Lithium sulfur battery cathode electrode surface treatment during discharge

Patent metadata

Field	Value
Publication number	US-9379417-B2
Application number	US-201414171971-A
Country	US
Kind code	B2
Filing date	Feb 4, 2014
Priority date	Feb 4, 2014
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

Methods and apparatus are provided for discharging a Li—S battery having at least one battery unit comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between. One method comprises electrochemically surface treating the sulfur-containing cathode during discharge of the battery. A method of electrochemically surface treating a cathode of a lithium-sulfide battery comprises applying at least one oxidative voltage pulse during a pulse application period while the lithium-sulfur battery discharges and controlling pulse characteristics during the pulse application period, the pulse characteristics configured to affect a morphology of lithium sulfide forming on the sulfur-containing cathode during discharge.

First claim

What is claimed is:

1. A method of interrupting lithium-sulfide morphology during normal cycling of a lithium-sulfur battery having at least one battery unit comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between, the method comprising:
during a pulse application period of a discharge cycle occurring through normal use of the lithium sulfur-battery, superimposing at least one oxidative voltage pulse onto a discharge voltage at the time of the pulse application period to electrochemically treat a surface of the sulfur-containing cathode during discharge of the battery, wherein the oxidative voltage pulse during the pulse application period is less than a constant current charging voltage.

2. The method of claim 1 , wherein the pulse application period is only between depths of discharge of 50% to 80%.

3. The method of claim 1 , wherein the discharge cycle of the battery is unaffected by the at least one superimposed oxidative voltage pulse.

4. The method of claim 1 , further comprising:
controlling pulse characteristics during the pulse application period, the pulse characteristics configured to affect a morphology of lithium sulfide forming on the sulfur-containing cathode during discharge.

5. The method of claim 4 , wherein the pulse characteristics include one or more of a number of pulses, a frequency of pulses, a pulse duration, a peak voltage, a peak duration, a pulse shape and a valley duration.

6. The method of claim 4 , wherein the at least one oxidative voltage pulse is a plurality of oxidative voltage pulses and controlling pulse characteristics comprises gradually increasing or decreasing the peak voltage of each of the oxidative voltage pulses, each peak voltage being less than a constant current charging voltage.

7. The method of claim 4 , wherein controlling pulse characteristics comprises applying the peak voltage of the at least one oxidative voltage pulse for a duration of time before the peak voltage is decreased.

8. The method of claim 4 , wherein the at least one oxidative voltage pulse is a plurality of oxidative voltage pulses and controlling pulse characteristics comprises applying a subsequent oxidative voltage pulse immediately after a preceding oxidative pulse has returned to a discharge voltage.

9. The method of claim 4 , wherein the at least one oxidative voltage pulse is a plurality of oxidative voltage pulses and controlling pulse characteristics comprises applying a subsequent oxidative voltage pulse a duration of time after a preceding oxidative pulse has returned to a discharge voltage.

10. The method of claim 4 , wherein the pulse characteristics are controlled to optimize dissolution of lithium sulfide formed at the sulfur-containing cathode of the battery.

11. A method of electrochemically surface treating a cathode of a lithium-sulfide battery, the method comprising:
commencing a discharge cycle during normal operation of the lithium sulfide battery;
applying at least one oxidative voltage pulse during a pulse application period occurring during the discharge cycle, the pulse application period being only a portion of the discharge cycle;
controlling pulse characteristics during the pulse application period, the pulse characteristics configured to affect a morphology of lithium sulfide forming on the sulfur-containing cathode during discharge; and
continuing with the discharge cycle when the pulse application period is completed.

12. The method of claim 11 , wherein the pulse application period is between depths of discharge of 50% to 80%.

13. An apparatus for discharging a lithium-sulfur battery having at least one unit cell comprising a lithium-containing anode and a sulfur-containing cathode with an electrolyte layer there between, the apparatus comprising:
a memory; and
a processor configured to execute instructions stored in the memory to electrochemically treat a surface of the sulfur-containing cathode during discharge of the battery, the instructions comprising:
commencing a discharge cycle during normal operation of the lithium sulfide battery;
applying at least one oxidative voltage pulse during a pulse application period occurring during the discharge cycle, the pulse application period being only a portion of the discharge cycle;
controlling pulse characteristics during the pulse application period, the pulse characteristics configured to affect a morphology of lithium sulfide forming on the sulfur-containing cathode during discharge; and
continuing with the discharge cycle when the pulse application period is completed.

14. The apparatus of claim 13 , wherein the pulse application period is between depths of discharge of 50% to 80%.

15. The apparatus of claim 13 , wherein the at least one oxidative voltage pulse is superimposed and discharge of the battery is unaffected.

16. The apparatus of claim 13 , wherein the pulse characteristics include a number of pulses, a frequency of pulses, a pulse duration, a peak voltage, a peak duration, a pulse shape, and a valley duration.

17. The method of claim 11 , wherein a length of the pulse application period during the discharge cycle increases based on an increase in a number of discharge cycles the lithium-sulfur battery has experienced.

Assignees

• Nissan North America Inc

Inventors

• Ramaswamy Nagappan
• Aurora Peter
• Dileo Gregory
• Hao Xiaoguang
• Han Taehee
• Yadav Rameshwar
• Niangar Ellazar
• Oshihara Kenzo

Classifications

• H01M10/42

  Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells (H01M10/60 takes precedence) · CPC title

• H01M10/4242

  Regeneration of electrolyte or reactants · CPC title

• H02J2007/0067

  Electricity · mapped topic

• H02J7/00

  Circuit arrangements for charging or discharging batteries or for supplying loads from batteries · CPC title

• H02J7/0063

  Electricity · mapped topic