KR101778348B1 - System capacity measure of secondary battery and method for measuring capacity of secondary battery - Google Patents

Abstract

A method of measuring a capacity of a secondary battery according to an exemplary embodiment of the present invention includes the steps of measuring a capacity of a plurality of secondary batteries by performing secondary charging and uniformizing a charging potential to a predetermined voltage, A step of performing tertiary charging for the secondary battery, a step of advancing the secondary charging, and a step of measuring the capacity of the secondary battery by summing up the charging amount in the tertiary charging and the charging amount in the quaternary charging .

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a capacity measuring system and a measuring method for a secondary battery,

The present invention relates to a capacity measurement system and a measurement method for a secondary battery, and more particularly, to a method for selecting a capacity failure cell of a secondary battery based on a sum of charge amounts of the secondary battery.

In recent years, lithium secondary batteries, which are chargeable and dischargeable and light in weight and have high energy density and high output density, are widely used as energy sources for wireless mobile devices. In addition, Hybrid Electric Vehicle (HEV), Plug-in Hybrid Electric Vehicle (PHEV), Battery Electric Vehicle (PHEV), and Electric Vehicle BEV), electric vehicle (EV), and the like. Lithium secondary batteries are attracting attention as a power source for such an internal combustion engine replacement vehicle.

The lithium secondary battery includes an electrode assembly including an anode, a cathode, and a separation membrane formed between the anode and the cathode to insulate the anode and the cathode, and is formed by performing an aging process and a formation process , It is important to accurately select these defects because defects often occur due to various causes during the process.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a system and a method for improving reliability of capacity measurement of a secondary battery.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided a method of measuring a capacity of a secondary battery, comprising: a step of measuring a capacity of a plurality of secondary batteries by performing a secondary charging operation to equalize a charging potential to a predetermined voltage; A step of advancing a tertiary charge to a secondary battery having a uniform charging potential, a step of advancing a quadratic charge, a step of calculating a capacity of the secondary battery by summing the charge amount during the third charge and the charge amount during the fourth charge, And a step of measuring the temperature.

Further, the method may further include a step of performing an aging process before each of the secondary charging, the tertiary charging, and the fourth charging steps.

The method further comprises a step of advancing the primary aging step and a step of advancing the primary charging before the step of advancing the secondary aging step.

Further, the secondary charge is characterized by a range of 10 to 20% of the design capacity.

Further, the method may further include the step of determining whether the secondary battery is defective using the measured capacity of the secondary battery after measuring the capacity of the secondary battery.

Further, when the measured capacity of the secondary battery is less than the reference value, it is determined that the secondary battery is defective.

Further, when the measured capacity of the secondary battery is equal to or greater than the reference value, it is determined to be normal.

According to another aspect of the present invention, there is provided a system for measuring the capacity of a rechargeable battery, the system comprising: a recharge amount measuring unit for measuring a rechargeable amount of the rechargeable battery; a charged amount storing unit for storing a charged amount measured by the charged amount measuring unit; And a charge amount summing unit for measuring a capacity of the secondary battery.

The battery pack further includes a reference value storing unit that stores a reference value that is set in advance to determine whether the secondary battery is defective and a capacity failure determining unit that determines whether the capacity of the secondary battery measured by the charging amount summing unit satisfies a predetermined reference value range .

Further, the failure determining unit may determine that the measured capacity of the secondary battery is normal if it is greater than or equal to the reference value, and the failure determining unit determines that the measured capacity of the secondary battery is less than the reference value.

In the present invention, after the step of equalizing the charge potential is performed, an additional charging step is subsequently carried out, and the capacity of the secondary battery is measured by summing the amounts of charged charges in the charging step, And the sorting accuracy can be improved.

It will be apparent to those skilled in the art that various modifications, additions, and substitutions are possible, and that various modifications, additions and substitutions are possible, within the spirit and scope of the appended claims. As shown in Fig.

1 is a block diagram of a system for measuring the capacity of a secondary battery according to an embodiment of the present invention.
2 is a flowchart showing a failure detection method of a secondary battery according to an embodiment of the present invention.
3 is a graph illustrating an activation process for measuring the capacity of a secondary battery according to an embodiment of the present invention.
4A is a graph showing the correlation of product inspection capacity of an arch battery according to the prior art.
FIG. 4B is a graph showing the correlation of the product inspection capacity of the secondary battery according to the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or preliminary meaning and the inventor shall properly define the concept of the term in order to describe its invention in the best possible way The present invention should be construed in accordance with the spirit and concept of the present invention.

Therefore, the embodiments described in the present specification and the configurations shown in the drawings are only the most preferred embodiments of the present invention, and not all of the technical ideas of the present invention are described. Therefore, It should be understood that various equivalents and modifications may be present. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

Hereinafter, a capacity measurement system and a capacity measurement method of a secondary battery according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings.

1 is an overall configuration diagram of a system for measuring the capacity of a secondary battery according to the present invention.

Referring to FIG. 1, a system 100 for measuring the capacity of a secondary battery includes a secondary battery process control unit 110, a charged amount measuring unit 120, a charged amount summing unit 130, a charged amount storage unit 140, (150) and a failure judging unit (160).

The secondary battery process control unit 110 controls the overall process of the secondary battery. That is, the secondary cell process control unit 110 controls the process to be performed according to a predetermined process recipe. At this time, the process can be performed by a first aging process, a first charging process, a second aging process, a second charging process, a third charging process, a third aging process, a fourth charging process, and the like. Here, the aging process may be performed at a constant temperature and a constant humidity, and natural discharge may occur during the aging process.

The charged amount measuring unit 120 measures the charged amount during the charging process under the control of the secondary battery process control unit 110. [ The charged amount storage unit 130 stores the values of the charged amount of each step measured by the charged amount measuring unit 120.

The charge amount summing unit 140 calculates the sum of the charge amount by summing the values of the charge amounts of the respective steps measured by the charge amount measuring unit 120. At this time, the charge amount summing unit 140 can calculate the sum of the third charge amount measured in the third charge and the fourth charge measured in the fourth charge. The summed value becomes the capacity measurement value of the secondary battery.

The reference value storage unit 150 stores a reference value for determining whether or not the secondary battery is defective.

The failure judging unit 160 judges whether the summed charge amount summed value in the charge amount summing unit 140 satisfies a predetermined reference value range. If the summed charge amount sum is satisfied, it is judged as normal. For example, when the summed charge amount sum value is equal to or greater than the reference value, it is determined to be normal, and when the summed charge amount is less than the reference value, it can be selected to be defective.

FIG. 2 and FIG. 3 are flowcharts and graphs showing a method of measuring a capacity of a secondary battery and a procedure of the activation process according to an embodiment of the present invention.

The procedure of measuring the capacity of the secondary battery and the process of activating will be described in detail with reference to FIG. 2 and FIG.

First, the primary aging step is carried out (step S10, see 'A' in FIG. 3).

3) (Step S20, see 'B' in FIG. 3) After the primary charging is proceeded, the secondary aging process proceeds (step S30, see 'C' The amount of charged electricity may be partially discharged through the aging process of the charged secondary battery, and the amount of the natural discharge may not be constant for each cell. , A voltage deviation may occur between the respective cells.

Then, the secondary charging is continued until each of the cells reaches a certain voltage level (S 40, see 'D' in FIG. 3). It proceeds to reduce the variation in the amount of charge generated between the cells after the first charge, wherein the secondary charge preferably proceeds within a range of 10-20% of the design capacity of the secondary battery.

Next, the third charging is performed on the secondary battery having the uniformed charging voltage (step S50, see 'E' in FIG. 3). In this case, the charged amount measured in the third charging step in the charging amount measuring unit 120 is measured , And the charge amount value is stored in the charge amount storage unit 140. [

Next, a third aging step is performed (step S60, see 'F' in FIG. 3). As in the second aging step, some of the charged amount may be spontaneously discharged while passing through the third aging step.

Next, the fourth charging is proceeded (step S70, see G in FIG. 3). Similarly to the third charging step, the charged amount measured in the fourth charging step in the charged amount measuring unit 120 is measured, And is stored in the charge storage unit 140.

Then, the charged amount of the third charging step and the charged amount of the fourth charging step stored in the charged amount storage unit 140 in the charge amount summing unit 130 are added up, and this value is measured as the capacity of the secondary battery. The capacity failure of the secondary battery is selected based on the measured capacity. The charge amount summing unit 130 compares the summed charge amount with the reference value stored in the reference value storing unit 150 to determine whether the capacity of the secondary battery is defective or not (step S80).

At this time, it is determined whether the sum of the charged amount in the third charging step and the charged amount in the fourth charging step satisfies a range of a predetermined reference value. However, if the sum of the charged amount in the third charging step and the charged amount in the fourth charging step does not satisfy the range of the predetermined reference value, it is determined to be defective (step S100). For example, when the summed charge amount is equal to or greater than the reference value, it is determined to be normal, and when the summed charge amount is less than the reference value, it can be selected to be defective. At this time, since the secondary battery selected as defective is a defective battery which can not exhibit a normal function, it is sorted and discarded, and the battery determined to be normal is discharged as a normal battery.

As described above, according to the present invention, the secondary charging is performed so as to equalize the potentials of the plurality of cells in which the potential difference occurs, and then the tertiary charging and the quadratic charging are progressed, The capacity of the secondary battery can be measured by summing up the values of the charged amount at the time of charging the secondary battery and the capacity of the secondary battery measured in this way can be improved compared to the capacity of the secondary battery measured through the discharging amount .

FIGS. 4A and 4B are graphs showing the results of capacity test correlation analysis of a secondary battery. FIG. 4A is a graph showing the results of capacity test correlation analysis of a secondary battery according to the related art, and FIGS. 4B and 4B show results of capacity test correlation analysis of the secondary battery according to the present invention. Referring to FIGS. 4A and 4B, the results of capacity test correlation analysis of the secondary battery will be described below.

Referring to FIG. 4A, the X axis represents the total discharge amount (X1, mAh) measured during full discharge of the secondary battery, and the Y axis represents the product inspection capacity value (mAh) which is the cell capacity of the actual secondary battery. As a result of the test of correlation between total discharge and product capacity with 205 products, it is found that there is a correlation of about 57%.

4B, the X-axis represents a charge amount value (X2 = X3 + X4, mAh) obtained by adding the third charge amount (X3 'of FIG. 3 and the fourth charge amount (MAh), which is the cell capacity of the secondary battery. The correlation test of the product capacity with the charge amount (X2) obtained by adding the third charge amount (X3) and the fourth charge amount (X4) As a result, it can be seen that there is a correlation of about 74.1%.

Generally, when the correlation test of the product capacity is 74% or more, it is determined that the reliability is high. However, if the capacity measurement is carried out with the charge amount X2 obtained by adding the third charge amount X3 and the fourth charge amount X4 as in the present invention, It can be seen that a high reliability can be obtained.

As described above, according to the present invention, the secondary charging is performed so as to equalize the potentials of the plurality of cells in which the potential difference occurs, and then the tertiary charging and the quadratic charging are progressed, The capacity of the secondary battery can be measured by summing up the values of the charged amount at the time of charging the secondary battery and the capacity of the secondary battery measured in this way can be improved compared to the capacity of the secondary battery measured through the discharging amount .

110: Secondary battery process control unit 120:
130: charge accumulation unit 140: charge accumulation unit
150: reference value storage unit 160:
X1: discharge amount X2: third charge amount + fourth charge amount
X3: 3rd charge amount X4: fourth charge amount

Claims (11)

In the step of measuring the capacity of a plurality of secondary batteries,
Performing secondary charging to equalize the charge potential to a predetermined voltage;
Conducting a third charging for the secondary cells having a uniform charging potential;
Performing aging after the third charging to cause the secondary batteries to be spontaneously discharged;
Conducting the fourth charge after the aging; And
Measuring the capacity of the secondary battery by summing up the charge amount during the third charge and the charge amount during the fourth charge;
And measuring the capacity of the secondary battery. The method according to claim 1,
Further comprising the step of performing an aging process before each of the secondary charging and the tertiary charging. The method according to claim 1,
Prior to the step of proceeding with the secondary charging,
Performing a first aging step; And
Steps to proceed with primary charging
Further comprising the steps of: measuring the capacity of the secondary battery; The method according to claim 1,
Wherein the secondary charging progresses to a range of 10-20% of the design capacity. The method according to claim 1,
After the capacity of the secondary battery is measured
Determining whether the secondary battery is defective using the measured capacity value of the secondary battery;
Further comprising the steps of: measuring the capacity of the secondary battery; The method of claim 5,
And determining that the secondary battery is defective when the measured capacity of the secondary battery is less than the reference value. The method of claim 5,
And determining that the measured capacity of the secondary battery is normal if the measured capacity of the secondary battery is equal to or greater than a reference value. A charge amount measuring unit for measuring a charge amount in a second charge period in which a first charge period and an aging period of a certain time after the first charge period have elapsed, with respect to the secondary batteries;
A charge amount storage unit for storing a charge amount of the first charge period and a charge amount of the second charge period measured by the charge amount measuring unit; And
A charge accumulation unit for accumulating the charge amount of the first charge period stored in the charge storage unit and the charge amount of the second charge period to measure the capacity of the secondary battery,
And a secondary battery capacity measuring system for measuring the secondary battery capacity. The method of claim 8,
A reference value storage unit for storing a preset reference value for determining whether the secondary battery is defective; And
A capacity failure determining unit for determining whether the capacity of the secondary battery measured by the charge accumulating unit satisfies a predetermined reference value range,
Wherein the secondary battery capacity measuring system further comprises: The method of claim 9,
Wherein the failure determination unit determines that the measured capacity of the secondary battery is normal when the measured capacity of the secondary battery is equal to or greater than a reference value. The method of claim 9,
Wherein the failure determining unit determines that the measured secondary battery has a failure if the capacity of the secondary battery is less than a reference value.

Images