MODULATED, TEMPERATURE-BASED MULTI-CC-CV CHARGING TECHNIQUE FOR LI-ION/LI-POLYMER BATTERIES

• US 20110037438A1
• Filed: 08/17/2009
• Published: 02/17/2011
• Est. Priority Date: 08/17/2009
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Mank, Richard M., Hwang, Taisup, Bhardwaj, Ramesh C.
• Granted Patent: US 8,816,648 B2
• Time in Patent Office: Days
• US Class Current: 320/152
• CPC Class Codes: H02J 7/0071 with a programmable schedule

Abstract

Some embodiments of the present invention provide a system that charges a battery. During operation, the system obtains a set of charging currents {I₁, . . . , I_n} and a set of charging voltages {V₁, . . . , V_n}. Next, the system repeats constant-current and constant-voltage charging operations, starting with i=1 and incrementing i with every repetition, until a termination condition is reached. These constant-current and constant-voltage charging operations involve charging the battery using a constant current I_i until a cell voltage of the battery reaches V_i, and then charging the battery using a constant voltage V_i until a charging current is less than or equal to I_i+1.

Claims

1. A method for charging a battery, comprising:

obtaining a set of charging currents {I₁, . . . , I_n} and a set of charging voltages {V₁, . . . , V_n}; and

repeating constant-current and constant-voltage charging operations, starting with i=1 and incrementing i with every repetition, until a termination condition is reached, wherein the constant-current and constant-voltage charging operations include,

charging the battery using a constant current I_i until a cell voltage of the battery reaches V_i, and then

charging the battery using a constant voltage V_i until a charging current is less than or equal to I_i+1.

2. The method of claim 1, wherein obtaining the set of charging currents and the set of charging voltages involves looking up the set of charging currents and the set of charging voltages in a lookup table based on a measured temperature of the battery.

3. The method of claim 2, wherein looking up the set of charging currents and the set of charging voltages additionally involves using a battery type of the battery to look up the set of charging currents and the set of charging voltages.

4. The method of claim 1, wherein the termination condition is reached when the charging current I_i equals a terminal charging current I_term.

5. The method of claim 1, wherein the battery is a rechargeable lithium battery.

6. The method of claim 1, wherein the rechargeable lithium battery is a lithium-polymer battery.

7. The method of claim 1, wherein the rechargeable lithium battery is a lithium-ion battery.

8. The method of claim 7, wherein the lithium-ion battery includes:

a transport-limiting electrode;

an electrolyte;

a separator permeated with the electrolyte; and

a non-transport-limiting electrode.

9. The method of claim 8,

wherein the transport-limiting electrode is a negative electrode;

and

wherein the non-transport-limiting electrode is a positive electrode.

10. A battery with a charging mechanism, comprising:

the battery;

a voltage sensor configured to monitor a cell voltage of the battery;

a current sensor configured to monitor a charging current for the battery;

a charging source configured to apply a charging current and a charging voltage to the battery; and

a controller configured to receive inputs from the voltage sensor and the current sensor, and to send a control signal to the charging source, wherein the controller is configured to use a set of charging currents {I₁, . . . , I_n} and a set of charging voltages {V₁, . . . , V_n} to charge the battery;

wherein the controller is configured to charge the battery by repeating constant-current and constant voltage charging operations using the set of charging currents and the set of charging voltages until a termination condition is reached.

11. The battery of claim 10, wherein repeating the constant-current and constant-voltage charging operations involves repeating the following operations starting with i=1:

charging the battery using a constant current I_i until the cell voltage of the battery reaches V_i;

charging the battery using a constant voltage V_i until the charging current is less than or equal to I_i+1; and

incrementing i.

12. The battery of claim 10,

wherein the battery further comprises a temperature sensor configured to measure a temperature of the battery;

and

wherein the controller is configured to use the measured temperature to look up the set of charging currents and the set of charging voltages in a lookup table.

13. The battery of claim 10, wherein the termination condition is reached when the charging current I_i equals a terminal charging current I_term.

14. The battery of claim 10, wherein the battery is a rechargeable lithium battery.

15. The battery of claim 10, wherein the rechargeable lithium battery is a lithium-polymer battery.

16. The battery of claim 10, wherein the rechargeable lithium battery is a lithium-ion battery.

17. The battery of claim 15, wherein the lithium-ion battery includes:

a transport-limiting electrode;

an electrolyte;

a separator permeated with the electrolyte; and

a non-transport-limiting electrode.

18. The battery of claim 17,

wherein the transport-limiting electrode is a negative electrode;

and

wherein the non-transport-limiting electrode is a positive electrode.

19. A charging mechanism for a battery, comprising:

a voltage sensor configured to monitor a cell voltage of the battery;

a current sensor configured to monitor a charging current for the battery;

a temperature sensor configured to measure a temperature of the battery;

a charging source configured to apply a charging current and a charging voltage to the battery; and

a controller configured to receive inputs from the voltage sensor, the current sensor and the temperature sensor, and to send a control signal to the charging source, wherein the controller is configured to look up a set of charging currents {I₁, . . . I_n} and a set of charging voltages {V₁, . . . , V_n} in a lookup table based on the measured temperature; and

wherein the controller is configured to charge the battery by repeating constant-current and constant-voltage charging operations until a termination condition is reached.

20. The charging mechanism of claim 19, wherein repeating the constant-current and constant-voltage charging operations involves repeating the following operations starting with i=1:

charging the battery using a constant current I_i until the cell voltage of the battery reaches V_i;

charging the battery using a constant voltage V_i until the charging current is less than or equal to I<sub>i′

1</sub>; and

incrementing i.

21. The charging mechanism of claim 19, wherein the termination condition is reached when the charging current I_i equals a terminal charging current I_term.

22. The charging mechanism of claim 19, wherein the battery is a rechargeable lithium battery.