# US 9,882,406 B2 · Charging control method for lithium-ion battery, charging control apparatus for lithium-ion battery and lithium-ion battery system

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- Number: US 9,882,406 B2
- Document ID: US9882406B2
- Status: Granted
- Kind: B2
- Application number: 14/828,727
- Filed: 2015-08-18
- Published: 2016-03-10
- Granted: 2018-01-30
- Earliest claimed: 2014-09-04
- Assignees: Denso Corporation
- Applicants: Denso Corporation
- Inventors: Yoshinori Satou; Masaki Uchiyama; Nobuo Yamamoto; Koji Ohira
- Web page: https://patentgrep.com/patent/US9882406B2

## CPC

- 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 10/46: Accumulators structurally combined with charging apparatus (circuits for charging H02J7/00)
- H02J 7/90: Regulation of charging or discharging current or voltage
- 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
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A lithium-ion battery includes a cathode active material of the Olivine-type crystal structure. The lithium-ion battery is charged under control of a charging control apparatus, which performs a charging process for charging up to a target voltage according to a constant-current and constant-voltage charging method, a negative-electrode potential evaluation process for evaluating a potential change quantity at the negative-electrode, and a voltage setting process for setting the target voltage to a lower voltage based on the potential change quantity of the negative-electrode evaluated by the negative-electrode potential evaluation process. The charging voltage is changed from the target voltage to the set voltage even when the negative-electrode potential changes with an increase in the number of charging and aging deterioration. Thus a positive-electrode potential is suppressed from rising because of less susceptibility to the increase in number of charging and aging deterioration.

## Claims

### Claim 1

A charging control method for controlling charging of a lithium-ion battery, which is provided with a positive electrode and a negative electrode, the charging control method comprising:
charging processing for charging the lithium-ion battery to a target voltage by a constant-current and constant-voltage charging method, the lithium-ion battery including a cathode active material having Olivine-type crystal structure;
negative-electrode potential evaluation processing for evaluating a potential change quantity of the negative electrode; and
voltage setting processing for setting the target voltage to decrease based on the potential change quantity of the negative-electrode evaluated by the negative-electrode potential evaluation processing; wherein
the negative-electrode potential evaluation processing evaluates the potential change quantity of the negative-electrode based on one of or both of a charging voltage, which is measured as a voltage charged to the lithium-ion battery, and a discharging voltage, which is measured as a voltage discharged from the lithium-ion battery; and
the negative-electrode potential evaluation processing specifies a stepwise change point, at which a quantity of change in one of or both of the charging voltage and the discharging voltage relative to the charging rate changes in excess of a threshold value, and evaluates the potential change quantity of the negative electrode based on a shift quantity of the stepwise change point in increasing and decreasing directions.

### Claim 2 (depends on 1)

The charging control method for controlling charging of a lithium-ion battery according to claim 1, wherein:
the negative-electrode potential evaluation processing evaluates the potential change quantity of the negative electrode based on a difference value between the charging voltage and the discharging voltage, which are at a same charging rate.

### Claim 3 (depends on 1)

The charging control method for controlling charging of a lithium-ion battery according to claim 1, wherein:
the negative-electrode potential evaluation processing specifies the stepwise change point, with respect to a characteristic curve of one of or both of the charging voltage and the discharging voltage, based on a differentiation coefficient, which is calculated by differentiating the voltage by the charging rate.

### Claim 4

A charging control apparatus for controlling charging of a lithium-ion battery, which is provided with a positive electrode and a negative electrode, the charging control apparatus comprising:
a charging part for charging the lithium-ion battery to a target voltage by a constant-current and constant-voltage charging method, the lithium-ion battery including a cathode active material having Olivine-type crystal structure;
a negative-electrode potential evaluation part for evaluating a potential change quantity of the negative electrode; and
voltage setting part for setting the target voltage to decrease based on the potential change quantity of the negative-electrode evaluated by the negative-electrode potential evaluation part; wherein
the negative-electrode potential evaluation part evaluates the potential change quantity of the negative-electrode based on one of or both of a charging voltage, which is measured as a voltage charged to the lithium-ion battery, and a discharging voltage, which is measured as a voltage discharged from the lithium-ion battery; and
the negative-electrode potential evaluation part specifies a stepwise change point, at which a quantity of change in one of or both of the charging voltage and the discharging voltage relative to the charging rate changes in excess of a threshold value, and evaluates the potential change quantity of the negative electrode based on a shift quantity of the stepwise change point in increasing and decreasing directions.

### Claim 5 (depends on 4)

The charging control method for controlling charging of a lithium-ion battery according to claim 4, wherein:
the negative-electrode potential evaluation part evaluates the potential change quantity of the negative electrode based on a difference value between the charging voltage and the discharging voltage, which are at a same charging rate.

### Claim 6 (depends on 4)

The charging control method for controlling charging of a lithium-ion battery according to claim 4, wherein:
the negative-electrode potential evaluation part specifies the stepwise change point, with respect to a characteristic curve of one of or both of the charging voltage and the discharging voltage, based on a differentiation coefficient, which is calculated by differentiating the voltage by the charging rate.

### Claim 7 (depends on 4)

A lithium-ion battery system comprising:
the charging control apparatus according to claim 4; and
the lithium battery.