NON-AQUEOUS ELECTROLYTE SECONDARY BATTERY CHARGING METHOD, ELECTRONIC DEVICE, BATTERY PACK, AND CHARGING DEVICE

• US 20100072951A1
• Filed: 12/11/2007
• Published: 03/25/2010
• Est. Priority Date: 12/26/2006
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Nakashima, Takuya
• Granted Patent: US 8,193,777 B2
• Time in Patent Office: Days
• US Class Current: 320/145
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 50/409 Separators, membranes or diaphragms characterised by the material
• CPC Class Codes: H01M 50/443 Particulate material
• CPC Class Codes: H02J 7/00711 with introduction of pulses during the charging process
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention aims to quickly charge a non-aqueous electrolyte secondary battery including a heat-resistant layer between a negative electrode and a positive electrode. A method according to the present invention for charging a non-aqueous electrolyte secondary battery including a heat-resistant layer between a negative electrode and a positive electrode is provided with a step of performing pulse charge on the secondary battery, a step of detecting a change amount of a cell voltage associated with a change in the concentration polarization of the non-aqueous electrolyte as a polarization voltage, and a step of terminating the pulse charge when the polarization voltage increases to or above a predetermined threshold value. According to the present invention, it is possible to quickly charge the non-aqueous electrolyte secondary battery including the heat-resistant layer between the negative electrode and the positive electrode at such a borderline level as not to cause overcharge.

Claims

1. A charging method for charging a non-aqueous electrolyte secondary battery including a heat-resistant layer between a negative electrode and a positive electrode, comprising:

a pulse charging step of performing pulse charge by applying a pulse to a secondary battery;

a polarization detecting step of detecting a change amount of a cell voltage associated with a change in the concentration polarization of a non-aqueous electrolyte as a polarization voltage after the cell voltage is changed due to a voltage drop caused by an internal resistance of the secondary battery when a charge current flowing in the secondary battery changes as an applied state of the pulse changes; and

a deterioration detecting step of terminating the pulse charge if the polarization voltage detected in the polarization detecting step increases to or above a predetermined first threshold value.

2. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein the polarization detecting step is a step of detecting a difference between a cell voltage of the secondary battery when the pulse is applied to the secondary battery and a cell voltage upon entering a steady state reached by an increase of the cell voltage after the application of the pulse as the polarization voltage associated with the progress of the concentration polarization of the non-aqueous electrolyte.

3. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein the polarization detecting step is a step of detecting a difference between a first cell voltage, which is the cell voltage of the secondary battery when the pulse application to the secondary battery is completed, and a second cell voltage, which is the cell voltage upon entering a steady state reached by a decrease of the cell voltage after the pulse application is completed as the polarization voltage associated with the elimination of the concentration polarization of the non-aqueous electrolyte.

4. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 3, wherein the polarization detecting step is a step of detecting the cell voltage after the lapse of a time equal to or longer than a polarization elimination time set beforehand as a time necessary to eliminate the concentration polarization after the detection of the first cell voltage as the second cell voltage.

5. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 4, wherein the pulse charging step is a step of extending a pulse interval to or longer than the polarization elimination time when the polarization voltage is detected in the polarization detecting step while performing the pulse charge by applying the pulse to the secondary battery in a specified cycle.

6. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein the polarization detecting step includes:

a step of detecting a difference between the cell voltage of the secondary battery when the pulse is applied to the secondary battery and the cell voltage upon entering a steady state by an increase of the cell voltage after the pulse application as a voltage α

;

a step of calculating an accumulated polarization voltage Vca produced by the concentration polarization caused by one previous pulse in accordance with the following equation (a) if A denotes a polarization relaxation coefficient set beforehand as an inclination of a voltage curve of the cell voltage when the concentration polarization is eliminated, B a first cell voltage, which is the cell voltage of the secondary battery when the pulse application to the secondary battery is completed and T a time from the end of one previous pulse application to the start of the pulse application this time; and

a step of calculating the polarization voltage Vc in accordance with the following equation (b) if Vc denotes the polarization voltage;

Vca=B−

A·

T  

 

(a)

Vc=α

+Vca  

 

(b)

7. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, further comprising a pulse changing step of reducing at least one of a charge voltage, a charge current and a pulse width in the pulse charging step if the polarization voltage detected in the polarization detecting step increases to or above a second threshold value set to a voltage value smaller than the first threshold value.

8. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 7, wherein:

a plurality of second threshold values are provided; and

the pulse changing step is a step of reducing at least one of the charge voltage, charge current and pulse width every time the polarization voltage detected in the polarization detecting step increases to or above each second threshold value in an increasing process.

9. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein the first threshold value is 0.1 V per cell.

10. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein:

a maximum value of the voltage of the pulse is 4.5 V;

a maximum value of the current thereof is 50 A;

a maximum value of a pulse width is 1 sec;

a minimum value of a pulse cycle is 3 sec; and

a maximum value of a pulse duty is 33%.

11. A charging method for charging a non-aqueous electrolyte secondary battery according to claim 1, wherein the heat-resistant layer is a porous protection film including resin binders and organic oxide fillers.

12. An electronic device, comprising:

a battery pack including secondary battery having a heat-resistant layer between a positive electrode and a negative electrode;

a charging device including a charge current supplying section and a charge controlling section for charging the secondary battery; and

a load device to be driven by the secondary battery,

wherein;

the battery pack includes a voltage detecting section for detecting a cell voltage of the secondary battery and a transmitting section for transmitting a detection result of the voltage detecting section to the charging device;

the charging device includes a receiving section for receiving the cell voltage from the transmitting section; and

the charge controlling section includes;

a pulse charging section for performing pulse charge by applying a pulse to the secondary battery by means of the charge current supplying section,

a polarization detecting section for causing the receiving section to receive the cell voltage detected by the voltage detecting section and detecting a change amount of the cell voltage received by the receiving section associated with a change in concentration polarization of a non-aqueous electrolyte as a polarization voltage after the cell voltage received by the receiving section is changed due to a voltage drop caused by an internal resistance of the secondary battery when a charge current flowing in the secondary battery changes as an applied state of the pulse changes, and

a deterioration detecting section for terminating the pulse charge by the pulse charging section if the polarization voltage detected by the polarization detecting section increases to or above a predetermined first threshold value.

13. A battery pack, comprising:

a non-aqueous electrolyte secondary battery including a heat-resistant layer between a positive electrode and a negative electrode;

a voltage detecting section for detecting a cell voltage of the secondary battery;

a switching element for switching a charge current from an externally connected charging device, thereby applying a pulse to the secondary battery to perform pulse charge;

a polarization detecting section for detecting a change amount of the cell voltage associated with a change in concentration polarization of the non-aqueous electrolyte as a polarization voltage based on the cell voltage detected by the voltage detecting section after the cell voltage is changed due to a voltage drop caused by an internal resistance of the secondary battery when a charge current flowing in the secondary battery changes as an applied state of the pulse changes; and

a deterioration detecting section for stopping the switching of the switching element to terminate the pulse charge if the polarization voltage detected by the polarization detecting section increases to or above a predetermined first threshold value.

14. A charging device, comprising:

a charge current supplying section for charging a battery pack including a non-aqueous electrolyte secondary battery having a heat-resistant layer between a negative electrode and a positive electrode;

a charge controlling section for controlling the charge current supplying section; and

a voltage detecting section for detecting a terminal voltage of the battery pack,

the charge controlling section including;

a pulse charging section for performing pulse charge by applying a pulse to the secondary battery by means of the charge current supplying section,

a polarization detecting section for detecting a voltage change amount associated with a change in concentration polarization of the non-aqueous electrolyte as a polarization voltage based on the cell voltage detected by the voltage detecting section after the cell voltage is changed due to a voltage drop caused by an internal resistance of the secondary battery when a charge current flowing in the secondary battery changes as an applied state of the pulse changes, and

a deterioration detecting section for terminating the pulse charge by the pulse charging section if the polarization voltage detected by the polarization detecting section increases to or above a predetermined first threshold value.