Rapid Detection Method and System for the Cycle Life of Lithium Batteries Based on the Principle of Accelerated Aging

Abstract

The present invention provides a rapid detection method and system for the cycle life of a lithium battery based on the principle of accelerated aging, including: obtaining test data of the number of charge and discharge cycles when the capacity of the lithium battery decays to a preset percentage at different temperatures; constructing a temperature rise-acceleration matrix combining the charge and discharge rate, the standing time, and the number of charge and discharge cycles based on the test data; based on the temperature rise-acceleration matrix, with the goal of minimizing the number of charge and discharge cycles, obtaining the optimal heating temperature and its corresponding minimum number of charge and discharge cycles of the lithium battery; according to the minimum number of charge and discharge cycles at the optimal temperature, using polynomial fitting to construct a functional relationship between the remaining capacity of the lithium battery, the detection temperature, and the number of cycles; according to the number of charge and discharge cycles when the lithium battery decays to a preset percentage at the optimal temperature, combining with the functional relationship, obtaining the equivalent number of charge cycles of the battery at a preset conventional detection temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium battery life detection, and particularly relates to a method and system for rapidly detecting the cycle life of a lithium battery based on the principle of accelerated aging. Background Art

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Currently, lithium batteries are increasingly widely used in the field of electric vehicles, and the detection technology for their performance indicators is becoming increasingly mature. Detection technologies such as cycle life, SOC (State of Charge) / SOH (State of Health), offline and online have become the key to evaluating the performance of power batteries. The length of the detection cycle directly affects the real-time monitoring and accurate evaluation of the performance of lithium batteries. Generally speaking, the detection cycle should be flexibly adjusted according to factors such as the type of lithium battery, charge-discharge rate, and environmental conditions. Different types of lithium batteries, such as lithium cobalt oxide batteries and lithium iron phosphate batteries, have different performance characteristics, so the requirements for the detection cycle will also vary.

[0004] Particularly, when detecting the cycle life of a lithium battery, a battery cycle charge-discharge instrument is conventionally used to perform charge-discharge tests on the battery under limited conditions (temperature, standing time, discharge rate, etc.), and the number of cycles when the capacity decays to 80% is used as the key indicator to measure the cycle life of the lithium battery. This conventional method faces bottleneck problems such as a long detection cycle, cumbersome steps, and low accuracy. To improve the detection speed of the lithium battery cycle life and shorten the detection cycle, currently, sampling detection and experiments are used to directly or indirectly detect the cycle life of the lithium battery by obtaining the relationship between the terminal voltage, internal resistance, and capacity curve of the lithium battery. To a certain extent, the detection time is shortened, but these methods cannot essentially reduce the detection cycle, and the effect is limited. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a method and system for rapidly detecting the cycle life of a lithium battery based on the principle of accelerated aging. The solution heats the lithium battery externally to the detection temperature and keeps it constant, and then performs cycle charge-discharge tests; based on the experimental test data, a temperature rise-acceleration matrix combining the charge-discharge rate, standing time, and number of cycles is established, and the simulated annealing algorithm is used for optimization to obtain the quantitative relationship between the number of cycles and the remaining capacity at the optimal temperature. Based on the principle of accelerated aging, a functional relationship between the remaining capacity, detection temperature, and number of cycles is established, and the equivalent number of cycles of the battery at the conventional detection temperature (25°C) is obtained, essentially reducing the cycle charge-discharge detection cycle, reducing energy consumption, and improving the detection efficiency of the cycle life of power lithium batteries.

[0006] According to the first aspect of the embodiments of the present invention, a method for rapidly detecting the cycle life of a lithium battery based on the principle of accelerated aging is provided, including:

[0007] Obtaining test data of the number of charge-discharge cycles when the capacity of the lithium battery decays to a preset percentage at different temperatures;

[0008] Based on the test data, constructing a temperature rise-acceleration matrix that combines the charge-discharge rate, the rest time, and the number of charge-discharge cycles;

[0009] Based on the temperature rise-acceleration matrix, with the goal of minimizing the number of charge-discharge cycles, obtaining the optimal heating temperature and the corresponding minimum number of charge-discharge cycles of the lithium battery;

[0010] According to the minimum number of charge-discharge cycles at the optimal temperature, adopting the method of polynomial fitting to construct the functional relationship between the remaining capacity of the lithium battery, the detection temperature, and the number of cycles;

[0011] According to the number of charge-discharge cycles when the lithium battery decays to a preset percentage at the optimal temperature, combined with the functional relationship, obtaining the equivalent number of charge cycles of the battery at a preset conventional detection temperature.

[0012] Further, the functional relationship is specifically expressed as follows:

[0013] Q loss =a 1 N 1 / 2 +a 2 N+a 3

[0014] a i =kexp(-Ea / RT), i = 1, 2, 3

[0015] Wherein, a 1 , a 2 , a 3 are respectively functions of temperature and discharge rate, N is the number of battery cycles, k is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, T represents the thermodynamic absolute temperature, and Q loss is the total capacity loss value caused by temperature rise aging.

[0016] Further, the construction of the temperature rise-acceleration matrix is specifically: taking the charge rate, the discharge rate, the rest time, and the number of cycles as the matrix dimensions, and taking the temperature rise as the eigenvalue of the matrix, obtaining a temperature rise-acceleration matrix representing the coupling relationship between multiple indicators.

[0017] Further, aiming to minimize the number of charge-discharge cycles, the optimal heating temperature and the corresponding minimum number of charge-discharge cycles of the lithium battery are obtained as follows: The simulated annealing algorithm is adopted. Based on the data in the temperature rise-acceleration matrix, a test temperature is randomly selected, and the corresponding charge-discharge rate, standing time, and number of cycles are jointly used as the initial solution. Based on the pre-constructed objective function, with temperature, charge-discharge rate, and standing time as inputs and the number of charge-discharge cycles as the output, the optimal heating temperature and the corresponding minimum number of charge-discharge cycles of the lithium battery are obtained by minimizing the number of charge-discharge cycles.

[0018] Further, the equivalent number of charge cycles of the battery at the preset conventional detection temperature is obtained specifically by using the following formula:

[0019]

[0020] where N 2 (25°C, SOC) is the equivalent number of charge cycles of the battery at the conventional detection temperature of 25°C, and N 1 (T x , SOC) is the minimum number of charge-discharge cycles of the lithium battery at the optimal heating temperature, T x is the optimal heating temperature, Q 0 is the standard capacity of the battery, SOC refers to the battery capacity, and Q loss is the total capacity loss value caused by temperature rise aging.

[0021] Further, the acquisition of the test data is specifically as follows: A number of lithium batteries are divided into several groups according to the test temperature; each group of lithium batteries is heated to its corresponding test temperature and kept at a constant temperature; after maintaining the preset standing time, a standard charge-discharge experiment is carried out until the battery capacity decays to the preset percentage to obtain the test data.

[0022] Further, in the acquisition of the test data, the charge-discharge rate, standing time, and charge-discharge cut-off voltage of the lithium battery are the same as those in the standard charge-discharge test.

[0023] According to the second aspect of the embodiments of the present invention, a rapid detection system for the cycle life of a lithium battery based on the principle of accelerated aging is provided, including:

[0024] A data acquisition unit for acquiring test data of the number of charge-discharge cycles when the capacity of the lithium battery decays to a preset percentage at different temperatures;

[0025] A matrix construction unit for constructing a temperature rise-acceleration matrix combining the charge-discharge rate, standing time, and number of charge-discharge cycles based on the test data;

[0026] An optimization solving unit, which is used to obtain the optimal heating temperature and the corresponding minimum number of charge-discharge cycles of the lithium battery with the goal of minimizing the number of charge-discharge cycles based on the temperature rise-acceleration matrix.

[0027] A fitting unit, which is used to construct the functional relationship between the remaining capacity of the lithium battery, the detection temperature, and the number of cycles by using polynomial fitting according to the minimum number of charge-discharge cycles at the optimal temperature.

[0028] A cycle life detection unit, which is used to obtain the equivalent charge-discharge cycles of the battery at the preset conventional detection temperature by combining the functional relationship with the number of charge-discharge cycles when the lithium battery decays to a preset percentage at the optimal temperature.

[0029] According to the third aspect of the embodiments of the present invention, an electronic device is provided, including a memory, a processor, and a computer program running on the memory. When the processor executes the program, the rapid detection method for the cycle life of a lithium battery based on the principle of accelerated aging is implemented.

[0030] According to the fourth aspect of the embodiments of the present invention, a non-transitory computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the rapid detection method for the cycle life of a lithium battery based on the principle of accelerated aging is implemented.

[0031] The above one or more technical solutions have the following beneficial effects:

[0032] (1) The present invention provides a rapid detection method and system for the cycle life of a lithium battery based on the principle of accelerated aging. The solution heats the lithium battery to the detection temperature by an external constant temperature and keeps it at a constant temperature, and then conducts a charge-discharge cycle test; based on the experimental test data, a temperature rise-acceleration matrix combining the charge-discharge rate, the standing time, and the number of cycles is established, and the simulated annealing algorithm is used for optimization to obtain the quantitative relationship between the number of cycles and the remaining capacity at the optimal temperature. Based on the principle of accelerated aging, a functional relationship between the remaining capacity, the detection temperature, and the number of cycles is established, and the equivalent number of cycles of the battery at the conventional detection temperature (25 °C) is obtained, which essentially reduces the charge-discharge cycle detection period, reduces energy consumption, and improves the detection efficiency of the cycle life of power lithium batteries.

[0033] (2) Compared with the cycle life attenuation process of a lithium battery at the conventional detection temperature, the solution of the present invention is based on the occurrence of accelerated aging side reactions inside the lithium battery after heating by an external heat source, which intensifies the capacity attenuation and indirectly reduces the number of charge-discharge cycles, effectively shortening the detection period of the cycle life.

[0034] (3) The solution of the present invention considers the coupling relationship of each detection index in the cycle detection process. Based on the construction of the temperature rise - acceleration matrix, the simulated annealing algorithm is used for optimization, and the optimal temperature and the corresponding minimum number of cycles are accurately and effectively obtained from the temperature range.

[0035] (4) The solution of the present invention fits the remaining capacity - detection temperature - number of cycles curve according to the experimental data of the minimum number of cycles at the optimal temperature. Under this curve, based on the principle of accelerated aging, the number of charge - discharge cycles of the lithium battery at the conventional detection temperature is equivalently deduced.

[0036] Advantages of additional aspects of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0038] Figure 1 is a schematic diagram of the heating principle of the external heating wire of the lithium battery helically wound in the embodiment of the present invention;

[0039] Figure 2 is a basic flowchart of the battery cycle life test after heating in the embodiment of the present invention;

[0040] Figure 3 is a flowchart of selecting the minimum number of cycles at the optimal temperature using the annealing algorithm in the embodiment of the present invention;

[0041] Figure 4 is a graph of the remaining capacity - number of charge - discharge cycles of the lithium battery at four heating temperatures obtained from the charge - discharge test of the battery after heating in the embodiment of the present invention;

[0042] Figure 5 is a charge - discharge mode diagram in the process of lithium battery cycle life detection in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0044] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention.

[0045] Without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0046] Term Explanation:

[0047] The equivalent cycle number of a lithium battery refers to the number of times of cyclic charge and discharge of the lithium battery after heating, and through accelerated aging inference, the equivalent cycle number of the lithium battery at the conventional detection temperature is obtained.

[0048] Embodiment 1

[0049] The purpose of this embodiment is to provide a rapid detection method for the cycle life of a lithium battery based on the principle of accelerated aging.

[0050] A rapid detection method for the cycle life of a lithium battery based on the principle of accelerated aging includes:

[0051] Obtaining test data of the number of cyclic charge and discharge times when the capacity of the lithium battery decays to a preset percentage at different temperatures;

[0052] Based on the test data, constructing a temperature rise - acceleration matrix combining charge - discharge rate, standing time, and the number of cyclic charge and discharge times;

[0053] Based on the temperature rise - acceleration matrix, with the goal of minimizing the number of cyclic charge and discharge times, obtaining the optimal heating temperature and its corresponding minimum number of cyclic charge and discharge times of the lithium battery;

[0054] According to the minimum number of cyclic charge and discharge times at the optimal temperature, adopting polynomial fitting to construct a functional relationship between the remaining capacity of the lithium battery, the detection temperature, and the number of cycles;

[0055] According to the number of cyclic charge and discharge times when the lithium battery decays to a preset percentage at the optimal temperature, combined with the functional relationship, obtaining the equivalent cycle charge times of the battery at the preset conventional detection temperature.

[0056] In specific implementation, the functional relationship is specifically expressed as follows:

[0057] Q loss =a 1 N 1 / 2 +a 2 N+a 3

[0058] a i =kexp(-Ea / RT), i = 1, 2, 3

[0059] Wherein, a 1 、a 2 、a 3They are respectively functions of temperature and discharge rate. N is the number of battery cycles, k is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, T represents the absolute thermodynamic temperature, and Q loss is the total capacity loss value caused by temperature rise aging.

[0060] In a specific implementation, the construction of the temperature rise-acceleration matrix is specifically as follows: taking the charge rate, discharge rate, rest time, and number of cycles as matrix dimensions, and taking the temperature rise as the eigenvalue of the matrix, a temperature rise-acceleration matrix representing the coupling relationship between multiple indicators is obtained.

[0061] In a specific implementation, aiming to minimize the number of cyclic charge and discharge, the optimal heating temperature and the corresponding minimum number of cyclic charge and discharge of the lithium battery are obtained as follows: using the simulated annealing algorithm, based on the data in the temperature rise-acceleration matrix, randomly select a test temperature, and jointly use its corresponding charge and discharge rate, rest time, and number of cycles as the initial solution. Based on the pre-constructed objective function, with temperature, charge and discharge rate, and rest time as inputs and the number of cyclic charge and discharge as the output, by minimizing the number of cyclic charge and discharge, the optimal heating temperature and the corresponding minimum number of cyclic charge and discharge of the lithium battery are obtained.

[0062] In a specific implementation, the equivalent cyclic charge number of the battery at the preset conventional detection temperature is obtained specifically by using the following formula:

[0063]

[0064] where N 2 (25°C, SOC) is the equivalent cyclic charge number of the battery at the conventional detection temperature of 25°C, and N 1 (T x , SOC) is the minimum number of cyclic charge and discharge of the lithium battery at the optimal heating temperature, and T x is the optimal heating temperature, Q 0 is the standard capacity of the battery, SOC refers to the battery capacity, and Q loss is the total capacity loss value caused by temperature rise aging.

[0065] In a specific implementation, the acquisition of the test data is specifically as follows: dividing a number of lithium batteries into several groups according to the test temperature; heating each group of lithium batteries to its corresponding test temperature and keeping it constant; after maintaining the preset rest time, performing a standard cyclic charge and discharge experiment until the capacity of the lithium battery decays to the preset percentage to obtain the test data.

[0066] In a specific implementation, in the acquisition of the test data, the charge and discharge rate, rest time, and charge and discharge cut-off voltage of the lithium battery are all consistent with the standard cyclic charge and discharge test.

[0067] Specifically, for ease of understanding, the solution of this embodiment will be described in detail below with reference to the accompanying drawings:

[0068] The SOC of a lithium battery represents its ability to store charge capacity, and numerically equals the percentage of the available capacity to the rated capacity. As shown in Equation (1):

[0069]

[0070] Among them, P i is the available capacity, P is the actual capacity, and the remaining capacity is (1 - SOC)%.

[0071] The cycle life of a lithium battery refers to the maximum number of charge and discharge cycles reached when the actual capacity decays to 80% of the rated capacity under certain usage conditions. Generally, in experiments, a charge and discharge cycle tester is used to test the cycle life of a lithium battery, and the test is carried out in an environment with a test temperature of 25°C ± 2°C, a relative humidity of 25% - 85%, and an atmospheric pressure of 86 kPa - 106 kPa.

[0072] Compared with the decay of the lithium battery life caused by charge and discharge cycles at a conventional temperature (25°C), the cycle charge and discharge life detection based on external heat source heating aims to promote the occurrence of internal aging side reactions of the lithium battery by externally applying a constant heat source to accelerate the capacity loss of the lithium battery on the premise of avoiding violent side reactions of the lithium battery, equivalently simulating the aging behavior during the use of the lithium battery, and obtaining the quantitative relationship among the remaining capacity - detection temperature - number of cycles of the lithium battery by analyzing the relationship between the internal microscopic aging mechanism and temperature rise of the lithium battery, so as to obtain the life decay situation of the lithium battery during long-term use in a relatively short time.

[0073] Specifically, the solution of this embodiment specifically includes the following processing steps:

[0074] Step 1: Based on the principle of accelerated aging, obtain the functional relationship between the capacity loss of the lithium battery, temperature, and number of cycles;

[0075] Among them, in the above Step 1, based on the test data of the lithium battery at the optimal temperature obtained from experiments and the principle of accelerated aging, combined with the Arrhenius equation, the functional relationship between the capacity loss of the lithium battery, temperature, and number of cycles is obtained, that is, the following Equation (2).

[0076] Specifically, the Arrhenius equation (i.e., the Arrhenius formula) is an empirical formula for the relationship between the chemical reaction rate constant and temperature, and its specific expression is:

[0077] k = Ae -Ea / RT (Exponential form).

[0078] Among them, k is the rate constant, R is the molar gas constant, T is the thermodynamic temperature, Ea is the apparent activation energy, and A is the pre-exponential factor.

[0079] Preferably, in the first step, the specific method of target fitting is as follows: The polynomial fitting method is adopted, the polynomial order is 2, the optimal fitting parameters are determined, and the function relation after fitting is as shown in formula (2) below.

[0080] Q loss = a 1 N 1 / 2 + a 2 N + a 3 (2)

[0081] In the above formula, it is the relationship between the lithium capacity decay and the number of cycles. Among them, Q loss is the total value of capacity loss caused by temperature rise aging, a 1 , a 2 , a 3 are respectively functions of temperature and discharge rate, and N is the number of battery cycles. Among them, a i = kexp(-Ea / RT), k is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, and T represents the thermodynamic absolute temperature.

[0082] In the specific implementation, the acquisition of the test data specifically includes the following processing procedures:

[0083] First step, select X lithium batteries of all samples for grouping, and each group of several lithium batteries is spirally wound with a heating wire outside to make the outside of the lithium battery evenly heated.

[0084] Second step, set the heating range as [25°C ± 2°C, 50°C ± 2°C]. According to the above grouping, each group of lithium batteries is heated to different interval temperatures by the heating wire at a constant temperature, and the heating time is t i . Specifically, when the temperature of a certain group of lithium batteries reaches T i , keep it at a constant temperature. It should be noted that the value of T i should be greater than 25°C ± 2°C, that is, greater than the temperature under the conventional detection conditions, and at the same time should be less than 50°C ± 2°C to prevent further complex and dangerous side reactions caused by too high external temperature of the lithium battery.

[0085] Third step, conduct a standard cycle charge and discharge experiment. The experimental conditions are set as follows:

[0086] 1. The termination index of the lithium battery cycle charge and discharge test is that the lithium battery capacity decays to 80%;

[0087] 2. Set the charge and discharge rate, rest time, charge and discharge cut-off voltage and other conditions to be the same as the values specified in the standard cycle charge and discharge test.

[0088] Step 4: Fitting experimental data. According to the cyclic charge and discharge experimental data of each group of lithium batteries, through polynomial fitting, the remaining capacity - cyclic charge and discharge times curve of each group of lithium batteries is obtained.

[0089] Step 2: Determine the equivalent cyclic charge and discharge times when the capacity of the lithium battery decays to 80% at the conventional temperature.

[0090] In the above Step 2, according to the cyclic charge and discharge times when the capacity of the lithium battery decays to 80% at the optimal temperature, combined with the function relationship of battery remaining capacity - detection temperature - cycle times, the equivalent cyclic charge and discharge times of the battery at the conventional detection temperature are obtained.

[0091] Among them, the acquisition of the cyclic charge and discharge times when the capacity of the lithium battery decays to 80% at the optimal temperature specifically adopts the following technical concept: According to the experimental data, establish a temperature rise - acceleration matrix combining charge - discharge rate, standing time, and cycle times, and use the simulated annealing algorithm to obtain the minimum cycle times at the optimal temperature. It specifically includes the following steps:

[0092] Step 1: Data collection and state estimation. Collect the experimental data of the battery cyclic charge and discharge tester in the temperature range [20°C, 50°C], remove outliers and missing values of other indicators such as temperature and cycle times to ensure data quality.

[0093] Step 2: Establishment of the temperature rise - acceleration matrix. Take the charge - discharge rate, discharge rate, standing time, and cycle times as the matrix dimensions, and take the temperature rise as the eigenvalue of the matrix to construct a temperature rise - acceleration matrix considering the coupling relationship between each indicator, specifically expressed as the column vectors being the charge - discharge rate, discharge rate, standing time, and cycle times respectively.

[0094] Step 3: Optimization by the simulated annealing algorithm. Based on the temperature rise - acceleration matrix data, randomly select a set of temperature, combined charge - discharge rate, standing time, and cycle times as the initial solution. Define the objective function, whose input is charge - discharge indicators such as temperature, charge - discharge rate, and standing time, and the output is the corresponding cyclic charge and discharge times. The optimization goal is to minimize the cyclic charge and discharge times, and the specific algorithm process is as Figure 3 shown.

[0095] Step 4: Result analysis and optimization. Record the results of each simulation annealing search of temperature, combined charge - discharge rate, standing time, and cycle times to obtain the minimum cyclic charge and discharge times N of the lithium battery at the optimal heating temperature T x under. Part of the heating curve is as x shown. According to the analysis results, adjust the parameters such as the initial temperature, discharge rate, and standing time of the simulated annealing algorithm to improve the search efficiency and result accuracy. Figure 4 shown. According to the analysis results, adjust the initial temperature, discharge rate, standing time and other parameters of the simulated annealing algorithm to improve the search efficiency and result accuracy.

[0096] It is easy to know that since the temperature rise accelerates the internal aging side reactions of the lithium battery, causing capacity loss of the lithium battery to a certain extent, the minimum number of cycles N x is less than the number of cycles in the standard cycle life test, shortening the detection period.

[0097] Preferably, in the second step, the charge and discharge times N of the lithium battery at the optimal temperature 1 , according to formula (2), the cyclic charge and discharge times N of the lithium battery at the conventional detection temperature are obtained 2 , and a capacity-temperature-cycle number function relationship needs to be established. The calculation formula is:

[0098]

[0099] where Q 0 refers to the standard capacity of the battery, SOC refers to the battery capacity, and Q loss is the total capacity loss value caused by temperature rise aging.

[0100] It should be noted here that formula (2) is the expression of capacity loss after temperature rise with temperature and cycle number, and formula (3) is the expression at the conventional temperature (25°C), that is, the final target formula.

[0101] Currently, for the conventional lithium battery cycle life test, generally according to GB / T2900.41-2008 and the standards for the cycle performance requirements of power batteries for electric vehicles, the detection method is generally to conduct charge and discharge cycle experiments on the lithium battery under a cycle charge and discharge instrument. This test cycle takes about one week, with a long time and high energy consumption.

[0102] This detection method is proposed based on the original detection. First, the temperature of the lithium battery is raised and then charge and discharge cycle experiments are carried out. After obtaining the experimental data, using the simulated annealing algorithm, the remaining capacity-detection temperature-cycle number curve of the battery at the optimal temperature is obtained. According to the principle of accelerated aging, the cyclic charge and discharge times at the conventional temperature are equivalently deduced, effectively shortening the battery cyclic charge and discharge detection period. The specific detection steps are as follows:

[0103] First, group the sample batteries, with each group containing several single cells.

[0104] Furthermore, determine the heating temperature of the lithium battery. Within the heating range [25°C ± 2°C, 40°C ± 2°C], each group of batteries is preheated according to different heating temperatures. It should be noted that the temperature value reached during preheating should be higher than the conventional detection temperature.

[0105] Furthermore, conduct the charge and discharge cycle test of the lithium battery.

[0106] Specifically, the charge and discharge cycle method is as follows:

[0107] ①Standard 1C charging, and the charging steps and detailed instructions can refer to the detection steps provided by the corresponding battery manufacturer.

[0108] ②Let it stand for 30 min to keep the battery temperature constant.

[0109] ③Discharge at a 1C rate until the state of charge is 0%, and the detailed discharge cut-off state can refer to the requirements in the battery manufacturer's instructions.

[0110] In addition, during the cyclic charge and discharge process, when the temperature fluctuates or is higher than the constant temperature, the standing time of the battery can be appropriately increased to keep the temperature constant. The test environment should also be carried out in an environment with a relative humidity of 25% - 85% and an atmospheric pressure of 86 kPa - 106 kPa.

[0111] The above is to complete one charge and discharge cycle. In particular, after N cycles, if the battery capacity decays to less than 80% after the (N + 1)th cycle, that is, the cyclic charge and discharge capacity value of the battery exceeds the [20% - 100%] interval, the detection stops, and the final number of cycles is used as an index to measure the battery cycle life. In addition, when the battery voltage and other indicators do not meet the test requirements during the cyclic charging process, the cycle life detection stops.

[0112] Furthermore, according to the experimental data of each group of batteries, a temperature rise - acceleration matrix is constructed, and the simulated annealing algorithm is used for optimization to obtain the minimum cyclic charge and discharge times of the battery at the optimal temperature. Based on this group of data, a remaining capacity - detection temperature - number of cycles curve at the optimal temperature is further obtained.

[0113] Finally, based on the principle of accelerated aging, the cyclic charge and discharge times of lithium batteries at the conventional detection temperature are derived, that is, the cycle life of the battery at the conventional detection temperature is equivalently obtained.

[0114] Embodiment 2

[0115] The purpose of this embodiment is to provide a rapid detection system for the cycle life of lithium batteries based on the principle of accelerated aging.

[0116] A rapid detection system for the cycle life of lithium batteries based on the principle of accelerated aging includes:

[0117] A data acquisition unit, which is used to acquire test data on the number of cyclic charge and discharge times when the capacity of a lithium battery decays to a preset percentage at different temperatures;

[0118] A matrix construction unit, which is used to construct a temperature rise - acceleration matrix combining charge and discharge rate, standing time, and the number of cyclic charge and discharge times based on the test data;

[0119] An optimization and solution unit, which is used to obtain the optimal heating temperature and the corresponding minimum cyclic charge and discharge times of the lithium battery with the goal of minimizing the number of cyclic charge and discharge times based on the temperature rise - acceleration matrix;

[0120] A fitting unit, which is used to construct the functional relationship between the remaining capacity of the lithium battery, the detection temperature and the number of cycles by means of polynomial fitting according to the minimum number of cyclic charge and discharge times at the optimal temperature.

[0121] A cycle life detection unit, which is used to obtain the equivalent cyclic charge times of the battery at the preset conventional detection temperature by combining the functional relationship with the number of cyclic charge and discharge times when the lithium battery decays to a preset percentage at the optimal temperature.

[0122] It should be noted here that each module in this embodiment corresponds to each step in Embodiment 1 one by one, and its specific implementation process is the same, so it will not be repeated here.

[0123] In more embodiments, there is also provided:

[0124] An electronic device, including a memory, a processor, and computer instructions stored on the memory and running on the processor. When the computer instructions are run by the processor, the method described in Embodiment 1 is completed. For the sake of brevity, it will not be elaborated here.

[0125] It should be understood that in this embodiment, the processor may be a central processing unit CPU, and the processor may also be other general-purpose processors, digital signal processors DSP, application-specific integrated circuits ASIC, off-the-shelf programmable gate arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0126] The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A part of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the device type.

[0127] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, complete the method described in Embodiment 1.

[0128] The method in Embodiment 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules in the processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0129] Those of ordinary skill in the art can realize that the units or algorithm steps of the examples described in conjunction with this embodiment can be implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0130] The foregoing is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A rapid detection method for the cycle life of lithium batteries based on the principle of accelerated aging, characterized in that: include: Obtain test data on the number of charge and discharge cycles when the capacity of the lithium battery decays to a preset percentage at different temperatures; Based on the test data, a temperature rise-acceleration matrix combining charge and discharge rate, rest time and number of charge and discharge cycles is constructed; Based on the temperature rise-acceleration matrix, with the goal of minimizing the number of charge and discharge cycles, the optimal heating temperature and its corresponding minimum charge and discharge cycle number of the lithium battery are obtained; The method aims to minimize the number of charge and discharge cycles, and obtains the optimal heating temperature and the corresponding minimum charge and discharge cycle number of the lithium battery. Specifically, the method comprises: using a simulated annealing algorithm, randomly selecting a test temperature based on the data in the temperature rise-acceleration matrix, combining the corresponding charge and discharge rate, rest time and number of cycles as an initial solution, and based on a pre-constructed objective function, using temperature, charge and discharge rate and rest time as inputs, and the number of charge and discharge cycles as output, and obtaining the optimal heating temperature and the corresponding minimum charge and discharge cycle number of the lithium battery by minimizing the number of charge and discharge cycles; According to the minimum number of charge and discharge cycles at the optimal temperature, a polynomial fitting method is used to construct a functional relationship between the remaining capacity of the lithium battery and the detection temperature and the number of cycles; The functional relationship is specifically expressed as follows: <h2 style=";text-align:left;direction:ltr">Q<h2 style=";text-align:left;direction:ltr"> loss <h2 style=";text-align:left;direction:ltr"> =a1N<h2 style=";text-align:left;direction:ltr"> 1 / 2 <h2 style=";text-align:left;direction:ltr"> +a2N+a3 a i =kexp(-Ea / RT),i=1,2,3 Among them, a1, a2, and a3 are functions of temperature and discharge rate, respectively, N is the number of battery cycles, k is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, T represents the absolute thermodynamic temperature, Q loss It is the total capacity loss value caused by temperature aging; According to the number of charge and discharge cycles when the lithium battery decays to a preset percentage at the optimal temperature, combined with the functional relationship, the equivalent number of charge cycles of the battery at a preset conventional detection temperature is obtained.

2. A rapid detection method for lithium battery cycle life based on the accelerated aging principle as claimed in claim 1, characterized in that: The construction of the temperature rise-acceleration matrix is ​​specifically as follows: the charge rate, discharge rate, rest time, and cycle number are used as matrix dimensions, and the temperature rise is used as the eigenvalue of the matrix to obtain a temperature rise-acceleration matrix representing the coupling relationship between multiple indicators.

3. A rapid detection method for lithium battery cycle life based on accelerated aging principle as claimed in claim 1, characterized in that: The equivalent number of charging cycles of the battery at the preset conventional detection temperature is obtained by using the following formula: Among them, N2 (25 ° C, SOC) is the equivalent number of battery cycle charging at the normal detection temperature of 25 ° C, N1 (T x , SOC) is the minimum charge and discharge cycle number of lithium battery at the optimal heating temperature, T x is the optimal heating temperature, Q0 is the standard capacity of the battery, SOC refers to the battery capacity, Q loss It is the total capacity loss value caused by temperature aging.

4. A rapid detection method for lithium battery cycle life based on accelerated aging principle as claimed in claim 1, characterized in that: The test data is obtained by dividing a number of lithium batteries into a number of groups according to the test temperature; heating each group of lithium batteries to its corresponding test temperature and maintaining a constant temperature; performing a standard cycle charge and discharge experiment after a preset standing time until the lithium battery capacity decays to a preset percentage to obtain the test data.

5. A rapid detection method for lithium battery cycle life based on the accelerated aging principle as claimed in claim 1, characterized in that: In acquiring the test data, the charge and discharge rate, standing time and charge and discharge cut-off voltage of the lithium battery are all consistent with the standard cycle charge and discharge test.

6. A rapid detection system for lithium battery cycle life based on the principle of accelerated aging, characterized in that: include: A data acquisition unit, which is used to acquire test data of the number of charge and discharge cycles when the capacity of the lithium battery decays to a preset percentage at different temperatures; A matrix construction unit, which is used to construct a temperature rise-acceleration matrix of combined charge and discharge rate, rest time and number of cycle charge and discharge based on the test data; An optimization solving unit, which is used to obtain the optimal heating temperature and its corresponding minimum charge and discharge cycle number of the lithium battery based on the temperature rise-acceleration matrix with the goal of minimizing the number of charge and discharge cycles; The method aims to minimize the number of charge and discharge cycles, and obtains the optimal heating temperature and the corresponding minimum charge and discharge cycle number of the lithium battery. Specifically, the method comprises: using a simulated annealing algorithm, randomly selecting a test temperature based on the data in the temperature rise-acceleration matrix, combining the corresponding charge and discharge rate, rest time and number of cycles as an initial solution, and based on a pre-constructed objective function, using temperature, charge and discharge rate and rest time as inputs, and the number of charge and discharge cycles as output, and obtaining the optimal heating temperature and the corresponding minimum charge and discharge cycle number of the lithium battery by minimizing the number of charge and discharge cycles; A fitting unit, which is used to construct a functional relationship between the remaining capacity of the lithium battery and the detection temperature and the number of cycles by using a polynomial fitting method according to the minimum number of charge and discharge cycles at the optimal temperature; The functional relationship is specifically expressed as follows: <h2 style=";text-align:left;direction:ltr">Q<h2 style=";text-align:left;direction:ltr"> loss <h2 style=";text-align:left;direction:ltr"> =a1N<h2 style=";text-align:left;direction:ltr"> 1 / 2 <h2 style=";text-align:left;direction:ltr"> +a2N+a3 a i =kexp(-Ea / RT),i=1,2,3 Among them, a1, a2, and a3 are functions of temperature and discharge rate, respectively, N is the number of battery cycles, k is the pre-exponential factor, Ea is the activation energy, R is the universal gas constant, T represents the absolute thermodynamic temperature, Q loss It is the total capacity loss value caused by temperature aging; The cycle life detection unit is used to obtain the equivalent cycle charging number of the battery at a preset conventional detection temperature based on the number of cycle charge and discharge when the lithium battery decays to a preset percentage at the optimal temperature, combined with the functional relationship.

7. An electronic device comprising a memory, a processor and a computer program stored and running on the memory, characterized in that: When the processor executes the program, a rapid detection method for the cycle life of a lithium battery based on the accelerated aging principle as described in any one of claims 1 to 5 is implemented.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, a rapid detection method for the cycle life of a lithium battery based on the accelerated aging principle as described in any one of claims 1 to 5 is implemented.

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