Charging method for lithium ion secondary battery and charging control system therefor, and electronic apparatus and battery pack having charging control system

• US 10,320,038 B2
• Filed: 12/10/2015
• Issued: 06/11/2019
• Est. Priority Date: 12/25/2014
• Status: Active Grant

• Current Assignee: Maxell, Ltd.
• Original Assignee: Maxell Holdings, Ltd.
• Inventors: Nomura, Hirokazu, Koyama, Kunihiko
• Primary Examiner(s): Tso, Edward
• Assistant Examiner(s): Piggush, Aaron
• Application Number:
  US15/533,306
• Publication Number:
  US 20180013179A1
• Time in Patent Office: 1,279 Days
• Field of Search: 320134, 320145, 320157, 320164
• 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 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/448 End of discharge regulating measures
• CPC Class Codes: H01M 10/46 Accumulators structurally combined with charging apparatus circuits for charging H02J7/00
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H02J 7/00716 in response to integrated charge or discharge current
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: Y02B 40/00 Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for charging a lithium ion secondary battery of the present invention includes a first step and a second step. In the first step, A, B, and C satisfy the relationship A>B and B<C, where A represents an average charging current value in the range where a charge rate of the lithium ion secondary battery is 0% or more and less than 40%, B represents an average charging current value in the range where the charge rate is 40% or more and 60% or less, and C represents an average charging current value in the range where the charge rate is more than 60%. In the first step, the ratio of C_MAX to C_MIN (C_MAX/C_MIN) is 1.01 to 3.00, where C_MAX represents the maximum value of the charging current value and C_MIN represents the minimum value of the charging current value.

Claims

1. A method for charging a lithium ion secondary battery comprising:

a first step of charging the lithium ion secondary battery by increasing or decreasing a charging current until a predetermined set voltage is reached; and

a second step of charging the lithium ion secondary battery that has reached the set voltage with a constant voltage while decreasing the charging current to maintain the set voltage,

wherein, in the first step, I_A, I_B, and I_C satisfy a relationship I_A>

I_B and I_B<

I_C, where I_A represents an average charging current value in a range where a state of charge (SOC) of the lithium ion secondary battery is 0%≤

SOC<

40%, I_B represents an average charging current value in a range where the state of charge is 40%≤

SOC≤

60%, and I_Crepresents an average charging current value in a range where the state of charge is 60%<

SOC, and

wherein, in the first step, a ratio of I_MAX to I_MIN (I_MAX/I_MIN) is 1.01 to 3.00, where I_MAX represents a maximum value of the charging current value and I_MIN represents a minimum value of the charging current value.

2. The method according to claim 1, wherein, in the first step, the minimum value I_MIN is set in the range where the state of charge is 40%≤

SOC≤

60%.

3. The method according to claim 1, wherein the maximum value I_MAX is 0.4 C to 4.0 C, and the minimum value I_MIN is 0.2 C to 2.0 C.

4. The method according to claim 1, wherein a negative electrode of the lithium ion secondary battery includes graphite as a negative electrode active material.

5. The method according to claim 4, wherein the negative electrode active material includes 40% by mass or more of the graphite.

6. The method according to claim 1, wherein, in the first step, the minimum value I_MIN is set in the range where the state of charge is 40%≤

SOC≤

60%, and

the maximum value I_MAX is 0.4 C to 4.0 C, and the minimum value I_MIN is 0.2 C to 2.0 C.

7. The method according to claim 1, wherein, in the first step, the minimum value I_MIN is set in the range where the state of charge is 40%≤

SOC≤

60%,

the maximum value I_MAX is 0.4 C to 4.0 C, and the minimum value I_MIN is 0.2 C to 2.0 C, and

a negative electrode of the lithium ion secondary battery includes graphite as a negative electrode active material.

8. The method according to claim 7, wherein the negative electrode active material includes 40% by mass or more of the graphite.

9. A charging control apparatus for a lithium ion secondary battery, executing:

a first step of charging the lithium ion secondary battery by increasing or decreasing a charging current until a predetermined set voltage is reached, and a second step of charging the lithium ion secondary battery that has reached the set voltage with a constant voltage while decreasing the charging current to maintain the set voltage,

wherein, in the first step, I_A, I_B, and I_C satisfy a relationship I_A>

I_B and I_B<

I_C, where I_A represents an average charging current value in a range where a state of charge (SOC) of the lithium ion secondary battery is 0%<

SOC<

40%, I_B represents an average charging current value in a range where the state of charge is 40%≤

SOC≤

60%, and I_C represents an average charging current value in a range where the state of charge is 60%<

SOC, and

wherein, in the first step, a ratio of I_MAX to I_MIN (I_MAX/I_MIN) is1.01 to 3.00, where I_MAX represents a maximum value of the charging current value and I_MIN represents a minimum value of the charging current value.

10. The charging control apparatus according to claim 9, wherein, in the first step, the minimum value I_MIN is set in the range where the state of charge is 40%≤

SOC≤

60%.

11. The charging control apparatus according to claim 9, wherein the maximum value I_MAX is 0.4 C to 4.0 C, and the minimum value I_MIN is 0.2 C to 2.0 C.

12. The charging control apparatus according to claim 9, wherein, in the first step, the minimum value I_MIN is set in the range where the state of charge is 40% ≤

SOC≤

60%, and

the maximum value I_MAX is 0.4 C to 4.0 C, and the minimum value I_MIN is 0.2 C to 2.0 C.

13. A battery pack comprising a charging control apparatus for a lithium ion secondary battery,

the charging control apparatus for a lithium ion secondary battery, executing:

a first step of charging the lithium ion secondary battery by increasing or decreasing a charging current until a predetermined set voltage is reached, and a second step of charging the lithium ion secondary battery that has reached the set voltage with a constant voltage while decreasing the charging current to maintain the set voltage,

wherein, in the first step, I_A, I_B, and I_C satisfy a relationship I_A>

I_B and I_B<

I_C, where I_A represents an average charging current value in a range where a state of charge (SOC) of the lithium ion secondary battery is 0%≤

SOC<

40%, I_B represents an average charging current value in a range where the state of charge is 40%≤

SOC≤

60%, and I_C represents an average charging current value in a range where the state of charge is 60%<

SOC, and

wherein, in the first step, a ratio of I_MAX to I_MiN (I_MAX/I_MIN) is 1.01 to 3.00, where I_MAX represents a maximum value of the charging current value and I_MINrepresents a minimum value of the charging current value.