Method and device for determining number of critical cycles of battery, storage medium and product

Abstract

The method for determining the critical cycle number of the battery comprises the following steps: circularly charging and discharging a reference battery in an air pressure monitoring mold until the cycle number reaches a preset first cycle number, and recording data of multiple groups of generated air pressures and the cycle number of the reference battery so as to construct a pressure-cycle number basic model; circularly charging and discharging the to-be-detected battery in the air pressure monitoring mold until the number of circulation turns reaches a preset second number of circulation turns; recording data of multiple groups of gas production pressures and circulation turns of the to-be-tested battery so as to adjust parameters of the pressure-circulation turn number basic model to obtain a pressure-circulation turn number target model; determining the critical pressure intensity of the to-be-detected battery in the air pressure monitoring mold during CID overturning; and inputting the critical pressure into the target model to obtain the number of critical cycles of the to-be-tested battery. And inputting the critical pressure intensity of the to-be-detected battery in the air pressure monitoring mold during CID overturning into the target model to obtain the critical cycle number of the to-be-detected battery.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to a method, device, storage medium and product for determining a critical cycle number of a battery. Background Art

[0002] The positive electrode of lithium-ion batteries with high nickel and high silicon systems is generally prone to serious battery gassing problems under high temperature conditions. When the battery gassing is serious, it will reduce the high-temperature electrochemical performance of the lithium-ion battery. For example, the interface impedance of the lithium-ion battery is abnormal, lithium precipitation, material breakage, internal resistance increase, etc., and it may even trigger the CID (Current Interrupt Device) to flip, reaching the end of the battery life.

[0003] In the process of developing and producing lithium-ion batteries, it is usually necessary to screen and compare the differences in high-temperature cycle performance of different electrolytes. After each electrolyte produces the corresponding battery, it is necessary to cyclically charge and discharge to evaluate the critical number of cycles corresponding to the CID flip of the battery in a high-temperature environment. This is more important for evaluating the service life of the battery. However, it takes a lot of time for a large number of batteries to charge from 0 cycles to CID flip (triggering the CID action to cut off the battery current), which brings huge time costs and delays the material development cycle and progress.

[0004] Therefore, the efficiency of the critical number of cycles corresponding to the CID flipping of the existing battery needs to be improved. Summary of the invention

[0005] The main technical problem solved by the present invention is how to improve the efficiency of obtaining the critical cycle number corresponding to the battery CID flipping.

[0006] According to the first aspect, an embodiment provides a method for determining a critical cycle number of a battery, comprising:

[0007] The reference battery in the air pressure monitoring mold is charged and discharged cyclically until the number of cycles reaches a preset first number of cycles; the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process are recorded to obtain multiple sets of gas production pressure and cycle number data of the reference battery;

[0008] Based on the multiple sets of data on gas production pressure and number of cycles, a basic model of pressure-number of cycles is constructed;

[0009] The battery to be tested in the air pressure monitoring mold is charged and discharged cyclically until the number of cycles reaches a preset second number of cycles; the gas production pressure and the corresponding number of cycles of the battery to be tested during the charging and discharging process are recorded to obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second number of cycles is less than the first number of cycles;

[0010] Adjusting the parameters of the basic model of pressure-cycle number according to the data of multiple groups of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested;

[0011] Determine the critical pressure of the battery under test in the air pressure monitoring mold when the CID is turned over;

[0012] The critical pressure is input into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested.

[0013] According to the second aspect, an embodiment provides a device for determining the critical cycle number of a battery, the device comprising:

[0014] The processing unit is used to cyclically charge and discharge the reference battery in the air pressure monitoring mold until the number of cycles reaches a preset first number of cycles; record the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the reference battery;

[0015] A construction unit, configured to construct a basic model of pressure-cycle number based on the plurality of sets of data of gas production pressure and cycle number;

[0016] The processing unit is also used to cyclically charge and discharge the battery to be tested in the air pressure monitoring mold until the number of cycles reaches a preset second number of cycles; record the gas production pressure and the corresponding number of cycles of the battery to be tested during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second number of cycles is less than the first number of cycles;

[0017] An adjustment unit, configured to adjust the parameters of the basic model of pressure-cycle number according to the data of multiple groups of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested;

[0018] A determination unit, used to determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is turned over;

[0019] The processing unit is further used to input the critical pressure into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested.

[0020] According to a third aspect, an embodiment provides a computer-readable storage medium, comprising a program, wherein the program can be executed by a processor to implement the method as described above.

[0021] According to a fourth aspect, an embodiment provides a computer program product, comprising a computer program and / or instructions, wherein the computer program and / or instructions implement the above method when executed by a processor.

[0022] According to the method for determining the critical cycle number of a battery in the above embodiment, the battery to be tested is subjected to a certain number of cycles of charge and discharge, and after obtaining the gas production pressure and the corresponding number of cycles, these data are used to adjust the parameters of the basic model to obtain a target model of pressure-cycle number adapted to the battery to be tested. The critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped is determined, and the critical cycle number of the battery to be tested can be obtained by inputting the critical pressure into the target model, which is equivalent to being able to predict the critical cycle number of the battery to be tested with a certain amount of data, so the battery to be tested does not need to be charged and discharged cyclically until the CID flips, thereby improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a flow chart of a method for determining a critical cycle number of a battery provided in this embodiment;

[0024] Figure 2 A schematic diagram of a corresponding relationship curve between dP / dn and the number of cycles of a reference battery provided in this embodiment;

[0025] Figure 3 A schematic diagram of a corresponding relationship curve between the gas production pressure and the number of cycles of the reference battery provided in this embodiment;

[0026] Figure 4 A schematic diagram of a corresponding relationship curve between the capacity retention rate and the number of cycles of the reference battery provided in this embodiment;

[0027] Figure 5 A curve diagram of a target model of pressure-cycle number provided for this embodiment;

[0028] Figure 6 A structural block diagram of a device for determining the critical cycle number of a battery provided in this embodiment. DETAILED DESCRIPTION

[0029] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0030] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0031] The serial numbers of the components in this document, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0032] At present, lithium-ion batteries with high nickel and high silicon systems play an extremely important role in consumer electronics, electric vehicles, energy storage and other fields due to their excellent energy density, rate performance and good cycle stability. However, there are some safety issues with high nickel positive electrodes, such as severe battery gas production. Severe gas production problems will reduce its high-temperature electrochemical performance, such as abnormal interface impedance, lithium precipitation, material breakage, increased internal resistance, etc., until the battery current cut-off device is triggered and the battery life ends. Therefore, how to avoid severe battery gas production and triggering the battery current cut-off device is an urgent problem to be solved. At present, the charge and discharge of the battery can be controlled by obtaining the number of cycles when the battery CID flips, thereby solving the above problems. However, it currently takes a long time to detect the number of cycles when the battery CID flips. Therefore, it is particularly important to be able to quickly predict the number of cycles when the CID flips during high-temperature cycling of the battery, so as to quickly evaluate the gas production performance of different electrode materials.

[0033] Based on this, the scheme of the present invention is proposed. In an embodiment of the present invention, first, after cyclically charging and discharging the reference battery in the air pressure monitoring mold, multiple sets of gas production pressure and cycle number data of the reference battery are obtained, and a basic model of pressure-cycle number is constructed based on the data; then, after cyclically charging and discharging the battery to be tested in the air pressure monitoring mold, multiple sets of gas production pressure and cycle number data of the battery to be tested are obtained, and the parameters of the basic model of pressure-cycle number are adjusted based on the data, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested; after further determining the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped, the critical pressure is input into the target model of pressure-cycle number, and finally the critical cycle number of the battery to be tested is obtained. In this way, the purpose of accurately predicting the critical cycle number corresponding to the CID flip of the battery in a high temperature environment can be achieved. This is described in detail below through some embodiments.

[0034] Example 1, please refer to Figure 1 , Figure 1 FIG. 1 is a flow chart of a method for determining the critical cycle number of a battery provided in this embodiment. Figure 1 As shown, the method specifically includes the following steps 101-106:

[0035] Step 101, cyclically charge and discharge the reference battery in the air pressure monitoring mold until the number of cycles reaches a preset first number of cycles; record the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the reference battery.

[0036] It should be noted that the air pressure monitoring mold can be used to monitor the air pressure changes inside the battery pack or battery module under sealed conditions. In this embodiment, the air pressure monitoring mold is specifically used to monitor the air pressure changes inside the reference battery under sealed conditions, that is, the gas production pressure.

[0037] It should be noted that the reference battery can represent a battery in any battery system. For example, the reference battery can be a battery in a high-nickel and high-silicon system, or a battery in a lithium iron phosphate system. The present invention does not impose any limitation on this.

[0038] It should be noted that the preset first cycle number can represent the cycle number corresponding to the CID flipping of the reference battery in the air pressure monitoring mold. The preset first cycle number can be any cycle number. For example, the preset first cycle number can be 300 cycles, as long as the CID flipping occurs within the first cycle number.

[0039] Step 102: Based on multiple sets of data on gas production pressure and number of cycles, a basic model of pressure-number of cycles is constructed.

[0040] Here, when constructing the basic model of pressure-cycle number, it is possible to obtain extreme value data from multiple sets of gas production pressure and cycle number data; fit the extreme value data with a first preset function to obtain a first fitting function and a first fitting error; and when the first fitting error is less than a preset threshold, use the first fitting function as the basic model of pressure-cycle number.

[0041] It should be noted that the extreme value data in each set of data of gas production pressure and number of cycles include the maximum gas production pressure and the minimum gas production pressure. That is to say, when the reference battery is charged and discharged in the air pressure monitoring mold, each charge and discharge cycle can generate the maximum gas production pressure and the minimum gas production pressure. In step 101, multiple gas production pressures can be recorded in each charge and discharge cycle, for example, each gas production pressure under each number of cycles can be continuously recorded, so that the maximum gas production pressure and the minimum gas production pressure corresponding to each number of cycles can be identified, that is, a set of data of gas production pressure and number of cycles can at least include the number of cycles and its corresponding extreme value data (maximum gas production pressure and minimum gas production pressure). Since each set of extreme value data includes the maximum gas production pressure and the minimum gas production pressure, after fitting multiple sets of data of gas production pressure and number of cycles with the first preset function, the basic model of pressure-cycle number corresponding to the maximum gas production pressure and the basic model of pressure-cycle number corresponding to the minimum gas production pressure can be obtained.

[0042] It should be noted that the first preset function may be any fitting function, such as a linear function, a quadratic function, a cubic function, etc. The method used when fitting the extreme value data to the first preset function includes but is not limited to the least squares curve fitting method.

[0043] It should be noted that the first fitting error may represent the fitting error between the first preset function and the maximum value of the gas production pressure; it may also represent the fitting error between the first preset function and the minimum value of the gas production pressure.

[0044] It should be noted that the preset threshold value may be any value. For example, the preset threshold value may be 5%.

[0045] In practical applications, the pressure-cycle basic model can be constructed by performing cyclic charge and discharge tests on reference batteries through an air pressure monitoring mold. For example, the test conditions are: high temperature 60°C and 300 cycles.

[0046] Specifically, record the maximum gas production pressure P of each cycle. max , minimum gas production pressure P min ; Calculate the derivative dP / dn between gas production pressure and cycle number, and the maximum gas production pressure P max and minimum gas production pressure P min The difference between ΔP. Figure 2-3 As shown, after identifying the area where gas production pressure increases rapidly, the area where gas production pressure increases slowly, and the area where gas production pressure increases rapidly through the dP / dn-n curve, the first section model of the basic model of pressure-cycle number is constructed in the area where gas production pressure increases rapidly, and the second section model of the basic model of pressure-cycle number is constructed in the area where gas production pressure increases slowly and the area where gas production pressure increases rapidly.

[0047] For example, Figure 3 As shown, the model in this embodiment can be a curve equation (fitting function), and the first segment model in the basic model of pressure-cycle number is: 1 =a 1 *x^b 1 ; The second model in the basic model of pressure-cycle number is y 2 =b 2 *x+b 3 *x^2+b 4 *x^3+b 5 , where a 1 、b 1 、b 2 、b 3 、b 4 、b 5 are all unknown parameters of the basic model, x is the number of cycles, y is 1 is the gas production pressure corresponding to the first model, y 2 is the gas production pressure corresponding to the second stage model. In this embodiment, there are two basic models: the pressure-cycle number basic model corresponding to the maximum gas production pressure (such as Figure 3 The solid line curve in the middle) and the basic model of pressure-cycle number corresponding to the minimum gas production pressure (such as Figure 3 middle dashed curve).

[0048] Here, after constructing the basic model of pressure-cycle number, we can further judge whether the basic model of pressure-cycle number is reasonable. For example, we can cyclically charge and discharge the reference battery outside the air pressure monitoring mold until the CID of the reference battery flips, that is, set up another reference battery and do not put it in the air pressure monitoring mold for testing; record the actual number of cycles corresponding to the reference battery when the CID flips; determine the critical pressure of the reference battery in the air pressure monitoring mold when the CID flips; input the critical pressure into the basic model of pressure-cycle number to determine the reference cycle number range; based on the actual number of cycles and the reference cycle number range, judge whether the basic model of pressure-cycle number is reasonable.

[0049] It should be noted that the reference cycle number range can represent the maximum reference cycle number determined after the critical pressure is input into the basic model of the pressure-cycle number corresponding to the maximum gas production pressure, and the minimum reference cycle number determined after the critical pressure is input into the basic model of the pressure-cycle number corresponding to the minimum gas production pressure, which constitutes the cycle number range. Figure 3 In the figure, the number of cycles corresponding to the critical pressure of P = 273 kPa on the solid line curve is one end point of the cycle number range, and the number of cycles corresponding to the critical pressure of P = 273 kPa (CID inversion transition pressure) on the dotted line curve is the other end point of the cycle number range. These two end points constitute the cycle number range.

[0050] Here, when determining the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped, the first space volume remaining inside the air pressure monitoring mold containing the reference battery can be recorded before the reference battery in the air pressure monitoring mold is charged or discharged; the corresponding gas production volume and gas production pressure of the reference battery outside the air pressure monitoring mold when the CID is flipped; the second space volume remaining inside the air pressure monitoring mold when the reference battery in the air pressure monitoring mold is flipped; based on the first space volume, the second space volume, the gas production volume and the gas production pressure, the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped can be determined. That is, the critical pressure can be calculated or deduced.

[0051] It should be noted that after the CID of the battery is flipped, there may be powdered particles or thickened SEI film on the surface of the battery. At this time, the volume of the battery will increase, and correspondingly, the remaining internal space of the air pressure monitoring mold will be reduced accordingly. In other words, the volume of the first space remaining inside the air pressure monitoring mold containing the reference battery before the reference battery is charged and discharged is larger than the volume of the second space remaining inside the air pressure monitoring mold containing the reference battery when the CID of the reference battery is flipped.

[0052] In practical applications, when the battery / different electrolytes in the air pressure monitoring mold are not cycled, the gas flow meter calibration method can be used to test the internal space in the air pressure monitoring mold with the battery, and the internal space is recorded as V 0 (First spatial volume); After the battery in the air pressure monitoring mold is cycled and discharged, and the CID of the battery is flipped, the gas flow meter calibration method can be used to test the remaining internal space in the air pressure monitoring mold with the battery, and the remaining internal space is recorded as ΔV 0 '(Second space volume); The gas production volume of the battery CID after flipping the pressure monitoring mold is recorded as V 0 ',V 0'That is, the volume of all gases generated by the reference battery outside the air pressure monitoring mold from the start of cyclic charge and discharge until the CID flips; the gas production pressure of the battery outside the air pressure monitoring mold when the CID flips is recorded as P 0 '. For example, the recorded V 0 9.34 ml, ΔV 0 ' is 1.14ml, V 0 ' is 18.1ml, P 0 ' is 1.2Mpa.

[0053] The ideal gas state equation is as follows:

[0054] PV=nRT (1)

[0055] In formula (1), P is the gas production pressure corresponding to the battery charging and discharging, V is the gas production volume corresponding to the battery charging and discharging, n is the number of cycles corresponding to the battery charging and discharging, R is the ideal gas constant, and T is the ambient temperature.

[0056] According to P 0 'V 0 '=P 0 (V 0 -ΔV 0 '), the corresponding gas pressure P when the CID of the battery in the pressure monitoring mold is turned over can be calculated 0 . For example, P 0 It is 273kPa.

[0057] Here, to judge whether the basic model of pressure-cycle number is reasonable, specifically, to judge whether the actual number of cycles is within the range of reference cycle number; if the actual number of cycles is within the range of reference cycle number, then it is determined that the basic model of pressure-cycle number is reasonable; if the actual number of cycles is not within the range of reference cycle number, then it is determined that the basic model of pressure-cycle number is unreasonable.

[0058] It should be noted that the actual number of cycles is within the range of the reference number of cycles, which means that the basic model of pressure-cycle number can accurately predict the actual number of cycles of the reference battery, which is sufficient to show that the basic model of pressure-cycle number is reasonable; and the actual number of cycles is not within the range of the reference number of cycles, which means that the basic model of pressure-cycle number cannot predict the actual number of cycles of the reference battery, which is sufficient to show that the basic model of pressure-cycle number is unreasonable.

[0059] In practical applications, this basic model of pressure-cycle number is combined with the critical pressure P 0, the number of battery CID flipping circles in the air pressure monitoring mold can be obtained; by comparing the number of battery CID flipping circles with the actual number of battery flipping circles, the rationality of the basic model of pressure-cycle number can be verified.

[0060] Here, after determining that the pressure-cycle number curve model is unreasonable, the extreme value data can be fitted with a second preset function to obtain a second fitting function and a second fitting error; when the second fitting error is less than a preset threshold, the second fitting function is used as a new basic model of pressure-cycle number; the critical pressure is input into the new basic model of pressure-cycle number to determine a new reference range of cycles; based on the actual number of cycles and the new reference range of cycles, the rationality of the new basic model of pressure-cycle number is judged.

[0061] It should be noted that the second preset function can be any fitting function different from the first preset function, and the method used to fit the extreme value data to the second preset function includes but is not limited to the least square curve fitting method. Some empirical functions can be obtained based on the relationship curve between the gas production pressure of the battery and the number of cycles as the first preset function, the second preset function, or even the third preset function, etc. If the basic model obtained by fitting this preset function with the extreme value data is unqualified, another preset function is used to continue fitting until a qualified basic model is fitted.

[0062] It should be noted that the second fitting error can represent the fitting error between the second preset function and the maximum value of the gas production pressure; it can also represent the fitting error between the second preset function and the minimum value of the gas production pressure.

[0063] It should be noted that when the first fitting function is unreasonable, that is, when the previous basic model of pressure-cycle number is unreasonable, the previous basic model of pressure-cycle number can be updated, that is, the previous basic model of pressure-cycle number can be updated to the basic model of pressure-cycle number obtained by fitting based on the second preset function (second fitting function).

[0064] For example, the number of cycles corresponding to the CID flip of the reference battery predicted by the basic model of pressure-cycle number is 196±13; the actual number of cycles corresponding to the CID flip of the reference battery outside the air pressure monitoring mold is 207, such as Figure 4 As shown in the figure, since the actual cycle number 207 of the reference battery is greater than the minimum predicted cycle number 183 and less than the maximum predicted cycle number 209, the basic model of pressure-cycle number can predict the corresponding cycle number of the battery when the CID is flipped, that is, the basic model of pressure-cycle number is reasonable.

[0065] Step 103, cyclically charge and discharge the battery to be tested in the air pressure monitoring mold until the number of cycles reaches a preset second number of cycles; record the gas production pressure and the corresponding number of cycles of the battery to be tested during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second number of cycles is less than the first number of cycles.

[0066] It should be noted that the second cycle number is smaller than the first cycle number, that is, the battery under test cycles less charge and discharge times in the air pressure monitoring mold than the reference battery in the air pressure monitoring mold. This effectively shortens the time for predicting the critical cycle number of the battery under test and improves efficiency.

[0067] Step 104 , adjusting the parameters of the basic model of pressure-cycle number according to the data of multiple groups of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number suitable for the battery to be tested.

[0068] It should be noted that the parameters of the previous basic model such as a 1 、b 1 、b 2 、b 3 、b 4 、b 5 Etc., the specific values ​​are obtained from the data of the reference battery. Therefore, the parameters of the basic model of pressure-cycle number can be adjusted according to the data of multiple sets of gas production pressure and cycle number of the battery to be tested. It can be that multiple maximum gas production pressures and corresponding cycle numbers, multiple minimum gas production pressures and corresponding cycle numbers after the battery to be tested in the air pressure monitoring mold has been charged and discharged for a preset number of times, are selected, and then substituted into the basic model of pressure-cycle number, and its parameters are solved to determine the target model of pressure-cycle number that is suitable for the battery to be tested, that is, the data of the battery to be tested is substituted into the curve equation corresponding to the basic model, and the parameters such as a that are suitable for the battery to be tested are solved. 1 、b 1 、b 2 、b 3 、b 4 、b 5 Then we can get the target model, such as Figure 5 shown.

[0069] For example, after the battery to be tested is charged and discharged for 50 cycles in the air pressure monitoring mold, the extreme value data of the gas production pressure corresponding to each cycle are recorded; within the first 25 cycles, two extreme value data of the gas production pressure and the corresponding cycle numbers are randomly selected and substituted into the first segment model of the above pressure-cycle number basic model to solve a 1 、b 1; Randomly select 4 extreme value data of gas production pressure and the corresponding number of cycles in the 15th to 50th cycle, substitute them into the second model of the basic model of pressure-cycle number, and you can solve b 2 、b 3 、b 4 、b 5 In this way, a target model of pressure-cycle number suitable for the battery to be tested can be determined.

[0070] For example, the first model in the basic model of pressure-cycle number corresponding to the area where the gas production pressure increases rapidly is:

[0071] y max =159.94x^0.08222,y min =140.45x^0.09404.

[0072] For example, the second segment model in the basic model of pressure-cycle number corresponding to the area where the gas production pressure increases slowly and the area where the gas production pressure increases rapidly is:

[0073] y max =0.23115*x-0.00124*x^2+9.52653E-6*x^3+210.79,

[0074] y min =0.22709*x-0.00103*x^2+8.22184E-6*x^3+193.08.

[0075] Step 105: determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is turned over.

[0076] Here, when determining the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped, for the reference battery and the battery to be tested of the same system, the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped can be determined as the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped.

[0077] It should be noted that for the reference battery and the test battery of the same system, the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped is basically the same as the critical pressure of the test battery in the air pressure monitoring mold when the CID is flipped. The critical pressure of the reference battery outside the air pressure monitoring mold when the CID is flipped is also basically the same as the critical pressure of the test battery outside the air pressure monitoring mold when the CID is flipped.

[0078] It should be noted that, for reference batteries and test batteries of different systems, the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped may be the same as or different from the critical pressure of the test battery in the air pressure monitoring mold when the CID is flipped; the critical pressure of the reference battery outside the air pressure monitoring mold when the CID is flipped may be the same as or different from the critical pressure of the test battery outside the air pressure monitoring mold when the CID is flipped, and the present application does not make any limitation on this.

[0079] Step 106: Input the critical pressure into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested.

[0080] It should be noted that when the critical pressure is in the area where the gas production pressure increases rapidly, the critical pressure is input into the first section of the basic model of pressure-cycle number to solve the critical cycle number of the battery to be tested. When the critical pressure is in the area where the gas production pressure increases slowly and the area where the gas production pressure increases rapidly, the critical pressure is input into the second section of the basic model of pressure-cycle number to solve the critical cycle number of the battery to be tested. That is, the maximum number of cycles corresponding to the CID of the battery to be tested is not flipped.

[0081] In this embodiment, a method for determining the critical cycle number of a battery includes: cyclically charging and discharging a reference battery in an air pressure monitoring mold until the number of cycles reaches a preset first number of cycles; recording the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process, and obtaining multiple sets of gas production pressure and cycle number data of the reference battery; constructing a basic model of pressure-cycle number based on the multiple sets of gas production pressure and cycle number data; cyclically charging and discharging the battery to be tested in the air pressure monitoring mold until the number of cycles reaches a preset second number of cycles; recording the charging and discharging ... The gas production pressure and the corresponding number of cycles of the battery to be tested during the charging process are used to obtain multiple sets of data on the gas production pressure and the number of cycles of the battery to be tested; the second number of cycles is less than the first number of cycles; the parameters of the basic model of pressure-cycle number are adjusted according to the multiple sets of data on gas production pressure and cycle number of the battery to be tested to obtain a target model of pressure-cycle number adapted to the battery to be tested; the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped; the critical pressure is input into the target model of pressure-cycle number to obtain the critical number of cycles of the battery to be tested. After the gas production pressure and the corresponding number of cycles are obtained by performing a certain number of cycles of charge and discharge on the battery to be tested, the parameters of the basic model are adjusted using these data to obtain a target model of pressure-cycle number adapted to the battery to be tested. Determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped, and input the critical pressure into the target model to obtain the critical cycle number of the battery to be tested, which is equivalent to being able to predict the critical cycle number of the battery to be tested with a certain amount of data, so the battery to be tested does not need to be cyclically charged and discharged until the CID is flipped, which improves efficiency. Using the method of the present invention, it is also possible to quickly evaluate the gas production performance of batteries of different materials in the same system (such as different electrolytes, different electrode materials, etc.) during high-temperature cycling. In addition to the two reference batteries inside and outside the air pressure monitoring mold that need to be cyclically charged until the CID is flipped, the batteries of other different materials in the reference battery system only need to be cyclically charged a small number of times to deduce their critical cycle number, which greatly shortens the research and development cycle of lithium batteries.

[0082] The present invention also provides a device 20 for determining the critical cycle number of a battery, such as Figure 6 The structure block diagram of a device for determining the critical cycle number of a battery is shown, the device 20 includes a processing unit 201, a construction unit 202, an adjustment unit 203, and a determination unit 204. Among them:

[0083] The processing unit 201 is used to cyclically charge and discharge the reference battery in the air pressure monitoring mold until the number of cycles reaches a preset first number of cycles; for example, the processing unit 201 can be connected to the battery charging and discharging equipment, and the reference battery in the air pressure monitoring mold is cyclically charged and discharged through the charging and discharging equipment until the number of cycles reaches a preset first number of cycles; of course, the processing unit 201 can also include the charging and discharging equipment. The processing unit 201 records the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process, and obtains multiple sets of gas production pressure and cycle number data of the reference battery. The specific process is shown in the above step 101, which will not be repeated here.

[0084] The construction unit 202 is used to construct a basic model of pressure-cycle number based on multiple sets of gas production pressure and cycle number data. The specific process is shown in the above step 102 and will not be repeated here.

[0085] The processing unit 201 is also used to cyclically charge and discharge the battery to be tested in the air pressure monitoring mold until the number of cycles reaches a preset second number of cycles; record the gas production pressure and the corresponding number of cycles of the battery to be tested during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second number of cycles is less than the first number of cycles. The specific process is shown in the above step 103, which will not be repeated here.

[0086] The adjustment unit 203 is used to adjust the parameters of the basic model of pressure-cycle number according to the data of multiple sets of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested. The specific process is shown in the above step 104 and will not be described here.

[0087] The determination unit 204 is used to determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is turned over. The specific process is shown in the above step 105 and will not be described here.

[0088] The processing unit 201 is also used to input the critical pressure into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested. The processing unit 201 can be connected to a display so that the critical cycle number of the battery to be tested is displayed on the display. The specific process is shown in the above step 106 and will not be repeated here.

[0089] The device for determining the critical cycle number of a battery provided in an embodiment of the present application, wherein the processing unit in the device is used to cyclically charge and discharge the reference battery in the air pressure monitoring mold until the cycle number reaches a preset first cycle number; record the gas production pressure and the corresponding cycle number of the reference battery during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the reference battery. The construction unit is used to construct a basic model of pressure-cycle number based on multiple sets of gas production pressure and cycle number data. The processing unit is also used to cyclically charge and discharge the battery to be tested in the air pressure monitoring mold until the cycle number reaches a preset second cycle number; record the gas production pressure and the corresponding cycle number of the battery to be tested during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second cycle number is less than the first cycle number. The adjustment unit is used to adjust the parameters of the basic model of pressure-cycle number according to the multiple sets of gas production pressure and cycle number data of the battery to be tested, and obtain a target model of pressure-cycle number adapted to the battery to be tested. The determination unit is used to determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped. The processing unit is also used to input the critical pressure into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested. After the gas production pressure and the corresponding number of cycles are obtained by subjecting the battery to be tested to a certain number of cycles of charge and discharge, these data are used to adjust the parameters of the basic model to obtain the target model of pressure-cycle number adapted to the battery to be tested. Determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped, and input the critical pressure into the target model to obtain the critical cycle number of the battery to be tested, which is equivalent to being able to predict the critical cycle number of the battery to be tested with a certain amount of data, so the battery to be tested does not need to be charged and discharged cyclically until the CID is flipped, thereby improving efficiency. By adopting the method of the present invention, the gas production performance of batteries made of different materials (such as different electrolytes, different electrode materials, etc.) under the same system during high-temperature cycling can be quickly evaluated. Except for the two reference batteries inside and outside the air pressure monitoring mold that need to be cyclically charged until the CID flips, the batteries made of other materials in the reference battery system only need to be cycled a small number of times to calculate their critical cycle number, which greatly shortens the research and development cycle of lithium batteries.

[0090] Those skilled in the art will appreciate that all or part of the functions of the various methods in the above-mentioned embodiments can be implemented by hardware or by computer programs. When all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can be stored in a computer-readable storage medium, and the storage medium can include: read-only memory, random access memory, disk, optical disk, hard disk, etc., and the program is executed by a computer to implement the above-mentioned functions. For example, the program is stored in the memory of the device, and when the program in the memory is executed by the processor, all or part of the above-mentioned functions can be implemented. In addition, when all or part of the functions in the above-mentioned embodiments are implemented by computer programs, the program can also be stored in a storage medium such as a server, another computer, disk, optical disk, flash disk or mobile hard disk, and can be downloaded or copied and saved in the memory of the local device, or the system of the local device is updated, and when the program in the memory is executed by the processor, all or part of the functions in the above-mentioned embodiments can be implemented.

[0091] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A method for determining the critical cycle number of a battery, characterized in that: include: The reference battery in the air pressure monitoring mold is charged and discharged cyclically until the number of cycles reaches a preset first number of cycles; Recording the gas production pressure and the corresponding number of cycles of the reference battery during the charge and discharge process, and obtaining multiple sets of data of the gas production pressure and the number of cycles of the reference battery; Based on the multiple sets of data on gas production pressure and number of cycles, a basic model of pressure-number of cycles is constructed; The battery to be tested in the air pressure monitoring mold is charged and discharged cyclically until the number of cycles reaches a preset second number of cycles; Recording the gas production pressure and the corresponding number of cycles of the battery under test during the charge and discharge process, and obtaining multiple sets of data of gas production pressure and number of cycles of the battery under test; The second number of cycles is less than the first number of cycles; Adjusting the parameters of the basic model of pressure-cycle number according to the data of multiple groups of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested; Determine the critical pressure of the battery under test in the air pressure monitoring mold when the CID is turned over; The critical pressure is input into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested.

2. The method according to claim 1, characterized in that The method further comprises: Cyclic charging and discharging of a reference battery outside the air pressure monitoring mold until the CID of the reference battery flips; Record the actual number of cycles of the reference battery when the CID is flipped; Determining the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped; Inputting the critical pressure into the basic model of pressure-cycle number to determine a reference cycle number range; Based on the actual number of cycles and the reference number of cycles range, it is determined whether the basic model of pressure-number of cycles is reasonable.

3. The method according to claim 2, characterized in that The judging whether the basic model of pressure-cycle number is reasonable based on the actual cycle number and the reference cycle number range includes: In the case where the actual number of cycles is within the range of the reference number of cycles, it is determined that the basic model of the pressure-number of cycles is reasonable; When the actual number of cycles is not within the reference number of cycles, the basic model for determining the pressure-number of cycles is unreasonable.

4. The method according to claim 3, characterized in that The method of constructing a basic model of pressure-cycle number based on the multiple sets of data of gas production pressure and cycle number includes: Obtaining extreme value data from the plurality of sets of data on gas production pressure and cycle number; Fitting the extreme value data with a first preset function to obtain a first fitting function and a first fitting error; When the first fitting error is less than a preset threshold, the first fitting function is used as the basic model of the pressure-cycle number.

5. The method according to claim 4, characterized in that After determining that the pressure-cycle number curve model is unreasonable, the method further includes: Fitting the extreme value data with a second preset function to obtain a second fitting function and a second fitting error; When the second fitting error is less than the preset threshold, using the second fitting function as a new basic model of pressure-cycle number; Inputting the critical pressure into the new pressure-cycle number basic model to determine a new reference cycle number range; Based on the actual number of cycles and the new reference number of cycles range, the rationality of the new pressure-cycle number basic model is judged.

6. The method according to any one of claims 2 to 5, characterized in that The determining of the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped includes: Recording the remaining first space volume inside the air pressure monitoring mold containing the reference battery before the reference battery in the air pressure monitoring mold is charged or discharged; Recording the gas production volume and gas production pressure of the reference battery outside the gas pressure monitoring mold when the CID is flipped; Recording the remaining second space volume inside the air pressure monitoring mold when the reference battery in the air pressure monitoring mold is flipped over by the CID; Based on the first spatial volume, the second spatial volume, the gas production volume, and the gas production pressure, the critical pressure of the reference battery in the gas pressure monitoring mold when the CID is flipped is determined.

7. The method according to any one of claims 2 to 5, characterized in that The step of determining the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped includes: For the reference battery and the battery to be tested of the same system, the critical pressure of the reference battery in the air pressure monitoring mold when the CID is flipped is determined as the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is flipped.

8. A device for determining the critical cycle number of a battery, characterized in that: The device comprises: The processing unit is used to cyclically charge and discharge the reference battery in the air pressure monitoring mold until the number of cycles reaches a preset first number of cycles; record the gas production pressure and the corresponding number of cycles of the reference battery during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the reference battery; A construction unit, configured to construct a basic model of pressure-cycle number based on the plurality of sets of data of gas production pressure and cycle number; The processing unit is also used to cyclically charge and discharge the battery to be tested in the air pressure monitoring mold until the number of cycles reaches a preset second number of cycles; record the gas production pressure and the corresponding number of cycles of the battery to be tested during the charging and discharging process, and obtain multiple sets of gas production pressure and cycle number data of the battery to be tested; the second number of cycles is less than the first number of cycles; An adjustment unit, configured to adjust the parameters of the basic model of pressure-cycle number according to the data of multiple groups of gas production pressure and cycle number of the battery to be tested, so as to obtain a target model of pressure-cycle number adapted to the battery to be tested; A determination unit, used to determine the critical pressure of the battery to be tested in the air pressure monitoring mold when the CID is turned over; The processing unit is further used to input the critical pressure into the target model of pressure-cycle number to obtain the critical cycle number of the battery to be tested.

9. A computer-readable storage medium, characterized in that: The method comprises a program which can be executed by a processor to implement the method according to any one of claims 1 to 7.

10. A computer program product comprising a computer program and / or instructions, characterized in that: When the computer program and / or the instructions are executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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