Process for battery capacity calibration

Abstract

The application provides a battery capacity calibration process method. The battery capacity calibration process method comprises the following steps: providing a base production battery; dividing the battery into a first group of batteries, a second group of batteries and a third group of batteries in a standard test room; performing temperature calibration on the first group of batteries to obtain temperature coefficients of the first group of batteries at different temperature stages; performing cycle calibration on the second group of batteries to obtain a capacity improvement value of the second group of batteries; performing rate calibration on the third group of batteries to obtain a rate calibration coefficient of the third group of batteries; a capacity calibration formula: delivery battery capacity=(base capacity calibration battery capacity+temperature coefficient*(test temperature-battery temperature before discharging))*rate calibration coefficient)+capacity improvement value. The capacity calibration formula is introduced into a base capacity calibration system to perform battery capacity standardization, which can be used for guiding the base battery delivery, avoiding the influence of temperature, rate and cycle and other factors on the battery capacity, and reducing the battery manufacturing cost and improving the battery capacity consistency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery, in particular, to a process method for battery capacity calibration. BACKGROUND

[0002] The battery capacity consistency of lithium ion power battery has certain influence on preparation of battery cell module and PACK, so different capacity ranges need to be formulated for selection, and the batteries in the range need to be grouped and paired. However, the discharge capacity values of the batteries appearing under the same capacity process are not accurate values, because the battery capacity is affected by factors such as workshop environment temperature, cycle number and discharge rate, so the calibration of battery capacity is needed, which can ensure the consistency of battery grouping. At present, there is no perfect capacity calibration standard in the industry, and the capacity calibration is controlled by controlling the workshop environment temperature, formulating a unified charge and discharge process, etc. However, the above solutions in the industry cannot accurately obtain the actual capacity of the battery, and there is still a certain difference between the capacity value and the standard test capacity accurate value; if all the batteries are tested in the standard test room, it will cause the battery preparation cost to increase too much, and there is no market competitiveness SUMMARY

[0003] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a process method for battery capacity calibration, which does not worry about the influence of temperature, rate and cycle on the final battery capacity, can reduce the battery manufacturing cost and improve the battery capacity consistency, and is beneficial to battery grouping.

[0004] In one aspect of the present application, a process method for battery capacity calibration is provided. According to an embodiment of the present application, the process method for battery capacity calibration comprises: providing base production batteries; dividing the batteries into a first group of batteries, a second group of batteries and a third group of batteries in a standard test room; performing temperature calibration on the first group of batteries to obtain temperature coefficients of the first group of batteries at different temperature stages; performing cycle calibration on the second group of batteries at a test temperature to obtain a capacity improvement value of the second group of batteries; performing rate calibration on the third group of batteries at the test temperature to obtain a rate calibration coefficient of the third group of batteries; and bringing the temperature coefficients, the capacity improvement value and the rate calibration coefficient into a capacity calibration formula to obtain a shipment battery capacity, wherein the capacity calibration formula is: the shipment battery capacity = (base capacity of the batteries + temperature coefficients * (the test temperature - battery temperature before discharging)) * rate calibration coefficient) + the capacity improvement value. Thus, the capacity calibration formula is introduced into a base capacity system to standardize the battery capacity, which can be used to guide the base battery shipment and meet the battery capacity requirements of vehicle enterprises, and is beneficial to battery grouping. Moreover, the influence of temperature, rate and cycle on the final battery capacity can be avoided, the battery manufacturing cost can be reduced and the battery capacity consistency can be improved, which is beneficial to battery grouping.

[0005] According to an embodiment of the present application, the method for performing the temperature calibration on the first group of batteries comprises: performing a first pretreatment on the first group of batteries, wherein the pretreatment comprises: adjusting the temperature of the standard test room to a first set temperature, and performing charge-discharge cycles on the first group of batteries at the first set temperature for multiple times; performing charge-discharge cycles on the first group of batteries that have undergone the first pretreatment at different temperatures to obtain battery capacity values at different temperatures; and performing linear fitting on the temperatures and the battery capacity values to obtain the temperature coefficients.

[0006] According to an embodiment of the present application, the step of obtaining the battery capacity data comprises: performing first constant-current constant-voltage charging on different batteries in the first group of batteries that have undergone the pretreatment at different temperatures; placing the first group of batteries for a first interval time after the first constant-current constant-voltage charging is completed; and then performing first constant-current discharging on the first group of batteries to obtain the battery capacity values at different temperatures.

[0007] According to an embodiment of the present application, at each temperature, the first group of batteries performs multiple charge-discharge cycles, and the temperature coefficient is an average value of test results of the multiple charge-discharge cycles.

[0008] According to an embodiment of the present application, the step of obtaining the temperature coefficient comprises: S1: performing the first pretreatment on the first group of batteries: adjusting the temperature in the standard test chamber to 25 DEG C, and performing 0.5C charge-discharge cycles on the first group of batteries at 25 DEG C; S2: resting the first group of batteries after the first pretreatment for a certain period of time; S3: selecting a plurality of different temperature values in the range of 20-40 DEG C, and performing 0.5C first constant-current constant-voltage charging on different batteries in the first group of batteries; S4: resting the first group of batteries after the first constant-current constant-voltage charging for a certain period of time; S5: performing 0.5C first constant-current discharging on the first group of batteries again, and obtaining the battery capacity values at different temperatures; S6: resting the first group of batteries after the first constant-current discharging for a certain period of time; S7: repeating steps S2-S6, obtaining two groups of battery capacity values at each temperature value, averaging the values, and obtaining the battery capacity value at each temperature value; and S8: performing linear fitting on the temperature and the battery capacity value, and obtaining the temperature coefficient.

[0009] According to an embodiment of the present application, the method of performing the cycle calibration on the second group of batteries comprises: performing multiple charge-discharge cycles on the second group of batteries at a second set temperature until the capacity of the second group of batteries tends to be stable, obtaining the capacity value of the first charge-discharge cycle and the capacity value at the stable state, and the capacity improvement value being the difference between the capacity value of the first charge-discharge cycle and the capacity value at the stable state.

[0010] According to an embodiment of the present application, the method of performing the cycle calibration on the second group of batteries comprises: D1: resting the second group of batteries in the standard test chamber for a certain period of time; D2: adjusting the temperature in the standard test chamber to 25 DEG C, and performing 1C second constant-current constant-voltage charging on the second group of batteries; D3: resting the second group of batteries after the second constant-current constant-voltage charging for a certain period of time; D4: performing 1C second constant-current discharging on the second group of batteries again, and obtaining the capacity value of the first charge-discharge cycle; D5: resting the second group of batteries after the second constant-current discharging for a certain period of time; and D6: repeating steps D2-D5, and performing multiple charge-discharge cycles on the second group of batteries until the capacity of the second group of batteries tends to be stable.

[0011] According to the embodiment of the present application, the method for performing the rate calibration on the third group of batteries comprises: performing pretreatment on the third group of batteries, the pretreatment comprising: adjusting the temperature in the standard test room to a third set temperature, and performing multiple 0.5C charge-discharge cycles on the third group of batteries at the third set temperature; performing multiple 0.5C charge-discharge cycles on the third group of batteries after the pretreatment to obtain a first capacity-temperature curve, and obtaining a 0.5C capacity value according to the first capacity-temperature curve; performing multiple 1C charge-discharge cycles on the third group of batteries to obtain a second capacity-temperature curve, and obtaining a 1C capacity value according to the second capacity-temperature curve; and calculating the rate calibration coefficient, the rate calibration coefficient = the 1C capacity value / the 0.5C capacity value.

[0012] According to the embodiment of the present application, the method for performing the rate calibration on the third group of batteries comprises: T1: performing the third pretreatment on the third group of batteries: adjusting the temperature in the standard test room to 25℃, and performing multiple 0.5C charge-discharge cycles on the third group of batteries at 25℃; T2: adjusting the temperature in the standard test room to 25℃, and allowing the third group of batteries after the third pretreatment to stand for a certain period of time; T3: performing 0.5C third constant-current constant-voltage charging on the third group of batteries; T4: allowing the third group of batteries to stand for a certain period of time after the third constant-current constant-voltage charging is completed; T5: performing 0.5C third constant-current discharging on the third group of batteries again; T6: allowing the third group of batteries to stand for a certain period of time after the third constant-current discharging is completed; T7: repeating steps T3-T6 to perform multiple charge-discharge cycles on the third group of batteries, obtaining multiple sets of temperature and capacity value data of the third group of batteries and performing linear fitting to obtain the first capacity-temperature curve, fitting a first formula according to the first capacity-temperature curve, and inputting 25℃ into the first formula to obtain the 0.5C capacity value of the third group of batteries; T8: performing 1C fourth constant-current constant-voltage charging on the third group of batteries; T9: allowing the third group of batteries to stand for a certain period of time after the fourth constant-current constant-voltage charging is completed; T10: performing 1C fourth constant-current discharging on the third group of batteries again; T11: allowing the third group of batteries to stand for a certain period of time after the fourth constant-current discharging is completed; T12: repeating steps T8-T11 to perform multiple charge-discharge cycles on the third group of batteries, obtaining multiple sets of temperature and capacity value data of the third group of batteries and performing linear fitting to obtain the second capacity-temperature curve, fitting a second formula according to the second capacity-temperature curve, and inputting 25℃ into the second formula to obtain the 1C capacity value of the third group of batteries.

[0013] According to the embodiment of the present application, the test temperature is 25 DEG C, the temperature coefficient is 0.9 when the battery temperature is 21 DEG C-28.5 DEG C, and the temperature coefficient is 0.7 when the battery temperature is 28.5 DEG C-33 DEG C; the capacity improvement value is 2.95 Ah; and the rate calibration coefficient is 99.27%.

[0014] According to the embodiment of the present application, the above technical solution of the present application has at least the following technical effects:

[0015] 1. The capacity calibration formula is introduced into the base capacity grading system to standardize the battery capacity, which can be used to guide the battery delivery of the base and meet the battery capacity requirements of the vehicle enterprise, that is, the battery capacity produced by the base can be directly converted into the standard test room capacity, which is consistent with the capacity test value required by the vehicle enterprise, and the problem of qualified base test capacity but unqualified vehicle enterprise test capacity does not occur.

[0016] 2. The influence of temperature, rate and cycle on the final battery capacity does not need to be worried about, the influence of the workshop environment on the battery capacity can be avoided, the management and control requirements of the workshop environment can be reduced, the power cost of the management and control of the workshop environment can be reduced, the battery manufacturing cost can be reduced, and the battery grouping is beneficial.

[0017] 3. The standard capacity of the battery can be obtained, and the design allowance of 3%-5% does not need to be increased in the design (the traditional design is to increase the design allowance to ensure that the battery capacity meets different test requirements of the vehicle enterprise), the BOM cost (raw material cost) of the battery preparation can be reduced, and the market competitiveness of the battery can be increased.

[0018] 4. Different rates of charging and discharging can be carried out according to different types of batteries to ensure the compatibility of the capacity grading equipment, the conversion of 1C charging and discharging can be completed through the formula in the later period, the equipment modification caused by the fact that the early planning capacity grading equipment does not meet 1C charging and discharging when large-capacity batteries are produced in the later period can be saved, and the cost of purchasing new equipment in the later period can be saved. BRIEF DESCRIPTION OF DRAWINGS

[0019] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description, taken in conjunction with the following drawings, in which:

[0020] Figure 1 is a flow chart of the process method for battery capacity calibration in one embodiment of the present application;

[0021] Figure 2 is a temperature-capacity curve diagram obtained at 20 DEG C and 25 DEG C in another embodiment of the present application;

[0022] Figure 3 is a temperature-capacity change curve diagram obtained at 20 DEG C to 40 DEG C in another embodiment of the present application;

[0023] Figure 4 is a cycle number-capacity curve of charge-discharge cycles of two batteries in the second group of batteries in yet another embodiment of the present application. DETAILED DESCRIPTION

[0024] The scheme of the present application will be explained below in connection with examples. Those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If a specific technique or condition is not mentioned in the examples, the technique or condition described in the literature in the art or according to the product manual is used. If the manufacturer of a reagent or instrument is not mentioned, it is a conventional product that can be obtained commercially.

[0025] The present application will be described below with reference to specific examples. It should be noted that these examples are merely illustrative in nature and should not be regarded as limiting the present application in any way.

[0026] In one aspect of the present application, the present application provides a process for battery capacity calibration. According to an embodiment of the present application, with reference to Figure 1 , the process for battery capacity calibration comprises:

[0027] S100: providing a base-produced battery.

[0028] According to an embodiment of the present application, the OCV, IR, formation charge capacity, size, weight and manufacturing process parameters of the provided battery are all qualified, which ensures that the battery meets the process requirements, and the battery is subjected to Busbar welding. This standard is to ensure that the later evaluation results of the battery can guide the base production.

[0029] S200: dividing the battery into a first group of batteries, a second group of batteries and a third group of batteries in a standard test room.

[0030] S300: temperature calibration of the first group of batteries to obtain the temperature coefficient of the first group of batteries at different temperature stages.

[0031] According to an embodiment of the present application, the method for temperature calibration of the first group of batteries comprises:

[0032] S301: first pretreatment of the first group of batteries, the pretreatment steps comprising: adjusting the temperature of the standard test room to a first set temperature, and charging and discharging the first group of batteries at the first set temperature for multiple times. In this way, through the pretreatment of multiple charge-discharge cycles, the influence of the capacity increase of the first group of batteries itself on the temperature can be removed in advance, so as to ensure the accuracy of the temperature calibration. In some specific embodiments, the first set temperature can be 25℃, and the first group of batteries is charged and discharged for 10 times.

[0033] S302: performing charge-discharge cycles on the first group of batteries after the first pretreatment at different temperatures to obtain battery capacity values at different temperatures. In some embodiments, the first group of batteries can be subjected to charge-discharge cycles at different temperatures of 20℃, 25℃, 30℃, 35℃ and 40℃. Further, at each temperature, the first group of batteries can be subjected to multiple charge-discharge cycles, and the temperature coefficient is the average of the test results of the multiple charge-discharge cycles, so as to further improve the accuracy of the test results. For example, at 20℃, the first group of batteries can be subjected to 2 charge-discharge cycles to obtain two groups of battery capacity values at 20℃, and the same applies to other temperatures. Then, two fitted straight lines are obtained for the two groups of battery capacity values obtained at different temperatures, and two groups of temperature coefficients are obtained by the two fitted straight lines. Then, the final temperature coefficient of the first group of batteries is the average of the two groups of temperature coefficients.

[0034] It should be noted that when the first group of batteries is subjected to charge-discharge cycles at different temperatures of 20℃, 25℃, 30℃, 35℃ and 40℃, different batteries are used for charge-discharge cycle tests at different temperatures, i.e., the same battery cannot be subjected to different temperature tests.

[0035] According to the embodiments of the present application, the step of obtaining battery capacity data (or the step of charge-discharge cycle) includes: performing first constant current and constant voltage charging on different batteries in the first group of batteries after the pretreatment at different temperatures; resting the first group of batteries for a first interval time after the first constant current and constant voltage charging; and then performing first constant current discharging on the first group of batteries to obtain battery capacity values at different temperatures. When multiple charge-discharge cycles are performed at the same temperature, the battery can be rested for a certain period of time after each charge-discharge cycle, such as 150-200 minutes, so as to ensure that the battery temperature can reach the initial temperature at the start of the cycle, thereby ensuring the accuracy of the temperature parameter.

[0036] S303: performing linear fitting on the temperature and the battery capacity value to obtain a temperature coefficient.

[0037] In some embodiments of the present application, the first group of batteries is subjected to 0.5C charge-discharge cycles, and the specific steps of obtaining the temperature coefficient include:

[0038] S1: performing first pretreatment on the first group of batteries: adjusting the temperature in the standard test interval to 25℃, and performing 0.5C charge-discharge cycles on the first group of batteries at 25℃ for multiple times.

[0039] S2: resting the first group of batteries after the first pretreatment for a certain period of time, so as to ensure that the battery temperature can reach the initial temperature at the start of the cycle, thereby ensuring the accuracy of the temperature parameter.

[0040] S3: Select multiple different temperature values ​​(e.g., 20℃, 25℃, 30℃, 35℃ and 40℃) within the range of 20 to 40℃ to perform 0.5C constant current and constant voltage charging on different batteries in the first group of batteries respectively;

[0041] S4: After the first constant current and constant voltage charging is completed, the first group of batteries will be left to stand for a certain period of time.

[0042] S5: Then perform a 0.5C constant current discharge on the first group of batteries to obtain the battery capacity values ​​at different temperatures;

[0043] S6: After the first constant current discharge ends, the first group of batteries will be left to stand for a certain period of time in order to ensure that the battery temperature can reach the initial temperature at the start of the cycle, thereby ensuring the accuracy of the temperature parameters.

[0044] S7: Repeat steps S3 to S6 to obtain two sets of battery capacity values ​​at each temperature value, calculate the average value, and obtain the battery capacity value at each temperature value.

[0045] S8: Perform a linear fit between temperature and battery capacity values ​​to obtain the temperature coefficient. For example... Figure 2 ( Figure 2 The two fitted straight lines were obtained by performing two charge-discharge cycles on the battery at each temperature. Figure 3 As shown, Figure 2 The temperature-capacity curves were obtained at 20℃ and 25℃. Figure 3 The figures show temperature-capacity variation curves generated at different stages from 20℃ to 40℃. Note that due to the temperature rise after a full charge, a problem also present in the base battery, in some specific embodiments, the temperature coefficients obtained under 20℃ and 25℃ conditions are substituted into a range of 21-28.5℃. Figure 2 The obtained battery temperature coefficient is 0.9 within the range of 21-28.5℃ (i.e., a 1℃ temperature difference corresponds to a 0.9Ah capacity difference). Similarly... Figure 3 The temperature coefficient of the battery in the range of 28.5-33℃ is 0.7Ah (that is, a difference of 1℃ in temperature results in a difference of 0.7Ah in capacity). The temperature coefficient for each segment can be obtained by analogy.

[0046] According to embodiments of the present invention, the calibration steps for the temperature coefficient and the selection of calibration coefficients corresponding to the temperature range effectively ensure the accuracy of battery temperature capacity calibration.

[0047] Table 1

[0048]

[0049] S400: The second set of batteries is cyclically calibrated at the test temperature to obtain the capacity improvement value of the second set of batteries;

[0050] According to the embodiment of the present application, the method for cycle calibration of the second group of batteries comprises: performing multiple charge-discharge cycles on the second group of batteries at a second set temperature until the capacity of the second group of batteries tends to be in a stable state, obtaining the capacity value of the first charge-discharge cycle and the capacity value in the stable state, and the capacity improvement value is the difference between the capacity value of the first charge-discharge cycle and the capacity value in the stable state. Thus, the above-mentioned battery cycle capacity calibration step and the cycle stability number node can effectively ensure the battery cycle capacity improvement value of the battery, and can be used for standardizing the influence of the cycle on the battery capacity.

[0051] In some embodiments of the present application, the second group of batteries is subjected to 1C charge-discharge cycles, and the charge-discharge cycle steps can refer to Table 2. The method for cycle calibration of the second group of batteries comprises:

[0052] In some specific embodiments of the present application, the second group of batteries is subjected to 1C charge-discharge cycles, and the charge-discharge cycle steps can refer to Table 2. The method for cycle calibration of the second group of batteries comprises:

[0053] D1: The second group of batteries is first placed in the standard test room for a certain period of time. The specific time is not particularly limited, and can be flexibly selected by those skilled in the art according to the actual situation. For example, the second group of batteries can be placed for 5-10 minutes to adapt to the environment of the standard test room.

[0054] D2: The temperature of the standard test room is adjusted to 25°C, and the second group of batteries is subjected to 1C second constant current constant voltage charging;

[0055] D3: After the second constant current constant voltage charging is completed, the second group of batteries is placed for a certain period of time;

[0056] D4: The second group of batteries is subjected to 1C second constant current discharging to obtain the capacity value of the first charge-discharge cycle;

[0057] D5: After the second constant current discharging is completed, the second group of batteries is placed for a certain period of time to ensure that the battery temperature can reach the initial temperature at the start of the cycle, thereby ensuring the accuracy of the temperature parameter.

[0058] D6: Steps D2-D5 are repeated to perform multiple charge-discharge cycles on the second group of batteries until the capacity of the second group of batteries tends to be in a stable state.

[0059] Table 2

[0060]

[0061] According to some specific embodiments of the present application, the second group of batteries comprises two batteries, each of which is subjected to the charge-discharge cycle as shown in Table 1. According to the test data, the cycle number-capacity curve of the two batteries is fitted, as shown inFigure 4 As shown, the average capacity of the first charge-discharge cycle of the two batteries is 134.8 Ah, and the average capacity of the two batteries when they tend to be stable after multiple charge-discharge cycles is 137.75 Ah, so the capacity increase value obtained is 2.95 Ah.

[0062] S500: rate calibration is performed on the third group of batteries at the test temperature to obtain a rate calibration coefficient of the third group of batteries. According to an embodiment of the present application, the method for performing the rate calibration on the third group of batteries comprises:

[0063] S501: The third group of batteries is pretreated, and the pretreatment step comprises adjusting the temperature in the standard test room to a third set temperature and performing multiple charge-discharge cycles on the third group of batteries at the third set temperature. In this way, through the pretreatment of multiple charge-discharge cycles, the influence of the capacity increase of the third group of batteries itself on the temperature can be removed in advance, so as to ensure the accuracy of the temperature calibration. In some specific embodiments, the third set temperature can be 25℃, and the third group of batteries is subjected to 10 charge-discharge cycles.

[0064] S502: The pretreated third group of batteries is subjected to multiple 0.5C charge-discharge cycles to obtain a first capacity-temperature curve, and a 0.5C capacity value is obtained according to the first capacity-temperature curve. During the multiple charge-discharge cycles, the set temperature in the standard test room can be 25℃, but there is a certain fluctuation in the battery temperature after charging. In order to accurately obtain the rate coefficient, a fitting formula can be obtained according to the first capacity-temperature curve of the 0.5C charge-discharge cycle, and then the set temperature in the standard test room (such as 25℃) is substituted into the fitting formula to obtain the capacity value of 0.5C discharge (i.e. the 0.5C capacity value).

[0065] S503: The third group of batteries is subjected to multiple 1C charge-discharge cycles to obtain a second capacity-temperature curve, and a 1C capacity value is obtained according to the second capacity-temperature curve. During the multiple charge-discharge cycles, the set temperature in the standard test room can be 25℃, but there is a certain fluctuation in the battery temperature after charging. In order to accurately obtain the rate coefficient, a fitting formula can be obtained according to the first capacity-temperature curve of the 1C charge-discharge cycle, and then the set temperature in the standard test room (such as 25℃) is substituted into the fitting formula to obtain the capacity value of 1C discharge (i.e. the 1C capacity value).

[0066] S504: The rate calibration coefficient is calculated, and the rate calibration coefficient = 1C capacity value / 0.5C capacity value.

[0067] According to an embodiment of the present application, the steps of the above battery rate calibration coefficient and the rate coefficient selection can effectively ensure the accuracy of the battery rate capacity calibration.

[0068] In some embodiments of the present application, the third group of batteries is subjected to 0.5C charge-discharge cycles and 1C charge-discharge cycles in turn, and the steps of the charge-discharge cycles can refer to Table 1. The method for calibrating the third group of batteries comprises:

[0069] T1: The third group of batteries is subjected to the third pretreatment: the temperature in the standard test room is adjusted to 25°C, and the third group of batteries is subjected to 0.5C charge-discharge cycles at 25°C for multiple times;

[0070] T2: The temperature in the standard test room is adjusted to 25°C, and the third group of batteries subjected to the third pretreatment is left for a certain period of time;

[0071] T3: The third group of batteries is subjected to 0.5C third constant current constant voltage charging;

[0072] T4: After the third constant current constant voltage charging is completed, the third group of batteries is left for a certain period of time;

[0073] T5: The third group of batteries is subjected to 0.5C third constant current discharging again;

[0074] T6: After the third constant current discharging is completed, the third group of batteries is left for a certain period of time;

[0075] T7: Steps T3-T6 are repeated, and the third group of batteries is subjected to multiple charge-discharge cycles to obtain multiple sets of temperature and capacity values of the third group of batteries and perform linear fitting to obtain a first capacity-temperature curve. A first formula is fitted according to the first capacity-temperature curve, 25°C is brought into the first formula, and a 0.5C capacity value of the third group of batteries is obtained;

[0076] T8: The third group of batteries is subjected to 1C fourth constant current constant voltage charging;

[0077] T9: After the fourth constant current constant voltage charging is completed, the third group of batteries is left for a certain period of time;

[0078] T10: The third group of batteries is subjected to 1C fourth constant current discharging again;

[0079] T11: After the fourth constant current discharging is completed, the third group of batteries is left for a certain period of time;

[0080] T12: Steps T8-T11 are repeated, and the third group of batteries is subjected to multiple charge-discharge cycles to obtain multiple sets of temperature and capacity values of the third group of batteries and perform linear fitting to obtain a second capacity-temperature curve. A second formula is fitted according to the second capacity-temperature curve, 25°C is brought into the second formula, and a 1C capacity value of the third group of batteries is obtained.

[0081] Table 1

[0082]

[0083] The 0.5C capacity value obtained according to the above steps and Table 3 is 138.025 Ah, the 1C capacity value is 137.013 Ah, and the calculated rate calibration coefficient is 99.27%.

[0084] S600: The temperature coefficient, the capacity improvement value, and the rate calibration formula are brought into the capacity calibration formula to obtain the shipment battery capacity, wherein the capacity calibration formula is: shipment battery capacity = (base capacity battery capacity + temperature coefficient * (test temperature - battery temperature before discharge)) * rate calibration coefficient) + capacity improvement value.

[0085] In some embodiments of the present application, as described above, the test temperature is 25℃, the temperature coefficient is 0.9 when the battery temperature is 21℃-28.5℃, and the temperature coefficient is 0.7 when the battery temperature is 28.5℃-33℃; the capacity improvement value is 2.95 Ah; and the rate calibration coefficient is 99.27%. Therefore, when the battery temperature is 21℃-28.5℃, the shipment battery capacity = (base capacity battery capacity + 0.9 * (25℃-battery temperature before discharge)) * 9.27%) + 2.95 Ah; and when the battery temperature is 28.5℃-33℃, the shipment battery capacity = (base capacity battery capacity + 0.7 * (25℃-battery temperature before discharge)) * 9.27%) + 2.95 Ah.

[0086] The terms "first", "second", "third", etc. are used herein only to describe different ones of the elements, and do not imply a relative importance or a specific order of the elements. Thus, a feature defined with a "first" and a "second" can include one or more of either feature. The term "plurality" means two or more, unless otherwise specifically stated.

[0087] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0088] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A process for calibrating battery capacity, characterized in that, include: Provide batteries produced at the base; The batteries were divided into three groups in a standard testing room: a first group of batteries, a second group of batteries, and a third group of batteries. Temperature calibration is performed on the first group of batteries to obtain the temperature coefficients of the first group of batteries at different temperature stages; The second group of batteries was cyclically calibrated at the test temperature to obtain the capacity improvement value of the second group of batteries; At the test temperature, the rate of the third group of batteries is calibrated to obtain the rate calibration coefficient of the third group of batteries; Substituting the temperature coefficient, the capacity increase value, and the rate calibration coefficient into the capacity calibration formula, the shipped battery capacity is obtained, wherein the capacity calibration formula is: The shipped battery capacity = (base capacity + temperature coefficient * (test temperature - battery temperature before discharge)) * rate calibration coefficient + capacity increase value.

2. The process method according to claim 1, characterized in that, The method for calibrating the temperature of the first group of batteries includes: The first group of batteries is subjected to a first pretreatment, the first pretreatment steps of which include: adjusting the temperature of the standard test room to a first set temperature, and charging and discharging the first group of batteries multiple times at the first set temperature; The first group of batteries that have undergone the first pretreatment are subjected to charge-discharge cycles at different temperatures to obtain battery capacity values ​​at different temperatures; The temperature coefficient is obtained by linearly fitting the temperature and the battery capacity value.

3. The process method according to claim 2, characterized in that, The steps for obtaining the battery capacity value data include: At different temperatures, different batteries in the first group of batteries that have undergone the first pretreatment are subjected to a first constant current and constant voltage charging. After the first constant current and constant voltage charging is completed, the first group of batteries is left to stand for a first interval time. The first group of batteries is then subjected to a first constant current discharge to obtain the battery capacity values ​​at different temperatures.

4. The process method according to claim 3, characterized in that, At each temperature, the first group of batteries undergoes multiple charge-discharge cycles, and the temperature coefficient is the average value of the test results of multiple charge-discharge cycles.

5. The process method according to claim 4, characterized in that, The steps for obtaining the temperature coefficient include: S1: Perform the first pretreatment on the first group of batteries: adjust the temperature of the standard test room to 25°C, and perform multiple 0.5C charge-discharge cycles on the first group of batteries at 25°C. S2: Let the first group of batteries that have undergone the first pretreatment rest for a certain period of time; S3: Select multiple different temperature values ​​within the range of 20 to 40°C to perform 0.5C constant current and constant voltage charging on different batteries in the first group of batteries respectively; S4: After the first constant current and constant voltage charging is completed, the first group of batteries is left to stand for a certain period of time. S5: Then, the first group of batteries is subjected to the first constant current discharge at 0.5C to obtain the battery capacity values ​​at different temperatures; S6: After the first constant current discharge is completed, the first group of batteries is left to stand for a certain period of time. S7: Repeat steps S3 to S6 to obtain two sets of battery capacity values ​​for each temperature value, calculate the average value, and obtain the battery capacity value for each temperature value. S8: Perform a linear fit between the temperature and the battery capacity value to obtain the temperature coefficient.

6. The process method according to claim 1, characterized in that, The method for performing the cycle calibration on the second group of batteries includes: The second group of batteries is subjected to multiple charge-discharge cycles at a second set temperature until the capacity of the second group of batteries tends to stabilize. The capacity value of the first charge-discharge cycle and the capacity value at the stable state are obtained. The capacity increase value is the difference between the capacity value of the first charge-discharge cycle and the capacity value at the stable state.

7. The process method according to claim 6, characterized in that, The method for performing the cycle calibration on the second group of batteries includes: D1: The second group of batteries is first placed in the standard test room for a certain period of time; D2: Adjust the temperature of the standard test chamber to 25°C and perform 1C constant current and constant voltage charging on the second group of batteries; D3: After the second constant current and constant voltage charging is completed, the second group of batteries will be left to stand for a certain period of time. D4: Then perform a 1C second constant current discharge on the second group of batteries to obtain the capacity value of the first charge-discharge cycle; D5: After the second constant current discharge is completed, the second group of batteries is left to stand for a certain period of time. D6: Repeat steps D2 to D5 to perform multiple charge-discharge cycles on the second group of batteries until the capacity of the second group of batteries tends to stabilize.

8. The process method according to claim 1, characterized in that, The method for calibrating the rate of the third group of batteries includes: The third group of batteries undergoes a third pretreatment, the steps of which include: adjusting the temperature of the standard test chamber to a third set temperature, and performing multiple charge-discharge cycles on the third group of batteries at the third set temperature; The third group of batteries, after undergoing the third pretreatment, is subjected to multiple 0.5C charge-discharge cycles to obtain a first capacity-temperature curve, and the 0.5C capacity value is obtained based on the first capacity-temperature curve. The third group of batteries is then subjected to multiple 1C charge-discharge cycles to obtain a second capacity-temperature curve, and the 1C capacity value is obtained based on the second capacity-temperature curve. The multiplier calibration coefficient is calculated as follows: multiplier calibration coefficient = 1C capacity value / 0.5C capacity value.

9. The process method according to claim 8, characterized in that, The method for calibrating the rate of the third group of batteries includes: T1: Perform the third pretreatment on the third group of batteries: adjust the temperature of the standard test room to 25°C, and perform multiple 0.5C charge-discharge cycles on the third group of batteries at 25°C. T2: Adjust the temperature of the standard test room to 25°C and leave the third group of batteries that have undergone the third pretreatment for a certain period of time. T3: Perform a 0.5C constant current and constant voltage charge on the third group of batteries; T4: After the third constant current and constant voltage charging is completed, the third group of batteries is left to stand for a certain period of time. T5: Then perform a third constant current discharge of 0.5C on the third group of batteries; T6: After the third constant current discharge is completed, the third group of batteries is left to stand for a certain period of time. T7: Repeat steps T3 to T6 to perform multiple charge-discharge cycles on the third group of batteries to obtain temperature and capacity data of multiple groups of the third group of batteries and perform linear fitting to obtain the first capacity-temperature curve. Fit the first formula according to the first capacity-temperature curve, and substitute 25℃ into the first formula to obtain the 0.5C capacity value of the third group of batteries. T8: Perform 1C fourth constant current and constant voltage charging on the third group of batteries; T9: After the fourth constant current and constant voltage charging is completed, the third group of batteries is left to stand for a certain period of time. T10: Then perform a fourth constant current discharge of 1C on the third group of batteries; T11: After the fourth constant current discharge is completed, the third group of batteries is left to stand for a certain period of time. T12: Repeat steps T8 to T11 to perform multiple charge-discharge cycles on the third group of batteries to obtain temperature and capacity data of multiple groups of the third group of batteries. Perform linear fitting to obtain the second capacity-temperature curve. Fit the second formula according to the second capacity-temperature curve and substitute 25℃ into the second formula to obtain the 1C capacity value of the third group of batteries.

10. The process method according to any one of claims 1 to 9, characterized in that, The test temperature was 25°C. The temperature coefficient is 0.9 Ah / ℃ when the battery temperature is 21℃-28.5℃, and the temperature coefficient is 0.7 Ah / ℃ when the battery temperature is 28.5℃-33℃. The capacity increase is 2.95 Ah; The magnification factor is 99.27%.

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