Diffusion-limited adaptive battery charging

1. A method for adaptively charging a battery, wherein the battery is a lithium-ion battery that includes a transport-limiting electrode governed by diffusion, an electrolyte separator and a non-transport-limiting electrode, comprising while the battery is charging:

charging the battery with a fixed current for a fixed time period;

entering a zero current state in which the charging current is set to zero;

during the zero current state, measuring an open circuit voltage for the battery at two times while the open circuit voltage relaxes toward a steady state; and

calculating a charging current or a charging voltage based on the measured open circuit voltages; and

applying the calculated charging current or the calculated charging voltage to the battery.

2. The method of claim 1 , wherein calculating the charging current or the charging voltage based on the measured open circuit voltages includes:

calculating a diffusion time T based on the measured open circuit voltages;

calculating a lithium surface concentration based on the diffusion time T, a state of charge of the battery q and a temperature of the battery T; and

calculating the charging current or the charging voltage for the battery based on the calculated lithium surface concentration.

3. The method of claim 1 ,

wherein the transport-limiting electrode is a negative electrode; and

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

4. The method of claim 3 ,

wherein the negative electrode is comprised of graphite and/or TiS 2 ;

wherein the electrolyte separator is a liquid electrolyte comprised of LiPF 6 , LiBF 4 and/or LiClO 4 and an organic solvent; and

wherein the positive electrode is comprised of LiCoO 2 , LiMnO 2 , LiFePO 4 and/or Li 2 FePO 4 F.

5. A lithium-ion battery with an adaptive charging mechanism, comprising:

a transport-limiting electrode governed by diffusion;

an electrolyte separator;

a non-transport-limiting electrode;

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

a voltage sensor configured to measure a voltage across terminals of the battery;

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

a controller configured to receive inputs from the current sensor and the voltage sensor, and configured to send a control signal to the charging source;

wherein, while the battery is charging, the controller is configured to:

charge the battery with a fixed current for a fixed time period,

enter a zero current state in which the charging current is set to zero,

during the zero current state, measure an open circuit voltage for the battery at two times while the open circuit voltage relaxes toward a steady state, and

calculate a charging current or a charging voltage based on the measured open circuit voltages, and

apply the charging current or the charging voltage to the battery.

6. The lithium-ion battery of claim 5 , wherein while calculating the charging current or the charging voltage, the controller is configured to:

calculate a diffusion time τ based on the measured open circuit voltages;

calculate a lithium surface concentration based on the diffusion time τ, a state of charge of the battery q and a temperature of the battery T; and

calculate the charging current or the charging voltage for the battery based on the calculated lithium surface concentration.

7. The lithium-ion battery of claim 5 ,

wherein the transport-limiting electrode is a negative electrode; and

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

8. The lithium-ion battery of claim 7 ,

wherein the negative is comprised of graphite and/or TiS 2 ;

wherein the electrolyte separator is a liquid electrolyte comprised of LiPF 6 , LiBF 4 and/or LiClO 4 and an organic solvent; and

wherein the positive electrode is comprised of LiCoO 2 , LiMnO 2 , LiFePO 4 and/or Li 2 FePO 4 F.

9. A non-transitory computer-readable storage medium storing instructions that when executed by a controller for a battery cause the controller to perform a method for adaptively charging a battery, wherein the battery is a lithium-ion battery which includes a transport-limiting electrode governed by diffusion, an electrolyte separator and a non-transport-limiting electrode, the method comprising, while the battery is charging:

charging the battery with a fixed current for a fixed time period;

entering a zero current state in which the charging current is set to zero;

during the zero current state, measuring an open circuit voltage for the battery at two times while the open circuit voltage relaxes toward a steady state; and

calculating a charging current or a charging voltage based on the measured open circuit voltages; and

applying the charging current or the charging voltage to the battery.

10. The non-transitory computer-readable storage medium of claim 9 , wherein calculating the charging current or the charging voltage based on the measured open circuit voltages includes:

calculating a diffusion time τ based on the measured open circuit voltages;

calculating a lithium surface concentration based on the diffusion time τ, a state of charge of the battery q and a temperature of the battery T; and

calculating the charging current or the charging voltage for the battery based on the calculated lithium surface concentration.

11. A method for adaptively charging a battery, wherein the battery is a lithium-ion battery which includes a transport-limiting electrode governed by diffusion, an electrolyte separator and a non-transport-limiting electrode, comprising:

determining a lithium surface concentration at an interface between the transport-limiting electrode and the electrolyte separator based on a diffusion time for lithium in the transport-limiting electrode;

calculating a charging current or a charging voltage for the battery based on the determined lithium surface concentration; and

applying the charging current or the charging voltage to the battery.

12. The method of claim 11 , wherein the charging current or charging voltage is calculated to maintain the lithium surface concentration within set limits.

13. The method of claim 11 , wherein calculating the charging current or charging voltage involves maximizing the charging current or charging voltage while maintaining the lithium surface concentration within the set limits.

14. The method of claim 11 , wherein determining the lithium surface concentration involves:

measuring a diffusion time τ for lithium in the transport-limiting electrode; and

estimating the lithium surface concentration between τ measurements based on the diffusion time τ, a cell capacity Q max for the battery and a measured charging current I for the battery.

15. The method of claim 14 , wherein measuring the diffusion time τ involves periodically:

charging the battery with a fixed current for a fixed time period;

entering a zero current state in which the charging current is set to zero;

during the zero current state, measuring an open circuit voltage for the battery at two times while the open circuit voltage relaxes toward a steady state; and

calculating the diffusion time τ based on the measured open circuit voltages.

16. The method of claim 15 ,

wherein the transport-limiting electrode is a negative electrode; and

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

17. The method of claim 16 ,

wherein the negative electrode is comprised of graphite and/or TiS 2 ;

wherein the electrolyte separator is a liquid electrolyte comprised of LiPF 6 , LiBF 4 and/or LiClO 4 and an organic solvent; and

wherein the positive electrode is comprised of LiCoO 2 , LiMnO 2 , LiFePO 4 and/or Li 2 FePO 4 F.