Battery cell activation system and method

Abstract

The present invention provides a battery cell activation system comprising: a charging / discharging unit (100) for charging or discharging a first battery cell to a predetermined capacity or voltage; a voltage measurement unit (200) for measuring the voltage of the first battery cell a plurality of times for a predetermined time over a period including before and after voltage stabilization of the first battery cell, from a first charging / discharging time point at which the first battery cell has been charged or discharged to the predetermined capacity or voltage; and a stabilization time acquisition unit (300) including a voltage change rate acquisition unit (310) for acquiring change rates (dv / dt) of the voltage of the first battery cell over time on the basis of the measured voltage of the first battery cell, a reference change rate calculation unit (330) for calculating a reference change rate for at least partially distinguishing between the change rates before and after the voltage stabilization on the basis of the change rates of the voltage over time, and a stabilization time setting unit (340) for acquiring a reference time corresponding to the reference change rate and setting the reference time or a time similar to the reference time as a stabilization time (ST).

Description

Battery cell activation system and method

[0001] This application claims the benefit of priority from Republic of Korea Patent Application No. 10-2024-0081407, dated June 21, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a battery cell activation system and method, and more particularly, to a battery cell activation system and method that can easily obtain an optimal stabilization time suitable for a charging or discharging method or environment, optimize an activation process, and improve the accuracy of determining whether a battery cell is good or bad.

[0003] By performing an activation process including a series of processes such as charging, aging, and discharging on assembled battery cells (secondary batteries), the battery cells can be stabilized and made usable.

[0004] In the conventional activation process, the battery cell was slowly charged or discharged at a low current to the shipping SOC, and then the voltage of the battery cell was measured at two different times after the voltage stabilization time (ST) had elapsed to determine whether there was a low-voltage defect (abnormal self-discharge). Specifically, as shown in FIGS. 1 and 2, after the battery cell was charged (FIG. 1) or discharged (FIG. 2) at shipping, the presence of a low-voltage defect was determined based on the voltage difference (dOCV) of the battery cell at two different times after the voltage stabilization time (ST) had elapsed.

[0005] At this time, the voltage stabilization time (ST) of the conventional activation process is a constant (e.g., 12 hours) that is independent of the charging or discharging method of the battery cell or the environment in which the battery cell is placed. However, as shown in FIG. 3, the voltage stabilization time (ST) is different depending on the charging or discharging speed during constant current charging and discharging (five cases from 0.1 C-rate to 2 C-rate, upper left and lower left of FIG. 3), the termination speed during constant voltage charging (three cases from 0.02 C-rate to 0.1 C-rate, upper right of FIG. 3), and the step-by-step discharge speed in the two-step constant current discharge (three cases from 1 C-rate / 0.1 C-rate to 1 C-rate / 0.5 C-rate, lower right of FIG. 3). In addition, as shown in FIG. 4, the voltage stabilization time (ST) is different depending on the cutoff capacity of charging or discharging (five cases from SOC 10% to 90%, left side of FIG. 4) and the temperature at which the battery cell is placed when charging or discharging or afterward (four cases from 10 degrees to 60 degrees, right side of FIG. 4).

[0006] Therefore, it is necessary to obtain an optimal voltage stabilization time (ST) appropriate to the charging or discharging method and environment. Obtaining an optimal stabilization time optimizes the activation process and improves the accuracy of battery cell quality determination.

[0007] Prior art literature related to this is Korean Patent No. 10-2022-0039452.

[0008] The present invention has been devised to solve the above-described problems, and its purpose is to provide a battery cell activation system and method that can easily obtain an optimal stabilization time suitable for a charging or discharging method or environment.

[0009] In addition, it is an object of the present invention to provide a battery cell activation system and method in which a predetermined operation of the activation process is performed effectively or appropriately.

[0010] In addition, the purpose is to provide a battery cell activation system and method in which the activation process is optimized.

[0011] In addition, the purpose is to provide a battery cell activation system and method that improves the accuracy of battery cell quality determination.

[0012] In addition, the purpose is to provide a battery cell activation system and method in which the process of determining whether a battery cell is good or bad is optimized.

[0013] In addition, the purpose is to provide a battery cell activation system and method that can simply and easily obtain an optimal stabilization time.

[0014] In addition, the purpose is to provide a battery cell activation system and method that can appropriately and easily calculate a reference change rate.

[0015] In addition, the purpose is to provide a battery cell activation system and method in which the accuracy of stabilization time is improved.

[0016] The technical objectives of the present invention are not limited to the purposes mentioned above. Other objectives and advantages of the present invention not mentioned above can be understood through the following description and will be more clearly understood through the embodiments of the present invention. Furthermore, it will be readily apparent that the objectives and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0017] In order to solve the above-described problem, the present invention provides a battery cell activation system (10) including a charging / discharging unit (100), a voltage measuring unit (200), and a stabilization time obtaining unit (300).

[0018] The above charging and discharging unit (100) can charge or discharge the first battery cell to a predetermined capacity or voltage.

[0019] The voltage measuring unit (200) can measure the voltage of the first battery cell multiple times for a predetermined period of time from the first charging / discharging time after the first battery cell is charged or discharged to a predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized.

[0020] The above stabilization time acquisition unit (300) may be configured to include a voltage change rate acquisition unit (310), a reference change rate calculation unit (330), and a stabilization time setting unit (340).

[0021] The voltage change rate acquisition unit (310) can acquire the change rate of voltage over time (dv / dt) of the first battery cell based on the measured voltage of the first battery cell.

[0022] The above reference change rate calculation unit (330) can calculate a reference change rate that at least partially distinguishes the change rate before and after the voltage stabilization based on the change rate of the voltage over time.

[0023] The above stabilization time setting unit (340) can obtain a reference time corresponding to the reference change rate.

[0024] The above stabilization time setting unit (340) can set the reference time or a time similar to the reference time as the stabilization time (ST).

[0025] In one embodiment, the charging and discharging unit (100) can charge or discharge one or more second battery cells to a predetermined capacity or voltage.

[0026] The voltage measuring unit (200) can measure the voltage of each of the second battery cells at a second charge / discharge time after the second battery cell has been charged or discharged to a predetermined capacity or voltage, and at an elapsed time after the stabilization time (ST) has elapsed from the second charge / discharge time.

[0027] The above battery cell activation system may further include a good / bad judgment unit (400).

[0028] The above-mentioned quality judgment unit (400) can judge the quality of the second battery cell based on the voltage of the second battery cell measured at the second charge / discharge time and elapsed time for each of the second battery cells.

[0029] In one embodiment, the charging and discharging unit (100) can charge or discharge the first battery cell and one or more second battery cells in the same or similar manner.

[0030] In one embodiment, the environment in which the one or more second battery cells are placed from the second charge / discharge time to the elapsed time may be the same as or similar to the environment in which the first battery cell is placed from the first charge / discharge time to the predetermined time or stabilization time (ST).

[0031] In one embodiment, the stabilization time acquisition unit (300) may further include a sample extraction unit (320).

[0032] The above sample extraction unit (320) can extract multiple samples regarding the change rate from the change rate of voltage over time obtained from the voltage change rate acquisition unit (310).

[0033] The above-mentioned standard change rate calculation unit (330) can calculate the standard change rate based on the frequency or distribution of the plurality of samples.

[0034] In one embodiment, the reference change rate calculation unit (330) can calculate the reference change rate based on the interval frequency (categorical frequency) of the plurality of samples.

[0035] In one embodiment, the reference change rate calculation unit (330) can calculate a normal distribution using the average and standard deviation of the plurality of samples.

[0036] The above-mentioned standard change rate calculation unit (330) can calculate a difference value (e) obtained by subtracting the frequency of the first section from the corresponding value of the normal distribution corresponding to the first section for the first section, which is an arbitrary section.

[0037] The above-mentioned standard change rate calculation unit (330) can set the change rate included in the first section as the standard change rate when the difference value (e) is greater than the first threshold value (the first threshold value is a positive real number).

[0038] In one embodiment, the reference change rate calculation unit (330) may set the change rate included in the first candidate section that is farthest from the center of the normal distribution in a direction larger or smaller than the center of the normal distribution among the m candidate sections, as the reference change rate, when the number of candidate sections that are the first sections in which the difference value (e) is larger than the first threshold value is m (m is a natural number greater than or equal to 2).

[0039] In one embodiment, the reference change rate calculation unit (330) may set the change rate included in the first candidate section as the reference change rate when there are m (m is a natural number greater than or equal to 2) candidate sections, which are the first sections in which the difference value (e) is greater than or equal to the first threshold value, if the first candidate section, which is farthest from the center of the normal distribution in a direction greater than or less than the center of the normal distribution among the m candidate sections, is not adjacent to or continuous with other candidate sections, and if the first candidate section is adjacent to or continuous with n (n is a natural number greater than or equal to 1) other candidate sections, the change rate included in the second candidate section, which is closest to the center of the normal distribution among the n candidate sections, may be set as the reference change rate.

[0040] In one embodiment, the reference change rate calculation unit (330) can calculate the reference change rate based on the cumulative frequency distribution of the plurality of samples.

[0041] In one embodiment, the reference change rate calculation unit (330) can calculate a trend line for the cumulative frequency distribution of some samples among the plurality of samples.

[0042] The above reference change rate calculation unit (330) can calculate the reference change rate based on the slope of the trend line.

[0043] In one embodiment, the sample of the above part may be greater than or equal to a second threshold value among the plurality of samples, and the number of samples may be greater than or equal to a second threshold value.

[0044] In one embodiment, the stabilization time acquisition unit (300) may further include a sample extraction unit (320).

[0045] The above sample extraction unit (320) can extract multiple samples regarding the change rate from the change rate of voltage over time obtained from the voltage change rate acquisition unit (310).

[0046] The above-mentioned standard change rate calculation unit (330) can determine a stabilization range (stabilization section) to which the change rate after the voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and set a value corresponding to or similar to the boundary of the stabilization range as the standard change rate.

[0047] In one embodiment, when the plurality of samples are arranged according to the time corresponding to the plurality of samples, for each sample, a first sample and a second sample adjacent to the first sample, the time difference between the first time corresponding to the first sample and the second time corresponding to the second sample may be constant.

[0048] The above time difference may be more than 30 minutes and less than 2 hours.

[0049] In one embodiment, the stabilization time setting unit (340) can smooth data based on the rate of change of voltage over time.

[0050] The above stabilization time setting unit (340) can obtain a reference time corresponding to the reference change rate from the smoothed data.

[0051] In one embodiment, the data can be smoothed using the Local Equation Segmentation (LOESS) technique.

[0052] In addition, to solve the above-described problem, the present invention provides a battery cell activation method including a first charging / discharging process (S510), a first measurement process (S520), and a stabilization time acquisition process (S530).

[0053] In the first charging / discharging process (S510), the charging / discharging unit (100) can charge or discharge the first battery cell to a predetermined capacity or voltage.

[0054] In the first measurement process (S520), the voltage measurement unit (200) can measure the voltage of the first battery cell multiple times for a predetermined period of time from the first charge / discharge time after the first battery cell is charged or discharged to the predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized.

[0055] The above stabilization time acquisition process (S530) may be configured to include a voltage change rate acquisition process (S532), a reference change rate calculation process (S536), and a stabilization time setting process (S538).

[0056] In the above voltage change rate acquisition process (S532), the voltage change rate acquisition unit (310) can acquire the voltage change rate (dv / dt) of the first battery cell over time based on the measured voltage of the first battery cell.

[0057] In the above-mentioned standard change rate calculation process (S536), the standard change rate calculation unit (330) can calculate a standard change rate that at least partially distinguishes the change rate before and after the voltage stabilization based on the change rate of the voltage over time.

[0058] In the above stabilization time setting process (S538), the stabilization time setting unit (340) can obtain a reference time corresponding to the reference change rate and set the reference time or a time similar to the reference time as the stabilization time (ST).

[0059] In one embodiment, the battery cell activation method may further include a second charging / discharging process (S540), a second measurement process (S550), and a pass / fail determination process (S560).

[0060] In the second charging / discharging process (S540), the charging / discharging unit (100) can charge or discharge one or more second battery cells to a predetermined capacity or voltage.

[0061] In the second measurement process (S550), the voltage measurement unit (200) can measure the voltage of each of the second battery cells at a second charge / discharge time after the second battery cell is charged or discharged to a predetermined capacity or voltage, and at an elapsed time after the stabilization time (ST) has elapsed from the second charge / discharge time.

[0062] In the above-mentioned good / bad judgment process (S560), the good / bad judgment unit (400) can judge the good / bad of the second battery cell based on the voltage of the second battery cell measured at the second charge / discharge time and elapsed time for each of the second battery cells.

[0063] In one embodiment, the stabilization time acquisition process (S530) may further include a sampling process (S534).

[0064] In the above sample extraction process (S534), the sample extraction unit (320) can extract multiple samples regarding the change rate from the change rate of voltage over time obtained in the voltage change rate acquisition process (S532).

[0065] In the above-mentioned standard change rate calculation process (S536), the standard change rate calculation unit (330) may calculate the standard change rate based on the frequency or distribution of the plurality of samples, or may determine the stabilization range to which the change rate after voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and may set a value corresponding to or similar to the boundary of the stabilization range as the standard change rate.

[0066] In one embodiment, in the stabilization time setting process (S538), the stabilization time setting unit (340) can smooth data based on the rate of change of voltage over time and obtain a reference time corresponding to the reference rate of change from the smoothed data.

[0067] According to embodiments of the present invention, a battery cell activation system (10) comprises: a charging / discharging unit (100) that charges or discharges a first battery cell to a predetermined capacity or voltage; a voltage measuring unit (200) that measures the voltage of the first battery cell multiple times for a predetermined time from a first charging / discharging time after the first battery cell is charged or discharged to a predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized; And it may include a voltage change rate acquisition unit (310) that acquires a change rate of voltage (dv / dt) over time of the first battery cell based on the measured voltage of the first battery cell, a reference change rate calculation unit (330) that calculates a reference change rate that at least partially distinguishes the change rate before and after the voltage stabilization based on the change rate of voltage over time, and a stabilization time setting unit (340) that acquires a reference time corresponding to the reference change rate and sets the reference time or a time similar to the reference time as a stabilization time (ST).

[0068] Accordingly, it is possible to easily obtain an (optimal) stabilization time (ST) suitable for the charging or discharging method (e.g., shipping charging or shipping discharging) of the battery cell or the environment in which the battery cell is placed.

[0069] In addition, by utilizing the stabilization time (ST), a predetermined task can be performed on the battery cell after the voltage has been reliably stabilized, so that the predetermined task can be performed effectively or appropriately.

[0070] Additionally, the activation process of the battery cell can be optimized because the optimal stabilization time (ST) can be obtained.

[0071] According to embodiments of the present invention, the charging / discharging unit (100) charges or discharges one or more second battery cells to a predetermined capacity or voltage, and the voltage measuring unit (200) measures the voltage of the second battery cell at a second charging / discharging time after the second battery cell is charged or discharged to a predetermined capacity or voltage and at an elapsed time after the stabilization time (ST) has elapsed from the second charging / discharging time, for each of the second battery cells, and may further include a pass / fail determination unit (400) that determines whether the second battery cell is pass / fail based on the voltage of the second battery cell measured at the second charging / discharging time and the elapsed time for each of the second battery cells.

[0072] Accordingly, since the quality of a battery cell (e.g., low voltage defect) is determined based on the voltage measured after the voltage of the battery cell that has been charged or discharged (e.g., shipped charged or shipped discharged) has stabilized (i.e., after a stabilization period has elapsed), the accuracy of determining whether the battery cell is good or bad can be improved.

[0073] Additionally, the process of determining whether a battery cell is good or bad can be optimized by utilizing the optimal stabilization time (ST).

[0074] According to embodiments of the present invention, the charging and discharging unit (100) can charge or discharge the first battery cell and one or more second battery cells in the same or similar manner.

[0075] Accordingly, the actual stabilization time of the voltage of each of one or more battery cells can be equal to or similar to the stabilization time (ST) of the first battery cell. Accordingly, the accuracy of determining whether a battery cell is good or bad can be improved.

[0076] According to embodiments of the present invention, the environment in which the one or more second battery cells are placed from the second charge / discharge time to the elapsed time may be the same as or similar to the environment in which the first battery cell is placed from the first charge / discharge time to the predetermined time or stabilization time (ST).

[0077] Accordingly, the actual stabilization time of the voltage of each of one or more secondary battery cells can be equal to or similar to the stabilization time (ST) of the primary battery cell. Accordingly, the accuracy of determining whether a battery cell is good or bad can be improved.

[0078] According to embodiments of the present invention, the stabilization time acquisition unit (300) may further include a sample extraction unit (320) that extracts a plurality of samples regarding the change rate from the change rate of voltage over time acquired by the voltage change rate acquisition unit (310). The reference change rate calculation unit (330) may calculate the reference change rate based on the frequency or distribution of the plurality of samples.

[0079] Accordingly, since the reference change rate is calculated based on the frequency or distribution of multiple samples, the reference change rate can be easily calculated and effectively distinguishes between before and after voltage stabilization. This is because the frequency or distribution of samples before and after voltage stabilization of a battery cell is significantly different. Therefore, the optimal stabilization time (ST) can be simply and easily obtained.

[0080] According to embodiments of the present invention, the reference change rate calculation unit (330) can calculate the reference change rate based on the interval frequency (categorical frequency) of the plurality of samples.

[0081] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the frequency difference between each sample interval before and after voltage stabilization of the battery cell is significant.

[0082] According to embodiments of the present invention, the reference change rate calculation unit (330) calculates a normal distribution using the average and standard deviation of the plurality of samples, and calculates a difference value (e) obtained by subtracting the frequency of the first section from the corresponding value of the normal distribution corresponding to the first section for the first section, which is an arbitrary section, and when the difference value (e) is greater than a first threshold value (the first threshold value is a positive real number), the change rate included in the first section can be set as the reference change rate.

[0083] Accordingly, since the change rate in the interval in which the actual frequency of the sample is sufficiently smaller than the corresponding value of the normal distribution (to the extent that it exceeds the first critical value) is set as the reference change rate, the reference change rate can effectively distinguish before and after voltage stabilization.

[0084] According to embodiments of the present invention, the reference change rate calculation unit (330) may set the change rate included in the first candidate section that is farthest from the center of the normal distribution toward the side larger or smaller than the center of the normal distribution among the m candidate sections, as the reference change rate, when the number of candidate sections that are the first sections in which the difference value (e) is larger than the first threshold value is m (m is a natural number greater than or equal to 2).

[0085] Accordingly, the problem of the reference change rate not being able to correctly distinguish between the change rates before and after voltage stabilization and dividing the change rate after voltage stabilization can be prevented.

[0086] According to embodiments of the present invention, when there are m (m is a natural number greater than or equal to 2) candidate sections, which are the first sections in which the difference value (e) is greater than the first threshold value, the reference change rate calculation unit (330) sets the change rate included in the first candidate section as the reference change rate if the first candidate section, which is farthest from the center of the normal distribution in a direction greater than or less than the center of the normal distribution among the m candidate sections, is not adjacent to or continuous with other candidate sections, and if the first candidate section is adjacent to or continuous with n (n is a natural number greater than or equal to 1) other candidate sections, the change rate included in the second candidate section, which is closest to the center of the normal distribution among the n candidate sections, can be set as the reference change rate.

[0087] Accordingly, the problem of the reference change rate not properly distinguishing between the change rates before and after voltage stabilization and dividing the change rate after voltage stabilization can be prevented. Furthermore, by setting the change rate of the candidate interval closest to the center of the normal distribution among adjacent or consecutive candidate intervals as the reference change rate, an optimal reference change rate can be established.

[0088] According to embodiments of the present invention, the reference change rate calculation unit (330) can calculate the reference change rate based on the cumulative frequency distribution of the plurality of samples.

[0089] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the cumulative frequency distribution of samples before and after voltage stabilization of the battery cell is significantly different.

[0090] According to embodiments of the present invention, the reference change rate calculation unit (330) can calculate a trend line for the cumulative frequency distribution of some samples among the plurality of samples and calculate the reference change rate based on the slope of the trend line.

[0091] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the difference in slope of the trend line for the cumulative frequency distribution of samples before and after voltage stabilization of the battery cell is significant.

[0092] According to embodiments of the present invention, the number of the above-mentioned samples may be plural and is greater than or equal to the second threshold value among the plurality of samples.

[0093] Accordingly, the slope of the trend line for the cumulative frequency distribution of some samples that are presumed to be samples after voltage stabilization of the battery cell (samples above or below the second threshold value) can be easily calculated.

[0094] According to embodiments of the present invention, the stabilization time acquisition unit (300) may further include a sample extraction unit (320) that extracts a plurality of samples regarding the change rate from the change rate of voltage over time acquired by the voltage change rate acquisition unit (310). The reference change rate calculation unit (330) may determine a stabilization range (stabilization section) to which the change rate after voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and may set a value corresponding to or similar to the boundary of the stabilization range as the reference change rate.

[0095] Accordingly, the baseline change rate can be appropriately and easily calculated statistically. This is because the frequency and distribution of samples before and after voltage stabilization of battery cells differ significantly.

[0096] According to embodiments of the present invention, when the plurality of samples are arranged according to the time corresponding to the plurality of samples, the time difference between the first time corresponding to the first sample and the second time corresponding to the second sample may be constant for each sample, which is a first sample and a second sample adjacent to the first sample. The time difference may be 30 minutes or more and 2 hours or less.

[0097] Accordingly, noise can be removed from multiple samples when the time difference is greater than 30 minutes, and the number of samples can be increased when the time difference is less than 2 hours. Consequently, the accuracy of the stabilization time (ST) can be improved.

[0098] According to embodiments of the present invention, the stabilization time setting unit (340) can smooth data based on the rate of change of voltage over time and obtain a reference time corresponding to the reference rate of change from the smoothed data.

[0099] Accordingly, even if the reference change rate calculated by the reference change rate calculation unit (330) is close to the upper or lower limit of the stable section to which the voltage change rate after voltage stabilization belongs, or falls between the upper and lower limits, the correct reference time can be easily obtained.

[0100] According to embodiments of the present invention, the data can be smoothed using a local regression analysis (LOESS) technique.

[0101] Accordingly, even if the voltage change rate over time is smoothed, the trend of the voltage change rate over time at the boundary before and after voltage stabilization can be correctly maintained. Accordingly, the reference change rate and corresponding reference time at the boundary before and after voltage stabilization can be correctly obtained.

[0102] According to embodiments of the present invention, a battery cell activation method (S500) includes: a first charging / discharging process (S510) in which a charging / discharging unit (100) charges or discharges a first battery cell to a predetermined capacity or voltage; a first measuring process (S520) in which a voltage measuring unit (200) measures the voltage of the first battery cell multiple times for a predetermined time from a first charging / discharging time after the first battery cell is charged or discharged to the predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized; And it may include a voltage change rate acquisition process (S532) in which a voltage change rate acquisition unit (310) acquires a change rate of voltage (dv / dt) over time of the first battery cell based on the measured voltage of the first battery cell, a reference change rate calculation process (S536) in which a reference change rate calculation unit (330) calculates a reference change rate that at least partially distinguishes the change rate before and after voltage stabilization based on the change rate of voltage over time, and a stabilization time setting process (S538) in which a stabilization time setting unit (340) acquires a reference time corresponding to the reference change rate and sets the reference time or a time similar to the reference time as a stabilization time (ST).

[0103] Accordingly, it is possible to easily obtain an (optimal) stabilization time (ST) that is suitable for the charging or discharging method (e.g., shipping charging or shipping discharging) of the battery cell or the environment in which the battery cell is placed. For example, since the rate of change of the voltage of a battery cell over time generally exists within a certain rate of change range with an upper limit and a lower limit after voltage stabilization, a time corresponding to or similar to the upper or lower limit of this rate of change range can be set as the stabilization time (ST).

[0104] Additionally, by utilizing the stabilization time (ST), a predetermined task can be performed on a battery cell after the voltage has been reliably stabilized, so that the predetermined task can be performed effectively or appropriately. For example, since the voltage measurement unit (200) can measure the voltage of a battery cell whose voltage has been reliably stabilized after the stabilization time (ST) has elapsed, the measured voltage can be valid.

[0105] Additionally, the activation process of the battery cell can be optimized because the optimal stabilization time (ST) can be obtained.

[0106] According to embodiments of the present invention, the charging / discharging unit (100) may further include a second charging / discharging process (S540) in which one or more second battery cells are charged or discharged to a predetermined capacity or voltage; a second measuring process (S550) in which the voltage measuring unit (200) measures the voltage of each second battery cell at a second charging / discharging time after the second battery cell is charged or discharged to a predetermined capacity or voltage and at an elapsed time after the stabilization time (ST) has elapsed from the second charging / discharging time; and a pass / fail determination process (S560) in which the pass / fail determination unit (400) determines whether each second battery cell is pass / fail based on the voltage of the second battery cell measured at the second charging / discharging time and the elapsed time.

[0107] Accordingly, since the quality of a battery cell (e.g., low voltage defect) is determined based on the voltage measured after the voltage of the battery cell that has been charged or discharged (e.g., shipped charged or shipped discharged) has stabilized (i.e., after a stabilization period has elapsed), the accuracy of determining whether the battery cell is good or bad can be improved.

[0108] Additionally, the process of determining whether a battery cell is good or bad can be optimized by utilizing the optimal stabilization time (ST).

[0109] According to embodiments of the present invention, the stabilization time acquisition process (S530) may further include a sampling process (S534) in which the sampling unit (320) extracts a plurality of samples regarding the change rate from the change rate of voltage over time acquired in the voltage change rate acquisition process (S532). In the reference change rate calculation process (S536), the reference change rate calculation unit (330) may calculate the reference change rate based on the frequency or distribution of the plurality of samples, or may determine a stabilization range to which the change rate after voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and set a value corresponding to or similar to the boundary of the stabilization range as the reference change rate.

[0110] Accordingly, the standard change rate can be calculated appropriately and easily.

[0111] According to embodiments of the present invention, in the stabilization time setting process (S538), the stabilization time setting unit (340) can smooth data based on the rate of change of voltage over time and obtain a reference time corresponding to the reference rate of change from the smoothed data.

[0112] Accordingly, even if the reference change rate calculated by the reference change rate calculation unit (330) is close to the upper or lower limit of the stable section to which the voltage change rate after voltage stabilization belongs, or falls between the upper and lower limits, the correct reference time can be easily obtained.

[0113] In addition to the effects described above, specific effects of the present invention are described below while explaining specific details for carrying out the invention.

[0114] Figures 1 and 2 are graphs schematically showing the voltage over time after the shipment charge and shipment discharge of a battery cell, respectively.

[0115] Figures 3 and 4 are tables showing the stabilization time, stabilization voltage, and dOCV after stabilization according to various charging or discharging methods or environments.

[0116] FIG. 5 is a block diagram of a battery cell activation system according to one embodiment of the present invention.

[0117] Figure 6 is a graph showing the value obtained by multiplying the voltage change rate by -1 over time after the battery cell is shipped and charged.

[0118] Figure 7 is a graph showing multiple samples extracted from Figure 6.

[0119] Figure 8 is a diagram showing the interval-wise frequency distribution (histogram) and normal distribution of multiple samples of Figure 7.

[0120] Figure 9 is a diagram showing the cumulative probability distribution and normal cumulative probability distribution of multiple samples of Figure 7.

[0121] Figure 10 is a diagram showing a method for obtaining a reference time corresponding to a reference change rate based on the graph of Figure 7.

[0122] Figure 11 is a diagram showing a method for obtaining a reference time corresponding to a reference change rate based on the graph of the smoothed Figure 7.

[0123] Figure 12 is a diagram showing the frequency distribution (dispersion) of the first voltage of multiple battery cells measured before the stabilization time elapses after shipping charging.

[0124] FIG. 13 is a diagram showing the frequency distribution (dispersion) of the voltage difference between the first voltage of a plurality of battery cells measured before the stabilization time elapses, as in FIG. 12, and the second voltage of a plurality of battery cells measured after a predetermined time elapses from the time of measuring the first voltage.

[0125] Figure 14 is a diagram showing the frequency distribution (dispersion) of the first voltage of multiple battery cells measured after a stabilization time has elapsed after shipment charging.

[0126] FIG. 15 is a diagram showing the frequency distribution (dispersion) of the voltage difference between the first voltage of a plurality of battery cells measured after a stabilization time has elapsed, as in FIG. 14, and the second voltage of a plurality of battery cells measured after a predetermined time has elapsed from the measurement time of the first voltage.

[0127] Figure 16 is a flowchart showing a battery cell activation method according to one embodiment of the present invention.

[0128] [Explanation of symbols]

[0129] 10: Battery cell activation system

[0130] 100: Charging / discharging section 200: Voltage measurement section

[0131] 300: Stabilization time

[0132] 310: Voltage change rate acquisition unit 320: Sampling unit

[0133] 330: Baseline change rate calculation section 340: Stabilization time setting section

[0134] 400: Good or bad judgment department

[0135] ST: stabilization time SV: stabilization voltage

[0136] dOCV: voltage difference

[0137] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily practice the technical idea of ​​the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may unnecessarily obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0138] Although terms like "first" and "second" are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless otherwise specified, a "first" component may also be a "second" component.

[0139] Throughout the specification, unless otherwise specifically stated, each element may be singular or plural.

[0140] Hereinafter, the phrase "any configuration is placed on (or below)" a component or "on (or below)" a component may mean that any configuration is placed in contact with the upper surface (or lower surface) of said component, and that other configurations may be interposed between said component and any configuration placed on (or below) said component.

[0141] Additionally, when it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the components may be directly connected or connected to one another, but that other components may also be "interposed" between the components, or that each component may be "connected," "coupled," or "connected" through another component.

[0142] As used herein, singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consisting of" or "comprising" should not necessarily be construed to include all of the components or steps described in the specification, and should be construed to mean that some of the components or steps may not be included, or that additional components or steps may be included.

[0143] FIG. 1 and FIG. 2 are graphs schematically showing the voltage according to time after the shipment charge and shipment discharge of a battery cell, respectively. FIG. 3 and FIG. 4 are tables showing the stabilization time, stabilization voltage, and dOCV after stabilization according to various charging or discharging methods or environments. FIG. 5 is a block diagram of a battery cell activation system according to an embodiment of the present invention. FIG. 6 is a graph showing the value obtained by multiplying the voltage change rate according to time after the shipment charge of a battery cell by -1. FIG. 7 is a graph showing a plurality of samples extracted from FIG. 6. FIG. 8 is a diagram showing the interval-wise frequency distribution (histogram) and normal distribution of the plurality of samples of FIG. 7. FIG. 9 is a diagram showing the cumulative probability distribution and normal cumulative probability distribution of the plurality of samples of FIG. 7. FIG. 10 is a diagram showing a method for obtaining a reference time corresponding to a reference change rate based on the graph of FIG. 7. FIG. 11 is a diagram showing a method for obtaining a reference time corresponding to a reference change rate based on the smoothed graph of FIG. 7. FIG. 12 is a diagram showing a frequency distribution (dispersion) of the first voltages of a plurality of battery cells measured before the stabilization time has elapsed after the shipment charging. FIG. 13 is a diagram showing a frequency distribution (dispersion) of the voltage difference between the first voltages of a plurality of battery cells measured before the stabilization time has elapsed as in FIG. 12 and the second voltages of the plurality of battery cells measured after a predetermined time has elapsed from the time of measuring the first voltage. FIG. 14 is a diagram showing a frequency distribution (dispersion) of the first voltages of a plurality of battery cells measured after the stabilization time has elapsed after the shipment charging. FIG. 15 is a diagram showing a frequency distribution (dispersion) of the voltage difference between the first voltages of a plurality of battery cells measured after the stabilization time has elapsed as in FIG. 14 and the second voltages of the plurality of battery cells measured after a predetermined time has elapsed from the time of measuring the first voltage. Figure 16 is a flowchart showing a battery cell activation method according to one embodiment of the present invention.

[0144] [Battery Cell Activation System]

[0145] Referring to FIG. 5, a battery cell activation system (10) according to one embodiment may include a charging / discharging unit (100), a voltage measuring unit (200), and a stabilization time acquisition unit (300). The battery cell activation system (10) may further include a pass / fail determination unit (400).

[0146] The charging / discharging unit (100) can charge or discharge the first battery cell to a predetermined capacity or voltage. The charging / discharging unit (100) can charge or discharge one or more second battery cells to a predetermined capacity or voltage.

[0147] Here, charging may be a shipping charge, and discharging may be a shipping discharge. Shipping charging and shipping discharge may be methods for setting the shipping SOC of a secondary battery. Shipping charging may be a method of discharging (e.g., fully discharging) a charged (e.g., fully charged) secondary battery and then charging it to the shipping SOC, and shipping discharge may be a method of discharging a charged (e.g., fully charged) secondary battery to the shipping SOC.

[0148] The charging and discharging unit (100) can charge or discharge the first battery cell and one or more second battery cells in the same or similar manner. Here, the charging method may be, for example, a charge rate (C-rate), a cutoff capacity or cutoff voltage, constant current charging or constant voltage charging, a termination rate and / or a number of charging steps and a charging method for each step. In addition, the discharging method may be, for example, a discharge rate (C-rate), a cutoff capacity or voltage, constant current discharging or constant voltage discharging, a termination rate and / or a number of discharging steps and a discharging method for each step. Here, the termination rate may be a charge or discharge rate (C-rate) of a smaller magnitude than before, which is applied at the end to cut off at a predetermined voltage during charging or discharging.

[0149] Accordingly, the actual stabilization time of the voltage of each of one or more secondary battery cells can be equal to or similar to the stabilization time (ST) of the primary battery cell. Accordingly, the accuracy of determining whether the secondary battery cell is good or bad can be improved.

[0150] The voltage measuring unit (200) can measure the voltage of the first battery cell multiple times for a predetermined period of time from the first charge / discharge time after the first battery cell is charged or discharged to a predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized. For example, the voltage measuring unit (200) can measure the voltage of the first battery cell every unit time (e.g., 1 minute) for a predetermined period of time from the first charge / discharge time.

[0151] Here, "after" can mean immediately after. The predetermined time can be longer than the stabilization time (ST). For example, the predetermined time can be five times or more than the stabilization time (ST). The predetermined time can be, for example, four days (96 hours). The voltage can be the no-load voltage (OCV, Open Circuit Voltage).

[0152] The voltage measurement unit (200) can also measure the rate of change in voltage of the first battery cell over time. The rate of change in voltage may be the rate of change in voltage over a unit time (e.g., 1 minute) or the instantaneous rate of change in voltage.

[0153] The voltage measuring unit (200) can measure the voltage of each of one or more second battery cells at a second charge / discharge time after the second battery cell has been charged or discharged to a predetermined capacity or voltage, and at an elapsed time after a stabilization time (ST) has elapsed from the second charge / discharge time. One or more second battery cells can be left alone for the stabilization time (ST).

[0154] At this time, the environment in which one or more second battery cells are placed from the second charge / discharge time to the elapsed time may be the same as or similar to the environment in which the first battery cell is placed from the first charge / discharge time to the predetermined time or stabilization time (ST). Here, the environment may be temperature and / or pressure.

[0155] Accordingly, the actual stabilization time of the voltage of each of one or more secondary battery cells can be equal to or similar to the stabilization time (ST) of the primary battery cell. Accordingly, the accuracy of determining whether a battery cell is good or bad can be improved.

[0156] The stabilization time acquisition unit (300) may include a voltage change rate acquisition unit (310), a reference change rate calculation unit (330), and a stabilization time setting unit (340). The stabilization time acquisition unit (300) may further include a sample extraction unit (320).

[0157] The voltage change rate acquisition unit (310) can acquire the change rate of voltage over time (dv / dt) of the first battery cell based on the voltage of the first battery cell measured by the voltage measurement unit (200) (Fig. 6).

[0158] The sampling unit (320) can extract multiple samples of the voltage change rate from the voltage change rate over time obtained from the voltage change rate acquisition unit (310) (Fig. 7).

[0159] When multiple samples are arranged according to the time corresponding to the multiple samples, the time difference between the first time corresponding to the first sample and the second time corresponding to the second sample may be constant for each sample, i.e., the first sample and the second sample adjacent to the first sample. Here, the time corresponding to the sample may mean the time corresponding to the rate of change corresponding to the sample.

[0160] At this time, the time difference can be more than 30 minutes and less than 2 hours. For example, the time difference can be 1 hour.

[0161] Accordingly, noise can be removed from multiple samples when the time difference is greater than 30 minutes, and the number of samples can be increased when the time difference is less than 2 hours. Consequently, the accuracy of the stabilization time (ST) can be improved.

[0162] The reference change rate calculation unit (330) can calculate a reference change rate that at least partially distinguishes the voltage change rate before and after voltage stabilization based on the voltage change rate over time.

[0163] In one embodiment, the reference change rate calculation unit (330) can calculate the reference change rate based on the frequency or distribution of multiple samples extracted from the sample extraction unit (320) (Fig. 8, Fig. 9).

[0164] Accordingly, the reference change rate can be easily calculated and effectively distinguished between before and after voltage stabilization. This is because the frequency and distribution of samples before and after voltage stabilization of a battery cell significantly differ. Therefore, the optimal stabilization time (ST) can be easily and simply obtained.

[0165] The standard change rate calculation unit (330) can calculate the standard change rate based on the interval frequency (categorical frequency) of multiple samples. The interval frequency may be an interval frequency distribution (e.g., a histogram) (Fig. 8).

[0166] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the frequency difference between each sample interval before and after voltage stabilization of the battery cell is significant.

[0167] The reference change rate calculation unit (330) can calculate a normal distribution using the average and standard deviation of multiple samples. The reference change rate calculation unit (330) can calculate a difference value (e) obtained by subtracting the frequency of the first section from the corresponding value of the normal distribution corresponding to the first section, which is an arbitrary section, for the first section. Here, the corresponding value of the normal distribution corresponding to the first section may be a value obtained by multiplying the probability value of the normal distribution corresponding to the first section by the total number of samples. The reference change rate calculation unit (330) can set the voltage change rate included in the first section as the reference change rate when the difference value (e) is greater than the first threshold value (the first threshold value is a positive real number) (Fig. 8).

[0168] Accordingly, since the change rate in the interval in which the actual frequency of the sample is sufficiently smaller than the corresponding value of the normal distribution (to the extent that it exceeds the first critical value) is set as the reference change rate, the reference change rate can effectively distinguish before and after voltage stabilization.

[0169] Specifically, after the voltage of a battery cell is stabilized, the voltage change rate is generally repeated periodically within a constant voltage change rate range (Figs. 6 and 7), so the stable range to which the voltage change rate after voltage stabilization belongs generally has a large sample frequency and can follow the trend of a normal distribution (Figs. 8 and 9). On the other hand, before the voltage of a battery cell is stabilized, the voltage change rate is not constant and does not repeat periodically (Figs. 6 and 7), so the unstable range to which the voltage change rate before voltage stabilization belongs generally has a sample frequency that is smaller than the corresponding value of the normal distribution (Figs. 8 and 9). In particular, in the unstable range to which the voltage change rate before voltage stabilization belongs, the unstable range adjacent to the stable range (i.e., the boundary range, for example, s1 in Fig. 8) may have a sample frequency that is much smaller than the corresponding value of the normal distribution (to the extent of exceeding the first threshold value) compared to other unstable ranges. Therefore, if the change rate in the interval in which the actual frequency of the sample is sufficiently smaller than the corresponding value of the normal distribution (to the extent that it exceeds the first critical value) is set as the reference change rate, the reference change rate can correctly distinguish the change rates before and after voltage stabilization.

[0170] The reference change rate calculation unit (330) can set the voltage change rate included in the first candidate section that is farthest from the center of the normal distribution among the m candidate sections as the reference change rate when there are m (m is a natural number greater than or equal to 2) candidate sections in which the difference value (e) is greater than the first threshold value.

[0171] For example, in the case where there are two or more candidate sections (s1, s2, etc.) in which the difference value (e) is greater than the first threshold value as shown in FIG. 8, the reference change rate calculation unit (330) can set the change rate (e.g., 0.226) included in the first candidate section (s1) that is farthest from the center of the normal distribution toward the side larger or smaller than the center of the normal distribution (the larger side in FIG. 8) among the two or more candidate sections as the reference change rate.

[0172] Accordingly, the problem of the reference change rate not being able to correctly distinguish between the change rates before and after voltage stabilization and dividing the change rate after voltage stabilization can be prevented.

[0173] For example, due to a problem such as multiple samples not reflecting the population, even though the voltage change rate after voltage stabilization is a stable section, the frequency of the sample in the stable section may be much smaller (exceeding the first threshold) than the corresponding value of the normal distribution in the stable section, so that the stable section may be determined as a candidate section (s2 in Fig. 8). However, since the change rate of the candidate section farthest from the center of the normal distribution (i.e., the unstable section, s1 in Fig. 8) is set as the reference change rate, it is possible to prevent the change rate of the stable section (s2 in Fig. 8), which is relatively close to the center of the normal distribution, from being set as the reference change rate.

[0174] The reference change rate calculation unit (330) may set the voltage change rate included in the first candidate section as the reference change rate when there are m (m is a natural number greater than or equal to 2) candidate sections, which are first sections in which the difference value (e) is greater than the first threshold value, and when the first candidate section, which is farthest from the center of the normal distribution in a direction greater than or less than the center of the normal distribution among the m candidate sections, is not adjacent to or continuous with other candidate sections. The reference change rate calculation unit (330) may set the voltage change rate included in the second candidate section, which is closest to the center of the normal distribution among the n candidate sections, as the reference change rate when the first candidate section is adjacent to or continuous with n (n is a natural number greater than or equal to 1) other candidate sections.

[0175] For example, in the case where there are two or more candidate sections (s1, s2, etc.) in which the difference value (e) is greater than the first threshold value, as shown in FIG. 8, the reference change rate calculation unit (330) may set the change rate (e.g., 0.226) included in the first candidate section (s1) as the reference change rate if, among the two or more candidate sections, the first candidate section (s1) that is farthest from the center of the normal distribution toward the side larger or smaller than the center of the normal distribution (the larger side in FIG. 8) is not adjacent to or continuous with another candidate section (s2, etc.). Unlike FIG. 8, if the first candidate section (s1) is adjacent to or continuous with one or more other candidate sections, the change rate included in the second candidate section that is closest to the center of the normal distribution among one or more other candidate sections may be set as the reference change rate.

[0176] Accordingly, the problem of the reference change rate not properly distinguishing between the change rates before and after voltage stabilization and dividing the change rate after voltage stabilization can be prevented. Furthermore, by setting the change rate of the candidate interval closest to the center of the normal distribution among adjacent or consecutive candidate intervals as the reference change rate, an optimal reference change rate can be established.

[0177] The reference change rate calculation unit (330) can calculate the reference change rate based on the cumulative frequency distribution of multiple samples (Fig. 9). Here, the cumulative frequency may be, for each sample, the frequency of the sample (e.g., 1) plus the frequencies of all other samples having a sample value less than or equal to it, or the frequency of the sample (e.g., 1) plus the frequencies of all other samples having a sample value greater than or equal to it. The relative cumulative frequency may be a value obtained by dividing each cumulative frequency by the total number of multiple samples. The (relative) cumulative frequency distribution of multiple samples may be a diagram that corresponds to the sample values ​​and (relative) cumulative frequencies of multiple samples (Fig. 9).

[0178] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the cumulative frequency distribution of samples before and after voltage stabilization of the battery cell is significantly different.

[0179] The reference change rate calculation unit (330) can calculate a trend line for the cumulative frequency distribution of some samples among multiple samples and calculate the reference change rate based on the slope of the trend line. Here, the trend line may be a straight line. Additionally, the trend line may be a distribution line fitted to the cumulative frequency distribution of the samples (L1, L2 in FIG. 9).

[0180] Accordingly, the reference change rate can be appropriately and easily calculated. This is because the difference in slope of the trend line for the cumulative frequency distribution of samples before and after voltage stabilization of the battery cell is significant.

[0181] At this time, the above-mentioned part of the sample may be greater than or equal to the second threshold value among the plurality of samples, and there may be a plurality of them.

[0182] Accordingly, the slope of the trend line for the cumulative frequency distribution of some samples that are presumed to be samples after voltage stabilization of the battery cell (samples above or below the second threshold value) can be easily calculated.

[0183] In this regard, let us look at Figure 9.

[0184] The standard change rate calculation unit (330) can calculate the cumulative frequency distribution of N (e.g., N=95) samples (Fig. 9). The standard change rate calculation unit (330) can calculate the angle difference (A) between the first slope of the first trend line (L1) and the second slope of the second trend line (L2) while increasing or decreasing the second threshold (e.g., decreasing or increasing p, which will be described later). Here, the first trend line (L1) may be a trend line for the cumulative frequency distribution of Np (p is a natural number greater than or equal to 2 and less than N) samples that are smaller than the second threshold among N (N is a natural number greater than or equal to 2) samples. In addition, the second trend line (L2) may be a trend line for the cumulative frequency distribution of p samples that are greater than or equal to the second threshold among N samples. In cases where the voltage change rate before voltage stabilization is generally greater than the voltage change rate after voltage stabilization, as shown in FIGS. 6 to 9, the reference change rate calculation unit (330) can calculate the angle difference (A) between the first slope and the second slope while increasing the second threshold value (e.g., decreasing p).

[0185] The reference change rate calculation unit (330) can obtain the second threshold value when the angle difference (A) becomes greater than the third threshold value (the third threshold value is a positive real number, for example, 45 degrees). The reference change rate calculation unit (330) can set the second threshold value as the reference change rate. In Fig. 9, the second threshold value and the reference change rate are 0.226.

[0186] Meanwhile, the line (L) in Fig. 9 represents the normal cumulative probability distribution calculated using the mean and standard deviation of all (N) samples. The normal cumulative probability distribution is, in principle, S-shaped. In order to represent the normal cumulative probability distribution as a straight line, it can be confirmed that the tick marks on the Y-axis in Fig. 9 are set to be inversely proportional to the frequency distribution. Therefore, unlike Fig. 9, when the tick marks on the Y-axis are constant, the first slope, the second slope, and / or the angle difference (A) described above may differ from Fig. 9.

[0187] In another embodiment, the reference change rate calculation unit (330) can determine the stabilization range (stabilization section) to which the voltage change rate after voltage stabilization belongs based on the average and standard deviation of the plurality of samples. The reference change rate calculation unit (330) can set a value corresponding to or similar to the boundary of the stabilization range as the reference change rate.

[0188] Accordingly, the baseline change rate can be appropriately and easily calculated statistically. This is because the frequency and distribution of samples before and after voltage stabilization of battery cells differ significantly.

[0189] For example, the reference change rate calculation unit (330) can determine the stabilization range by subtracting or adding a standard deviation with a preset weight (e.g., 2) from the average of multiple samples. In other words, assuming that multiple samples follow a normal distribution, approximately 95% of the samples are distributed in a stabilization range having a lower limit obtained by subtracting the standard deviation * 2 from the average and an upper limit obtained by adding the standard deviation * 2 to the average. Accordingly, the stabilization range in which most (95%) of the samples are distributed can be easily set. Accordingly, by setting the boundary of the stabilization range in which most samples are distributed as the reference change rate, the range in which the voltage change rate after voltage stabilization belongs (a range with a large distribution or frequency) and the range in which the voltage change rate before voltage stabilization belongs (a range with a small distribution or frequency) can be easily distinguished.

[0190] The stabilization time setting unit (340) can obtain a reference time corresponding to the reference change rate. The stabilization time setting unit (340) can set the reference time or a time similar to the reference time as the stabilization time (ST).

[0191] In this way, the battery cell activation system (10) may include a voltage charging / discharging unit (100), a measuring unit (200), and a stabilization time acquisition unit (300), and the stabilization time acquisition unit (300) may include a voltage change rate acquisition unit (310), a reference change rate calculation unit (330), and a stabilization time setting unit (340). Accordingly, it is possible to easily acquire an (optimal) stabilization time (ST) suitable for a method of charging or discharging (e.g., shipping charge or shipping discharge) of the battery cell or the environment in which the battery cell is placed.

[0192] For example, since the change rate of the voltage of a battery cell over time generally exists within a certain change rate range having an upper limit and a lower limit after voltage stabilization, a time corresponding to or similar to the upper or lower limit of this change rate range (i.e., the reference change rate) can be set as the stabilization time (ST).

[0193] Additionally, by utilizing the stabilization time (ST), a predetermined task can be performed on a battery cell after the voltage has been reliably stabilized, so that the predetermined task can be performed effectively or appropriately. For example, since the voltage measurement unit (200) can measure the voltage of a battery cell whose voltage has been reliably stabilized after the stabilization time (ST) has elapsed, the measured voltage can be valid.

[0194] Additionally, the activation process of the battery cell can be optimized because the optimal stabilization time (ST) can be obtained.

[0195] The stabilization time setting unit (340) can smooth data based on the rate of change of voltage over time and obtain a reference time corresponding to the reference rate of change from the smoothed data. Here, the data based on the rate of change of voltage over time may be data regarding the rate of change of voltage over time obtained by the voltage rate of change obtaining unit (310) or data regarding multiple samples extracted by the sample extraction unit (320).

[0196] Accordingly, even if the reference change rate calculated by the reference change rate calculation unit (330) is close to the upper or lower limit of the stable section to which the voltage change rate after voltage stabilization belongs, or falls between the upper and lower limits, the correct reference time can be easily obtained.

[0197] In this regard, let us look at Figs. 10 and 11.

[0198] As shown in Fig. 10, before the voltage change rate over time is smoothed, there may be two times (t1, t2) corresponding to the reference change rate (R, 0.226). This may be because the reference change rate (R, 0.226) approximates the peak of the voltage change rate that changes periodically after the voltage stabilizes (after ST). Therefore, it may be difficult to determine which of the two times (t1, t2) will be the reference time.

[0199] On the other hand, if the rate of change of voltage over time is smoothed as in Fig. 11, the size of the peak and bottom of the voltage rate of change, which changes periodically after the voltage is stabilized (after ST), decreases, so that there can be one time (t1) corresponding to the reference rate of change (R, 0.226), and the corresponding time (t1) can be set as the reference time. In other words, the reference time can be prevented from being delayed to the time (t2) after the voltage is stabilized (after ST).

[0200] Meanwhile, if there are multiple times corresponding to the reference change rate (R) even after smoothing as in Fig. 11, the latest time among the multiple times can be set as the reference time.

[0201] The above data can be smoothed using the local regression analysis (LOESS) technique.

[0202] Accordingly, even if the voltage change rate over time is smoothed, the trend of the voltage change rate over time at the boundary before and after voltage stabilization can be correctly maintained. Accordingly, the reference change rate and corresponding reference time at the boundary before and after voltage stabilization can be correctly obtained.

[0203] The good / bad judgment unit (400) can judge the good / bad of the second battery cell based on the voltage of the battery cell measured at the second charge / discharge time and the elapsed time for each of one or more second battery cells. For example, the good / bad judgment unit (400) can judge the second battery cell as bad (low voltage bad) if the voltage difference between the second charge / discharge time and the elapsed time for each of one or more second battery cells is greater than a predetermined value.

[0204] Accordingly, since the quality of a battery cell (e.g., low voltage defect) is determined based on the voltage measured after the voltage of the battery cell that has been charged or discharged (e.g., shipped charged or shipped discharged) has stabilized (i.e., after a stabilization period has elapsed), the accuracy of determining whether the battery cell is good or bad can be improved.

[0205] Additionally, the process of determining whether a battery cell is good or bad can be optimized by utilizing the optimal stabilization time (ST).

[0206] Regarding the effect of determining whether a product is good or bad when using the stabilization time (ST), we examine Figs. 12 to 15.

[0207] Referring to Figure 12, it can be confirmed that the frequency distribution of the first voltage of multiple battery cells is non-uniform. Specifically, the frequency distribution not only has two peaks but is also divided into two sections (ranges). This is because the first voltage was measured approximately 2.5 hours after multiple battery cells were charged to 50% of their capacity (the shipping SOC), but before the stabilization time corresponding to this charging method (approximately 3.63 hours, Figure 4) had elapsed.

[0208] Referring to Fig. 13, it can be confirmed that the frequency distribution of the voltage difference (dOCV) between the first voltage and the second voltage of multiple battery cells is non-uniform. Specifically, the frequency distribution not only has two peaks but is also divided into two sections (ranges). This may be because, as shown in Fig. 12, the first voltage was measured about 2.5 hours after multiple battery cells were shipped and charged to 50% capacity, which is the shipping SOC, and before the stabilization time (about 3.63 hours, Fig. 4) corresponding to this charging method had elapsed, and the second voltage was measured after a predetermined time had elapsed from the time of measuring the first voltage. If the frequency distribution of the voltage difference (dOCV) is non-uniform, as shown in Fig. 13, it may be impossible to determine whether a battery cell is good or bad, or the determination accuracy may be low.

[0209] Referring to Fig. 14, it can be confirmed that the frequency distribution of the first voltages of multiple battery cells is uniform. Specifically, the frequency distribution follows a normal distribution calculated using the mean and standard deviation of the first voltages of multiple battery cells. This is because the first voltage was measured after the stabilization time (approximately 3.63 hours, Fig. 4) corresponding to this charging method had elapsed after the multiple battery cells were shipped and charged to 50% of their capacity, which is the shipping SOC.

[0210] Referring to Fig. 15, it can be confirmed that the frequency distribution of the voltage difference (dOCV) between the first voltage and the second voltage of multiple battery cells is uniform. Specifically, the frequency distribution follows a normal distribution calculated using the mean and standard deviation of the voltage differences of multiple battery cells. This may be because, as shown in Fig. 14, after multiple battery cells were shipped and charged to 50% of the capacity, which is the shipping SOC, the first voltage was measured after a stabilization time (approximately 3.63 hours, Fig. 4) corresponding to this charging method had elapsed, and the second voltage was measured after a predetermined time had elapsed from the measurement time of the first voltage. If the frequency distribution of the voltage difference (dOCV) is uniform, as shown in Fig. 15, the quality of the battery cell can be correctly determined, and the determination accuracy can be improved.

[0211] [How to activate battery cells]

[0212] Referring to FIG. 16, a battery cell activation method (S500) according to one embodiment may include a first charging / discharging process (S510), a first measurement process (S520), and a stabilization time acquisition process (S530). The battery cell activation method (S500) may further include a second charging / discharging process (S540), a second measurement process (S550), and a pass / fail determination process (S560).

[0213] In the first charging and discharging process (S510), the charging and discharging unit (100) can charge or discharge the first battery cell to a predetermined capacity or voltage.

[0214] In the first measurement process (S520), the voltage measurement unit (200) can measure the voltage of the first battery cell multiple times for a predetermined period of time from the first charge / discharge time after the first battery cell is charged or discharged to a predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized.

[0215] The stabilization time acquisition process (S530) may include a voltage change rate acquisition process (S532), a reference change rate calculation process (S536), and a stabilization time setting process (S538). The stabilization time acquisition process (S530) may further include a sampling process (S534).

[0216] In the voltage change rate acquisition process (S532), the voltage change rate acquisition unit (310) can acquire the voltage change rate (dv / dt) of the first battery cell over time based on the measured voltage of the first battery cell.

[0217] In the sampling process (S534), the sampling unit (320) can extract multiple samples of the voltage change rate from the voltage change rate over time acquired in the voltage change rate acquisition process (S532).

[0218] In the standard change rate calculation process (S536), the standard change rate calculation unit (330) can calculate a standard change rate that at least partially distinguishes the voltage change rate before and after voltage stabilization based on the voltage change rate over time.

[0219] In addition, in one embodiment, the reference change rate calculation unit (330) may calculate the reference change rate based on the frequency or distribution of a plurality of samples, or may determine the stabilization range to which the change rate after voltage stabilization belongs based on the average and standard deviation of a plurality of samples, and may set a value corresponding to or similar to the boundary of the stabilization range as the reference change rate.

[0220] Accordingly, the standard change rate can be calculated appropriately and easily.

[0221] In the stabilization time setting process (S538), the stabilization time setting unit (340) can obtain a reference time corresponding to the reference change rate and set the reference time or a time similar to the reference time as the stabilization time (ST).

[0222] In this way, the battery cell activation method (S500) includes a first charging / discharging process (S510), a first measurement process (S520), and a stabilization time acquisition process (S530), and the stabilization time acquisition process (S530) may include a voltage change rate acquisition process (S532), a reference change rate calculation process (S536), and a stabilization time setting process (S538).

[0223] Accordingly, it is possible to easily obtain an (optimal) stabilization time (ST) that is suitable for the charging or discharging method (e.g., shipping charging or shipping discharging) of the battery cell or the environment in which the battery cell is placed. For example, since the rate of change of the voltage of a battery cell over time generally exists within a certain rate of change range with an upper limit and a lower limit after voltage stabilization, a time corresponding to or similar to the upper or lower limit of this rate of change range can be set as the stabilization time (ST).

[0224] Additionally, by utilizing the stabilization time (ST), a predetermined task can be performed on a battery cell after the voltage has been reliably stabilized, so that the predetermined task can be performed effectively or appropriately. For example, since the voltage measurement unit (200) can measure the voltage of a battery cell whose voltage has been reliably stabilized after the stabilization time (ST) has elapsed, the measured voltage can be valid.

[0225] Additionally, the activation process of the battery cell can be optimized because the optimal stabilization time (ST) can be obtained.

[0226] In addition, the stabilization time setting unit (340) here can smooth data based on the change rate of voltage over time and obtain a reference time corresponding to the reference change rate from the smoothed data.

[0227] Accordingly, even if the reference change rate calculated by the reference change rate calculation unit (330) is close to the upper or lower limit of the stable section to which the voltage change rate after voltage stabilization belongs, or falls between the upper and lower limits, the correct reference time can be easily obtained.

[0228] In the second charging and discharging process (S540), the charging and discharging unit (100) can charge or discharge one or more second battery cells to a predetermined capacity or voltage.

[0229] In the second measurement process (S550), the voltage measuring unit (200) can measure the voltage of each of one or more second battery cells at a second charge / discharge time after the second battery cell is charged or discharged to a predetermined capacity or voltage, and at an elapsed time after the stabilization time (ST) has elapsed from the second charge / discharge time.

[0230] In the good / bad judgment process (S560), the good / bad judgment unit (400) can judge the good / bad of one or more second battery cells based on the voltage of the second battery cell measured at the second charge / discharge time and elapsed time.

[0231] Accordingly, since the quality of a battery cell (e.g., low voltage defect) is determined based on the voltage measured after the voltage of the battery cell that has been charged or discharged (e.g., shipped charged or shipped discharged) has stabilized (i.e., after a stabilization period has elapsed), the accuracy of determining whether the battery cell is good or bad can be improved.

[0232] Additionally, the process of determining whether a battery cell is good or bad can be optimized by utilizing the optimal stabilization time (ST).

[0233] Meanwhile, matters not mentioned regarding the battery cell activation method (S500) can be inferred from the battery cell activation system (10) described above.

[0234] It should be understood that the above-described embodiments are illustrative in all respects and not restrictive, and the scope of the present invention will be determined by the claims that follow rather than by the detailed description set forth above. Furthermore, the meaning and scope of the claims that follow, as well as all variations and modifications derived from their equivalent concepts, should be construed as encompassing the scope of the present invention.

[0235] Although the present invention has been described with reference to the drawings exemplified above, it is to be understood that the present invention is not limited to the embodiments and drawings disclosed herein, and that various modifications may be made by those skilled in the art within the scope of the technical idea of ​​the present invention. Furthermore, even if the operational effects according to the configuration of the present invention have not been explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be acknowledged.

Claims

1. A charging / discharging unit (100) that charges or discharges the first battery cell to a predetermined capacity or voltage; A voltage measuring unit (200) that measures the voltage of the first battery cell multiple times for a predetermined time from the first charge / discharge time after the first battery cell is charged or discharged to a predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized; and A stabilization time acquisition unit (300) comprising a voltage change rate acquisition unit (310) for acquiring a change rate of voltage (dv / dt) over time of the first battery cell based on the measured voltage of the first battery cell, a reference change rate calculation unit (330) for calculating a reference change rate that at least partially distinguishes the change rate before and after voltage stabilization based on the change rate of voltage over time, and a stabilization time setting unit (340) for acquiring a reference time corresponding to the reference change rate and setting the reference time or a time similar to the reference time as a stabilization time (ST). Battery cell activation system.

2. In claim 1, The above charging and discharging unit (100) charges or discharges one or more second battery cells to a predetermined capacity or voltage, The voltage measuring unit (200) measures the voltage of each of the second battery cells at a second charge / discharge time after the second battery cell is charged or discharged to a predetermined capacity or voltage, and at an elapsed time after the stabilization time (ST) has elapsed from the second charge / discharge time. A battery cell activation system further comprising a quality determination unit (400) for determining the quality of a second battery cell based on the voltage of the second battery cell measured at the second charge / discharge time and elapsed time for each of the second battery cells.

3. In claim 2, The above charging and discharging unit (100) is a battery cell activation system that charges or discharges the first battery cell and one or more second battery cells in the same or similar manner.

4. In claim 2 or claim 3, A battery cell activation system, wherein the environment in which the one or more second battery cells are placed from the second charge / discharge time to the elapsed time is the same as or similar to the environment in which the first battery cell is placed from the first charge / discharge time to the predetermined time or stabilization time (ST).

5. In any one of claims 1 to 4, The stabilization time acquisition unit (300) further includes a sample extraction unit (320) that extracts multiple samples of the change rate from the change rate of voltage over time acquired by the voltage change rate acquisition unit (310). The above-mentioned standard change rate calculation unit (330) is a battery cell activation system that calculates the standard change rate based on the frequency or distribution of the plurality of samples.

6. In claim 5, The above-mentioned standard change rate calculation unit (330) is a battery cell activation system that calculates the standard change rate based on the interval frequency (categorical frequency) of the plurality of samples.

7. In claim 6, The above-mentioned standard change rate calculation unit (330) calculates a normal distribution using the average and standard deviation of the plurality of samples, calculates a difference value (e) obtained by subtracting the frequency of the first section from the corresponding value of the normal distribution corresponding to the first section for the first section, which is an arbitrary section, and sets the change rate included in the first section as the standard change rate when the difference value (e) is greater than a first threshold value (the first threshold value is a positive real number). A battery cell activation system.

8. In claim 7, The above-mentioned standard change rate calculation unit (330) is a battery cell activation system that sets the change rate included in the first candidate section that is farthest from the center of the normal distribution in a direction larger or smaller than the center of the normal distribution among the m candidate sections, as the standard change rate, when the number of candidate sections that are the first sections in which the difference value (e) is larger than the first threshold value is m (m is a natural number greater than or equal to 2).

9. In claim 7, The above-mentioned reference change rate calculation unit (330) is a battery cell activation system in which, when there are m (m is a natural number greater than or equal to 2) candidate sections, which are the first sections in which the difference value (e) is greater than the first threshold value, if the first candidate section, which is farthest from the center of the normal distribution in a direction greater than or less than the center of the normal distribution among the m candidate sections, is not adjacent to or continuous with other candidate sections, the change rate included in the first candidate section is set as the reference change rate, and if the first candidate section is adjacent to or continuous with n (n is a natural number greater than or equal to 1) other candidate sections, the change rate included in the second candidate section, which is closest to the center of the normal distribution among the n candidate sections, is set as the reference change rate.

10. In any one of claims 5 to 9, The above-mentioned standard change rate calculation unit (330) is a battery cell activation system that calculates the standard change rate based on the cumulative frequency distribution of the plurality of samples.

11. In claim 10, The above-mentioned standard change rate calculation unit (330) is a battery cell activation system that calculates a trend line for the cumulative frequency distribution of some samples among the plurality of samples and calculates the standard change rate based on the slope of the trend line.

12. In claim 11, The above-mentioned part of the sample is a plurality of samples, more than or less than the second threshold value, and a plurality of individual, battery cell activation system.

13. In any one of claims 1 to 12, The stabilization time acquisition unit (300) further includes a sample extraction unit (320) that extracts multiple samples of the change rate from the change rate of voltage over time acquired by the voltage change rate acquisition unit (310). The above-mentioned standard change rate calculation unit (330) determines a stabilization range (stabilization section) to which the change rate after the voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and sets a value corresponding to or similar to the boundary of the stabilization range as the standard change rate. A battery cell activation system.

14. In any one of claims 5 to 13, When the above multiple samples are arranged according to the times corresponding to the multiple samples, in each sample, the first sample and the second sample adjacent to the first sample, the time difference between the first time corresponding to the first sample and the second time corresponding to the second sample is constant, A battery cell activation system wherein the above time difference is 30 minutes or more and 2 hours or less.

15. In any one of claims 1 to 14, The above stabilization time setting unit (340) is a battery cell activation system that smoothes data based on the rate of change of voltage over time and obtains a reference time corresponding to the reference rate of change from the smoothed data.

16. In claim 15, The above data is smoothed using the local regression analysis (LOESS) technique, a battery cell activation system.

17. A first charging / discharging process (S510) in which the charging / discharging unit (100) charges or discharges the first battery cell to a predetermined capacity or voltage; A first measurement process (S520) in which the voltage measuring unit (200) measures the voltage of the first battery cell multiple times for a predetermined time from the first charging / discharging time after the first battery cell is charged or discharged to the predetermined capacity or voltage before and after the voltage of the first battery cell is stabilized; and A voltage change rate acquisition process (S532) in which a voltage change rate acquisition unit (310) acquires a change rate (dv / dt) of voltage over time of a first battery cell based on the measured voltage of the first battery cell, a reference change rate calculation process (S536) in which a reference change rate calculation unit (330) calculates a reference change rate that at least partially distinguishes the change rate before and after voltage stabilization based on the change rate of voltage over time, and a stabilization time setting process (S538) in which a stabilization time setting unit (340) acquires a reference time corresponding to the reference change rate and sets the reference time or a time similar to the reference time as a stabilization time (ST), comprising a stabilization time acquisition process (S530). How to activate a battery cell.

18. In claim 17, A second charging / discharging process (S540) in which the above charging / discharging unit (100) charges or discharges one or more second battery cells to a predetermined capacity or voltage; A second measurement process (S550) in which the voltage measurement unit (200) measures the voltage of the second battery cell at a second charge / discharge time after the second battery cell is charged or discharged to a predetermined capacity or voltage, and at an elapsed time after the stabilization time (ST) has elapsed from the second charge / discharge time; and A battery cell activation method, wherein the battery quality determination unit (400) further includes a quality determination process (S560) for determining the quality of the second battery cell based on the voltage of the second battery cell measured at the second charge / discharge time and elapsed time for each of the second battery cells.

19. In claim 17 or claim 18, The above stabilization time acquisition process (S530) further includes a sampling extraction process (S534) in which the sampling unit (320) extracts a plurality of samples related to the change rate from the change rate of the voltage over time acquired in the voltage change rate acquisition process (S532). A battery cell activation method, wherein in the above-mentioned standard change rate calculation process (S536), the standard change rate calculation unit (330) calculates the standard change rate based on the frequency or distribution of the plurality of samples, or determines a stabilization range to which the change rate after voltage stabilization belongs based on the average and standard deviation of the plurality of samples, and sets a value corresponding to or similar to the boundary of the stabilization range as the standard change rate.

20. In any one of claims 17 to 19, A battery cell activation method in which, in the stabilization time setting process (S538), the stabilization time setting unit (340) smoothes data based on the rate of change of voltage over time and obtains a reference time corresponding to the reference rate of change from the smoothed data.

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