Method of rapidly charging a lithium ion cell

• US 5,481,174 A
• Filed: 12/27/1993
• Issued: 01/02/1996
• Est. Priority Date: 12/27/1993
• Status: Expired due to Term

• Current Assignee: Motorola Mobility LLC (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Garrett, Scott M., Martin, Lara J.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US08/172,975
• Time in Patent Office: 736 Days
• Field of Search: 320/2, 320/5, 320/14
• US Class Current: 320/129
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process

Abstract

A battery charger for lithium ion cells closely monitors cell voltage, and charge time, so as to avoid the over-application of charge to the cell. Charge pulses (104) are followed by a first rest (110), a discharge (112) and a second rest, (120) period prior to re-initiating the charge pulse. If the battery voltage reaches a preselected maximum, in less than a pre-selected period of time, the charge pulse is reduced by a preselected minimum factor. Cycling of the cell is continued until the cells are fully charged.

Claims

1. A method for rapidly charging a Lithium ion electrochemical cell, said method comprising the steps of:

(i) providing a Lithium ion electrochemical cell;

(ii) applying an electrical charge pulse current to said electrochemical cell, said charge pulse terminating upon the occurrence of either a pre-selected maximum charge time, or a pre-selected maximum cell voltage;

(iii) providing a rest period during which no load or current is applied to said cell; and

(iv) applying a discharge pulse to said electrochemical cell, said discharge pulse terminating upon the occurrence of either a pre-selected discharge period of time, or a pre-selected minimum cell voltage.

2. A method as described in claim 1, including the further step of providing a second rest period after applying said discharge pulse.

3. A method as described in claim 2, including the further step of repeating said charge, rest, and discharge steps.

4. A method as described in claim 3, including the further step of decreasing the charge pulse current when said pre-selected maximum cell voltage is reached in less than a pre-selected minimum charge time.

5. A method as described in claim 4, including the further step of charging said electrochemical cell until a pre-selected minimum charge pulse current causes said cell to reach said pre-selected maximum cell voltage in less than said pre-selected minimum charge time.

6. A method as described in claim 1, wherein the initial charge pulse current is 2C.

7. A method as described in claim 2, wherein one charge-rest-discharge-rest cycle has a duration of between 10 and 60 seconds.

8. A method as described in claim 7, wherein said pre-selected maximum charge time is at least about 80% of the total charge-rest-discharge-rest cycle.

9. A method as described in claim 1, wherein said pre-selected maximum cell voltage is 4.2 volts.

10. A method as described in claim 2, wherein the duration of the discharge pulse is between 0.5 and 5.0 seconds.

11. A method as described in claim 4, wherein the charge pulse current is reduced by a factor of 1/2 when said pre-selected maximum cell voltage is reached in less than the pre-selected minimum charge time.

12. A method as described in claim 1, wherein said pre-selected minimum cell voltage is 2.5 V.

13. A method for rapidly charging a lithium ion electrochemical cell, said method comprising the steps of:

providing a lithium ion electrochemical cell;

applying an electrical charge pulse current to said electrochemical cell, said charge pulse terminating upon the occurrence of either a pre-selected maximum charge time, or a pre-selected maximum cell voltage;

providing a first rest period during which no load or current is applied to said cell;

applying a discharge pulse to said electrochemical cell said discharge pulse terminating upon the occurrence of either a pre-selected minimum cell voltage, or a pre-selected discharge period of time; and

providing a second rest period during which no load or current supply to said cell; and

repeating said charge-rest-discharge-rest cycle until said electrochemical cell is substantially completely charged.

14. A method as described in claim 13 including the further step of decreasing the charge pulse current when said pre-selected maximum cell voltage is reached in less than a pre-selected minimum charge time.

15. A method as described in claim 14, including the further step of charging said electrochemical cell until a pre-selected minimum charge pulse current causes said cell to reach said pre-selected maximum cell voltage in less than said pre-selected minimum charge time.