Controlling battery charging based on current, voltage and temperature

• US 8,624,560 B2
• Filed: 06/08/2009
• Issued: 01/07/2014
• Est. Priority Date: 04/11/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Ungar, P. Jeffrey, Greening, Thomas C., Athas, William C., Field, J. Douglas, Mank, Richard M.
• Primary Examiner(s): Muralidar, Richard V
• Assistant Examiner(s): Chung, Steve T
• Application Number:
  US12/480,581
• Publication Number:
  US 20090273320A1
• Time in Patent Office: 1,674 Days
• Field of Search: 320/112, 320/164, 320/132, 320/152, 362/183, 429/96, 455/573, 324/432, 324/433
• US Class Current: 320/164
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/0568 characterised by the solutes
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/443 in response to temperature
• CPC Class Codes: H01M 10/48 Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/5815 Sulfides
• CPC Class Codes: H01M 4/582 Halogenides
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H02J 7/007194 of the battery
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Some embodiments of the present invention provide a system that charges a lithium-ion battery. During operation, the system monitors: a current through the battery, a voltage of the battery, and a temperature of the battery. Next, the system uses the monitored current, voltage and temperature to control a charging process for the battery. In some embodiments, controlling the charging process involves: inferring electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature; and applying the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits.

Claims

1. A method for charging a battery, wherein the battery is a lithium-ion battery, the method comprising:

monitoring a current through the battery;

monitoring a voltage of the battery;

monitoring a temperature of the battery;

inferring electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature; and

applying the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits, wherein maintaining the inferred electrode lithium surface concentrations for the battery within set limits comprises;

receiving a charging profile comprising a set of data points, wherein each data point specifies a current, a voltage and a temperature for the battery, wherein the specified current, voltage and temperature are associated with a maximum lithium surface concentration for the battery during the charging process;

using interpolation to compare the monitored current, temperature and voltage of the battery against a surface defined by the set of data points, wherein the surface is associated with the maximum lithium concentration of the battery; and

using results of the comparison to adjust the charging current and/or the charging voltage to maintain the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration during the charging process.

2. The method of claim 1, wherein inferring the electrode lithium surface concentrations involves determining potentials for one or more working electrodes with respect to a reference electrode, which can include a metallic lithium electrode, wherein the determined potentials are correlated with the electrode lithium surface concentrations;

and

wherein applying the charging current and/or the charging voltage involves using the determined potentials for the one or more working electrodes to adjust the charging current and/or the charging voltage to maintain the potentials of the one or more working electrodes at levels which keep the electrode lithium surface concentrations within the set limits.

3. The method of claim 2, wherein maintaining the potentials of the one or more working electrodes involves maintaining either a maximum potential or a minimum potential which keeps the electrode lithium surface concentrations within the set limits.

4. The method claim 1, wherein adjusting the charging current and/or the charging voltage involves:

applying a constant charging current to the battery until the monitored voltage reaches a maximum voltage, wherein the maximum voltage maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging current and the monitored temperature; and

/or

applying a constant charging voltage to the battery until the monitored current reaches a lower current, wherein the lower current maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging voltage and the monitored temperature.

5. The method claim 1, wherein prior to receiving the charging profile, the method further comprises generating the charging profile by taking measurements, including voltage, current and temperature, while charging a reference battery, which is similar to the battery, wherein the measurements are used to estimate the electrode lithium surface concentrations of the battery during the charging process.

6. The method of claim 5,

wherein taking the measurements involve determining the potentials of working electrodes in the reference battery with respect to a reference electrode, which can include a metallic lithium reference electrode;

and

wherein estimating the electrode lithium surface concentrations involves using the determined working electrode potentials with respect to the reference electrode to estimate the electrode lithium surface concentrations.

7. The method of claim 6, wherein determining the potentials of the working electrodes with respect to the reference electrode involves directly measuring the potentials of the working electrodes with respect to an integral reference electrode built into a cell in the reference battery.

8. The method of claim 6, wherein determining the potentials of the working electrodes with respect to the reference electrode involves:

determining a state of charge for the reference battery; and

determining the potentials of the working electrodes with respect to the reference electrode from the determined state of charge and other parameters related to the reference battery.

9. The method of claim 1, wherein the battery is a lithium-ion battery which includes:

a transport-limiting electrode;

an electrolyte;

a separator permeated with the electrolyte; and

a non-transport-limiting electrode.

10. The method of claim 9,

wherein the transport-limiting electrode is a negative electrode;

and

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

11. The method of claim 9,

wherein the negative electrode is comprised of graphite and/or TiS₂;

wherein the electrolyte is a liquid electrolyte comprised of LiPF₆, LiBF₄ and/or LiClO₄ and an organic solvent; and

wherein the positive electrode is comprised of LiCoO₂, LiMnO₂, LiFePO₄ and/or Li₂FePO₄F.

12. A battery with a charging mechanism, comprising:

the battery;

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

a current sensor configured to monitor a current through the battery;

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

a charging source configured to apply a charging current and/or 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,

infer electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature, and

apply the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits, wherein maintaining the inferred electrode lithium surface concentrations for the battery within set limits comprises;

receiving a charging profile comprising a set of data points, wherein each data point specifies a current, a voltage and a temperature for the battery, wherein the specified current, voltage and temperature are associated with a maximum lithium surface concentration for the battery during the charging process;

using interpolation to compare the monitored current, temperature and voltage of the battery against a surface defined by the set of data points, wherein the surface is associated with the maximum lithium concentration of the battery; and

using results of the comparison to adjust the charging current and/or the charging voltage to maintain the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration during the charging process.

13. The battery of claim 12, wherein while inferring the electrode lithium surface concentrations, the controller is configured to determine potentials for one or more working electrodes with respect to a reference electrode, which can include a metallic lithium electrode, wherein the determined potentials are correlated with the electrode lithium surface concentrations;

and

wherein while applying the charging current and/or the charging voltage, the controller is configured to use the determined potentials for the one or more working electrodes to adjust the charging current and/or the charging voltage to maintain the potentials of the one or more working electrodes at levels which keep the electrode lithium surface concentrations within the set limits.

14. The battery of claim 13, wherein while maintaining the potentials of the one or more working electrodes, the controller is configured to maintain either a maximum potential or a minimum potential which keeps the electrode lithium surface concentrations within the set limits.

15. The battery of claim 12, wherein the controller is configured to:

apply a constant charging current to the battery until the monitored voltage reaches a maximum voltage, wherein the maximum voltage maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging current and the monitored temperature; and

/or

apply a constant charging voltage to the battery until the monitored current reaches a lower current, wherein the lower current maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging voltage and the monitored temperature.

16. The battery of claim 12, wherein the charging profile was previously generated by taking measurements, including voltage, current and temperature, while charging a reference battery, which is similar to the battery, and wherein the measurements were used to estimate the electrode lithium surface concentrations of the battery during the charging process.

17. The battery of claim 12, wherein the battery is a lithium-ion battery which 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. The battery of claim 18,

wherein the negative electrode is comprised of graphite and/or TiS₂;

wherein the electrolyte is a liquid electrolyte comprised of LiPF₆, LiBF₄ and/or LiClO₄ and an organic solvent; and

wherein the positive electrode is comprised of LiCoO₂, LiMnO₂, LiFePO₄ and/or Li₂FePO₄F.

20. A charging mechanism for a battery, comprising:

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

a current sensor configured to monitor a current through the battery;

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

a charging source configured to apply a charging current and/or 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,

infer electrode lithium surface concentrations for the battery from the monitored current, voltage and temperature, and

apply the charging current and/or the charging voltage in a manner that maintains the inferred electrode lithium surface concentrations for the battery within set limits, wherein maintaining the inferred electrode lithium surface concentrations for the battery within set limits comprises;

receiving a charging profile comprising a set of data points, wherein each data point specifies a current, a voltage and a temperature for the battery, wherein the specified current, voltage and temperature are associated with a maximum lithium surface concentration for the battery during the charging process;

using interpolation to compare the monitored current, temperature and voltage of the battery against a surface defined by the set of data points, wherein the surface is associated with the maximum lithium concentration of the battery; and

using results of the comparison to adjust the charging current and/or the charging voltage to maintain the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration during the charging process.

21. The charging mechanism of claim 20, wherein while inferring the electrode lithium surface concentrations, the controller is configured to determine potentials for one or more working electrodes with respect to a reference electrode, which can include a metallic lithium electrode, wherein the determined potentials are correlated with the electrode lithium surface concentrations;

and

wherein while applying the charging current and/or the charging voltage, the controller is configured to use the determined potentials for the one or more working electrodes to adjust the charging current and/or the charging voltage to maintain the potentials of the one or more working electrodes at levels which keep the electrode lithium surface concentrations within the set limits.

22. The charging mechanism of claim 21, wherein while maintaining the potentials of the one or more working electrodes, the controller is configured to maintain either a maximum potential or a minimum potential which keeps the electrode lithium surface concentrations within the set limits.

23. The charging mechanism of claim 20, wherein the controller is configured to:

apply a constant charging current to the battery until the monitored voltage reaches a maximum voltage, wherein the maximum voltage maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging current and the monitored temperature;

or

apply a constant charging voltage to the battery until the monitored current reaches a lower current, wherein the lower current maintains the electrode lithium surface concentrations of the battery below the maximum lithium surface concentration given the constant charging voltage and the monitored temperature.

24. The charging mechanism of claim 20, wherein the charging profile was previously generated by taking measurements, including voltage, current and temperature, while charging a reference battery, which is similar to the battery, wherein the measurements were used to estimate the electrode lithium surface concentrations of the battery during the charging process.