AQUEOUS ELECTROLYTE LITHIUM SULFUR BATTERIES

• US 20130122334A1
• Filed: 05/18/2012
• Published: 05/16/2013
• Est. Priority Date: 11/15/2011
• Status: Active Grant

• Current Assignee: PolyPlus Battery Company
• Original Assignee: PolyPlus Battery Company
• Inventors: Visco, Steven J., Nimon, Yevgeniy S., De Jonghe, Lutgard C., Goncharenko, Nikolay, Katz, Bruce D., Loginova, Valentina
• Granted Patent: US 8,828,574 B2
• Time in Patent Office: Days
• US Class Current: 429/72
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 4/382 Lithium H01M4/405 takes precedence
• CPC Class Codes: H01M 4/405 Alloys based on lithium
• CPC Class Codes: H01M 4/5815 Sulfides
• CPC Class Codes: H01M 6/045 characterised by aqueous electrolyte
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y10T 29/49108 Electric battery cell making

Abstract

Provided are lithium sulfur battery cells that use water as an electrolyte solvent. In various embodiments the water solvent enhances one or more of the following cell attributes: energy density, power density and cycle life. Significant cost reduction can also be realized by using an aqueous electrolyte in combination with a sulfur cathode. For instance, in applications where cost per Watt-Hour (Wh) is paramount, such as grid storage and traction applications, the use of an aqueous electrolyte in combination with inexpensive sulfur as the cathode active material can be a key enabler for the utility and automotive industries, providing a cost effective and compact solution for load leveling, electric vehicles and renewable energy storage.

Claims

1. An aqueous lithium sulfur electrochemical cell comprising:

an anode structure comprising an electroactive material;

a cathode comprising a solid electron transfer medium;

an aqueous electrolyte in contact with the electron transfer medium; and

active sulfur species in contact with the aqueous electrolyte;

wherein the anode electroactive material is isolated from direct contact with the aqueous electrolyte.

2. The aqueous lithium sulfur cell of claim 1 wherein the active sulfur species comprises active sulfur species dissolved in the aqueous electrolyte.

3. The aqueous lithium sulfur cell of claim 2 wherein the active sulfur concentration in the aqueous electrolyte prior to initially operating the cell is selected from the group consisting of a value that is greater than 0.5 molar sulfur, 1 molar sulfur, 2 molar sulfur, 3 molar sulfur, 4 molar sulfur, 5 molar sulfur, 6 molar sulfur, 7 molar sulfur, 8 molar sulfur, 9 molar sulfur, 10 molar sulfur, 11 molar sulfur, and 12 molar sulfur.

4. The aqueous lithium sulfur electrochemical cell of claim 2 wherein just prior to initially operating the cell:

i) the concentration of the dissolved active sulfur species in the electrolyte is greater than 1 molar sulfur; and

ii) the active stoichiometric ratio is represented by the chemical formula selected from the group consisting of Li₂S;

Li₂S_x (x>

1);

Li₂S_x (1<

x<

5);

Li₂S₅; and

Li₂S_x (x>

5).

5. The aqueous lithium sulfur electrochemical cell of claim 2 wherein just prior to initially operating the cell:

i) the concentration of the dissolved active sulfur species in the electrolyte is greater than 3 molar sulfur; and

ii) the stoichiometric ratio of active sulfur to lithium dissolved in the electrolyte, exclusive of any non-active lithium sulfur salts, is represented by the chemical formula selected from the group consisting of Li₂S_x (2≦

x≦

5).

6. The aqueous lithium sulfur electrochemical cell of claim 2 wherein just prior to initially operating the cell:

i) the concentration of the dissolved active sulfur species in the electrolyte is greater than 1 molar sulfur; and

ii) the stoichiometric ratio of active sulfur to lithium dissolved in the electrolyte, exclusive of any non-active lithium sulfur salts, is represented by the chemical formula Li₂S.

7. The aqueous lithium sulfur electrochemical cell of claim 2 wherein just prior to initial cell operation the active sulfur species in contact with the aqueous electrolyte further comprises solid phase lithium sulfide.

8. The aqueous lithium sulfur electrochemical cell of claim 7 wherein the moles of active sulfur of solid phase lithium sulfide is greater than the moles of active sulfur dissolved in the electrolyte by a factor selected from the group consisting of at least 2, at least 3, at least 5 and at least 10.

9. The aqueous lithium sulfur cell of claim 7 wherein the full charge capacity of the cell is derived from the dissolved active sulfur species and the solid phase lithium sulfide.

10. The aqueous lithium sulfur electrochemical cell of claim 1 wherein upon cell fabrication and prior to initial cell operation the anode electroactive material is substantially devoid of active lithium.

11-45. -45. (canceled)

46. A method of making an aqueous lithium sulfur cell, the method comprising the steps of:

i) providing a lithium anode structure comprising an electroactive material;

ii) providing a cathode comprising an electron transfer medium for electro-reducing active sulfur species during cell discharge;

iii) providing an aqueous electrolyte comprising water; and

iv) configuring the electrolyte, anode structure and cathode into a battery cell;

wherein at least one or both of the cathode and electrolyte comprises active sulfur species.

47. The method of claim 46 wherein the electrolyte comprises dissolved lithium sulfide.

48. The method of claim 47 wherein the cell further comprises solid phase lithium sulfide in contact with the electrolyte.

49. The method of claim 46 wherein the cathode is devoid of elemental sulfur.

50. The method of claim 46 further comprising the step of charging the cell, wherein said charging step is the initial electrochemical operation, and whereby the charging reaction involves electro-reductive lithiation of the anode electroactive material and electro-oxidation of dissolved active sulfur species at the surface of the electron transfer medium.

51. The method of claim 50 wherein the anode electroactive material is devoid of electroactive lithium prior to the start of the initial charging step.

52. The method of claim 51 wherein the amount of active sulfur species and lithium ions in the as-fabricated cell is sufficient for providing the necessary ampere-hour capacity to fully charge the cell during the initial charging step.

54. The method of claim 46 wherein the anode electroactive material is an intercalation material capable of intercalating lithium ions whence electro-reduced.

56. The method of claim 46 wherein anode electroactive material is lithium metal or a lithium metal alloy.

53. (canceled)

55. (canceled)

57-65. -65. (canceled)

66. A lithium sulfur flow cell system comprising:

a lithium sulfur cell comprising;

an anode structure comprising an electroactive material;

a cathode comprising a solid electron transfer medium;

an aqueous electrolyte in contact with the electron transfer medium;

active sulfur species in contact with the aqueous electrolyte;

wherein the anode electroactive material is isolated from direct contact with the aqueous electrolyte;

and further comprising;

an external reservoir system comprising a storage tank comprising aqueous catholyte in flow communication with the aqueous electrolyte in the cell, the aqueous catholyte in the storage tank comprising one or more of a dispersion of solid elemental sulfur, dissolved elemental sulfur, dissolved lithium polysulfide species, dissolved lithium sulfide, and a dispersion of solid lithium sulfide.