Lithium-ion battery self-discharge screening method and device

Abstract

The present invention discloses a method and device for self-discharge screening of lithium-ion batteries, the method comprising: performing a primary screening on batteries in a single frame, selecting batteries in the single frame that meet a first screening standard, the primary screening being overall self-discharge screening; determining a secondary screening standard corresponding to the single frame; performing a secondary screening on batteries in the single frame that meet the first screening standard according to the secondary screening standard, and determining qualified batteries in the single frame. The scheme of the present invention can improve the accuracy of screening batteries with abnormal self-discharge, and reduce the safety risks brought by batteries with abnormal self-discharge.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion battery quality detection, and in particular to a lithium ion battery self-discharge screening method and device. Background Art

[0002] Lithium-ion batteries have become the mainstream choice for power batteries due to their high energy density and long cycle life. The higher the energy density, the higher the safety requirements for lithium batteries. It is well known that a certain amount of self-discharge is the natural result of chemical reactions in the battery. This self-discharge is a chemical self-discharge with recoverable capacity. However, if there is a leakage current path inside the battery, it can also cause self-discharge. For example, particulate contaminants or the growth of dendrites will form a micro-short circuit inside the battery, thereby forming this leakage current path and causing self-discharge. This self-discharge is an irreversible physical self-discharge. These are not normal phenomena. Their existence poses great safety risks and may cause battery fires, explosions, etc. Therefore, it is extremely important to screen for self-discharge during battery design and manufacturing. During the manufacturing process, it is necessary to ensure that any battery with abnormal self-discharge screening is screened out as early as possible. Since the change in OCV (Open Circuit Voltage) of lithium batteries is very small during self-discharge, in order to shorten the screening time, a high-temperature warehouse (usually 45°C) is generally used for static placement, but there are many warehouse locations in the high-temperature warehouse. Due to the different distribution of warehouse locations, the temperature of each warehouse location may be different. For the same lithium battery, the higher the temperature, the greater the change in OCV; the lower the temperature, the smaller the change in OCV. However, if there is a micro-short circuit inside the battery, and it is left at a low temperature, the change in OCV may be smaller than the actual value, so there is a possibility that the self-discharge standard cannot screen out this defect, and this risky battery will flow to the module or even the vehicle, posing a great safety risk. Therefore, how to improve the accuracy of self-discharge screening in the presence of differences in storage temperature is an issue that the industry urgently needs to solve. Summary of the invention

[0003] The present invention provides a lithium ion battery self-discharge screening method and device, so as to improve the accuracy of screening batteries with abnormal self-discharge and reduce the safety risks brought by batteries with abnormal self-discharge.

[0004] To this end, the present invention provides the following technical solutions:

[0005] In one aspect, the present invention provides a method for screening lithium ion battery self-discharge, the method comprising:

[0006] Performing a primary screening on the batteries in the single frame to select the batteries in the single frame that meet the first screening criteria, wherein the primary screening is an overall self-discharge screening;

[0007] Determining a secondary screening criterion corresponding to the single frame;

[0008] A secondary screening is performed on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame.

[0009] Optionally, the determining of the secondary screening criteria corresponding to the single frame includes:

[0010] respectively collecting the voltages of the batteries in the single frame that meet the first screening criteria before and after being placed in a high-temperature storage;

[0011] Calculate the voltage difference before and after standing still;

[0012] A secondary judgment standard corresponding to the single frame is determined according to the voltage difference.

[0013] Optionally, determining the secondary judgment standard according to the voltage difference includes:

[0014] Calculate the average value of the voltage difference ΔV 平均 ;

[0015] Determine the secondary judgment standard as ΔV 平均 ±Nδ1, where N≥1, δ1 is based on the average value ΔV 平均 The standard deviation of .

[0016] Optionally, performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame includes:

[0017] If the voltage difference ΔV of the battery in the single frame that meets the first screening standard before and after being placed in the high temperature storage is a Satisfies -Nδ1|≤ΔV a -ΔV 平均 |≤+Nδ1, the battery is determined to be qualified.

[0018] Optionally, determining the secondary judgment standard according to the voltage difference includes:

[0019] Select an intermediate value ΔV from the voltage difference 中值 ;

[0020] Determine the secondary judgment standard as ΔV 中值 ±Nδ2, where N≥1, δ2 is based on the intermediate value ΔV 中值 The standard deviation of .

[0021] Optionally, performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame includes:

[0022] If the voltage difference ΔV of the battery in the single frame that meets the first screening standard before and after being placed in the high temperature storage is a Satisfies -Nδ2|≤ΔV a -ΔV 中值 |≤+Nδ2, the battery is determined to be qualified.

[0023] On the other hand, the present invention also provides a lithium ion battery self-discharge screening device, the device comprising:

[0024] A first screening module is used to perform a first-level screening on the batteries in a single frame, and select the batteries in the single frame that meet the first screening criteria, wherein the first-level screening is an overall self-discharge screening;

[0025] A dynamic standard determination module, used to determine the secondary screening standard corresponding to the single frame;

[0026] The second screening module is used to perform secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria, and determine qualified batteries in the single frame.

[0027] Optionally, the dynamic standard determination module includes:

[0028] A voltage difference acquisition unit, used to respectively acquire the voltage of the batteries in the single frame that meet the first screening standard before and after being placed in a high-temperature storage;

[0029] A calculation unit, used for calculating the voltage difference before and after standing still;

[0030] The standard determination unit is used to determine the secondary judgment standard corresponding to the single frame according to the voltage difference.

[0031] Optionally, the standard determination unit is specifically configured to calculate an average value ΔV of the voltage difference. 平均 , determine the secondary judgment standard as ΔV 平均 ±Nδ1, where N≥1, δ1 is based on the average value ΔV 平均 The second screening module is specifically used to determine the voltage difference ΔV before and after the battery meets the first screening standard in the single frame is placed in the high temperature library a Satisfies -Nδ1|≤ΔV a -ΔV 平均 |≤+Nδ1, the battery is determined to be qualified.

[0032] Optionally, the standard determination unit is specifically configured to select an intermediate value ΔV from the voltage difference. 中值 , determine the secondary judgment standard as ΔV 中值 ±Nδ2, where N≥1, δ2 is based on the intermediate value ΔV 中值The second screening module is specifically used to determine the voltage difference ΔV before and after the battery meets the first screening standard in the single frame is placed in the high temperature library a Satisfies -Nδ2|≤ΔV a -ΔV 中值 |≤+Nδ2, the battery is determined to be qualified.

[0033] The lithium-ion battery self-discharge screening method and device provided by the embodiment of the present invention performs two-level self-discharge screening on the battery. During the first-level screening, the batteries in the single frame are screened and judged as a whole, and the batteries corresponding to the points that are very discrete relative to the judgment criteria can be eliminated. During the second-level screening, the second-level screening criteria corresponding to each single frame are dynamically determined, that is, the corresponding second-level screening criteria are determined respectively for the batteries in each single frame and the batteries in different batches of the same single frame. Correspondingly, for the batteries in the single frame that have undergone the first-level screening, the second-level screening is performed again according to the second-level screening criteria corresponding to the single frame. Using the scheme of the present invention, even if different single frames have temperature differences due to their different storage locations when they are stationary, since the second-level screening criteria corresponding to each single frame are dynamically determined, through the second-level screening, the influence of the temperature difference between different storage locations in the high-temperature warehouse on the self-discharge screening can be effectively avoided, and the batteries with self-discharge anomalies are discharged as much as possible, the possibility of defective products flowing out is reduced, and the reliability of the battery is further improved.

[0034] By utilizing the solution of the present invention, abnormal self-discharging batteries that pose safety risks can be more accurately identified, and the self-discharging differences caused by differences in storage temperature can be eliminated, thereby reducing the safety risks caused by the inaccurate self-discharging screening that is currently in place. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a method for screening lithium-ion battery self-discharge according to an embodiment of the present invention;

[0036] Figure 2 It is a flow chart for determining secondary screening standards and performing secondary screening on batteries in the lithium ion battery self-discharge screening method according to an embodiment of the present invention;

[0037] Figure 3 Another flow chart for determining secondary screening criteria and performing secondary screening on batteries in the lithium ion battery self-discharge screening method according to an embodiment of the present invention;

[0038] Figure 4 It is a structural schematic diagram of a lithium-ion battery self-discharge screening device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0039] Self-discharge screening is a method to control the quality of lithium-ion battery products. If the self-discharge of batteries in the same batch is too large, it means that there may be quality problems. If such batteries cannot be accurately screened out, it will bring great safety hazards during use.

[0040] Existing self-discharge screening usually uses the voltage difference method, which calculates the voltage difference ΔV before and after the battery is placed in a high-temperature warehouse by measuring the voltage test value OCV1 before the lithium-ion battery is placed in a high-temperature warehouse and the voltage test value OCV2 after the battery is placed. The self-discharge screening standard for each batch is determined as follows: First, select a part of the batteries in the batch, test the voltage difference of the batteries, select the median value and calculate the standard deviation δ, then the self-discharge screening standard range of the batch of batteries is: median ±Nδ, N is a positive value, and its value can be determined based on test results and experience. After that, the voltage difference ΔV before and after the placement is calculated for other untested batteries in the batch, and the discrete points corresponding to each voltage difference ΔV are determined according to this standard, and the batteries that exceed the standard range are selected for analysis and judgment.

[0041] The existing self-discharge screening standard does not take into account the impact of temperature differences at different locations in a high-temperature warehouse. For batteries with internal micro-short circuits, if they are left at rest in a low-temperature location, the voltage difference may be smaller than the actual value. Based on the above judgment criteria, there may be a risk of defective products flowing out.

[0042] To this end, the present invention provides a lithium-ion battery self-discharge screening method and device, which can effectively avoid the influence of temperature differences between different storage locations in a high-temperature warehouse on self-discharge screening, exclude batteries with abnormal self-discharge as much as possible, reduce the possibility of defective products flowing out, and improve battery reliability.

[0043] like Figure 1 , which is a flow chart of the lithium ion battery self-discharge screening method of the present invention. The lithium ion battery self-discharge screening method of this embodiment comprises the following steps:

[0044] Step 101, performing a primary screening on the batteries in a single frame, selecting the batteries in the single frame that meet a first screening standard, wherein the primary screening is an overall self-discharge screening.

[0045] The first-level screening is to conduct an overall screening and judgment of the batteries to eliminate the batteries corresponding to points that are very discrete relative to the judgment criteria. The first-level screening can specifically adopt existing technologies. For example, by testing the voltage OCV1 of the battery before standing in the high-temperature warehouse and the voltage OCV2 after standing, the voltage difference ΔV before and after the battery is standing is calculated, and the voltage difference ΔV is compared with the self-discharge screening standard range of the batch of batteries: the median voltage difference ±Nδ (where N is a positive value and δ is the standard deviation), and the batteries within the standard range are regarded as batteries that meet the first screening standard. Accordingly, the batteries corresponding to the discrete points, that is, the batteries outside the standard range, are picked out and reworked or other corresponding treatments are performed on them.

[0046] It should be noted that the self-discharge screening standard range of the batch of batteries can be obtained by selecting a part of the batteries in the batch for testing, and then statistically analyzing and calculating the test results to obtain the corresponding parameters.

[0047] Of course, in practical applications, there may be other ways to perform the primary screening of batteries, which are not limited in the embodiments of the present invention.

[0048] Step 102, determining the secondary screening criteria corresponding to the single frame.

[0049] Since the temperatures at different locations in a high-temperature warehouse may vary, for the same lithium battery, the higher the temperature, the greater the change in OCV; the lower the temperature, the smaller the change in OCV. Usually, each single frame occupies one location, and each single frame contains multiple (for example, 20-40) batteries. In view of this feature, after selecting the batteries that meet the first screening criteria for the single frame in the above step 101, the secondary screening criteria corresponding to the single frame can be dynamically determined based on these batteries that meet the first screening criteria.

[0050] Since the batteries in each single frame are located in the same storage location, the secondary screening criteria determined based on these batteries can effectively avoid the impact of temperature differences between different storage locations in the high-temperature storage on self-discharge screening.

[0051] Specifically, the voltages of the batteries in the single frame that meet the first screening criteria before and after standing in the high-temperature storage can be collected respectively; the voltage difference before and after standing can be calculated; and then the secondary judgment criteria corresponding to the single frame can be determined according to the voltage difference.

[0052] In the embodiment of the present invention, there are multiple ways to determine the secondary screening criteria, which will be described in detail later.

[0053] Step 103 , performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria, and determining qualified batteries in the single frame.

[0054] In practical applications, multiple methods can be used to determine the secondary judgment criteria. For example:

[0055] (1) using the average value of the voltage difference to determine the secondary judgment standard;

[0056] (2) The secondary judgment standard is determined by using the median value of the voltage difference.

[0057] The following is a detailed description of the process of determining the secondary screening standard and performing secondary screening on batteries in the embodiment of the present invention.

[0058] Reference Figure 2 , Figure 2 This is a flow chart for determining secondary screening standards and performing secondary screening on batteries in the lithium ion battery self-discharge screening method according to an embodiment of the present invention, comprising the following steps:

[0059] Step 201, respectively collect the voltages of the batteries in a single frame that meet the first screening criteria before and after being placed in a high-temperature storage, and calculate the voltage difference before and after being placed. a -△V 平均 |≤+Nδ1

[0060] Step 202, calculating the average value of the voltage difference ΔV 平均 .

[0061] Step 203, determine the secondary judgment standard as ΔV 平均 ±Nδ1, where N≥1, δ1 is based on the average value ΔV 平均 The standard deviation can be calculated using the following formula:

[0062]

[0063]

[0064] Where n represents the total number of batteries in a single frame that meet the first screening criteria, ΔV i It represents the voltage difference of the ith battery before and after it is placed in the high temperature storage.

[0065] Step 204: If the voltage difference ΔV of the battery in the single frame that meets the first screening criteria before and after being placed in the high temperature storage is a Satisfies -Nδ1|≤ΔV a -ΔV 平均 |≤+Nδ1, the battery is determined to be qualified.

[0066] Reference Figure 3 , Figure 3 Another flow chart for determining secondary screening criteria and performing secondary screening on batteries in the lithium ion battery self-discharge screening method according to an embodiment of the present invention includes the following steps:

[0067] Step 301 , respectively collecting the voltages of the batteries in a single frame that meet the first screening criteria before and after standing in a high-temperature storage, and calculating the voltage difference before and after standing.

[0068] Step 302, selecting an intermediate value ΔV from the voltage difference 中值 .

[0069] Step 303, determine the secondary judgment standard as ΔV 中值 ±Nδ2, where N≥1, δ2 is based on the intermediate value ΔV 中值 The standard deviation can be calculated using the following formula:

[0070]

[0071]

[0072] Where n represents the total number of batteries in a single frame that meet the first screening criteria, ΔV i It represents the voltage difference of the ith battery before and after it is placed in the high temperature storage.

[0073] Step 304: If the voltage difference ΔV of the battery in the single frame that meets the first screening criteria before and after being placed in the high temperature storage is a Satisfies -Nδ2|≤ΔV a -ΔV 中值 |≤+Nδ2, the battery is determined to be qualified.

[0074] It should be noted that the above Figure 2 and Figure 3 These are just two specific examples for determining the secondary judgment criteria. In practical applications, there may be other secondary judgment criteria, which are not limited in the embodiments of the present invention.

[0075] Accordingly, an embodiment of the present invention further provides a lithium ion battery self-discharge screening device, such as Figure 4 Shown is a structural schematic diagram of the device.

[0076] In this embodiment, the lithium-ion battery self-discharge screening device 400 includes the following modules:

[0077] The first screening module 401 is used to perform a first-level screening on the batteries in a single frame, and select the batteries in the single frame that meet the first screening criteria, wherein the first-level screening is an overall self-discharge screening;

[0078] A dynamic standard determination module 402, used to determine the secondary screening standard corresponding to the single frame;

[0079] The second screening module 403 is used to perform secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria, and determine qualified batteries in the single frame.

[0080] The first screening module 401 performs a primary screening on the battery, which is to perform an overall screening and determination on the battery, so as to eliminate the battery corresponding to the points that are very discrete relative to the determination criteria. The primary screening can specifically adopt the existing technology, which will not be described in detail here.

[0081] The dynamic standard determination module 402 may specifically include the following units:

[0082] A voltage difference acquisition unit, used to respectively acquire the voltage of the batteries in the single frame that meet the first screening standard before and after being placed in a high-temperature storage;

[0083] A calculation unit, used for calculating the voltage difference before and after standing still;

[0084] The standard determination unit is used to determine the secondary judgment standard corresponding to the single frame according to the voltage difference.

[0085] The standard determination unit may specifically determine the secondary screening standard corresponding to the single frame in a variety of ways.

[0086] For example, the standard determination unit is specifically configured to calculate the average value ΔV of the voltage difference. 平均 , determine the secondary judgment standard as ΔV 平均 ±Nδ1, where N≥1, δ1 is based on the average value ΔV 平均 Accordingly, the second screening module 403 can be used to screen the voltage difference ΔV of the batteries that meet the first screening standard in the single frame before and after being placed in the high temperature storage. a Satisfies -Nδ1|≤ΔV a -ΔV 平均 |≤+Nδ1, the battery is determined to be qualified.

[0087] For another example, the standard determination unit is specifically configured to select an intermediate value ΔV from the voltage difference. 中值 , determine the secondary judgment standard as ΔV 中值 ±Nδ2, where N≥1, δ2 is based on the intermediate value ΔV 中值 Accordingly, the second screening module 403 can be used to screen the voltage difference ΔV of the batteries that meet the first screening standard in the single frame before and after being placed in the high temperature storage. a Satisfies -Nδ2|≤ΔV a -ΔV 中值 |≤+Nδ2, the battery is determined to be qualified.

[0088] It should be noted that, in the solution of the present invention, the first-level screening is a coarse screening, and its corresponding first screening standard is applicable to all batteries produced, that is, all batteries in each single frame must be coarsely screened according to the first screening standard; the second-level screening is a fine screening, and its corresponding second screening standard is determined in real time according to the data of the batteries in the single frame, that is, the second screening standard corresponding to different single frames is only applicable to the batteries in the single frame, and the batteries in each single frame need to be finely screened according to the second screening standard corresponding to the single frame.

[0089] In addition, it should be noted that the battery mentioned in the embodiment of the present invention may be a battery cell in a battery module. In practical applications, a lithium-ion battery product may include one or more of the battery modules.

[0090] The lithium-ion battery self-discharge screening method and device provided by the embodiment of the present invention performs two-level self-discharge screening on the battery. During the first-level screening, the batteries in the single frame are screened and judged as a whole, and the batteries corresponding to the points that are very discrete relative to the judgment criteria can be eliminated. During the second-level screening, the second-level screening criteria corresponding to each single frame are dynamically determined, that is, the corresponding second-level screening criteria are determined respectively for the batteries in each single frame and the batteries in different batches of the same single frame. Correspondingly, for the batteries in the single frame that have undergone the first-level screening, the second-level screening is performed again according to the second-level screening criteria corresponding to the single frame. Using the scheme of the present invention, even if different single frames have temperature differences due to their different storage locations when they are stationary, since the second-level screening criteria corresponding to each single frame are dynamically determined, through the second-level screening, the influence of the temperature difference between different storage locations in the high-temperature warehouse on the self-discharge screening can be effectively avoided, and the batteries with self-discharge anomalies are discharged as much as possible, the possibility of defective products flowing out is reduced, and the reliability of the battery is further improved.

[0091] By utilizing the solution of the present invention, the safety risks of electric vehicles in the process of using the above-mentioned batteries can be greatly reduced.

[0092] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. Moreover, the device embodiments described above are merely schematic, in which the modules and units described as separate components may or may not be physically separated, that is, they may be located on one network unit, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. A person of ordinary skill in the art can understand and implement it without creative work.

[0093] A person skilled in the art can understand that all or part of the steps in the above method implementation can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc.

[0094] Accordingly, an embodiment of the present invention further provides a device for a method for predicting long-term pavement performance, the device being an electronic device, such as a mobile terminal, a computer, a tablet device, a personal digital assistant, etc. The electronic device may include one or more processors and memories; wherein the memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions to implement the methods described in the above embodiments.

[0095] The embodiments of the present invention are described in detail above. The present invention is described in detail using specific implementation methods herein. The description of the above embodiments is only used to help understand the method and device of the present invention. It is only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should belong to the scope of protection of the present invention, and the content of this specification should not be understood as limiting the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for screening self-discharge of lithium-ion batteries, characterized in that: The method comprises: Performing a primary screening on the batteries in the single frame, selecting the batteries in the single frame that meet the first screening criteria, wherein the primary screening is an overall self-discharge screening; wherein there are multiple storage locations in the high-temperature storage, the temperatures of different storage locations are different, and each single frame occupies one storage location; Determine the secondary screening criteria corresponding to the single frame; the secondary screening criteria corresponding to each single frame are dynamically determined; Performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame; The determining of the secondary screening criteria corresponding to the single frame includes: respectively collecting the voltages of the batteries in the single frame that meet the first screening criteria before and after being placed in a high-temperature storage; Calculate the voltage difference before and after standing still; Determining a secondary judgment standard corresponding to the single frame according to the voltage difference; Determining the secondary judgment standard according to the voltage difference includes: Calculate the average value of the voltage difference ; Determine the secondary judgment criteria as ,in, N ≥1, Based on the average The standard deviation of The step of performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame includes: If the voltage difference of the battery in the single frame that meets the first screening standard before and after being placed in the high temperature storage is satisfy , it is determined that the battery is qualified.

2. The method according to claim 1, characterized in that Determining the secondary judgment standard according to the voltage difference includes: Select an intermediate value from the voltage differences ; Determine the secondary judgment criteria as ,in, N ≥1, Based on the intermediate value The standard deviation of .

3. The method according to claim 2, characterized in that The step of performing secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria to determine qualified batteries in the single frame includes: If the voltage difference of the battery in the single frame that meets the first screening standard before and after being placed in the high temperature storage is satisfy , it is determined that the battery is qualified.

4. A lithium-ion battery self-discharge screening device, characterized in that: The device comprises: The first screening module is used to perform a first-level screening on the batteries in the single frame, and select the batteries in the single frame that meet the first screening criteria. The first-level screening is an overall self-discharge screening to eliminate batteries corresponding to points that are very discrete relative to the judgment criteria. There are multiple storage locations in the high-temperature warehouse, and the temperatures of different storage locations are different. Each single frame occupies one storage location. A dynamic standard determination module is used to determine the secondary screening standard corresponding to the single frame; the secondary screening standard corresponding to each single frame is dynamically determined; A second screening module, configured to perform secondary screening on the batteries in the single frame that meet the first screening criteria according to the secondary screening criteria, to determine qualified batteries in the single frame; The dynamic standard determination module includes: A voltage difference acquisition unit, used to respectively acquire the voltage of the batteries in the single frame that meet the first screening standard before and after being placed in a high-temperature storage; A calculation unit, used for calculating the voltage difference before and after standing still; A standard determination unit, used to determine a secondary judgment standard corresponding to the single frame according to the voltage difference; The standard determination unit is specifically used to calculate the average value of the voltage difference , determine the secondary judgment criteria as ,in, N ≥1, Based on the average The standard deviation of The second screening module is specifically used to screen the voltage difference of the batteries that meet the first screening criteria in the single frame before and after being placed in the high temperature storage. satisfy In this case, it is determined that the battery is qualified.

5. The device according to claim 4, characterized in that The standard determination unit is specifically used to select an intermediate value from the voltage difference , determine the secondary judgment criteria as ,in, N ≥1, Based on the intermediate value The standard deviation of The second screening module is specifically used to screen the voltage difference of the batteries that meet the first screening criteria in the single frame before and after being placed in the high temperature storage. satisfy In this case, it is determined that the battery is qualified.

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