Methods of charging lithium sulfur cells

• US 20050156575A1
• Filed: 01/06/2004
• Published: 07/21/2005
• Est. Priority Date: 01/06/2004
• Status: Active Grant

• Current Assignee: Sion Power Corporation
• Original Assignee: Moltech Corporation
• Inventors: Mikhaylik, Yuriy V.
• Granted Patent: US 7,019,494 B2
• Time in Patent Office: Days
• US Class Current: 320/137
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/0569 characterised by the solvents
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 4/38 of elements or alloys
• CPC Class Codes: H01M 6/168 by additives
• CPC Class Codes: H02J 7/0071 with a programmable schedule
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors

Abstract

Disclosed is a method of charging a lithium-sulfur electrochemical cell wherein the lithium-sulfur cell comprises a cathode comprising an electroactive sulfur-containing material, an anode comprising lithium, and a nonaqueous electrolyte.

Claims

1. A method of charging a lithium-sulfur electrochemical cell wherein the method comprises:

(A) supplying electrical energy to the cell at a constant current;

(B) monitoring the voltage during charging; and

(C) terminating the charge when the monitored voltage is in the range of about 2.35 volts to about 2.7 volts;

and wherein the cell comprises;

(a) a cathode comprising an electroactive sulfur-containing material;

(b) an anode comprising lithium; and

(c) a nonaqueous electrolyte, wherein the electrolyte comprises;

(i) one or more nonaqueous solvents selected from the group consisting of acyclic ethers, cyclic ethers, polyethers, and sulfones; and

(ii) one or more N—

O additives.

2. The method of claim 1 wherein the electrolyte further comprises one or more lithium salts.

3. The method of claim 1 wherein the termination voltage is the range of about 2.4 volts to about 2.6 volts.

4. The method of claim 1 wherein the termination voltage is about 2.5 volts.

8. The method of claim 1 wherein the one or more N—

O additives is selected from one or more of the group consisting of inorganic nitrates, organic nitrates, inorganic nitrites, and organic nitro compounds.

9. The method of claim 8 wherein the inorganic nitrate is selected from one or more of the group consisting of lithium nitrate, potassium nitrate, cesium nitrate, barium nitrate, and ammonium nitrate.

10. The method of claim 8 wherein the inorganic nitrite is selected from one or more of the group consisting of lithium nitrite, potassium nitrite, cesium nitrite, and ammonium nitrite.

11. The method of claim 8 wherein the organic nitro compound is selected from one or more of the group consisting of nitromethane, nitropropane, nitrobenzene, dinitrobenzene, nitrotoluene, dinitrotoluene, and nitropyridine.

12. The method of claim 2 wherein the one or more lithium salts is selected from one or more of the group consisting of LiSCN, LiCF₃SO₃, and LiN(CF₃SO₂)₂.

13. The method of claim 1 wherein the concentration of the one or more N—

O additives in the electrolyte is from about 0.1 m to 2.0 m.

14. The method of claim 1 wherein the concentration of the one or more N—

O additives in the electrolyte is from about 0.1 m to 1.0 m.

15. The method of claim 1 wherein the concentration of the one or more N—

O additives in the electrolyte is from about 0.1 m to 0.5 m.

16. The method of claim 2 wherein the concentration of the one or more lithium salts in the electrolyte is from about 0.2 m to about 2.0 m.

17. The method of claim 1 wherein the electroactive sulfur-containing material comprises elemental sulfur.

18. The method of claim 1 wherein the anode comprises lithium metal.

5. A method of charging a lithium-sulfur electrochemical cell wherein the method comprises:

(A) supplying electrical energy to the cell at a constant current;

(B) monitoring the voltage during charging;

(C) supplying electrical energy until the monitored voltage reaches about 2.5 volts;

(D) holding the cell voltage at about 2.5 volts while monitoring the current density; and

(E) terminating the charge when the charge current density is less than 0.025 mA/cm²;

and wherein the cell comprises;

(a) a cathode comprising an electroactive sulfur-containing material;

(b) an anode comprising lithium; and

(c) a nonaqueous electrolyte, wherein the electrolyte comprises;

(i) one or more nonaqueous solvents selected from the group consisting of acyclic ethers, cyclic ethers, polyethers, and sulfones; and

(ii) one or more N—

O additives.

6. The method of claim 5 wherein the electrolyte further comprises one or more lithium salts.

7. The method claim 5 wherein the charge is terminated when the charge current density is less than 0.012 mA/cm².

19. A method of charging a lithium-sulfur electrochemical cell wherein the method comprises:

(A) supplying electrical energy to the cell at a constant current;

(B) monitoring the voltage during charging;

(C) calculating the rate of change of voltage with time (dV/dt); and

(D) terminating the charge when the value of dV/dt increases by more than 5 times;

and wherein the cell comprises;

(a) a cathode comprising an electroactive sulfur-containing material;

(b) an anode comprising lithium; and

(c) a nonaqueous electrolyte, wherein the electrolyte comprises;

(i) one or more nonaqueous solvents selected from the group consisting of acyclic ethers, cyclic ethers, polyethers, and sulfones;

(ii) one or more lithium salts; and

(iii) one or more N—

O additives.

20. The method of claim 19 wherein the charge is terminated when the value of dV/dt increases by more than 10 times.