A lithium battery thermodynamic loss analysis method, device and electronic equipment

Abstract

The embodiments of this specification disclose a method, device, and electronic device for analyzing the thermodynamic loss of a lithium battery. The method obtains the total capacity of a test battery of a target lithium battery under a test state, determines a target differential curve of the target lithium battery under a test state, and then determines the extreme left peak point and the extreme right peak point in the first curve, and determines the difference in the amount of negative electrode lithium insertion corresponding to the extreme left peak point and the extreme right peak point. Finally, based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion, and the total capacity of the test battery, the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value of the target lithium battery are quantitatively determined. This method satisfies the requirement of quantitatively analyzing the loss of each part of the lithium battery's thermodynamics, clarifies the optimization direction of subsequent battery cell cycles, and improves the service life of the lithium battery.

Description

Technical Field

[0001] One or more embodiments of this specification relate to the field of intelligent analysis technology, and in particular, to a method, device, and electronic device for analyzing thermodynamic losses of lithium batteries. Background Art

[0002] Lithium batteries will produce capacity loss during the use cycle, which in turn affects the service life of lithium batteries. Among them, the reasons for the capacity loss during the lithium battery cycle are divided into two parts: kinetic capacity loss and thermodynamic capacity loss. The main sources of thermodynamic loss include positive electrode active material loss, negative electrode active material loss and active lithium loss. Therefore, it is necessary to clarify the source of lithium battery cycle capacity loss to improve the cycle life of lithium batteries. However, the existing conventional thermodynamic loss analysis method can only determine the possible causes of thermodynamic loss, and cannot clarify the specific proportion of positive electrode active material loss, negative electrode active material loss and active lithium loss, which is not conducive to reverse optimization of battery cell cycle. Summary of the Invention

[0003] The embodiments of this specification provide a method, device, and electronic device for analyzing thermodynamic losses of lithium batteries, and the technical solutions are as follows:

[0004] In a first aspect, an embodiment of this specification provides a method for analyzing thermodynamic losses of a lithium battery, the method comprising:

[0005] Obtaining a total test battery capacity of a target lithium battery in a test state, wherein the test state is a state of the target lithium battery after a target number of charge and discharge cycles in an initial state;

[0006] Determine a target differential curve of the target lithium battery under the test state, the target differential curve comprising a first curve and a second curve, the first curve being a discharge capacity-voltage differential curve, and the second curve being a negative electrode lithium insertion amount-voltage differential curve;

[0007] Determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, wherein the difference in the negative electrode lithium insertion amount is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve;

[0008] The thermodynamic loss value of the target lithium battery under the test state is determined based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0009] In a second aspect, a lithium battery thermodynamic loss analysis device is provided, the device comprising:

[0010] The first module is used to obtain the total capacity of the test battery of the target lithium battery in the test state, where the test state is the state of the target lithium battery after the target number of charge and discharge cycles in the initial state;

[0011] The second module is used to determine a target differential curve of the target lithium battery under the test state, wherein the target differential curve includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve;

[0012] The third module is used to determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, where the difference in the negative electrode lithium insertion amount is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve;

[0013] The fourth module is used to determine the thermodynamic loss value of the target lithium battery under the test state based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0014] In a third aspect, an electronic device is provided, including a device processor and a memory;

[0015] The device processor is connected to the memory;

[0016] The memory is used to store executable program code;

[0017] The device processor runs a program corresponding to the executable program code by reading the executable program code stored in the memory, so as to execute the steps of the method provided in the first aspect or any possible implementation manner of the first aspect.

[0018] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored, and the computer-readable storage medium stores instructions. When the instructions are executed on a computer or device processor, the computer or device processor executes the method provided in the first aspect or any possible implementation of the first aspect.

[0019] The beneficial effects of the technical solutions provided by some embodiments of this specification include at least:

[0020] In one or more embodiments of the present specification, after obtaining the total capacity of the test battery of the target lithium battery under the test state, the target differential curve of the target lithium battery under the test state is determined, and then the extreme left peak point and the extreme right peak point in the first curve are determined, and the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point is determined. Finally, according to the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the negative electrode lithium insertion amount and the total capacity of the test battery, the positive electrode active material loss value, the negative electrode active material loss value and the active lithium loss value of the target lithium battery are quantitatively determined, which meets the requirement of quantitatively analyzing the losses of various thermodynamic parts of the lithium battery, clarifies the optimization direction of subsequent battery cell cycles, and improves the service life of the lithium battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of the system architecture of a lithium battery thermodynamic loss analysis method provided in an embodiment of this specification;

[0023] Figure 2 A flow chart of a lithium battery thermodynamic loss analysis method provided in an embodiment of this specification;

[0024] Figure 3 A schematic diagram of the structure of a lithium battery thermodynamic loss analysis device provided in an embodiment of this specification;

[0025] Figure 4 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this specification. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application.

[0027] Throughout this specification, the claims, and the accompanying drawings, the terms "first," "second," "third," and the like are used to distinguish between different items, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may include other steps or elements inherent to the process, method, product, or apparatus.

[0028] The following description provides examples and does not limit the scope, applicability, or examples set forth in the claims. Changes may be made to the functions and arrangements of the elements described without departing from the scope of this specification. Various examples may appropriately omit, replace, or add various processes or components. For example, the described methods may be performed in an order different from the order described, and various steps may be added, omitted, or combined. Furthermore, features described with respect to some examples may be combined in other examples.

[0029] See also Figure 1 , Figure 1 A schematic diagram of the system architecture of a lithium battery thermodynamic loss analysis method provided in an embodiment of this specification is shown.

[0030] like Figure 1 As shown, the system architecture of the lithium battery thermodynamic loss analysis method may include at least a terminal 10 , a server 20 and a network 30 .

[0031] Terminal 10 includes, but is not limited to, electronic devices such as smartphones, desktop computers, tablet computers, laptops, smart speakers, digital assistants, and smart wearable devices. It may also be software running on these electronic devices, such as applications. Optionally, the operating system running on the electronic device may include, but is not limited to, Android, iOS, Linux, Windows, etc. Optionally, terminal 10 provides users with a lithium battery thermodynamic loss analysis service. Terminal 10 may obtain a lithium battery thermodynamic loss analysis instruction from an application program interface and send a lithium battery thermodynamic loss analysis request to server 20.

[0032] The server 20 can provide background services for the terminal 10. Based on the lithium battery thermodynamic loss analysis request sent by the terminal 10, the server 20 will obtain a series of lithium battery thermodynamic loss analysis instructions, and the server 20 will transmit the lithium battery thermodynamic loss analysis instructions to other terminals 10 through the network 30. Specifically, the server 20 can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers. It can also be a cloud server that provides basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN (Content Delivery Network), and big data and artificial intelligence platforms.

[0033] The network 30 is used to provide a medium for a communication link between the terminal 10 and the server 20. The network 30 may include various connection types, such as wired or wireless communication links or fiber optic cables.

[0034] In addition, it should be noted that Figure 1 What is shown is only one system provided by the present disclosure. In actual applications, other systems may also be included, for example, more terminals may be included.

[0035] In the embodiments of this specification, the terminal 10 and the server 20 may be connected directly or indirectly via wired or wireless communication, which is not limited in this disclosure.

[0036] See next Figure 2 , Figure 2 The overall flow chart of a lithium battery thermodynamic loss analysis method provided in an embodiment of this specification is shown. The lithium battery thermodynamic loss analysis method can be used in the server 20.

[0037] like Figure 2 As shown, the lithium battery thermodynamic loss analysis method may include at least the following steps:

[0038] Step 201: Obtain the total test battery capacity of the target lithium battery in a test state.

[0039] The test state is the state of the target lithium battery after it has undergone a target number of charge and discharge cycles in the initial state.

[0040] In the embodiments of this specification, a lithium battery can be defined as being in an initial state when it is activated at the factory and has not undergone any charge or discharge. Furthermore, in order to analyze the thermodynamic losses of a lithium battery after a charge and discharge cycle, it is necessary to perform a target number of charge and discharge cycles on the target lithium battery in the initial state. When charging, a constant current and constant voltage charging mode is used to charge the battery to the standard voltage, and then switch to constant voltage charging until the charging current drops to the set cutoff value. The discharge process is performed at a constant current until the battery voltage drops to the cutoff voltage. After completing the target number of charge and discharge cycles, the battery enters the test state. Next, the total test battery capacity of the target lithium battery in the test state can be obtained using the constant current charge and discharge method, the DC resistance method, the AC impedance method, or the coulomb counting method. Each method has its advantages and limitations. In actual application, the appropriate method can be selected based on the test conditions and the availability of equipment. When performing a battery capacity test, in order to improve the accuracy of the test results, it is necessary to control the test environment temperature as much as possible so that the target battery is tested under conditions that achieve thermal equilibrium.

[0041] Among them, the constant current charge and discharge method is to measure the battery capacity by charging the battery to a standard voltage, then discharging it to the cut-off voltage, and recording the amount of electricity during the discharge process. The DC resistance method is to measure the DC internal resistance of the battery during the charge and discharge process, combined with the open circuit voltage of the battery, and use a specific model to estimate the remaining capacity of the battery. The AC impedance method is to measure the AC impedance spectrum of the battery, analyze the internal impedance and electrochemical reaction state of the battery, and thus infer the battery capacity. The coulomb counting method uses a coulomb counter to measure the amount of charge flowing through the battery during the charge and discharge process to calculate the battery capacity.

[0042] In one embodiment, obtaining the total test battery capacity of the target lithium battery in the test state includes:

[0043] Charge the target lithium battery to the target voltage under test;

[0044] After receiving the charging completion signal, the target lithium battery is discharged to the cut-off voltage, and the released capacity during the discharge process is counted to obtain the total test battery capacity of the target lithium battery.

[0045] In the embodiments of this specification, in combination with the actual available equipment and test conditions, a constant current charge and discharge method can be used to obtain the battery capacity of the target lithium battery. First, the target lithium battery in the test state can be charged with a constant current so that the voltage of the target lithium battery reaches the target voltage. Then, the target lithium battery is charged in a constant voltage charging mode, and a charging completion signal is generated after the charging current drops to a set value. Furthermore, after receiving the charging completion signal, the target lithium battery is discharged in a constant current mode. When the voltage of the target lithium battery drops to the cut-off voltage, the release capacity during the entire discharge process is recorded and counted, and the total release capacity obtained is represented as the total test battery capacity of the target lithium battery.

[0046] Step 202: Determine a target differential curve of the target lithium battery under the test state.

[0047] The target differential curve diagram includes a first curve and a second curve, the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve.

[0048] In the embodiments of this specification, in order to analyze the thermodynamic loss of the target lithium battery under the test state compared to the initial state, the charge and discharge parameter state of the target lithium battery can be detected. First, after obtaining various test data through charge and discharge tests, the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve of the target lithium battery can be constructed. Then, the constructed discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve are differentiated at each point or curve fitting is performed to obtain the discharge capacity-voltage differential curve and the negative electrode lithium insertion amount-voltage differential curve, and the two differential curves are combined into a curve composite graph, that is, the target differential curve graph of the target lithium battery under the test state is obtained.

[0049] In one embodiment, the target differential curve of the target lithium battery under the test state is determined, and the target differential curve includes a first curve and a second curve, the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve, including:

[0050] Performing a discharge process on the target lithium battery to obtain real-time monitoring data, and determining a discharge capacity-voltage curve and a negative electrode lithium insertion amount-voltage curve of the target lithium battery under the test state based on the real-time monitoring data;

[0051] A composite graph of the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve is constructed, and each curve point in the composite graph is simultaneously derivatized based on a differential algorithm to obtain a target differential curve graph of the target lithium battery under the test state, wherein the target differential curve graph includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve.

[0052] In the embodiments of this specification, when determining the target differential curve of the target lithium battery under test, first, under the test state, the target lithium battery can be subjected to a constant current discharge process to obtain real-time detection data of the target lithium battery, including real-time voltage data, real-time discharge capacity data, and real-time negative electrode lithium insertion amount data, and then the corresponding discharge capacity-voltage curve and negative electrode lithium insertion amount-voltage curve are drawn based on the respective test data. The two axis coordinates of the discharge capacity-voltage curve are the discharge capacity value and the voltage value, respectively, and the two axis coordinates of the negative electrode lithium insertion amount-voltage curve are the negative electrode lithium insertion amount and the voltage value, respectively. Next, the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve are constructed into a composite graph by defining different coordinate axes, and the derivative calculations are performed on each curve point in the composite graph at the same time through the differential algorithm, the slope value of each point is obtained and a straight line fitting is performed to obtain the differential curves corresponding to the two curves respectively, and the two differential curves are also composited with the coordinate axes to obtain the target differential curve graph of the target lithium battery under the test state, which includes a first curve, namely the discharge capacity-voltage differential curve, and a second curve, namely the negative electrode lithium insertion amount-voltage differential curve.

[0053] Step 203: Determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point.

[0054] The difference in the amount of lithium embedded in the negative electrode is the difference in the mapped values ​​of the extreme left peak point and the extreme right peak point in the second curve.

[0055] In the embodiments of this specification, since the target lithium battery will produce different thermodynamic losses after different target numbers of charge and discharge cycles, which causes the peak points in the first curve to shift, the thermodynamic losses of the target lithium battery can be analyzed by determining the peak points in the first curve. First, since the first curve may include multiple extreme points, and only the extreme left peak point and the extreme right peak point correspond to the key transition points of the electrochemical reaction inside the battery, they appear as sharp changes in voltage in the first curve of the target lithium battery, reflecting different electrochemical processes inside the battery, such as different phase changes or lithium ion insertion and deinsertion processes. Therefore, the extreme left peak point and the extreme right peak point in the first curve can be determined first. Then, due to the physical properties of the battery, after the composite graph is formed, as the different numerical values ​​in the first curve change, the mapping value corresponding to the second curve will also change accordingly. Therefore, after determining the peak point, the mapping point corresponding to the point in the second curve can be directly determined in the vertical direction of the composite graph, and the mapping point is also a peak point. The mapping peak points of the extreme left peak point and the extreme right peak point in the second curve can be further determined, and the mapping value difference of the two mapping peak points can be determined and defined as the difference in the amount of lithium embedded in the negative electrode.

[0056] Among them, the extreme left peak point is usually connected to the rapid voltage drop stage at the initial stage of discharge of the target lithium battery, which may be related to the rapid reaction of certain active substances inside the battery, while the extreme right peak point may be connected to the rapid voltage drop stage at the end of battery discharge. At this time, the active substances inside the battery may be close to exhaustion, resulting in a sharp drop in voltage.

[0057] In one embodiment, determining the extreme left peak point and the extreme right peak point in the first curve includes:

[0058] determining all peak points in the first curve based on a peak algorithm;

[0059] The peak points are screened out based on the coordinate positions of the peak points to determine the extreme left peak point and the extreme right peak point in the first curve.

[0060] In the embodiments of this specification, when determining the extreme left and right peak points in a first curve, a peak algorithm can be used to first determine all peak points in the first curve. Specifically, a first-order derivative of each segment of the fitting function of the first curve is taken to determine the zero points of each derivative. The positive and negative values ​​of the left and right derivative functions at each derivative zero point are then analyzed to determine all corresponding peak points. Next, the coordinate positions, i.e., the horizontal coordinate values, of all peak points are determined, and the peak point with the smallest horizontal coordinate value and the peak point with the largest horizontal coordinate value are selected from these points and defined as the extreme left and right peak points, respectively, in the first curve.

[0061] In one embodiment, determining the difference in the amount of lithium embedded in the negative electrode corresponding to the extreme left peak point and the extreme right peak point, wherein the difference in the amount of lithium embedded in the negative electrode is the difference in the mapped values ​​of the extreme left peak point and the extreme right peak point in the second curve, includes:

[0062] Determine mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve based on a curve mapping relationship, respectively, to obtain an extreme left mapping value and an extreme right mapping value, wherein the curve mapping relationship is a mapping relationship between each point in the first curve and the second curve;

[0063] The difference between the extreme left mapping value and the extreme right mapping value is calculated to obtain the difference in the amount of lithium embedded in the negative electrode.

[0064] In the embodiment of this specification, since the first curve is a discharge capacity-voltage differential curve and the second curve is a negative electrode lithium insertion amount-voltage differential curve, and the negative electrode lithium insertion amount generally represents the state of charge of the battery and can be obtained by the existing capacity of the battery, the parameters of the second curve and the first curve are correlated with each other, so that the change trends of the first curve and the second curve are the same, so that the mapping relationship of each point in the first curve and the second curve can be obtained as follows: in the composite graph, the horizontal coordinate geometric positions of each corresponding mapping point are the same. Optionally, when determining the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, the mapping peak points of the extreme left peak point and the extreme right peak point in the second curve can be determined respectively through the curve mapping relationship between the two curves. As an example, taking the extreme left peak point as an example, determine the vertical axis parallel line passing through the extreme left peak point, and find the intersection of the vertical axis parallel line and the second curve, which is the mapping peak point corresponding to the extreme left peak point. Furthermore, after determining the corresponding two mapping peak points, the corresponding horizontal coordinate values ​​are queried to obtain the extreme left mapping value and the extreme right mapping value, and the difference between the extreme left mapping value and the extreme right mapping value is calculated, and the absolute value of the difference calculation result is used as the difference in the negative electrode lithium insertion amount.

[0065] In one embodiment, after determining the extreme left peak point and the extreme right peak point in the first curve and determining the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, the method further includes:

[0066] Obtaining an initial total battery capacity and an initial differential curve graph of the target lithium battery in the initial state;

[0067] An initial extreme left peak point and an initial extreme right peak point in the initial differential curve graph are determined.

[0068] In the embodiments of this specification, in order to subsequently obtain data such as the first capacity change of the extreme left peak point relative to the initial differential curve graph and the second capacity change of the extreme right peak point relative to the initial differential curve graph, it is necessary to obtain the initial battery total capacity and the initial differential curve graph of the target lithium battery in the initial state through the same test steps as the above steps, and similarly determine the initial extreme left peak point and the initial extreme right peak point in the initial differential curve graph.

[0069] Optionally, since the initial state of each target lithium battery is the state when it is activated at the factory and has not undergone any charge or discharge, the above same principle test steps can be used for all types of lithium batteries in their initial state before the thermodynamic loss of the lithium battery occurs, to obtain the initial total battery capacity of each lithium battery in the initial state, as well as the initial extreme left peak point and the initial extreme right peak point in the initial differential curve, and record and count them by battery type to obtain an initial database. When analyzing the thermodynamic loss of lithium batteries later, it is only necessary to directly call the initial data according to the battery type of the target lithium battery.

[0070] Step 204: Determine the thermodynamic loss value of the target lithium battery under the test state based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the negative electrode lithium insertion amount difference, and the total capacity of the test battery.

[0071] The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0072] In the embodiments of this specification, to determine the thermodynamic loss value of the target lithium battery under test, it is possible to analyze and obtain that each thermodynamic loss is related to the first capacity change at the extreme left peak point relative to the initial differential curve after the target lithium battery has been charged and discharged for a target number of times, the second capacity change at the extreme right peak point relative to the initial differential curve, the difference in the amount of lithium inserted in the negative electrode, and the change in the total battery capacity of the target lithium battery before and after the test. Therefore, after obtaining each change, the thermodynamic loss value of the target lithium battery under test can be determined by substituting it into the preset loss value formula. The thermodynamic loss value generally includes three loss values: the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0073] Among them, the negative electrode active material loss value LAM anode The calculation formula is Among them, Q1 Bef0.05C 、Q1 Post0.05C They are the capacitance corresponding to the extreme left peak point in the initial differential curve and the target differential curve, Q4 Bef0.05C 、Q4 Post0.05C They are the capacitance corresponding to the extreme right peak point in the initial differential curve and the target differential curve, and x1-x4 is the difference in the amount of lithium embedded in the negative electrode.

[0074] Positive electrode active material loss value LAM cathode The calculation formula is LAM cathode =(Q Bef0.05C -Q4 Bef0.05C )-(Q Post0.05C -Q4 Post0.05C )-LAM anode *(x4-0), where Q Bef0.05c is the initial total battery capacity, Q Post0.05C To test the total capacity of the battery.

[0075] The calculation formula of active lithium loss value LLI is LLI=(Q1 Bef0.05C -0)-(Q1 Post0.05C -0).

[0076] In one embodiment, the thermodynamic loss value of the target lithium battery under the test state is determined according to the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the negative electrode lithium insertion amount difference and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value, including:

[0077] determining a first capacity change based on the extreme left peak point and the initial extreme left peak point;

[0078] determining a second capacity change based on the extreme right peak point and the initial extreme right peak point;

[0079] Determining an active lithium loss value of the target lithium battery according to the first capacity change;

[0080] Determine a negative electrode active material loss value of the target lithium battery according to the first capacity change, the second capacity change and the difference in the negative electrode lithium insertion amount;

[0081] Determine the positive electrode active material loss value of the target lithium battery according to the total capacity of the test battery, the initial total capacity of the battery, the second capacity change and the negative electrode active material loss value;

[0082] The active lithium loss value, the negative electrode active material loss value and the positive electrode active material loss value are counted to obtain the thermodynamic loss value of the target lithium battery under the test state.

[0083] In the embodiment of this specification, when determining the various thermodynamic loss values ​​of the target lithium battery under the test state, the first capacity change can be determined by the horizontal coordinate values ​​of the extreme left peak point and the initial extreme left peak point in the first curve. Then, the second capacity change is determined according to the horizontal coordinate values ​​of the extreme right peak point and the initial extreme right peak point in the first curve. Further, after obtaining the first capacity change, the active lithium loss value LLI is calculated by the formula LLI=(Q1 Bef0.05C -0)-(Q1 Post0.05C -0), the active lithium loss value can be calculated. After obtaining the first capacity change, the second capacity change and the difference between the negative electrode lithium insertion amount, the negative electrode active material loss value LAM anode The calculation formula After obtaining the total capacity of the test battery, the initial total capacity of the battery, the second capacity change and the loss value of the negative electrode active material, the loss value of the positive electrode active material LAM is calculated. cathode The calculation formula of LAM cathode =(Q Bef0.05C -Q4 Bef0.05C )-(QPost0.05C -Q4 Post0.05C )-LAM anode *(x4-0), the loss value of positive electrode active material can be calculated.

[0084] As an example, the initial total battery capacity Q of the target lithium battery is obtained through the test steps. Bef0.05C The total capacity of the battery is 2.9973Ah after 1200 cycles. Post0.05C The capacitance Q1 corresponding to the extreme left peak point in the initial differential curve is 2.5878Ah. Bef0.05C The capacitance Q4 corresponding to the extreme right peak point in the initial differential curve is 0.9627Ah. Bef0.05C The capacitance Q1 corresponding to the extreme left peak point in the target differential curve is 2.508Ah. Post0.05C The capacitance corresponding to the extreme right peak point in the target differential curve is Q4. Post0.05C =2.1501Ah, the extreme left mapping value x1 is 58.550%, and the extreme right mapping value x4 is 13.211%. Then the negative electrode lithium insertion amount difference x1-x4 is 58.550%-13.211%=45.339%. Therefore, the active lithium loss value LLI=(Q1 Bef0.05C -0)-(Q1 Post0.05C -0)=(0.9627-0)-(0.6088-0)=0.3539Ah; Negative electrode active material loss value Positive electrode active material loss value LAM cathode =(Q Bef0.05C -Q4 Bef0.05C )-(Q Post0.05C -Q4 Post0.05C )-LAM anode *(x4-0)=(2.9973-2.508)-(2.5878-2.1501)-0.0088*0.1321=0.0504Ah.

[0085] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0086] See next Figure 3 , Figure 3The figure shows a schematic diagram of the structure of a lithium battery thermodynamic loss analysis device provided in the embodiment of this specification. It should be noted that: Figure 3 The lithium battery thermodynamic loss analysis device shown is used to perform the present application Figure 2 For the convenience of explanation, only the part related to the embodiment of the present application is shown. For the specific technical details not disclosed, please refer to the present application. Figure 2 The embodiment shown.

[0087] like Figure 3 As shown, the lithium battery thermodynamic loss analysis device may include at least:

[0088] The first module 301 is used to obtain the total capacity of a test battery of a target lithium battery in a test state, where the test state is the state of the target lithium battery after a target number of charge and discharge cycles in an initial state;

[0089] The second module 302 is used to determine a target differential curve of the target lithium battery under the test state, wherein the target differential curve includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve;

[0090] The third module 303 is used to determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, where the difference in negative electrode lithium insertion amount is the difference in mapping values ​​of the extreme left peak point and the extreme right peak point to the peak points mapped in the second curve;

[0091] The fourth module 304 is used to determine the thermodynamic loss value of the target lithium battery under the test state based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion, and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0092] In one embodiment, the first module 301 is specifically configured to:

[0093] Charge the target lithium battery to the target voltage under test;

[0094] After receiving the charging completion signal, the target lithium battery is discharged to the cut-off voltage, and the released capacity during the discharge process is counted to obtain the total test battery capacity of the target lithium battery.

[0095] In one embodiment, the second module 302 is specifically configured to:

[0096] Performing a discharge process on the target lithium battery to obtain real-time monitoring data, and determining a discharge capacity-voltage curve and a negative electrode lithium insertion amount-voltage curve of the target lithium battery under the test state based on the real-time monitoring data;

[0097] A composite graph of the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve is constructed, and each curve point in the composite graph is simultaneously derivatized based on a differential algorithm to obtain a target differential curve graph of the target lithium battery under the test state, wherein the target differential curve graph includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve.

[0098] In one embodiment, the third module 303 is specifically configured to:

[0099] determining all peak points in the first curve based on a peak algorithm;

[0100] The peak points are screened out based on the coordinate positions of the peak points to determine the extreme left peak point and the extreme right peak point in the first curve.

[0101] In one embodiment, the third module 303 is further configured to:

[0102] Determine mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve based on a curve mapping relationship, respectively, to obtain an extreme left mapping value and an extreme right mapping value, wherein the curve mapping relationship is a mapping relationship between each point in the first curve and the second curve;

[0103] The difference between the extreme left mapping value and the extreme right mapping value is calculated to obtain the difference in the amount of lithium embedded in the negative electrode.

[0104] In one embodiment, the third module 303 is further configured to:

[0105] Obtaining an initial total battery capacity and an initial differential curve graph of the target lithium battery in the initial state;

[0106] An initial extreme left peak point and an initial extreme right peak point in the initial differential curve graph are determined.

[0107] In one embodiment, the fourth module 304 is specifically configured to:

[0108] determining a first capacity change based on the extreme left peak point and the initial extreme left peak point;

[0109] determining a second capacity change based on the extreme right peak point and the initial extreme right peak point;

[0110] Determining an active lithium loss value of the target lithium battery according to the first capacity change;

[0111] Determine a negative electrode active material loss value of the target lithium battery according to the first capacity change, the second capacity change and the difference in the negative electrode lithium insertion amount;

[0112] Determine the positive electrode active material loss value of the target lithium battery according to the total capacity of the test battery, the initial total capacity of the battery, the second capacity change and the negative electrode active material loss value;

[0113] The active lithium loss value, the negative electrode active material loss value and the positive electrode active material loss value are counted to obtain the thermodynamic loss value of the target lithium battery under the test state.

[0114] Those skilled in the art will clearly understand that the technical solutions of the embodiments of the present application can be implemented with the help of software and / or hardware. "Unit" and "module" in this specification refer to software and / or hardware that can independently perform or cooperate with other components to perform specific functions, where the hardware can be, for example, a field programmable gate array (FPGA), an integrated circuit (IC), etc.

[0115] Each processing unit and / or module in the embodiments of the present application may be implemented by an analog circuit that implements the functions described in the embodiments of the present application, or may be implemented by software that executes the functions described in the embodiments of the present application.

[0116] See next Figure 4 , Figure 4 A schematic structural diagram of an electronic device provided in an embodiment of this specification is shown.

[0117] like Figure 4 As shown, the electronic device 400 may include: at least one device processor 401 , at least one network interface 404 , a user interface 403 , a memory 405 and at least one communication bus 402 .

[0118] The communication bus 402 may be used to implement connection and communication among the above components.

[0119] The user interface 403 may include buttons, and the optional user interface may also include a standard wired interface or a wireless interface.

[0120] The network interface 404 may include, but is not limited to, a Bluetooth module, an NFC module, a Wi-Fi module, and the like.

[0121] Among them, the device processor 401 may include one or more processing cores. The device processor 401 uses various interfaces and lines to connect the various parts of the entire electronic device 400, and executes various functions of the electronic device 400 and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory 405, and calling data stored in the memory 405. Optionally, the device processor 401 can be implemented in at least one hardware form of DSP, FPGA, and PLA. The device processor 401 can integrate one or a combination of CPU, GPU, and modem. Among them, the CPU mainly processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing the content to be displayed on the display screen; and the modem is used to handle wireless communications. It is understandable that the above-mentioned modem may not be integrated into the device processor 401, but may be implemented separately through a chip.

[0122] Among them, the memory 405 may include RAM and ROM. Optionally, the memory 405 includes a non-transitory computer-readable medium. The memory 405 can be used to store instructions, programs, codes, code sets or instruction sets. The memory 405 may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory 405 may also be optionally at least one storage device located away from the aforementioned device processor 401. As Figure 4 As shown, the memory 405 as a computer storage medium may include an operating system, a network communication module, a user interface module, and program instructions.

[0123] Specifically, the device processor 401 may be used to call the lithium battery thermodynamic loss analysis application stored in the memory 405 and perform the following operations:

[0124] Obtaining a total test battery capacity of a target lithium battery in a test state, wherein the test state is a state of the target lithium battery after a target number of charge and discharge cycles in an initial state;

[0125] Determine a target differential curve of the target lithium battery under the test state, the target differential curve comprising a first curve and a second curve, the first curve being a discharge capacity-voltage differential curve, and the second curve being a negative electrode lithium insertion amount-voltage differential curve;

[0126] Determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, wherein the difference in the negative electrode lithium insertion amount is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve;

[0127] The thermodynamic loss value of the target lithium battery under the test state is determined based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

[0128] As an optional embodiment of this specification, it is characterized in that obtaining the total test battery capacity of the target lithium battery in the test state includes:

[0129] Charge the target lithium battery to the target voltage under test;

[0130] After receiving the charging completion signal, the target lithium battery is discharged to the cut-off voltage, and the released capacity during the discharge process is counted to obtain the total test battery capacity of the target lithium battery.

[0131] As an optional embodiment of this specification, it is characterized in that the target differential curve of the target lithium battery under the test state is determined, and the target differential curve includes a first curve and a second curve, the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve, including:

[0132] Performing a discharge process on the target lithium battery to obtain real-time monitoring data, and determining a discharge capacity-voltage curve and a negative electrode lithium insertion amount-voltage curve of the target lithium battery under the test state based on the real-time monitoring data;

[0133] A composite graph of the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve is constructed, and each curve point in the composite graph is simultaneously derivatized based on a differential algorithm to obtain a target differential curve graph of the target lithium battery under the test state, wherein the target differential curve graph includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve.

[0134] As an optional embodiment of this specification, it is characterized in that determining the extreme left peak point and the extreme right peak point in the first curve includes:

[0135] determining all peak points in the first curve based on a peak algorithm;

[0136] The peak points are screened out based on the coordinate positions of the peak points to determine the extreme left peak point and the extreme right peak point in the first curve.

[0137] As an optional embodiment of this specification, it is characterized in that the determining the difference in the amount of negative electrode lithium insertion corresponding to the extreme left peak point and the extreme right peak point, the difference in the amount of negative electrode lithium insertion is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve mapping the peak points, includes:

[0138] Determine mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve based on a curve mapping relationship, respectively, to obtain an extreme left mapping value and an extreme right mapping value, wherein the curve mapping relationship is a mapping relationship between each point in the first curve and the second curve;

[0139] The difference between the extreme left mapping value and the extreme right mapping value is calculated to obtain the difference in the amount of lithium embedded in the negative electrode.

[0140] As an optional embodiment of this specification, it is characterized in that after determining the extreme left peak point and the extreme right peak point in the first curve, and determining the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, it also includes:

[0141] Obtaining an initial total battery capacity and an initial differential curve graph of the target lithium battery in the initial state;

[0142] An initial extreme left peak point and an initial extreme right peak point in the initial differential curve graph are determined.

[0143] As an optional embodiment of this specification, it is characterized in that the thermodynamic loss value of the target lithium battery under the test state is determined according to the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the negative electrode lithium insertion amount difference and the total capacity of the test battery, and the thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value, including:

[0144] determining a first capacity change based on the extreme left peak point and the initial extreme left peak point;

[0145] determining a second capacity change based on the extreme right peak point and the initial extreme right peak point;

[0146] Determining an active lithium loss value of the target lithium battery according to the first capacity change;

[0147] Determine a negative electrode active material loss value of the target lithium battery according to the first capacity change, the second capacity change and the difference in the negative electrode lithium insertion amount;

[0148] Determine the positive electrode active material loss value of the target lithium battery according to the total capacity of the test battery, the initial total capacity of the battery, the second capacity change and the negative electrode active material loss value;

[0149] The active lithium loss value, the negative electrode active material loss value and the positive electrode active material loss value are counted to obtain the thermodynamic loss value of the target lithium battery under the test state.

[0150] The embodiments of this specification also provide a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the above method. The computer-readable storage medium may include, but is not limited to, any type of disk, including a floppy disk, an optical disk, a DVD, a CD-ROM, a microdrive, a magneto-optical disk, a ROM, a RAM, an EPROM, an EEPROM, a DRAM, a VRAM, a flash memory device, a magnetic or optical card, a nanosystem (including a molecular memory IC), or any type of medium or device suitable for storing instructions and / or data.

[0151] It should be noted that for the aforementioned method embodiments, for the sake of simplicity, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and modules involved are not necessarily required by this application.

[0152] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0153] In the several embodiments provided in this application, it should be understood that the disclosed devices can be implemented in other ways. For example, the device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some service interface, and the indirect coupling or communication connection of the device or unit can be electrical or other forms.

[0154] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0155] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0156] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a memory, including a number of instructions for enabling a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned memory includes: various media that can store program codes, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0157] Those skilled in the art will appreciate that all or part of the steps in the various methods of the above embodiments can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable memory, which may include: a flash drive, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0158] The foregoing description of this specification describes specific embodiments. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be performed in an order different from that described in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the accompanying drawings do not necessarily require the specific order shown or the sequential order to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A method for analyzing thermodynamic loss of lithium batteries, characterized in that: The method comprises: Obtaining a total test battery capacity of a target lithium battery in a test state, wherein the test state is a state of the target lithium battery after a target number of charge and discharge cycles in an initial state; Determine a target differential curve of the target lithium battery under the test state, the target differential curve comprising a first curve and a second curve, the first curve being a discharge capacity-voltage differential curve, and the second curve being a negative electrode lithium insertion amount-voltage differential curve; Determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, wherein the difference in the negative electrode lithium insertion amount is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve; The thermodynamic loss value of the target lithium battery under the test state is determined based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

2. The method according to claim 1, characterized in that The obtaining of the total test battery capacity of the target lithium battery in the test state includes: Charge the target lithium battery to the target voltage under test; After receiving the charging completion signal, the target lithium battery is discharged to the cut-off voltage, and the released capacity during the discharge process is counted to obtain the total test battery capacity of the target lithium battery.

3. The method according to claim 1, characterized in that The target differential curve of the target lithium battery under the test state is determined, wherein the target differential curve includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve, including: Performing a discharge process on the target lithium battery to obtain real-time monitoring data, and determining a discharge capacity-voltage curve and a negative electrode lithium insertion amount-voltage curve of the target lithium battery under the test state based on the real-time monitoring data; A composite graph of the discharge capacity-voltage curve and the negative electrode lithium insertion amount-voltage curve is constructed, and each curve point in the composite graph is simultaneously derivatized based on a differential algorithm to obtain a target differential curve graph of the target lithium battery under the test state, wherein the target differential curve graph includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve.

4. The method according to claim 1, wherein The determining of the extreme left peak point and the extreme right peak point in the first curve includes: determining all peak points in the first curve based on a peak algorithm; The peak points are screened out based on the coordinate positions of the peak points to determine the extreme left peak point and the extreme right peak point in the first curve.

5. The method according to claim 1, characterized in that The determining of the difference in the amount of lithium inserted in the negative electrode corresponding to the extreme left peak point and the extreme right peak point, wherein the difference in the amount of lithium inserted in the negative electrode is the difference in the mapped values ​​of the extreme left peak point and the extreme right peak point in the second curve, includes: Determine mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve based on a curve mapping relationship, respectively, to obtain an extreme left mapping value and an extreme right mapping value, wherein the curve mapping relationship is a mapping relationship between each point in the first curve and the second curve; The difference between the extreme left mapping value and the extreme right mapping value is calculated to obtain the difference in the amount of lithium embedded in the negative electrode.

6. The method according to claim 1, characterized in that After determining the extreme left peak point and the extreme right peak point in the first curve, and determining the difference in negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, the method further includes: Obtaining an initial total battery capacity and an initial differential curve graph of the target lithium battery in the initial state; An initial extreme left peak point and an initial extreme right peak point in the initial differential curve graph are determined.

7. The method according to claim 6, characterized in that The thermodynamic loss value of the target lithium battery under the test state is determined based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of lithium inserted in the negative electrode, and the total capacity of the test battery. The thermodynamic loss value includes a positive electrode active material loss value, a negative electrode active material loss value, and an active lithium loss value, including: determining a first capacity change based on the extreme left peak point and the initial extreme left peak point; determining a second capacity change based on the extreme right peak point and the initial extreme right peak point; Determining an active lithium loss value of the target lithium battery according to the first capacity change; Determine a negative electrode active material loss value of the target lithium battery according to the first capacity change, the second capacity change and the difference in the negative electrode lithium insertion amount; Determine the positive electrode active material loss value of the target lithium battery according to the total capacity of the test battery, the initial total capacity of the battery, the second capacity change and the negative electrode active material loss value; The active lithium loss value, the negative electrode active material loss value and the positive electrode active material loss value are counted to obtain the thermodynamic loss value of the target lithium battery under the test state.

8. A lithium battery thermodynamic loss analysis device, characterized in that: The device comprises: The first module is used to obtain the total capacity of the test battery of the target lithium battery in the test state, where the test state is the state of the target lithium battery after the target number of charge and discharge cycles in the initial state; The second module is used to determine a target differential curve of the target lithium battery under the test state, wherein the target differential curve includes a first curve and a second curve, wherein the first curve is a discharge capacity-voltage differential curve, and the second curve is a negative electrode lithium insertion amount-voltage differential curve; The third module is used to determine the extreme left peak point and the extreme right peak point in the first curve, and determine the difference in the negative electrode lithium insertion amount corresponding to the extreme left peak point and the extreme right peak point, where the difference in the negative electrode lithium insertion amount is the difference in the mapping values ​​of the extreme left peak point and the extreme right peak point in the second curve; The fourth module is used to determine the thermodynamic loss value of the target lithium battery under the test state based on the first capacity change of the extreme left peak point relative to the initial differential curve, the second capacity change of the extreme right peak point relative to the initial differential curve, the difference in the amount of negative electrode lithium insertion and the total capacity of the test battery. The thermodynamic loss value includes the positive electrode active material loss value, the negative electrode active material loss value, and the active lithium loss value.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, wherein the computer-readable storage medium stores instructions, which, when the instructions are executed on a computer or a processor, cause the computer or processor to execute the steps of the method according to any one of claims 1 to 7.

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