a porosity that is equal to or greater than the porous silica precursor. The porous silicon is suitable for use in electrodes.

First claim

We claim:

1. A method for preparing porous silicon, comprising:
forming a mixture comprising (i) porous silica, (ii) a metal comprising aluminum, magnesium, or a combination thereof, and (iii) a metal halide comprising a metal M, where the metal M is Ti, Zn, Ga, Ge, Aq, Sn, Sb, Au, Hq, Tl, Bi, or a combination thereof, and the metal halide has a melting point ≤400° C.;
heating the mixture in a sealed vessel at a temperature greater than or equal to the melting point of the metal halide and ≤400° C. under an inert atmosphere to form a product comprising porous silicon; and
combining the product with acid to remove any by-products from the porous silicon.

2. The method of claim 1 , wherein the metal M is Zn, Sn, Sb, Ti, or a combination thereof.

3. The method of claim 1 , wherein the metal halide is a metal chloride, metal bromide, metal iodide, or a combination thereof.

4. The method of claim 1 , wherein the metal halide is a metal chloride.

5. The method of claim 4 , wherein the metal chloride is ZnCl 2 , SnCl 2 , SbCl 3 , TiCl 4 , or a combination thereof.

6. The method of claim 4 , wherein the metal chloride is ZnCl 2 , SnCl 2 , or SbCl 3 , and the mixture is heated at a temperature within a range of from 250° C. to 350° C.

7. The method of claim 1 , wherein the mixture is heated for a period of time within a range of from one hour to 24 hours to form the porous silicon.

8. The method of claim 1 , wherein the acid is hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, or a combination thereof.

9. The method of claim 1 , wherein the porous silica, the metal comprising aluminum, magnesium, or a combination thereof, and the metal halide comprising the metal M are combined in a molar ratio of 1 mole silica, 2-6 moles metal, and 1-6 moles metal halide.

10. The method of claim 1 , wherein the porous silica has an initial Brunauer-Emmett Teller (BET) surface area as determined by nitrogen adsorption and the porous silicon has a BET surface area within a range of 1.0-1.8X the initial BET surface area of the porous silica.

11. A method for preparing porous silicon, comprising:
forming a mixture comprising (i) porous silica, (ii) a metal comprising aluminum, magnesium, or a combination thereof, and (iii) an iron halide having a melting point ≤400° C.;
heating the mixture in a sealed vessel at a temperature greater than or equal to the melting point of the iron halide and ≤400° C. under an inert atmosphere to form a product comprising porous silicon; and
combining the product with acid to remove any by-products from the porous silicon, wherein the porous silica, the metal comprising aluminum, magnesium, or a combination thereof, and the iron halide are combined in a molar ratio of 1 mole silica, 2-6 moles metal, and 0.2-0.3 moles iron halide.

12. The method of claim 11 , wherein the iron halide is FeCl 3 .

Assignees

• Battelle Memorial Institute

Inventors

• Li Xiaolin
• Zhang Ji-Guang
• Liu Jun

Classifications

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01B33/023 Primary

  by reduction of silica or {free} silica-containing material · CPC title

• C01P2006/40

  Electric properties · CPC title

• C01P2006/12

  Surface area · CPC title

• C01P2004/03

  obtained by SEM · CPC title