Anaerobic Aluminum-Water Electrochemical Cell

Patent metadata

Field	Value
Publication number	US-2019036182-A1
Application number	US-201816057166-A
Country	US
Kind code	A1
Filing date	Aug 7, 2018
Priority date	Dec 4, 2012
Publication date	Jan 31, 2019
Grant date	—

Abstract

Provided is a method for generating an electrical current. The method includes: introducing water between the anode and at least one cathode of an electrochemical cell, to form an electrolyte; anaerobically oxidizing aluminum or an aluminum alloy; and electrochemically reducing water at the at least one cathode. When the cell is in operation, the hydroxyaluminate (Al(OH) 4 − ) in the electrolyte reaches a concentration maximum and thereafter a concentration minimum. The concentration maximum is above 125% of the saturation concentration and below 2000% of the saturation concentration. The concentration minimum is below 125% of the saturation concentration and above 50% of the saturation concentration.

First claim

1 . A method for generating an electrical current using an electrochemical cell comprising: a plurality of electrode stacks, each electrode stack comprising an anode including the aluminum or aluminum alloy, and at least one cathode configured to be electrically coupled to the anode; one or more physical separators between each electrode stack adjacent to the cathode; a housing configured to hold the electrode stacks, an electrolyte, and the physical separators; and a water injection port, in the housing, configured to introduce water into the housing, the method comprising:
introducing water between the anode and at least one cathode of the electrochemical cell, to form the electrolyte; anaerobically oxidizing aluminum or an aluminum alloy; and electrochemically reducing water at the at least one cathode, wherein: when the cell is in operation, the hydroxyaluminate (Al(OH) 4 − ) in the electrolyte reaches a concentration maximum and thereafter a concentration minimum, wherein:
the concentration maximum is above 125% of the saturation concentration and below 2000% of the saturation concentration, and
the concentration minimum is below 125% of the saturation concentration and above 50% of the saturation concentration.

2 . The method according to claim 1 , wherein the concentration maximum is above 150% of the saturation concentration and below 1500% of the saturation concentration.

3 . The method according to claim 1 , where the concentration maximum is above 175% of the saturation concentration and below 1000% of the saturation concentration.

4 . The method according to claim 1 , where the concentration maximum is above 200% of the saturation concentration and below 500% of the saturation concentration.

5 . The method according to claim 1 , wherein the concentration minimum is below 125% of the saturation concentration and above 75% of the saturation concentration.

6 . The method according to claim 1 , wherein the concentration minimum is below 100% of the saturation concentration and above 50% of the saturation concentration.

7 . The method according to claim 1 , wherein substantially no aluminum hydroxide precipitate is formed by homogeneous precipitation.

8 . The method according to claim 1 , wherein the electrolyte includes a hydroxide base at a concentration of at least 0.1 M to at most 3 M.

9 . The method according to claim 1 , wherein the electrolyte includes a hydroxide base at a concentration of at least 0.25 M to at most 2.5 M.

10 . The method according to claim 1 , wherein the water includes sodium chloride.

11 . The method according to claim 1 , wherein the aluminum has a purity of at least 99.95 wt %.

12 . The method according to claim 1 , wherein the aluminum has a purity of at least 99.99 wt %.

13 . The method according to claim 1 , wherein the aluminum or aluminum alloy is substantially free of tin and boron.

14 . The method according to claim 1 , wherein the cathode is in the form of a solid plate.

15 . The method according to claim 1 , wherein the cathode is in the form of a sponge.

16 . The method according to claim 1 , wherein the cathode includes a nickel-molybdenum alloy.

17 . The method according to claim 1 , the cathode having a surface characterized by an electrochemical roughness factor of at least 5.

18 . The method according to claim 1 , the cathode having a surface characterized by an electrochemical roughness factor of at least 10.

19 . The method according to claim 1 , substantially free of aerobic oxidation of the aluminum or aluminum alloy.

20 . The method of according to claim 1 , wherein a waste separation system in fluid communication with the housing receives the electrolyte and aluminum hydroxide waste from the electrochemical cell and separates the aluminum hydroxide waste from the electrolyte, and a fuel injector, in fluid communication with the waste separation system and the water injection port, receives the electrolyte from the waste separation system and provides the electrolyte to the water injection port.

21 . The method according to claim 20 , wherein the fuel injector further receives water from a water supply.

22 . The method according to claim 20 , wherein each electrode stack includes two cathodes on either side of the anode.

23 . In a method for generating an electrical current, the method comprising: introducing water between the anode and at least one cathode of an electrochemical cell, to form an electrolyte, anaerobically oxidizing aluminum or an aluminum alloy, and electrochemically reducing water at the at least one cathode, the improvement comprising: when the cell is in operation, the hydroxyaluminate (Al(OH) 4 − ) in the electrolyte reaches a concentration maximum above 125% of the saturation concentration and below 2000% of the saturation concentration and thereafter a concentration minimum below 125% of the saturation concentration and above 50% of the saturation concentration.

Assignees

• Massachusetts Inst Technology

Inventors

• Mckay Ian Salmon
• Macdonald Ruaridh R
• Milnes Thomas B

Classifications

• H01M12/04 Primary

  composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type · CPC title

• H01M6/32

  activated through external addition of electrolyte or of electrolyte components · CPC title

• H01M4/0447

  of complete cells or cells stacks · CPC title

• H01M12/02

  Details (of electrodes H01M4/00; of non-active parts H01M50/00) · CPC title

• H01M2300/0014

  Alkaline electrolytes · CPC title