A device for diagnosing the resistance characteristics of a unit cell, a diagnostic method, and a unit cell for a secondary battery that satisfies specific conditions determined by the said method.

Abstract

The present invention provides a resistance characteristic diagnostic device, a diagnostic method, and a unit cell for a secondary battery that satisfies specific conditions according to the method, comprising: an acquisition unit that acquires a charge or discharge profile of a unit cell in a specified charge or discharge cycle; a generation unit that generates capacitance voltage differential data indicating the capacitance voltage differential value (dQ / dV) of the unit cell in the charge or discharge cycle included in the specified charge or discharge cycle based on the charge or discharge profile; and a diagnostic unit that diagnoses the resistance characteristics of the unit cell based on the capacitance voltage differential data.

Claims

1. An acquisition unit that acquires the charge or discharge profile of a unit cell in a specified charge / discharge cycle, A generation unit that generates capacitance voltage differential data showing the capacitance voltage differential value (dQ / dV) of the unit cell in the charge or discharge cycle included in the specified charge or discharge cycle, based on the charge or discharge profile, A resistance characteristic diagnostic device, comprising a diagnostic unit that diagnoses the resistance characteristics of a unit cell based on the capacitance voltage differential data.

2. The resistance characteristic diagnostic device according to claim 1, wherein the diagnostic unit diagnoses the resistance characteristics of the unit cell based on the maximum capacitance voltage derivative value of the capacitance voltage derivative data during the charging cycle and the minimum capacitance voltage derivative value of the capacitance voltage derivative data during the discharge cycle.

3. The capacitance voltage derivative data indicates the capacitance voltage derivative value with respect to the voltage of the unit cell, The system further includes an identification unit that identifies a target voltage corresponding to the maximum or minimum capacitance voltage derivative value of the unit cell based on the capacitance voltage derivative data, The resistance characteristic diagnostic device according to claim 2, wherein the diagnostic unit diagnoses the resistance characteristics of the unit cell based on the retention rate of the capacitance voltage differential value of the unit cell at the target voltage.

4. The generation unit generates first capacitance voltage differential data corresponding to the first charge-discharge cycle, and second capacitance voltage differential data corresponding to the second charge-discharge cycle after the first charge-discharge cycle. The identification unit identifies the target voltage corresponding to the maximum capacity voltage derivative value in the charging cycle included in the first charge-discharge cycle of the unit cell, or the minimum capacity voltage derivative value in the discharging cycle included in the first charge-discharge cycle of the unit cell, based on the first capacity voltage derivative data. The resistance characteristic diagnostic device according to claim 3, wherein the diagnostic unit calculates the capacitance voltage differential value maintenance rate based on the second capacitance voltage differential data, based on the difference between the capacitance voltage differential value at the target voltage of the charging cycle included in the second charge-discharge cycle of the unit cell and the maximum capacitance voltage differential value, or the difference between the capacitance voltage differential value at the target voltage of the discharge cycle included in the second charge-discharge cycle of the unit cell and the minimum capacitance voltage differential value.

5. The resistance characteristic diagnostic device according to any one of claims 1 to 4, wherein the diagnostic unit diagnoses that the smaller the capacitance voltage differential maintenance rate, the higher the resistance increase rate of the unit cell.

6. The resistance characteristic diagnostic device according to any one of claims 1 to 4, wherein the unit cell contains a high-manganese cathode having the highest manganese (Mn) content among its constituent components.

7. The operation of obtaining the charge or discharge profile of a unit cell in a specified charge / discharge cycle, Based on the charge or discharge profile, the operation generates capacitance voltage differential data indicating the capacitance voltage differential value (dQ / dV) of the unit cell in the charge or discharge cycle included in the specified charge or discharge cycle, A resistance characteristic diagnostic method, comprising the operation of diagnosing the resistance characteristics of a unit cell based on the capacitance voltage differential data.

8. The resistance characteristic diagnostic method according to claim 7, wherein the operation for diagnosing the resistance characteristics includes diagnosing the resistance characteristics of the unit cell based on the maximum capacitance voltage derivative value of the capacitance voltage derivative data in the charging cycle, and the minimum capacitance voltage derivative value of the capacitance voltage derivative data in the discharge cycle.

9. The capacitance voltage derivative data indicates the capacitance voltage derivative value with respect to the voltage of the unit cell, The operation further includes identifying a target voltage corresponding to the maximum or minimum capacitance voltage derivative of the unit cell based on the capacitance voltage derivative data, The resistance characteristic diagnosis method according to claim 8, wherein the operation for diagnosing the resistance characteristics includes an operation for diagnosing the resistance characteristics of the unit cell based on the retention rate of the capacitance voltage differential of the unit cell at the target voltage.

10. The operation for generating the capacitance voltage differential data includes the operation for generating first capacitance voltage differential data corresponding to the first charge-discharge cycle, and second capacitance voltage differential data corresponding to the second charge-discharge cycle after the first charge-discharge cycle. The operation to identify the target voltage includes, based on the first capacitance voltage derivative data, the operation to identify the target voltage corresponding to the maximum capacitance voltage derivative value in the charging cycle included in the first charge-discharge cycle of the unit cell, or the minimum capacitance voltage derivative value in the discharging cycle included in the first charge-discharge cycle of the unit cell, The resistance characteristic diagnostic method according to claim 9, wherein the operation for diagnosing the resistance characteristics includes the operation of calculating the capacitance voltage differential maintenance rate based on the second capacitance voltage differential data, based on the difference between the capacitance voltage differential value and the maximum capacitance voltage differential value at the target voltage in the charging cycle included in the second charge-discharge cycle of the unit cell, or the difference between the capacitance voltage differential value and the minimum capacitance voltage differential value at the target voltage in the discharge cycle included in the second charge-discharge cycle of the unit cell,

11. The resistance characteristic diagnostic method according to any one of claims 7 to 10, wherein the operation for diagnosing the resistance characteristics includes an operation for diagnosing that the smaller the capacitance voltage differential maintenance rate, the higher the resistance increase rate of the unit cell.

12. The resistance characteristic diagnostic method according to any one of claims 7 to 10, wherein the unit cell contains a high-manganese cathode having the highest manganese (Mn) content among its constituent components.

13. The maximum capacitance voltage derivative value (D) obtained from the first capacitance voltage derivative data in the first charging cycle of a unit cell for a secondary battery. １ The voltage corresponding to the target voltage (V) ｔ ) and the target voltage (V) is calculated from the second capacitance voltage differential data in the second charge / discharge cycle of the unit cell. ｔ The capacitance voltage derivative (D) corresponding to ) ２ ) to find, or, The minimum capacitance voltage derivative value (D) obtained from the first capacitance voltage derivative data in the first discharge cycle of the unit cell for the secondary battery. １ The voltage corresponding to the target voltage (V) ｔ ) and the target voltage (V) is calculated from the second capacitance voltage differential data in the second charge / discharge cycle of the unit cell. ｔ The capacitance voltage derivative (D) corresponding to ) ２ When determining the following, the unit cell for a secondary battery that satisfies condition 1 below is: [Condition 1] D ２ / D １ *100% > 70%, and it is so.

14. The unit cell for a secondary battery according to claim 13, wherein the unit cell is charged by CC-CV charging at 0.1C to 1C in the range of 2V to 4.25V, 3V to 4.3V, or 2V to 4.35V, and the unit cell is discharged by CC discharge at 0.1C to 1C in the range of 2V to 4.25V, 3V to 4.3V, or 2V to 4.35V.

15. The unit cell for a secondary battery according to claim 13 or 14, wherein the unit cell includes a high-manganese cathode having the highest manganese (Mn) content among its constituent components.

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