Battery offline method and system
Through the screening and step-by-step battery downlink method, the existing battery downlink problems are solved, and low-cost and efficient battery production and shipment accuracy is achieved.
Patent Information
- Application Number
- CN202510428838.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2025-08-01
AI Technical Summary
The existing battery downlink methods have problems such as high energy consumption, long time and high cost, and virtual capacity downlink leads to poor battery consistency, affecting the use of high-demand modules.
By screening out the initial battery with a voltage greater than the threshold as the first battery, after the melting and secondary injection, several constant current charges are performed and the voltage difference is measured, and the virtual capacity processing is achieved step by step to avoid the capacity separation step.
It reduces battery production energy consumption and cost, ensures the capacity and self-discharge consistency of batteries in the same gear, and improves shipment accuracy.
Smart Images
Figure CN120413745A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of batteries, and particularly to a method and system for offline production of batteries. Background Art
[0002] Currently, there are two ways of offline production of batteries, which are specifically as follows:
[0003] One is full-capacity offline production, which is carried out according to steps such as primary liquid injection, static aging, formation, aging, secondary liquid injection, capacity grading, grading and packaging, etc. Among them, during the capacity grading process, all batteries are fully charged and then discharged. It can be seen that this offline production method has the disadvantages of high energy consumption, long time and high cost.
[0004] The other is virtual-capacity offline production. Compared with full-capacity offline production, virtual-capacity offline production does not perform capacity grading. The specific steps of virtual-capacity offline production are primary liquid injection, static aging, formation, aging, secondary liquid injection and packaging. In this way, it is not necessary to fully charge the batteries during the entire battery manufacturing process. Obviously, this method can reduce energy consumption, time and cost.
[0005] Therefore, many enterprises choose to directly perform virtual-capacity offline production on the batteries after they complete stages such as formation, aging, and secondary liquid injection without going through capacity grading, so as to reduce the production cost of the batteries.
[0006] The process that the battery has not undergone a full charge before offline production is called virtual capacity. The definition of a virtual-capacity battery is a battery that has not undergone a full charge once before offline production. Virtual capacity will bring about differences in battery capacity and voltage, resulting in poor consistency of the batteries, which is not a favorable choice for some modules with relatively high requirements. Summary of the Invention
[0007] The embodiments of the present application provide a method and system for offline production of batteries, which can not only reduce the production cost of the batteries, but also ensure the consistency of the capacity and self-discharge of batteries in the same grade, and improve the accuracy of shipment.
[0008] In the first aspect, a method for offline production of batteries is provided, which includes:
[0009] Static aging the initial batteries obtained after the first liquid injection according to the first static aging condition, and screening out the initial batteries with voltages greater than the voltage threshold as the first batteries;
[0010] Performing formation and secondary liquid injection on the first batteries to obtain second batteries, and measuring the voltages of the second batteries at the end of the secondary liquid injection;
[0011] Perform a number of constant current chargeings on the second battery in ascending order of the current of each constant current charging, measure the voltage of each second battery at the end of each constant current charging, then perform a first normal temperature static storage, and measure the voltage of each second battery at the end of the first normal temperature static storage;
[0012] Perform step-by-step grading on the second battery according to the absolute value of the voltage difference before and after each constant current charging.
[0013] In some embodiments, the first static storage conditions include: the first static storage temperature is 40°C to 50°C, and the first static storage time is 12 to 48 h;
[0014] And / or, performing a number of constant current chargeings on the second battery in sequence includes: each constant current charging makes the state of charge of the second battery be 40% SOC - 85% SOC;
[0015] And / or, the first normal temperature static storage includes: the normal temperature static storage temperature is 20°C to 30°C, and the normal temperature static storage time is 1 to 48 h;
[0016] And / or, the current of the constant current charging is a preset multiple of the charging capacity of the second battery obtained by formation;
[0017] And / or, screening out the initial batteries with voltages greater than the voltage threshold as the first battery, specifically including:
[0018] Measure the voltages of each initial battery at a number of time points within the first static storage time included in the first static storage conditions;
[0019] Screen out the initial batteries whose voltages measured at each time point are all greater than the voltage thresholds corresponding to each time point as the first battery.
[0020] In some embodiments, the initial batteries whose voltages measured at each time point are greater than the corresponding voltage thresholds are called candidate batteries;
[0021] Sort the voltages measured at the same time point in descending order, and the voltage threshold corresponding to this time point is configured such that the proportion of the number of candidate batteries to the total number of initial batteries ≥ 90%.
[0022] In some embodiments, the remaining initial batteries after screening are the third battery;
[0023] The method further includes: performing full capacity off-line on the third battery.
[0024] In some embodiments, the full-capacity offline specifically includes: continuing to let the third battery stand at the first standing temperature included in the first standing condition until the total standing time of the third battery exceeds the first standing time included in the first standing condition by a certain period of time, and then performing formation, aging, secondary liquid injection, and grading in sequence.
[0025] In some embodiments, performing formation on the first battery specifically includes:
[0026] Charging the first battery during formation to a preset state of charge (SOC);
[0027] Performing formation standing and second normal-temperature standing on the first battery in sequence.
[0028] In some embodiments, the preset state of charge (SOC) is 30% to 40%;
[0029] And / or, the formation standing includes: the formation standing temperature is 40°C to 50°C, and the formation standing time is 24 to 48 hours;
[0030] And / or, the second normal-temperature standing includes: the normal-temperature standing temperature is 20°C to 30°C, and the normal-temperature standing time is 1 to 48 hours.
[0031] In some embodiments, the number of constant-current charging times is N, and the current of the nth constant-current charging is less than the current of the (n + 1)th constant-current charging, where n = 1, 2,..., N;
[0032] Denote the voltage measured for each of the second batteries at the end of secondary liquid injection as U 0,2 , and the voltage measured for each of the second batteries at the end of the nth constant-current charging as U n,1 , and the voltage measured for each of the second batteries at the end of the first normal-temperature standing as U n,2 ;
[0033] According to the absolute value of the voltage difference before and after each constant-current charging, grading the second batteries step by step specifically includes:
[0034] Based on the absolute value of the voltage difference between U n,1 and U 0,2 , where n in U n,1 is 1, grading the second batteries in the order of the magnitude of the absolute value of this voltage difference to obtain several first-level grades;
[0035] Based on the absolute value of the voltage difference between U n+1,1 and U n,2 , grading the second batteries included in each first-level grade in the order of the magnitude of the absolute value of this voltage difference to obtain several secondary grades included in each first-level grade;
[0036] And so on, to complete the step-by-step grading of the second battery.
[0037] In some embodiments, the second battery is graded in a way of equal quantity distribution.
[0038] In a second aspect, a battery off-line system is provided, which includes:
[0039] A screening unit, which is used to: screen out the initial batteries with voltages greater than the voltage threshold as the first batteries, where the initial batteries are the batteries that have completed the first liquid injection and are left standing according to the first standing condition;
[0040] A voltage measuring unit, which is used to: measure the voltage of the second battery obtained after formation and secondary liquid injection of the first battery; and measure the voltage of the second battery at the end of each constant current charge and at the end of the first normal temperature standing, where the second battery is subjected to constant current charging in ascending order of the current of each constant current charge, and is left standing at normal temperature for the first time after each constant current charge ends;
[0041] A grading unit, which is used to: grade the second battery step by step according to the absolute value of the voltage difference before and after each constant current charge.
[0042] The beneficial effects brought by the technical solution provided in this application include:
[0043] In order to reduce the energy consumption and production cost during battery production, realize battery off-line, and reduce or even eliminate the impact on the user side, this application does not perform formation, but performs virtual capacity processing on the second battery through several constant current charges, and then grades the second battery step by step according to the absolute value of the voltage difference of the second battery before and after each constant current charge, ensuring the consistency of the capacity and self-discharge of the batteries in the same grade and improving the accuracy of shipment. BRIEF DESCRIPTION OF THE DRAWINGS
[0044] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of this application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0045] Figure 1 It is a flowchart of the battery off-line method provided in the embodiment of this application. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0046] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Apparently, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.
[0047] As shown in Figure 1 the embodiments of this application provide a method for taking a battery offline, which includes the following steps:
[0048] 101: Let the initial battery obtained after the first liquid injection stand according to the first standing condition, and screen out the initial batteries with voltages greater than the voltage threshold as the first batteries.
[0049] In step 101, by screening the initial batteries, the initial batteries with voltages greater than the voltage threshold are retained as the first batteries, while the remaining initial batteries with smaller voltages are screened out. The reason for screening out such low-voltage initial batteries is that the performance of such low-voltage initial batteries is poor and may affect the self-discharge consistency. Eliminating such low-voltage initial batteries with poor performance and possible impact on self-discharge consistency can reduce the impact on the subsequent second batteries.
[0050] It can be understood that in the above step 101, the first standing condition includes the first standing temperature and the first standing time. Among them, for the specific values of the first standing temperature and the first standing time, they can be selected according to the actual situation in actual application. For example, as an example, the first standing condition includes: the first standing temperature is 40°C to 50°C, and the first standing time is 12 to 48 h.
[0051] It can be understood that when measuring the voltage, the test condition is to use an alternating current of 1 KHz for testing.
[0052] 102: Perform formation and secondary liquid injection on the first batteries to obtain second batteries, and measure the voltages of the second batteries at the end of the secondary liquid injection.
[0053] It can be understood that in step 102, after formation and before secondary liquid injection, an aging step is also included.
[0054] It can be understood that the aging step can be selected according to the actual situation in actual application. For example, the aging temperature is 45 ± 5°C; the aging time is 12 - 48 h.
[0055] 103: Perform a number of constant current chargings on the second battery in ascending order of the current for each constant current charging; wherein, after each constant current charging is completed, measure the voltage of each of the second batteries at the end of the constant current charging, then perform a first normal temperature static placement, and measure the voltage of each of the second batteries at the end of the first normal temperature static placement, and then perform the next constant current charging.
[0056] In step 103, according to actual needs, a number of constant current chargings can be performed. When performing constant current charging, the sequence is: first charge with a small current, measure the voltage at the end of the constant current charging, then perform a first normal temperature static placement, and measure the voltage again, then charge with a large current, measure the voltage at the end of the constant current charging, then perform a first normal temperature static placement, and measure the voltage again.
[0057] After each constant current charging, a voltage measurement is performed once, then a first normal temperature static placement is performed once, and then a voltage measurement is also performed once.
[0058] It should be noted that after the voltage measurement is completed after the last constant current charging, it can be determined whether to perform the first normal temperature static placement and voltage measurement according to actual needs.
[0059] It can be understood that in the above step 103, the first normal temperature static placement includes the normal temperature static placement temperature and the normal temperature static placement time. Among them, for the specific values of the normal temperature static placement temperature and the normal temperature static placement time, they can be selected according to actual situations in actual application processes. For example, by way of example, the first normal temperature static placement includes: the normal temperature static placement temperature is 20°C to 30°C, and the normal temperature static placement time is 1 to 48 h.
[0060] The temperature and time of the first normal temperature static placement corresponding to each constant current charging can be the same or different, and are selected according to actual needs.
[0061] 104: Classify the second battery step by step according to the absolute value of the voltage difference before and after each constant current charging.
[0062] It can be understood that the voltage before the first constant current charging is the voltage measured at the end of formation and secondary liquid injection in step 102, and the voltage after the first constant current charging is the voltage measured at the end of the constant current charging and before the first normal temperature static placement, rather than the voltage measured after the first normal temperature static placement.
[0063] Starting from the second constant current charging, the voltage before the current constant current charging is the voltage measured at the end of the first normal temperature static placement corresponding to the previous constant current charging, and the voltage after the current constant current charging is the voltage measured at the end of the constant current charging and before the first normal temperature static placement, rather than the voltage measured after the first normal temperature static placement.
[0064] In order to reduce the energy consumption during the battery production process, lower the production cost of the battery, achieve the battery off-line, and reduce or even eliminate the impact on the user side, this application does not perform grading, but in step 103, the second battery is subjected to virtual capacity treatment through several constant current chargings. Since it is virtual capacity treatment, each constant current charging does not fully charge the second battery. Then, in step 104, the second battery is graded step by step according to the absolute value of the voltage difference of the second battery before and after each constant current charging, ensuring the consistency of the capacity and self-discharge of the batteries in the same grade and improving the accuracy of shipment.
[0065] In step 103, performing several constant current chargings on the second battery in sequence includes: each constant current charging makes the state of charge of the second battery 40% SOC - 85% SOC.
[0066] It can be understood that each constant current charging is charged to 40% SOC - 85% SOC, that is, each constant current charging does not fully charge (virtual capacity off-line).
[0067] In step 101, the initial batteries with voltages greater than the voltage threshold are selected as the first batteries, which specifically includes the following steps:
[0068] 201: Measure the voltages of each of the initial batteries at several time points within the first static time included in the first static condition.
[0069] It can be understood that the first static time is a continuous time period, so several time points can be selected within this time period as the test opportunities. During the static process of the initial batteries, when the static time reaches each time point, a voltage measurement is performed, and the voltages of each initial battery at each time point can be obtained.
[0070] It can be understood that the last time point can be selected as the end of the first static time. For example, if the first static time is 48h, three time points are selected. The first time point can be the 12th h, the second time point can be the 24th h, and the third time point is the 48th h.
[0071] 202: Select the initial batteries whose measured voltages at each time point are all greater than the voltage thresholds corresponding to each time point as the first batteries.
[0072] For each time point, the corresponding voltage threshold can be the same or different, and this application does not make a limitation.
[0073] For each initial battery, if the voltages measured at each time point are all greater than the corresponding voltage thresholds, it can be selected as the first battery.
[0074] Among them, the above voltage threshold can be obtained by directly assigning the voltage value; it can also be obtained by setting the proportion of the number of batteries. For example, for the convenience of understanding, the initial batteries with voltages greater than the corresponding voltage threshold measured at each time point can be called candidate batteries. Then, the voltages measured at the same time point are sorted in descending order, and the voltage threshold corresponding to this time point is configured such that the proportion of the number of candidate batteries in the total number of initial batteries ≥ 90%. It should be noted that it is only necessary that this proportion is greater than a proportion threshold. Here, the proportion threshold can be set not only to 90% but also to other proportions, such as 95%, 94%, 93%, 92%, 91%, 85%, 75%, 65%, etc. The present application does not limit it to only 90%.
[0075] It can be understood that in the present application, the initial batteries are finally divided into the first batteries and the third batteries, and the second batteries are obtained by forming and secondary liquid injection from the first batteries.
[0076] For example, as an example, the first static condition includes: the first static temperature is 40°C, and the first static time is 48h. The time points include two, one of which is 12h of static, and the other is 48h of static. At this time, 1000 initial batteries are static. When the static time reaches 12h, the voltages of the 1000 initial batteries are measured once, and the measured voltages are sorted in descending order. Then, starting from the initial battery with the largest voltage, 90% of the initial batteries with larger voltages are selected, that is, the first 900 initial batteries with larger voltages. At this time, not all of these 900 initial batteries necessarily belong to the first batteries (that is, these 900 batteries belong to the candidate batteries), and subsequent time points (that is, 48h of static) screening is still required. The remaining 10% is the 100 initial batteries with smaller voltages, which belong to the third batteries; then the 900 initial batteries with larger voltages selected are continuously static. When the static time reaches 48h, the voltages of the 900 initial batteries are measured once in the same way, and the measured voltages are sorted in descending order. Then, starting from the initial battery with the largest voltage, 90% of the initial batteries with larger voltages are selected, that is, the first 810 initial batteries with larger voltages. At this time, the 810 initial batteries selected have been detected at two time points of 12h and 48h of static, and belong to the first batteries. At this time, the remaining 10% is the 90 initial batteries with smaller voltages, which belong to the third batteries even though the voltages measured at the time point of 12h of static are greater than the corresponding voltage threshold. Finally, after screening by the above method, among the 1000 initial batteries, 810 initial batteries become the first batteries, and 190 initial batteries become the third batteries.
[0077] In step 101, for the remaining initial batteries after screening, which are the third batteries, for the third batteries, the method further includes: taking the third batteries offline at full capacity.
[0078] Among them, the taking offline at full capacity specifically includes: continuing to let the third batteries stand at the first standing temperature included in the first standing condition until the total standing time of the third batteries exceeds the first standing time included in the first standing condition by a period of time, and then successively performing conventional steps such as formation, aging, secondary liquid injection, grading by capacity and grading (that is, the third batteries need to successively perform conventional formation, aging, secondary liquid injection, grading by full capacity and grading according to the conventional steps of the batteries).
[0079] It can be understood that since the third batteries are all relatively poor batteries, the total standing time of them should exceed the first standing time. And since the third batteries have been standing during the screening process, the total standing time of them includes the time that has been standing during the screening process. Therefore, when taking offline at full capacity, the sum of the time of continuing to stand and the time that has been standing during the screening process is equal to the total standing time of the third batteries.
[0080] For example, still taking the above 1000 initial batteries as an example, the first standing time is 48h, and there are two time points, one is standing for 12h and the other is standing for 48h. The total standing time of the third batteries is 72h, meeting the requirement of exceeding the first standing time of 48h by a period of time (that is, 24h). For the third batteries screened at the time point of standing for 12h, they have already stood for 12h, so when taking offline at full capacity, they only need to continue to stand for 60h. And for the third batteries screened at the time point of standing for 48h, they have already stood for 48h, so when taking offline at full capacity, they only need to continue to stand for 24h.
[0081] It can be understood that a battery that has undergone at least one full charge and taking offline is called a full-capacity battery.
[0082] In the above step 102, the formation of the first battery specifically includes the following steps:
[0083] 301: Charge the first battery for formation to a preset state of charge (SOC).
[0084] It can be understood that the above preset state of charge (SOC) can be set according to actual needs. For example, as an example, the preset state of charge (SOC) is 30% - 40%.
[0085] 302: Successively perform formation standing and second normal temperature standing on the first battery.
[0086] It can be understood that in the above step 302, the formation static rest includes a formation static rest temperature and a formation static rest time. Among them, for the specific values of the formation static rest temperature and the formation static rest time, they can be selected according to the actual situation in the actual application process. For example, as an example, the formation static rest includes: the formation static rest temperature is 40°C to 50°C, and the formation static rest time is 24 to 48 h.
[0087] It can be understood that the formation charging rate can be selected according to actual needs, such as 0.1C - 0.5C.
[0088] It can be understood that in the above step 302, the second normal temperature static rest includes a normal temperature static rest temperature and a normal temperature static rest time. Among them, for the specific values of the normal temperature static rest temperature and the normal temperature static rest time, they can be selected according to the actual situation in the actual application process. For example, as an example, the second normal temperature static rest includes: the normal temperature static rest temperature is 20°C to 30°C, and the normal temperature static rest time is 1 to 48 h.
[0089] In the above step 103, several constant current chargings are required, and the current magnitude is different each time during the constant current charging. The current magnitude can be determined according to the size of the second battery charging capacity. For example, as an example, the current of the constant current charging is a preset multiple of the second battery charging capacity obtained by formation.
[0090] The above preset multiple can be determined according to actual needs. For example, as an example, two constant current chargings are performed. The preset multiple of the first constant current charging is 1 - 2, and the preset multiple of the second constant current charging is 2 - 5.
[0091] As an example, if the first battery is charged to a preset SOC state of 30% of the obtained second battery, and the total capacity of the second battery is 1000 mAh, then the second battery charging capacity is 300 mAh. If the preset multiple of the first constant current charging is 2 and the preset multiple of the second constant current charging is 3, then the current of the first constant current charging is 600 mA, and the current of the first constant current charging is 900 mA.
[0092] It can be understood that during each constant current charging, charging is carried out according to its respective preset charging time, and each preset charging time can be set according to actual needs, and the magnitudes can be the same or different.
[0093] For example, the preset charging time of the above first constant current charging is 5 - 60 min, and the preset charging time of the second constant current charging is 5 - 20 min.
[0094] In the above step 103, record the number of constant current charging as N. The current of the nth constant current charging is less than the current of the (n + 1)th constant current charging, where n = 1, 2,..., N. Record the voltage measured by each of the second batteries at the end of the secondary liquid injection as U 0,2 , the voltage measured by each of the second batteries at the end of the nth constant current charging is U n,1 , and the voltage measured by each of the second batteries at the end of the first normal temperature standing is U n,2 .
[0095] Therefore, for step 104, according to the absolute value of the voltage difference before and after each constant current charging, the second batteries are graded step by step, which specifically includes the following steps:
[0096] 401: Based on the absolute value of the voltage difference between U n,1 and U 0,2 , the second batteries are graded in the order of the absolute value of this voltage difference to obtain several n-level grades (primary grades).
[0097] It can be understood that in step 401, at this time n = 1, and the corresponding n-level grade is actually the primary grade.
[0098] Therefore, in step 401, for the primary grade, when grading, the second batteries can be graded in a non-uniform quantity manner. For example, there are 1200 second batteries and three primary grades. One of the primary grades includes 600 second batteries, and the other two primary grades each include 300 second batteries; that is, the absolute value of the voltage difference between U 1,1 and U 0,2 is sorted in ascending (or descending) order. The 600 second batteries corresponding to the 1-600th absolute values of the voltage difference in the sorting are the first primary grade; the 300 second batteries corresponding to the 601-900th absolute values of the voltage difference in the sorting are the second primary grade, and the 300 second batteries corresponding to the 901-1200th absolute values of the voltage difference in the sorting are the third primary grade.
[0099] It is also possible to grade the second batteries in a uniform quantity manner. For example, there are 1200 second batteries and three primary grades, and each primary grade includes 400 second batteries.
[0100] 402: Based on the absolute value of the voltage difference between U n+1,1 and U n,2 , the second batteries included in each n-level grade (primary grade) are graded in the order of the absolute value of this voltage difference to obtain several n + 1-level grades (secondary grades) included in each primary grade.
[0101] It can be understood that in step 402, n = 1…, N. When n = 1, it indicates that on the basis of the first-level gear, each first-level gear is further divided into several second-level gears. When n = 2, it indicates that on the basis of the second-level gear, each second-level gear is further divided into several third-level gears. And so on.
[0102] It can be seen that in step 103, the number of constant-current charging times determines the number of levels for grading the second battery. For example, in step 103, if the number of constant-current charging times N is 2, then the number of levels for grading the second battery is also 2, that is, the second battery can finally be divided into the first-level gear and the second-level gear. Therefore, in step 103, the more the number of constant-current charging times, the more detailed the grading of the second battery, and the better the consistency of the second battery after grading.
[0103] Similarly, it can be understood that for the first-level gear, when grading, the second battery can be graded in a non-uniform quantity distribution manner.
[0104] It can also be graded in a uniform quantity distribution manner. For example, there are 1200 second batteries, and there are three first-level gears, and each first-level gear includes 400 second batteries. When performing second-level grading, each first-level gear is divided into four second-level gears, and each second-level gear includes 100 second batteries. It can be understood that at this time, the 1200 second batteries are divided into three first-level gears, each first-level gear contains 400 second batteries, each first-level gear is further divided into four second-level gears, and each second-level gear contains 100 second batteries.
[0105] 403: And so on, complete the step-by-step grading of the second battery.
[0106] For step 403, if further grading is continued, such as performing third-level grading, the second battery can also be graded in a non-uniform quantity distribution manner.
[0107] It can also be graded in a uniform quantity distribution manner. For example, when grading the above-mentioned second-level gears, each second-level gear can be divided into five third-level gears, and each third-level gear includes 20 second batteries. It can be understood that at this time, the 1200 second batteries are divided into three first-level gears, each first-level gear contains 400 second batteries, each first-level gear is further divided into four second-level gears, each second-level gear contains 100 second batteries, each second-level gear is further divided into five third-level gears, and each third-level gear contains 20 second batteries.
[0108] Through multiple formation processes (i.e., step 103), the second battery is graded step by step, ensuring the consistency of the capacity and self-discharge of the batteries in the same gear and improving the accuracy of shipment.
[0109] Based on the above battery off-line method, an embodiment of the present application further provides a battery off-line system, which includes a screening unit, a voltage measuring unit, and a grading unit, where:
[0110] The screening unit is configured to: screen out the initial batteries with voltages greater than the voltage threshold as the first batteries, where the initial batteries are the batteries that have completed the first liquid injection and are statically placed according to the first static condition.
[0111] The voltage measuring unit is configured to: measure the voltage of the second battery obtained by forming and second liquid injection of the first battery; and measure the voltage of the second battery at the end of each constant current charge and at the end of the first normal temperature static placement, where the second battery is subjected to constant current charging in ascending order of the current of each constant current charge, and a first normal temperature static placement is performed after the end of each constant current charge.
[0112] The grading unit is configured to: grade the second battery step by step according to the absolute value of the voltage difference before and after each constant current charge.
[0113] Inputting the measured data into the system of the present application can quickly grade the batteries.
[0114] The present application will be described in detail below through embodiments.
[0115] Suppose there are 1000 fresh batteries.
[0116] 501: After the fresh batteries complete the first liquid injection, initial batteries are obtained and statically placed according to the conditions of a static placement time of 48 h and a static placement temperature of 45 °C; during the static placement, when the static placement reaches 12 h, an alternating current of 1 kHz is used for testing, the voltage of the battery is measured, and then sorted in descending order of voltage. According to a ratio of 98%, 980 of the 1000 initial batteries are screened, and the remaining 20 initial batteries with a ratio of 2% are used as the third batteries for full capacity off-line; the 980 screened initial batteries are continuously statically placed at 45 °C until the total static placement time reaches 48 h. At this time, an alternating current of 1 kHz is used for testing, the voltage of the battery is measured, and then sorted in descending order of voltage. According to a ratio of 95%, 930 of the 980 initial batteries are screened, and the 930 initial batteries are used as the first batteries, and the remaining 50 initial batteries with a ratio of 5% are used as the third batteries for full capacity off-line.
[0117] 502: The 930 first batteries are formed and second liquid injected, charged to a preset SOC state of 40% at 0.3C, then statically placed at a high temperature of 45 °C for 24 h, and then statically placed at a normal temperature of 25 °C for 24 h to obtain the second batteries, and the voltage U of each second battery is measured 0,2 .
[0118] 503: Charge 930 secondary batteries for the first time with a constant current. The magnitude of the constant current for charging is twice the charging capacity corresponding to the preset SOC state of charge of 40% in step 502. The charging time is 30 minutes, and measure the voltage U of each secondary battery at the end of the constant current charging. 1,1 , and then leave them standing at room temperature of 25°C for 12 hours, and measure the voltage U of each secondary battery at the end of the standing. 1,2 .
[0119] 504: According to the absolute value of the voltage difference between U 1,1 and U 0,2 , divide the 930 secondary batteries into three first-level grades A1, A2, and A3 in ascending order. Each first-level grade includes 310 secondary batteries.
[0120] 505: Continue to charge the 930 secondary batteries for the second time with a constant current. The magnitude of the constant current for charging is twice the charging capacity corresponding to the preset SOC state of charge of 40% in step 502. The charging time is 10 minutes, and measure the voltage U of each secondary battery at the end of the constant current charging. 2,1 , and then leave them standing at room temperature of 25°C for 8 hours, and measure the voltage U of each secondary battery at the end of the standing. 2,2 .
[0121] 506: According to the absolute value of the voltage difference between U 2,1 and U 1,2 , in the three first-level grades A1, A2, and A3, divide the secondary batteries in each first-level grade into two second-level grades in ascending order to obtain a total of six second-level grades B1, B2, B3, B4, B5, and B6. Each second-level grade includes 155 secondary batteries.
[0122] 507: Conduct spot checks on the secondary batteries in each second-level grade. Subject the spot-checked secondary batteries to high-temperature storage at 45°C for 30 days, and calculate the self-discharge rate of the batteries.
[0123] Among them, the self-discharge rate test method is as follows: In step 507, record the initial capacity of the secondary battery before storage. After storage, conduct a constant current discharge on the battery with a rate of 1C, record the discharge capacity, and the self-discharge rate = 1 - discharge capacity / initial capacity.
[0124] Among them, the spot-check ratio can be determined according to actual needs. For example, if spot-checking is carried out at a ratio of 20%, the number of spot-checked secondary batteries is 31.
[0125] The spot-check results are shown in Table 1 below:
[0126] Table 1
[0127] Gear position Average self-discharge rate B1 0.86％ B2 1％ B3 1.10％ B4 1.30％ B5 1.60％ B6 2％
[0128] As can be seen from Table 1, since the B1 gear is the optimal battery, its self-discharge rate is also the lowest, and there are differences in the self-discharge rates between different gears, indicating that such a screening method is effective.
[0129] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application. Unless otherwise clearly specified and defined, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.
[0130] It should be noted that in the present application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such a process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.
[0131] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features claimed herein.
Claims
1. A method for taking a battery offline, characterized in that, It includes: The primary batteries obtained after the first liquid injection are statically placed according to the first static condition, and the primary batteries with voltages greater than the voltage threshold are selected as the first batteries; The first batteries are formed and secondarily injected with liquid to obtain second batteries, and the voltages of the second batteries are measured at the end of the second liquid injection; In the order of increasing current of each constant current charge, the second batteries are successively subjected to several constant current charges, and the voltages of the second batteries at the end of each constant current charge are measured, then a first normal temperature static placement is performed, and the voltages of the second batteries at the end of the first normal temperature static placement are measured; According to the absolute value of the voltage difference before and after each constant current charge, the second batteries are graded step by step.
2. The off-line method of the battery according to claim 1, characterized in that: The first static condition includes: the first static temperature is 40°C to 50°C, and the first static time is 12 to 48 h; And / or, successively subjecting the second batteries to several constant current charges includes: each constant current charge makes the state of charge of the second battery 40% SOC - 85% SOC; And / or, the first normal temperature static placement includes: the normal temperature static placement temperature is 20°C to 30°C, and the normal temperature static placement time is 1 to 48 h; And / or, the current of the constant current charge is a preset multiple of the charging capacity of the second battery obtained by formation; And / or, selecting the primary batteries with voltages greater than the voltage threshold as the first batteries specifically includes: Measuring the voltages of the primary batteries at several time points within the first static time included in the first static condition; Selecting the primary batteries with voltages measured at each time point greater than the voltage threshold corresponding to each time point as the first batteries.
3. The off-line method of the battery according to claim 1, characterized in that: The primary batteries with voltages measured at each time point greater than the corresponding voltage threshold are called candidate batteries; Sort the voltages measured at the same time point in ascending order, and the voltage threshold corresponding to this time point is configured such that the proportion of the number of candidate batteries in the total number of primary batteries ≥ 90%.
4. The off-line method of the battery according to claim 1, characterized in that: The remaining primary batteries after screening are the third batteries; The method further includes: performing full capacity off-line on the third batteries.
5. The off-line method of the battery according to claim 4, characterized in that: The full capacity off-line specifically includes: continuing to statically place the third batteries at the first static temperature included in the first static condition until the total static time of the third batteries exceeds the first static time included in the first static condition for a period of time, and then successively performing formation, aging, second liquid injection, and grading.
6. The off-line method of the battery according to claim 1, characterized in that: Performing formation on the first batteries specifically includes: Charging the first batteries to the preset SOC state of charge; Successively performing formation static placement and second normal temperature static placement on the first batteries.
7. The off-line method of the battery according to claim 6, characterized in that: The preset SOC state of charge is 30% - 40%; And / or, the formation static state includes: the formation static state temperature is 40°C to 50°C, and the formation static state time is 24 to 48 h; And / or, the second normal temperature static state includes: the normal temperature static state temperature is 20°C to 30°C, and the normal temperature static state time is 1 to 48 h.
8. The method for taking a battery off the production line according to claim 1, wherein: The number of constant current charging times is N, and the current of the nth constant current charging is less than the current of the (n + 1)th constant current charging, where n = 1, 2,..., N; Record the voltage measured by each of the second batteries at the end of the secondary liquid injection as U 0,2 , and record the voltage measured by each of the second batteries at the end of the nth constant current charge as U n,1 , and record the voltage measured by each of the second batteries at the end of the first normal temperature standing as U n,2 ; According to the absolute value of the voltage difference before and after each constant current charging, the second battery is graded step by step, specifically including: Based on U n,1 The absolute value of the voltage difference with U 0,2 where n in U n,1 is 1, the second battery is classified according to the magnitude order of the absolute value of the voltage difference to obtain a number of first-level grades; Based on U n+1,1 and U n,2 the absolute value of the voltage difference, the second batteries included in each of the first-level gears are classified in the order of the absolute value of the voltage difference to obtain a plurality of secondary gears included in each of the first-level gears; And so on, until the step-by-step grading of the second battery is completed.
9. The method for taking a battery off the production line according to claim 8, wherein: The second battery is graded in a way of equal quantity distribution.
10. A battery offline system, characterized in that, It includes: A screening unit, which is used for: screening out the initial battery with a voltage greater than the voltage threshold as the first battery, where the initial battery is the battery that has completed the first liquid injection and has been statically placed according to the first static state condition; A voltage measuring unit, which is used for: measuring the voltage of the second battery obtained after the first battery is formed and secondarily injected with liquid; and measuring the voltage of the second battery at the end of each constant current charging and at the end of the first normal temperature static state, where the second battery is subjected to constant current charging in ascending order of the current of each constant current charging, and a first normal temperature static state is performed after the end of each constant current charging; A grading unit, which is used for: grading the second battery step by step according to the absolute value of the voltage difference before and after each constant current charging.