A method, device and processing equipment for evaluating consistency of lithium batteries in the same batch

Abstract

The present application provides a method, device and processing equipment for evaluating the consistency of lithium batteries in the same batch, which is used to provide a convenient evaluation mechanism for the consistency of lithium batteries, so as to stably, quickly and accurately determine the consistency between single lithium batteries. The method includes: p , self-heating temperature T generation and the current ambient temperature T a Based on the data from the calculation, determine the cell energy H released by the battery at any time during the entire charging and discharging process; based on the cell volume V, normalized concentration dC / dt and cell energy H, determine the thermal energy Q from the chemical reaction of the battery; based on the thermal energy Q, calculate the instantaneous heat generation power P of the battery during the charging and discharging process; charge and discharge different batteries, and record their respective charging and discharging time, temperature rise inertia temperature difference; compare the standard deviation coefficients of the instantaneous heat generation power P, charging and discharging time and temperature rise inertia temperature difference among different batteries; according to the standard deviation coefficient, determine the consistency between different batteries.

Description

Technical Field

[0001] The present application relates to the field of lithium batteries, and specifically to a method, device and processing equipment for evaluating the consistency of lithium batteries in the same batch. Background Art

[0002] Lithium batteries are widely used as new energy power sources and electric energy storage devices due to their high energy density and long cycle life. A lithium battery module is composed of several single lithium batteries connected in series and parallel. When the lithium battery exceeds the standard range of temperature, voltage, charge and discharge current or charging state specified by the national standard, it will cause battery performance to decline, and even failure or thermal runaway. When thermal runaway spreads from one or several lithium batteries to other lithium batteries, a thermal runaway chain reaction occurs due to heat propagation. Therefore, thermal propagation can easily lead to serious consequences, such as electrolyte leakage, release of toxic substances, fire and even explosion.

[0003] The internal causes of thermal runaway are very complex, among which the most important and not to be ignored is the inconsistency between single lithium batteries. The inconsistency of lithium battery parameters mainly refers to the inconsistency of parameters such as capacity, internal resistance, open circuit voltage, and heat generation power. The initial inconsistency accumulates with the continuous charge and discharge cycles of the battery during use, resulting in greater differences in the conditions of each single battery (state of charge, voltage, etc.). The operating environment in the lithium battery pack is also different for each single battery. These complex factors cause the inconsistency of the single battery to gradually increase during use, and then in some cases, the function of some single lithium batteries is accelerated to decay, and eventually lead to premature failure of the lithium battery pack.

[0004] The main reasons for the inconsistency of lithium batteries are: there are problems such as process, manufacturing differences and material unevenness in the production process, which make the materials of lithium batteries have very slight differences. After the lithium battery pack is put into use, the individual lithium batteries in the lithium battery pack are affected by the different operating environments such as electrolyte density, temperature and ventilation conditions, self-discharge degree and charging and discharging process. The capacity and internal resistance of the same model batteries produced from the same batch may be different.

[0005] In the process of studying the existing related technologies, the inventors found that the most commonly used lithium battery consistency evaluation methods are the range coefficient method, the standard deviation coefficient method and the threshold method, combined with cluster analysis, and scientific classification is performed according to the shape, distance and area of ​​the battery charge and discharge curve formed by each detection point within a set time interval, so as to determine the consistency of the battery. On the basis of the capacity or voltage threshold, the shape of the charge and discharge curve, the distance between the curves, the area enclosed by the curves, etc. are calculated, and the parameters that can reflect the consistency of the curves are selected for judgment. The cells with closer curves, smaller relative distances, smaller areas enclosed by the curves, and smaller differences between groups during the charge and discharge process are selected for grouping, so as to achieve the optimal consistent grouping. However, in specific applications, the disadvantage of the above-mentioned consistency evaluation method is that the judgment process is more complicated, and a reasonable battery balancing strategy needs to be formulated to balance the battery. During the use of the lithium battery pack, the parameters of each single lithium battery are detected and the development law of the inconsistency of the single battery is mastered. There are considerable difficulties in the actual implementation process. Summary of the invention

[0006] The present application provides a method, device and processing equipment for evaluating the consistency of lithium batteries in the same batch, which is used to provide a convenient evaluation mechanism for the consistency of lithium batteries, so that the consistency between single lithium batteries can be determined stably, quickly and accurately, providing reliable data support for the application of lithium battery packs.

[0007] In a first aspect, the present application provides a method for evaluating the consistency of lithium batteries in the same batch, the method comprising:

[0008] Obtain the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate;

[0009] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, determine the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process;

[0010] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined;

[0011] Based on the thermal energy Q, calculate the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process;

[0012] Charge and discharge different single lithium batteries, and record the charge and discharge time of each single lithium battery, and the temperature difference due to temperature rise inertia after the temperature rises to the same temperature;

[0013] Compare the instantaneous heat generation power P, charge and discharge time and standard deviation coefficient of temperature rise inertia temperature difference between different single lithium batteries;

[0014] The consistency between different single-cell lithium batteries is determined based on the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

[0015] In combination with the first aspect of the present application, in a first possible implementation of the first aspect of the present application, the battery cell mass M, the specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a Based on this, the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process is determined, including:

[0016] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, the cell energy H released by different single-cell lithium batteries at any time during the entire charging and discharging process is determined by combining the following first formula:

[0017] H=M×C p ×(T generation -T a ).

[0018] In combination with the first aspect of the present application, in a second possible implementation of the first aspect of the present application, based on the cell volume V, the normalized concentration dC / dt and the cell energy H, the heat energy Q from the chemical reaction of different single lithium batteries is determined, including:

[0019] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined by combining the following second formula:

[0020] Q = 1 / V × H × dC / dt.

[0021] In combination with the first aspect of the present application, in a third possible implementation of the first aspect of the present application, charging and discharging are specifically performed at a temperature of 25°C ± 5°C and under the conditions of GB / T 31485-2015 standard, including:

[0022] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0023] Let stand for 30 minutes;

[0024] Charge with 1C constant current to the charging cut-off voltage, and then charge with constant voltage until the charging current drops to 0.05C;

[0025] Let stand for 30 minutes;

[0026] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0027] Let stand for 30 minutes;

[0028] Charge the battery with a 1C constant current rate until the charge cut-off voltage is reached, and then charge at a constant voltage until the charging current drops to 0.05C.

[0029] In combination with the first aspect of the present application, in a fourth possible implementation of the first aspect of the present application, different single-cell lithium batteries are charged and discharged, and the charge and discharge time of each of the different single-cell lithium batteries and the temperature rise inertia temperature difference after being raised to the same temperature due to the temperature rise inertia are recorded, including:

[0030] Carry out N rounds of charge and discharge on different single lithium batteries, and record the N rounds of charge and discharge time of different single lithium batteries, and the N rounds of temperature rise inertia temperature difference after the temperature is raised to the same temperature due to the temperature rise inertia;

[0031] The final data is taken based on the average of N rounds of charge and discharge time and N rounds of maximum temperature of different single-cell lithium batteries.

[0032] In combination with the fourth possible implementation of the first aspect of the present application, in the fifth possible implementation of the first aspect of the present application, the number N is specifically 5.

[0033] In combination with the first aspect of the present application, in a sixth possible implementation of the first aspect of the present application, the different single-cell lithium batteries are specifically 4 lithium batteries of the same manufacturer, the same model and the same batch selected.

[0034] In a second aspect, the present application provides a device for evaluating the consistency of lithium batteries in the same batch, the device comprising:

[0035] Acquisition unit, used to obtain the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate;

[0036] Determine the unit for the battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, determine the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process;

[0037] The determination unit is also used to determine the heat energy Q from the chemical reaction of different single lithium batteries based on the battery cell volume V, the normalized concentration dC / dt and the battery cell energy H;

[0038] A calculation unit, used to calculate the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process based on the heat energy Q;

[0039] The charge and discharge unit is used to charge and discharge different single lithium batteries, and record the charge and discharge time of different single lithium batteries, and the temperature difference of temperature rise inertia after they are raised to the same temperature due to the temperature rise inertia;

[0040] A comparison unit is used to compare the instantaneous heat generation power P, the charging and discharging time and the standard deviation coefficient of the temperature rise inertia temperature difference between different single lithium batteries;

[0041] The determination unit is also used to determine the consistency between different single-cell lithium batteries according to the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

[0042] In conjunction with the second aspect of the present application, in a first possible implementation manner of the second aspect of the present application, the determining unit is specifically configured to:

[0043] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, the cell energy H released by different single-cell lithium batteries at any time during the entire charging and discharging process is determined by combining the following first formula:

[0044] H=M×C p ×(T generation -T a ).

[0045] In conjunction with the second aspect of the present application, in a second possible implementation manner of the second aspect of the present application, the determining unit is specifically configured to:

[0046] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined by combining the following second formula:

[0047] Q = 1 / V × H × dC / dt.

[0048] In combination with the second aspect of the present application, in a third possible implementation of the second aspect of the present application, charging and discharging are specifically performed at a temperature of 25°C ± 5°C and under the conditions of GB / T 31485-2015 standard, including:

[0049] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0050] Let stand for 30 minutes;

[0051] Charge with 1C constant current to the charging cut-off voltage, and then charge with constant voltage until the charging current drops to 0.05C;

[0052] Let stand for 30 minutes;

[0053] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0054] Let stand for 30 minutes;

[0055] Charge the battery with a 1C constant current rate until the charge cut-off voltage is reached, and then charge at a constant voltage until the charging current drops to 0.05C.

[0056] In combination with the second aspect of the present application, in a fourth possible implementation of the second aspect of the present application, the charging and discharging unit is specifically used for:

[0057] Carry out N rounds of charge and discharge on different single lithium batteries, and record the N rounds of charge and discharge time of different single lithium batteries, and the N rounds of temperature rise inertia temperature difference after the temperature is raised to the same temperature due to the temperature rise inertia;

[0058] The final data is taken based on the average of N rounds of charge and discharge time and N rounds of maximum temperature of different single-cell lithium batteries.

[0059] In combination with the fourth possible implementation of the second aspect of the present application, in the fifth possible implementation of the second aspect of the present application, the number N is specifically 5.

[0060] In combination with the second aspect of the present application, in a sixth possible implementation of the second aspect of the present application, the different single-cell lithium batteries are specifically 4 lithium batteries of the same manufacturer, the same model and the same batch selected.

[0061] In a third aspect, the present application provides a processing device, including a processor and a memory, wherein a computer program is stored in the memory, and when the processor calls the computer program in the memory, the method provided in the first aspect of the present application or any possible implementation method of the first aspect of the present application is executed.

[0062] In a fourth aspect, the present application provides a computer-readable storage medium, which stores multiple instructions, and the instructions are suitable for a processor to load to execute the method provided by the first aspect of the present application or any possible implementation of the first aspect of the present application.

[0063] From the above content, it can be concluded that the present application has the following beneficial effects:

[0064] In response to the need for consistency evaluation between single-cell lithium batteries, this application focuses on the instantaneous heat generation power P calculated by parameters, and the standard deviation coefficients of the charge and discharge time and the temperature rise inertia temperature difference measured by charge and discharge. The consistency between different single-cell lithium batteries is determined through the standard deviation coefficients of these three aspects. Under this evaluation mechanism, it has the advantage of convenient operating costs and avoids the problem of high application costs caused by the existing evaluation schemes being too complicated. It can stably, quickly and accurately determine the consistency between single-cell lithium batteries, providing reliable data support for the application of lithium battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0066] Figure 1 A schematic diagram of a process for evaluating the consistency of lithium batteries in the same batch of this application;

[0067] Figure 2 This is a schematic diagram of the structure of a consistency evaluation device for lithium batteries of the same batch in this application;

[0068] Figure 3 A schematic diagram of the structure of the processing equipment of this application. DETAILED DESCRIPTION

[0069] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0070] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described here can be implemented in an order other than that illustrated or described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or modules is not necessarily limited to those steps or modules clearly listed, but may include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices. The naming or numbering of steps in this application does not mean that the steps in the method flow must be executed in the time / logical sequence indicated by the naming or numbering. The process steps that have been named or numbered can change the execution order according to the technical purpose to be achieved, as long as the same or similar technical effects can be achieved.

[0071] The division of modules in this application is a logical division. There may be other division methods when it is implemented in actual applications. For example, multiple modules can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, and the indirect coupling or communication connection between modules can be electrical or other similar forms, which are not limited in this application. In addition, the modules or submodules described as separate components may or may not be physically separated, may or may not be physical modules, or may be distributed in multiple circuit modules, and some or all of the modules may be selected according to actual needs to achieve the purpose of the present application.

[0072] Before introducing the consistency evaluation method for lithium batteries in the same batch provided in this application, the background content involved in this application is first introduced.

[0073] The consistency evaluation method, device and computer-readable storage medium for lithium batteries in the same batch provided in the present application can be applied to processing equipment to provide a convenient evaluation mechanism for the consistency of lithium batteries, so that the consistency between single lithium batteries can be determined stably, quickly and accurately, providing reliable data support for the application of lithium battery packs.

[0074] The consistency evaluation method for lithium batteries from the same batch mentioned in this application can be performed by a consistency evaluation device for lithium batteries from the same batch, or a server, physical host, or user equipment (UE) and other different types of processing equipment that integrate the consistency evaluation device for lithium batteries from the same batch. Among them, the consistency evaluation device for lithium batteries from the same batch can be implemented in hardware or software, and the UE can be a terminal device such as a smart phone, tablet computer, laptop computer, desktop computer, or personal digital assistant (PDA), and the processing device can be set in the form of a device cluster.

[0075] Among them, for the processing device, in actual applications, the relevant unique equipment or unique components that may be involved in the content of this application scheme can be included in the processing device, so that the processing device can complete the corresponding functional processing, or the processing device can prompt it to perform the corresponding functional processing in the form of control or triggering.

[0076] Next, we will introduce the consistency evaluation method for lithium batteries in the same batch provided by this application.

[0077] First, see Figure 1 , Figure 1 A schematic flow chart of the method for evaluating the consistency of lithium batteries in the same batch of the present application is shown. The method for evaluating the consistency of lithium batteries in the same batch provided by the present application may specifically include the following steps S101 to S107:

[0078] Step S101, obtaining the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate;

[0079] It can be understood that the present application determines the consistency between single lithium batteries by combining both static and dynamic aspects.

[0080] In terms of static state, the purpose of this application is to obtain the instantaneous heat generation power P of each single lithium battery in the subsequent charging and discharging process. For this purpose, some preset parameters of the single lithium battery can be retrieved and extracted for processing.

[0081] Specifically, these parameters include the cell mass M, specific heat capacity C p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate.

[0082] In addition, it should be understood that, for these parameters, in specific applications, although they are static parameters, the present application can also obtain them through real-time detection or real-time analysis.

[0083] Among them, as a practical implementation method, the consistency evaluation strategy configured in this application can be specifically carried out in units of 4 lithium batteries, and can specifically be 4 lithium batteries of the same manufacturer, model and batch selected. That is to say, each single lithium battery for consistency evaluation uses the same manufacturer, model and batch of the same conditions. Under this setting, the consistency evaluation has the advantages of low cost and convenient processing.

[0084] Step S102, when the cell mass M and specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, determine the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process;

[0085] After obtaining the cell mass M, specific heat capacity C p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a After obtaining the parameters such as the cell volume V and the normalized concentration dC / dt of the chemical reaction rate, the corresponding parameters can be processed to obtain the instantaneous heat generation power P.

[0086] Here, the cell mass M and specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a These four parameters are used to obtain the battery cell energy H released at any moment during the entire charging and discharging process, providing data support for the subsequent thermal energy Q from the chemical reaction of the battery.

[0087] Specifically, as another practical implementation, the determination process of the cell energy H can be specifically performed by the following contents:

[0088] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, the cell energy H released by different single-cell lithium batteries at any time during the entire charging and discharging process is determined by combining the following first formula:

[0089] H=M×C p ×(T generation -T a ) (1)

[0090] Step S103, determining the heat energy Q from chemical reactions of different single lithium batteries based on the cell volume V, the normalized concentration dC / dt and the cell energy H;

[0091] After determining the cell energy H released by a single lithium battery at any time during the entire charging and discharging process, we can then determine the heat energy Q from the chemical reaction of the battery as further data support.

[0092] As another practical implementation method, the processing of the heat energy Q from the chemical reaction of the single lithium battery can be specifically achieved in the following way:

[0093] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined by combining the following second formula:

[0094] Q=1 / V×H×dC / dt (2)

[0095] Step S104, based on the thermal energy Q, calculating the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process;

[0096] It is easy to understand that the thermal energy Q is obtained by accumulating the instantaneous heat generation power P during the charging and discharging process. Therefore, the instantaneous heat generation power P can be obtained in a differential form.

[0097] Specifically, as another practical implementation, the instantaneous heat generation power P can be obtained by the following third formula:

[0098] P=dQ / dt (3)

[0099] Among them, t is the charging and discharging time.

[0100] Step S105, charging and discharging different single lithium batteries, and recording the charging and discharging time of each of the different single lithium batteries, and the temperature difference of temperature rise inertia after the temperature rises to the same temperature due to the temperature rise inertia;

[0101] In addition to the static instantaneous heat generation power P mentioned above, the present application also needs to obtain two dynamic parameters corresponding to charging and discharging, namely the charging and discharging time of different single-cell lithium batteries, and the temperature rise inertia temperature difference after being raised to the same temperature due to the temperature rise inertia.

[0102] To this end, each single lithium battery participating in the consistency evaluation can be charged and discharged, and during the process, the charge and discharge time of each single lithium battery and the temperature rise inertia temperature difference after being raised to the same temperature due to the temperature rise inertia are recorded.

[0103] It can be understood that the present application can specifically select 4 lithium batteries as the consistency evaluation objects, and these batteries can be specifically configured to be from the same manufacturer, the same model and the same batch.

[0104] In specific applications, it is easy to understand that deviations may come from differences between battery samples, test operations and data collection processes. Selecting lithium battery samples from the same manufacturer, the same model and the same batch can greatly reduce the impact of differences between battery samples. As all processing uses the same instruments and even operators and is completed in accordance with standard test plans, the impact of test operations and data collection on the evaluation results can be minimized.

[0105] Among them, as an example, through testing, it was found that the diameter, height, weight, positive and negative electrode materials, and charge and discharge cut-off voltage of the four lithium batteries are the same, and the different parameters are the rated capacity and rated energy.

[0106] Further, as another practical implementation, the charge and discharge process involved in the present application may specifically include the following contents:

[0107] The charging and discharging is carried out at a temperature of 25℃±5℃ and in accordance with the GB / T 31485-2015 standard. The specific contents include:

[0108] 1. Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0109] 2. Let stand for 30 minutes;

[0110] 3. Charge with 1C constant current to the charging cut-off voltage, and then charge with constant voltage until the charging current drops to 0.05C;

[0111] 4. Let stand for 30 minutes;

[0112] 5. Discharge at 1C constant current until the discharge cut-off voltage is reached (the discharge capacity can be used as the rated capacity of the battery);

[0113] 6. Let stand for 30 minutes;

[0114] 7. Charge the battery with a 1C constant current rate until the charge cut-off voltage is reached, and then charge at a constant voltage until the charging current drops to 0.05C.

[0115] Specifically, under the same charge and discharge rate conditions, record the charge and discharge time when the battery temperature rises to the same temperature (set temperature). When the lithium battery temperature rises to the same temperature (set temperature), stop charging and discharging it, let it cool naturally, and conduct convection heat exchange with the air. At this time, due to the inertia of temperature rise, the temperature of the lithium battery will continue to rise until the maximum temperature is recorded, and the difference between the maximum temperature and the set temperature is calculated, and their difference results are recorded as the adopted data of the temperature difference due to temperature rise inertia.

[0116] Step S106, comparing the instantaneous heat generation power P, the charge and discharge time, and the standard deviation coefficient of the temperature rise inertia temperature difference between different single lithium batteries;

[0117] It can be understood that after the previous processing, the three parameters of instantaneous heat generation power P, charging and discharging time, and temperature rise inertia temperature difference of each single lithium battery can be obtained. At this time, the standard deviation coefficient of the same parameter index can be processed between the single lithium batteries to quantify the consistency and difference between the single lithium batteries.

[0118] Furthermore, it is understandable that the charge and discharge process performed in the present application may also involve multiple rounds of charge and discharge, thereby being able to better meet the parameters of actual conditions.

[0119] Specifically, as another practical implementation, the charge and discharge process may be:

[0120] Carry out N rounds of charge and discharge on different single lithium batteries, and record the N rounds of charge and discharge time of different single lithium batteries, and the N rounds of temperature rise inertia temperature difference after the temperature is raised to the same temperature due to the temperature rise inertia;

[0121] The final data is taken based on the average of N rounds of charge and discharge time and N rounds of maximum temperature of different single-cell lithium batteries.

[0122] It can be understood that the method of taking the average is used here to determine the final data. Of course, in specific applications, under N rounds of charging and discharging, other strategies can also be used to extract the final data from the N rounds of data, which is considered to be more in line with actual usage or with smaller errors.

[0123] Among them, for the N rounds of charging and discharging, the present application can be specifically configured as follows: the number N is specifically 5.

[0124] Step S107, determining the consistency between different single-cell lithium batteries according to the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

[0125] It can be understood that for the present application, the key parameters in the consistency evaluation of single lithium batteries are heat generation power P, charge and discharge time, and temperature rise inertia temperature difference. After obtaining the three, the standard deviation coefficient of instantaneous heat generation power P, charge and discharge time, and temperature rise inertia temperature difference is further calculated. At this time, if the standard deviation coefficient of instantaneous heat generation power P, charge and discharge time, and temperature rise inertia temperature difference between two single lithium batteries is closer, it can be said that the consistency between the two lithium batteries is better.

[0126] from Figure 1 It can be seen from the illustrated embodiments that, in response to the need for consistency evaluation between single-cell lithium batteries, the present application focuses on the instantaneous heat generation power P calculated by parameters, and the standard deviation coefficients of the charge and discharge time and the temperature rise inertia temperature difference measured by charge and discharge. The consistency between different single-cell lithium batteries is determined through the standard deviation coefficients of these three aspects. Under this evaluation mechanism, it has the advantage of convenient operating costs, avoids the problem of high application costs caused by the existing evaluation schemes being too complicated, and can stably, quickly and accurately determine the consistency between single-cell lithium batteries, providing reliable data support for the application of lithium battery packs.

[0127] The above is an introduction to the consistency evaluation method for lithium batteries from the same batch provided by this application. In order to facilitate better implementation of the consistency evaluation method for lithium batteries from the same batch provided by this application, this application also provides a consistency evaluation device for lithium batteries from the same batch from the perspective of functional modules.

[0128] See also Figure 2 , Figure 2 This is a schematic diagram of a structure of a device for evaluating the consistency of lithium batteries in the same batch of this application. In this application, the device 200 for evaluating the consistency of lithium batteries in the same batch may specifically include the following structure:

[0129] The acquisition unit 201 is used to obtain the cell mass M and specific heat capacity C of different single lithium batteries. p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate;

[0130] The determination unit 202 is used to determine the mass M of the battery cell and the specific heat capacity C. p , self-heating temperature T generation and the current ambient temperature T a On this basis, determine the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process;

[0131] The determination unit 202 is further used to determine the heat energy Q from the chemical reaction of different single lithium batteries based on the battery cell volume V, the normalized concentration dC / dt and the battery cell energy H;

[0132] The calculation unit 203 is used to calculate the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process based on the heat energy Q;

[0133] The charge and discharge unit 204 is used to charge and discharge different single lithium batteries, and record the charge and discharge time of each of the different single lithium batteries, and the temperature difference of the temperature rise inertia after the temperature rises to the same temperature due to the temperature rise inertia;

[0134] A comparison unit 205 is used to compare the instantaneous heat generation power P, the charge and discharge time and the standard deviation coefficient of the temperature rise inertia temperature difference between different single lithium batteries;

[0135] The determination unit 202 is further configured to determine the consistency between different single-cell lithium batteries according to the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

[0136] In yet another exemplary implementation, the determining unit 202 is specifically configured to:

[0137] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, the cell energy H released by different single-cell lithium batteries at any time during the entire charging and discharging process is determined by combining the following first formula:

[0138] H=M×C p ×(T generation -T a ).

[0139] In yet another exemplary implementation, the determining unit 202 is specifically configured to:

[0140] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined by combining the following second formula:

[0141] Q = 1 / V × H × dC / dt.

[0142] In another exemplary implementation, charging and discharging are performed at a temperature of 25°C ± 5°C and under the conditions of GB / T31485-2015 standard, including:

[0143] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0144] Let stand for 30 minutes;

[0145] Charge with 1C constant current to the charging cut-off voltage, and then charge with constant voltage until the charging current drops to 0.05C;

[0146] Let stand for 30 minutes;

[0147] Discharge at 1C constant current until the discharge cut-off voltage is reached;

[0148] Let stand for 30 minutes;

[0149] Charge the battery with a 1C constant current rate until the charge cut-off voltage is reached, and then charge at a constant voltage until the charging current drops to 0.05C.

[0150] In another exemplary implementation, the charge-discharge unit 204 is specifically configured to:

[0151] Carry out N rounds of charge and discharge on different single lithium batteries, and record the N rounds of charge and discharge time of different single lithium batteries, and the N rounds of temperature rise inertia temperature difference after the temperature is raised to the same temperature due to the temperature rise inertia;

[0152] The final data is taken based on the average of N rounds of charge and discharge time and N rounds of maximum temperature of different single-cell lithium batteries.

[0153] In yet another exemplary implementation, the number N is specifically 5.

[0154] In yet another exemplary implementation, the different single lithium batteries are specifically four lithium batteries selected from the same manufacturer, the same model, and the same batch.

[0155] This application also provides a processing device from the perspective of hardware structure, see Figure 3 , Figure 3 301, a memory 302, and an input / output device 303. The processor 301 is used to execute the computer program stored in the memory 302 to implement the following Figure 1 The steps of the method for evaluating the consistency of lithium batteries in the same batch in the corresponding embodiment; or, the processor 301 is used to execute the computer program stored in the memory 302 to implement the following Figure 2 Corresponding to the functions of each unit in the embodiment, the memory 302 is used to store the processor 301 executing the above Figure 1 The computer program required for the consistency evaluation method of the same batch of lithium batteries in the corresponding embodiment.

[0156] Exemplarily, the computer program may be divided into one or more modules / units, one or more modules / units are stored in the memory 302, and executed by the processor 301 to complete the present application. One or more modules / units may be a series of computer program instruction segments capable of completing specific functions, and the instruction segments are used to describe the execution process of the computer program in the computer device.

[0157] The processing device may include, but is not limited to, a processor 301, a memory 302, and an input / output device 303. Those skilled in the art will appreciate that the illustration is merely an example of a processing device and does not constitute a limitation on the processing device, and may include more or fewer components than shown in the illustration, or a combination of certain components, or different components. For example, the processing device may also include a network access device, a bus, etc., and the processor 301, the memory 302, the input / output device 303, etc. are connected via a bus.

[0158] The processor 301 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the processing device, and uses various interfaces and lines to connect various parts of the entire device.

[0159] The memory 302 can be used to store computer programs and / or modules. The processor 301 implements various functions of the computer device by running or executing the computer programs and / or modules stored in the memory 302 and calling the data stored in the memory 302. The memory 302 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created according to the use of the processing device, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (SecureDigital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0160] When the processor 301 is used to execute the computer program stored in the memory 302, the following functions can be implemented:

[0161] Obtain the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a, cell volume V and normalized concentration dC / dt of chemical reaction rate;

[0162] In the case of battery cell mass M, specific heat capacity C p , self-heating temperature T generation and the current ambient temperature T a On this basis, determine the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process;

[0163] Based on the cell volume V, normalized concentration dC / dt and cell energy H, the heat energy Q from chemical reactions of different single lithium batteries is determined;

[0164] Based on the thermal energy Q, calculate the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process;

[0165] Charge and discharge different single lithium batteries, and record the charge and discharge time of each single lithium battery, and the temperature difference due to temperature rise inertia after the temperature rises to the same temperature;

[0166] Compare the instantaneous heat generation power P, charge and discharge time and standard deviation coefficient of temperature rise inertia temperature difference between different single lithium batteries;

[0167] The consistency between different single-cell lithium batteries is determined based on the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

[0168] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the above-described same batch of lithium battery consistency evaluation device, processing equipment and corresponding units can refer to the following Figure 1 The description of the consistency evaluation method for the same batch of lithium batteries in the corresponding embodiment will not be repeated here.

[0169] A person of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0170] To this end, the present application provides a computer-readable storage medium, in which a plurality of instructions are stored, and the instructions can be loaded by a processor to execute the present application as follows: Figure 1 The steps of the consistency evaluation method for the same batch of lithium batteries in the corresponding embodiment, the specific operation can be referred to as follows Figure 1 The description of the consistency evaluation method for the same batch of lithium batteries in the corresponding embodiment will not be repeated here.

[0171] The computer-readable storage medium may include: a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0172] Due to the instructions stored in the computer-readable storage medium, the present application can be executed. Figure 1 The steps of the method for evaluating the consistency of lithium batteries in the same batch in the corresponding embodiment are as follows. Figure 1 The beneficial effects that can be achieved by the consistency evaluation method for the same batch of lithium batteries in the corresponding embodiment are detailed in the previous description and will not be repeated here.

[0173] The above is a detailed introduction to the consistency evaluation method, device, processing equipment and computer-readable storage medium for the same batch of lithium batteries provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for evaluating the consistency of lithium batteries in the same batch, characterized in that: The method comprises: Obtain the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate; In the battery core mass M, the specific heat capacity C p , the self-heating temperature T generation and the current ambient temperature T a On the basis of, determining the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process; Determining the heat energy Q from the chemical reaction of different single lithium batteries based on the battery cell volume V, the normalized concentration dC / dt and the battery cell energy H; Based on the thermal energy Q, calculating the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process; Charging and discharging the different single lithium batteries, and recording the respective charging and discharging time of the different single lithium batteries, and the temperature difference of the temperature rise inertia after the temperature is raised to the same temperature due to the temperature rise inertia; Comparing the instantaneous heat generation power P, the charge and discharge time and the standard deviation coefficient of the temperature rise inertia temperature difference between different single lithium batteries; The consistency between different single lithium batteries is determined according to the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

2. The method according to claim 1, characterized in that In the battery core mass M, the specific heat capacity C p , the self-heating temperature T generation and the current ambient temperature T a Based on the above, the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process is determined, including: In the case of the battery core mass M, the specific heat capacity C p , the self-heating temperature T generation and the current ambient temperature T a On this basis, the cell energy H released by different single-cell lithium batteries at any time during the entire charging and discharging process is determined in combination with the following first formula: H=M×C p ×(T generation -T a )。 3. The method according to claim 1, characterized in that Determining the heat energy Q from the chemical reaction of different single lithium batteries based on the battery cell volume V, the normalized concentration dC / dt and the battery cell energy H includes: Based on the cell volume V, the normalized concentration dC / dt and the cell energy H, the heat energy Q from the chemical reaction of different single lithium batteries is determined in combination with the following second formula: Q = 1 / V × H × dC / dt.

4. The method according to claim 1, characterized in that The charging and discharging is carried out at a temperature of 25℃±5℃ and in accordance with the GB / T31485-2015 standard, including: Discharge at 1C constant current until the discharge cut-off voltage is reached; Let stand for 30 minutes; Charge with 1C constant current to the charging cut-off voltage, and then charge with constant voltage until the charging current drops to 0.05C; Let stand for 30 minutes; Discharge at 1C constant current until the discharge cut-off voltage is reached; Let stand for 30 minutes; Charge the battery with a 1C constant current rate until the charge cut-off voltage is reached, and then charge at a constant voltage until the charging current drops to 0.05C.

5. The method according to claim 1, characterized in that The charging and discharging of different single lithium batteries and recording the respective charging and discharging time of the different single lithium batteries and the temperature difference of the temperature rise inertia after the temperature rises to the same temperature due to the temperature rise inertia include: Performing N rounds of charge and discharge on different single lithium batteries, and recording the N rounds of charge and discharge time of each of the different single lithium batteries, and the N rounds of temperature rise inertia temperature difference after the temperature is raised to the same temperature due to the temperature rise inertia; The average of the N rounds of charge and discharge time and the N rounds of temperature rise inertia temperature difference of different single lithium batteries is taken as the final data.

6. The method according to claim 5, characterized in that The number of N is specifically 5.

7. The method according to claim 1, characterized in that The different single lithium batteries are specifically 4 lithium batteries selected from the same manufacturer, the same model and the same batch.

8. A device for evaluating the consistency of lithium batteries in the same batch, characterized in that: The device comprises: Acquisition unit, used to obtain the cell mass M and specific heat capacity C of different single lithium batteries p , the self-heating temperature T at any time during the charge and discharge process generation 、Current ambient temperature T a , cell volume V and normalized concentration dC / dt of chemical reaction rate; The determination unit is used to determine the mass M of the battery cell and the specific heat capacity C p , the self-heating temperature T generation and the current ambient temperature T a On the basis of, determining the cell energy H released by different single lithium batteries at any time during the entire charging and discharging process; The determination unit is further used to determine the heat energy Q from the chemical reaction of different single lithium batteries based on the battery cell volume V, the normalized concentration dC / dt and the battery cell energy H; A calculation unit, used to calculate the instantaneous heat generation power P of different single lithium batteries during the charging and discharging process based on the heat energy Q; A charge and discharge unit, used to charge and discharge the different single lithium batteries, and record the charge and discharge time of the different single lithium batteries, and the temperature difference of the temperature rise inertia after the temperature rises to the same temperature due to the temperature rise inertia; A comparison unit, used for comparing the instantaneous heat generation power P, the charge and discharge time and the standard deviation coefficient of the temperature rise inertia temperature difference between different single lithium batteries; The determination unit is further used to determine the consistency between different single lithium batteries according to the standard deviation coefficient, wherein the smaller the standard deviation coefficient, the higher the consistency.

9. A processing device, characterized in that: The method comprises a processor and a memory, wherein the memory stores a computer program, and the processor executes the method according to any one of claims 1 to 7 when calling the computer program in the memory.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a plurality of instructions, and the instructions are suitable for being loaded by a processor to execute the method according to any one of claims 1 to 7.

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