# US 10,320,038 B2 · Charging method for lithium ion secondary battery and charging control system therefor, and electronic apparatus and battery pack having charging control system

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- Number: US 10,320,038 B2
- Document ID: US10320038B2
- Status: Granted
- Kind: B2
- Application number: 15/533,306
- Filed: 2015-12-10
- Published: 2018-01-11
- Granted: 2019-06-11
- Earliest claimed: 2014-12-25
- Assignees: Maxell Holdings, Ltd.
- Applicants: Maxell Holdings, Ltd.
- Inventors: Hirokazu Nomura; Kunihiko Koyama
- Web page: https://patentgrep.com/patent/US10320038B2

## CPC

- H01M 4/587: for inserting or intercalating light metals
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H01M 10/448: {End of discharge regulating measures}
- H01M 10/46: Accumulators structurally combined with charging apparatus (circuits for charging H02J7/00)
- H02J 7/04: Regulation of charging current or voltage
- H02J 7/947: {in response to integrated charge or discharge current}
- 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
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## 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 CMAX to CMIN (CMAX/CMIN) is 1.01 to 3.00, where CMAX represents the maximum value of the charging current value and CMIN represents the minimum value of the charging current value.

## Claims

### Claim 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, IA, IB, and IC satisfy a relationship IA>IB and IB<IC, where IA 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%, IB represents an average charging current value in a range where the state of charge is 40%≤SOC≤60%, and ICrepresents 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 IMAX to IMIN (IMAX/IMIN) is 1.01 to 3.00, where IMAX represents a maximum value of the charging current value and IMIN represents a minimum value of the charging current value.

### Claim 2 (depends on 1)

The method according to claim 1, wherein, in the first step, the minimum value IMIN is set in the range where the state of charge is 40%≤SOC≤60%.

### Claim 3 (depends on 1)

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

### Claim 4 (depends on 1)

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

### Claim 5 (depends on 4)

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

### Claim 6 (depends on 1)

The method according to claim 1, wherein, in the first step, the minimum value IMIN is set in the range where the state of charge is 40%≤SOC≤60%, and
the maximum value IMAX is 0.4 C to 4.0 C, and the minimum value IMIN is 0.2 C to 2.0 C.

### Claim 7 (depends on 1)

The method according to claim 1, wherein, in the first step, the minimum value IMIN is set in the range where the state of charge is 40%≤SOC≤60%,
the maximum value IMAX is 0.4 C to 4.0 C, and the minimum value IMIN 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.

### Claim 8 (depends on 7)

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

### Claim 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, IA, IB, and IC satisfy a relationship IA>IB and IB<IC, where IA 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%, IB represents an average charging current value in a range where the state of charge is 40%≤SOC≤60%, and IC 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 IMAX to IMIN (IMAX/IMIN) is1.01 to 3.00, where IMAX represents a maximum value of the charging current value and IMIN represents a minimum value of the charging current value.

### Claim 10 (depends on 9)

The charging control apparatus according to claim 9, wherein, in the first step, the minimum value IMIN is set in the range where the state of charge is 40%≤SOC≤60%.

### Claim 11 (depends on 9)

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

### Claim 12 (depends on 9)

The charging control apparatus according to claim 9, wherein, in the first step, the minimum value IMIN is set in the range where the state of charge is 40% ≤SOC≤60%, and
the maximum value IMAX is 0.4 C to 4.0 C, and the minimum value IMIN is 0.2 C to 2.0 C.

### Claim 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, IA, IB, and IC satisfy a relationship IA>IB and IB<IC, where IA 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%, IB represents an average charging current value in a range where the state of charge is 40%≤SOC≤60%, and IC 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 IMAX to IMiN (IMAX/IMIN) is 1.01 to 3.00, where IMAX represents a maximum value of the charging current value and IMINrepresents a minimum value of the charging current value.