Lithium sulfur battery cathode electrode surface treatment during discharge

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.