CN119179008A

CN119179008A - Method and device for detecting lithium precipitation of battery, electronic equipment and storage medium

Info

Publication number: CN119179008A
Application number: CN202411450302.9A
Authority: CN
Inventors: 李玲; 黄勇; 庄英; 孙剑彤; 宋书涛; 张小细
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2024-10-17
Filing date: 2024-10-17
Publication date: 2024-12-24

Abstract

The application provides a lithium precipitation detection method and device of a battery, electronic equipment and a storage medium. The method comprises the steps of obtaining a voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the completion of charge to the restoration of the battery to be tested to a steady state, the voltage difference in the relaxation period is a difference value between a voltage corresponding to the completion of charge of the battery to be tested and the voltage restored to the steady state, and lithium analysis detection is carried out on the battery to be tested based on the voltage differences in the relaxation periods corresponding to the charge-discharge cycles. According to the embodiment of the application, the voltage of the two points in the relaxation period after each charge is completed is collected, the voltage difference is obtained through the voltage calculation of the two points, and then the lithium precipitation detection is carried out on the battery to be detected according to the change condition of the voltage difference in the process of repeated charge and discharge cycles, so that the collected data volume is smaller, and the calculated volume is reduced.

Description

Method and device for detecting lithium precipitation of battery, electronic equipment and storage medium

Technical Field

The application relates to the technical field of battery detection, in particular to a lithium precipitation detection method and device of a battery, electronic equipment and a storage medium.

Background

The lithium separation phenomenon of the lithium battery refers to deposition and separation of lithium ions on an electrode in the charge and discharge process of the lithium battery. During this process, the deposition of metallic lithium, the so-called "lithium dendrites", may be formed, which may lead to degradation of battery performance and increase safety risks.

At present, a voltage relaxation method is mostly adopted for lithium analysis detection of a lithium battery, namely, a charging and discharging cycle is carried out on the lithium battery, the voltage of the lithium battery in the relaxation process after the charging is completed is recorded each time, a voltage time curve is obtained, and the voltage time curve is differentiated to obtain a U' time curve. If the U' time curve has an inflection point, the lithium precipitation exists when the battery is charged to the set SOC under the specific condition. According to the method, a plurality of voltage values are required to be acquired for single charge and discharge, and the voltage change condition is analyzed to determine whether the lithium precipitation phenomenon occurs, so that the calculated amount is large.

Disclosure of Invention

The embodiment of the application aims to provide a lithium analysis detection method and device for a battery, electronic equipment and a storage medium, which are used for reducing the calculated amount on the basis of realizing the lithium analysis detection of the battery.

In a first aspect, an embodiment of the present application provides a method for detecting lithium precipitation of a battery, including:

The method comprises the steps of obtaining a voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the completion of the charge to the restoration of the battery to be tested to a steady state;

and carrying out lithium precipitation detection on the battery to be detected based on the voltage difference in the relaxation period corresponding to the multiple charge-discharge cycles.

According to the embodiment of the application, the voltage of the two points in the relaxation period after each charge is completed is collected, the voltage difference is obtained through the voltage calculation of the two points, and then the lithium precipitation detection is carried out on the battery to be detected according to the change condition of the voltage difference in the process of repeated charge and discharge cycles, so that the collected data volume is smaller, and the calculated volume is reduced.

In any embodiment, the lithium analysis detection for the battery to be detected based on the voltage difference during relaxation corresponding to multiple charge-discharge cycles includes:

generating a change curve of the voltage difference along with the cycle times based on the voltage difference corresponding to the multiple charge-discharge cycles;

When the change of the voltage difference is larger than or equal to a preset threshold value, determining that the lithium precipitation phenomenon occurs in the battery to be tested, and recording the corresponding cycle times when the lithium precipitation phenomenon occurs.

In the embodiment of the application, the battery is in different lithium separation stages and can be reflected on the voltage change curve, so that the lithium separation degree and the corresponding charge and discharge cycle times can be intuitively determined through the voltage change curve.

In any embodiment, the preset threshold comprises a first preset threshold and a second preset threshold, the first preset threshold being less than the second preset threshold;

When the change of the voltage difference is larger than or equal to a first preset threshold value, determining that the lithium precipitation amount of the battery to be detected is a first lithium precipitation degree;

When the change of the voltage difference is larger than or equal to a second preset threshold value, determining that the lithium precipitation amount of the battery to be detected is a second lithium precipitation degree;

Wherein the first lithium precipitation degree is smaller than the second lithium precipitation degree.

In the embodiment of the application, since a large amount of lithium separation occurs in the battery, the corresponding lithium stripping and lithium re-intercalation reactions reach equilibrium, and the voltage difference is represented as the mixed voltage of the two reactions, the voltage difference can be obviously increased, and the lithium separation degree can be continuously increased along with the increase of the voltage difference. Therefore, by judging whether the variation of the voltage difference is larger than a preset threshold value, the accuracy of detecting whether a large amount of lithium precipitation occurs can be improved.

In any embodiment, the change amount of the voltage difference is determined to be greater than a preset threshold by at least one of:

The difference between the voltage differences corresponding to two adjacent charge-discharge cycles is larger than a preset difference;

generating a voltage difference curve based on the voltage differences respectively corresponding to the multiple charge-discharge cycles, wherein the slope of the voltage difference curve is larger than a preset slope;

Differential calculation is carried out based on voltage differences corresponding to the charge and discharge cycles, and the obtained differential value is larger than a preset differential value.

The embodiment of the application can improve the accuracy of detecting whether a large amount of lithium precipitation occurs by judging whether the variation of the voltage difference is larger than the preset threshold value.

In any embodiment, obtaining the voltage difference during relaxation of the battery to be tested after each charge is completed during the charge-discharge cycle includes:

Charging the battery to be tested, enabling the charged state of the battery to be tested to reach a preset state of charge, and recording the first voltage of the battery to be tested after the charging is completed;

Standing the charged battery to be tested for a preset time period, and recording a second voltage of the battery to be tested after standing;

the voltage difference during relaxation is determined from the voltage difference between the first voltage and the second voltage.

In the embodiment of the application, the voltage difference between two points after each charge is calculated, and the lithium precipitation detection of the battery to be detected is performed through the change condition of the voltage difference corresponding to the repeated charge and discharge cycles, so that the acquired data volume is smaller, and the calculated volume is reduced.

In any embodiment, charging the battery to be tested so that the charged state of the battery to be tested reaches a preset state of charge includes:

Constant-current charging is carried out on the battery to be tested, so that the voltage of the battery to be tested after constant-current charging reaches the charging cut-off voltage;

And carrying out constant voltage charging on the battery to be tested after constant current charging, so that the charge state of the battery to be tested after constant voltage charging reaches a preset charge state.

According to the embodiment of the application, the constant-current charge is carried out to the cut-off voltage, and then the constant-voltage charge is carried out, so that the influence of internal polarization of the battery is reduced, the real state of charge of the battery to be detected reaches the preset state of charge, and the accuracy of lithium analysis detection of the battery to be detected is improved.

In either embodiment, the preset duration is in the range of 10 minutes, 60 minutes.

In the embodiment of the application, the battery to be tested does not reach a steady state due to too short standing time, and the accuracy of lithium precipitation detection is affected, and if the standing time is too long, the battery to be tested is stored under high SOC, and the performance is deteriorated. Therefore, by presetting reasonable standing time, the application improves the accuracy of lithium precipitation detection on one hand and reduces the damage to the battery to be detected on the other hand.

In any embodiment, the method further comprises:

And outputting a jump warning signal after determining that the lithium precipitation amount of the battery to be detected is the first lithium precipitation degree.

According to the embodiment of the application, after the lithium precipitation amount of the battery to be detected reaches the first lithium precipitation degree, the jump warning signal is output, and the battery is in a state of a large amount of lithium precipitation after the lithium precipitation amount reaches the first lithium precipitation degree, so that danger can be caused if the battery is continuously used, and therefore, the jump warning signal is output, the warning effect is achieved, and the warning time is reasonable.

In any embodiment, the method further comprises:

collecting charge and discharge parameters of a battery to be tested, wherein the charge and discharge parameters comprise charge and discharge multiplying power, standing time length and SOC (state of charge) corresponding to charge and discharge completion respectively;

inputting the charge and discharge parameters into a lithium analysis prediction model to obtain the charge and discharge cycle times of the lithium analysis amount of the first lithium analysis degree of the battery to be detected, which is output by the lithium analysis prediction model;

the lithium analysis prediction model is obtained through training by the following method:

charging and discharging the test battery by adopting a plurality of different charging and discharging parameters, and acquiring a training voltage difference in a relaxation period after each charging is completed;

Determining the charge and discharge cycle times corresponding to the lithium precipitation amount of the test battery reaching the first lithium precipitation degree based on the training voltage difference;

and (3) taking the charge and discharge parameters as a model input, and taking the charge and discharge cycle times as a label to perform model training to obtain a lithium analysis prediction model.

According to the embodiment of the application, the charge and discharge parameters are analyzed through the lithium analysis prediction model, and an artificial intelligent model is introduced, so that the accuracy and the efficiency of lithium analysis prediction are improved.

In any embodiment, the method further comprises:

acquiring battery temperature and battery internal pressure information of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process;

Lithium analysis detection is carried out on a battery to be detected based on voltage differences in relaxation periods corresponding to multiple charge-discharge cycles, and the method comprises the following steps:

comparing the voltage difference with a first voltage threshold value to obtain a first comparison result;

comparing the battery temperature with a temperature threshold value to obtain a second comparison result;

Comparing the internal pressure information of the battery with a pressure threshold value to obtain a third comparison result;

and judging whether the battery to be tested reaches the lithium precipitation amount of the first lithium precipitation degree according to the first comparison result, the second comparison result and the third comparison result.

According to the embodiment of the application, whether the lithium precipitation amount of the battery to be detected reaches the first lithium precipitation degree is judged by combining the voltage difference, the battery temperature and the internal pressure of the battery, so that the accuracy of detecting the lithium precipitation degree is improved.

In a second aspect, an embodiment of the present application provides a lithium analysis detection apparatus for a battery, including:

The device comprises a voltage difference acquisition module, a voltage difference acquisition module and a voltage difference judgment module, wherein the voltage difference acquisition module is used for acquiring the voltage difference of a relaxation period of a battery to be tested after each charge is completed in a charge-discharge cycle process;

and the detection module is used for carrying out lithium precipitation detection on the battery to be detected based on the voltage difference in the relaxation period corresponding to the multiple charge-discharge cycles.

In a third aspect, an embodiment of the present application provides an electronic device comprising a processor, a memory, and a bus, wherein,

The processor and the memory complete the communication with each other through a bus;

The memory stores program instructions executable by the processor, the processor invoking the program instructions capable of performing the method of the first aspect.

In a fourth aspect, embodiments of the present application provide a non-transitory computer readable storage medium comprising:

the non-transitory computer readable storage medium stores computer instructions that cause a computer to perform the method of the first aspect.

In a fifth aspect, embodiments of the present application provide a computer program product comprising computer program instructions which, when read and run by a processor, perform the method of the first aspect.

Additional features and advantages of the application will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the embodiments of the application. The objectives and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic flow chart of a method for detecting lithium precipitation of a battery according to an embodiment of the present application;

FIG. 2 is a graph of capacity retention rate provided by an embodiment of the present application;

FIG. 3 is a graph of a voltage difference provided by an embodiment of the present application;

Fig. 4 is a schematic structural diagram of a lithium separation detection device of a battery according to an embodiment of the present application;

fig. 5 is a schematic diagram of an entity structure of an electronic device according to an embodiment of the present application.

Detailed Description

Embodiments of the technical scheme of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present application, and thus are merely examples, and are not intended to limit the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting of the application, and the terms "comprising" and "having" and any variations thereof in the description of the application and the claims and the above description of the drawings are intended to cover non-exclusive inclusions.

In the description of embodiments of the present application, the technical terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiment of the present application, the term "and/or" is merely an association relationship describing the association object, and indicates that three relationships may exist, for example, a and/or B, and may indicate that a exists alone, while a and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" means two or more (including two), and similarly, "plural sets" means two or more (including two), and "plural sheets" means two or more (including two).

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "fixed" and the like are to be construed broadly and include, for example, fixed connection, detachable connection, or integral therewith, mechanical connection, electrical connection, direct connection, indirect connection via an intermediary, communication between two elements, or interaction between two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to specific circumstances.

As a green energy source, lithium ion batteries have advantages of high voltage, high energy density, no memory effect, etc., and have been rapidly developed in recent years, and have been widely used in various fields.

Lithium precipitation is an abnormal phenomenon that is easily generated in the charging process of lithium ion batteries, especially in the case of quick charge or low temperature charging. When the battery potential of graphite is lower than the electrode potential of lithium, lithium ions accumulate on the surface of graphite to avoid intercalation, and lithium precipitation occurs. The lithium separation can accelerate capacity fading, shortens service life, and meanwhile, the separated lithium can puncture a battery diaphragm, so that the battery is short-circuited, and further safety problems are caused. All of the above conditions can accelerate the aging of the lithium ion battery, resulting in reduced battery performance and even more serious consequences. Therefore, in order to ensure the normal use of the battery and reduce the risk, the lithium precipitation phenomenon of the battery needs to be detected in time and the existing potential aging needs to be pre-warned.

In the prior art, a voltage relaxation method is adopted to carry out lithium analysis detection on a battery, more voltage data are required to be collected in the relaxation process after each charge and discharge, and then the collected voltage data are differentiated to determine whether lithium analysis occurs. In this method, a lot of data is collected every cycle, which increases the calculation amount.

In order to solve the technical problems, the embodiment of the application provides a lithium precipitation detection method and device of a battery, electronic equipment and a storage medium. According to the lithium analysis detection method, the lithium analysis condition of the battery to be detected is detected based on the voltage differences corresponding to the charge and discharge cycles respectively by acquiring the voltage differences in the relaxation period after each charge is completed. Therefore, the application can greatly reduce the number and the calculated amount of voltage data acquisition by acquiring the voltages of two points in the relaxation period.

It should be noted that, in the embodiment of the present application, lithium analysis detection may be performed on a lithium ion battery cell or a battery including a lithium ion battery cell, and for convenience of description, the battery cell and the battery including a battery cell are collectively referred to as a battery to be tested.

It can be appreciated that the lithium analysis detection method of the battery provided by the embodiment of the application can be applied to electronic equipment, wherein the electronic equipment comprises a terminal and a server, the terminal can be a smart phone, a tablet Personal computer, a Personal digital assistant (Personal DIGITAL ASSITANT, PDA) and the like, and the server can be an application server or a Web server.

Fig. 1 is a schematic flow chart of a method for detecting lithium precipitation of a battery according to an embodiment of the present application, as shown in fig. 1, the method includes:

Step 101, acquiring a voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the completion of charge to the restoration of the battery to be tested to a steady state;

And 102, performing lithium precipitation detection on the battery to be detected based on the voltage differences in relaxation periods respectively corresponding to the charge-discharge cycles.

In a specific implementation process, the battery to be tested may be a battery which is not started to be used just before leaving the factory, may be a battery which is used for a period of time, may be a retired battery, and the like. In the process of lithium precipitation detection of the battery to be detected, charge and discharge equipment can be adopted to carry out charge and discharge circulation on the battery to be detected. Wherein the charge-discharge device may be an electrochemical workstation or the like.

Since the lithium separation phenomenon generally occurs during the process of charging the battery, after the battery to be tested is charged once, the voltage difference during relaxation after the battery is charged can be collected by the voltage collecting device. It should be noted that, after the battery to be tested is charged, there is polarization inside the battery to be tested, and the embodiment of the present application is called a polar state. Through the operation of standing, the internal polarization of the battery to be tested can be reduced, so that the battery to be tested reaches a steady state or an approximate steady state. Thus, the time corresponding to the battery under test from the polar state to the steady state or near steady state is referred to as the relaxation period. Thus, the voltage difference during relaxation may be the difference between the voltage of the battery under test after charging is completed and the voltage that returns to steady state.

In the process of charging and discharging the battery to be tested, the voltage difference can be obtained by adopting the method after each charging, or the voltage difference can be obtained discontinuously, i.e. the voltage difference can be obtained once by interval of multiple charging and discharging cycles. Therefore, a plurality of voltage differences can be acquired, and then lithium analysis detection is performed on the battery to be detected based on the change condition of the plurality of voltage differences. The lithium precipitation degree of the battery to be detected and the corresponding charge and discharge cycle times can be determined through the lithium precipitation detection.

On the basis of the above embodiment, the lithium analysis detection is performed on the battery to be detected based on the voltage differences during the relaxation periods respectively corresponding to the charge and discharge cycles, including:

In a specific implementation process, the battery to be tested is restored to a steady state from an polar state during a relaxation period after charging, lithium ions in the battery to be tested are intercalated between graphite layers to form LixC6 or are separated to form lithium metal during the relaxation period, the open circuit voltage of the LixC6 is 93mV, the open circuit voltage of the lithium metal is 7.7mV, wherein a potential difference between the LixC6 and the lithium metal causes partial lithium discharge to become lithium ions, and the lithium ions are intercalated back into graphite. Therefore, the lithium separation phenomenon of the battery to be tested can be analyzed in three stages along with repeated charge and discharge cycles, namely, 1, no lithium separation or a small amount of lithium separation, if the lithium separation amount is small, lithium stripping current is lower than lithium heavy intercalation graphite current, the lithium ion intercalation graphite interlayer is used as a main part, the relaxation voltage is dominated by the open circuit voltage of LixC6, the voltage change in the relaxation period is small, namely, the voltage difference is small, 2, lithium separation is accumulated, a large amount of lithium separation is realized, the relaxation voltage is represented as the mixed voltage of the two reactions due to the balance between the lithium stripping reaction and the lithium heavy intercalation reaction, the lithium separation and the LixC6 coexist, the voltage change in the relaxation period is increased, namely, the voltage difference is suddenly increased, and 3, the serious lithium separation is dominated by the open circuit voltage of lithium metal, and the voltage difference in the relaxation period reaches the maximum value. Thus, the voltage difference behavior of the battery under test during relaxation is different in the different lithium separation phases.

To verify the above analysis, the examples of the present application were run with one comparative example and one example, wherein:

comparative example after charging to a charge cutoff voltage under Constant Current (CC) charging of 1C current, constant voltage charging was performed to 100% soc, and actual voltage ① was recorded. After 10min of standing, the actual voltage ② was recorded, and after discharging to the discharge cut-off voltage at 1C current (constant current discharge), the standing was relaxed for 10min. This process is a charge-discharge flow per cycle.

Example except that the charge-discharge ratio was 2C, the conditions were the same as those of the comparative example.

The comparative example and the example were charged and discharged in the above manner, and the capacity retention rate corresponding to each charge and discharge cycle was recorded, and a capacity retention rate change curve was generated according to the capacity retention rate and the corresponding number of cycles, and as shown in fig. 2, since the charge and discharge rate of the example was greater than that of the comparative example, the example had suddenly decreased in capacity retention rate from about 600 cycles, and at this time, it was explained that the battery corresponding to the example had a capacity jump phenomenon.

In the charge-discharge cycle process of the comparative example and the embodiment, the voltage difference during relaxation after each charge-discharge is completed can be recorded, and the recorded voltage difference and the corresponding cycle times generate a voltage change curve, as shown in fig. 3, based on the voltage change curve, the lithium precipitation condition of the battery to be tested can be determined. As can be seen from fig. 3, the batteries to be measured corresponding to the comparative example and the example, respectively, are all phenomena in which a sudden increase in voltage difference occurs around 600 charge and discharge cycles. Therefore, it was confirmed that the two batteries to be tested exhibited a large amount of lithium precipitation around 600 charge-discharge cycles. Therefore, the experimental results of fig. 3 and fig. 2 correspond.

In addition, the degree of lithium precipitation may include a case where serious lithium precipitation occurs in addition to a case where a large amount of lithium precipitation occurs. Severe lithium precipitation can be determined by the voltage difference reaching a maximum.

The existing methods for nondestructive testing can determine the lithium precipitation starting point of the battery to be tested, but the influence of a small amount of lithium precipitation on the battery performance cannot be directly determined, and the possible influence is small. If the early warning performance is deteriorated through the lithium precipitation starting point, an excessive early warning problem may exist. In the practical use battery process, when lithium is continuously separated and accumulated to form lithium dendrite, the safety accident can be caused when the isolating membrane is punctured, and the value of early warning on the battery before the safety accident is higher.

Therefore, when the lithium precipitation detection is performed on the battery, the preset threshold value of the battery can comprise a first preset threshold value and a second preset threshold value, wherein the first preset threshold value is smaller than the second preset threshold value, when the change of the voltage difference is larger than or equal to the first preset threshold value, the lithium precipitation amount of the battery to be detected is determined to be a first lithium precipitation degree, when the change of the voltage difference is larger than or equal to the second preset threshold value, the lithium precipitation amount of the battery to be detected is determined to be a second lithium precipitation degree, and the first lithium precipitation degree is smaller than the second lithium precipitation degree.

In a specific implementation process, when judging the lithium precipitation degree, the voltage difference can be compared with a preset threshold value, and if the voltage difference is greater than or equal to a first preset threshold value, it is determined that the lithium precipitation amount of the battery to be detected reaches the first lithium precipitation degree. The first lithium precipitation level is used to characterize a large amount of lithium precipitation, i.e. the lithium precipitation of the battery to be tested has accumulated into lithium dendrites, with the risk of puncturing the separator if continued use. Therefore, in practical application, if the lithium precipitation degree of the battery to be detected is detected to reach the first lithium precipitation degree, an alarm prompt can be performed.

If the voltage difference is greater than or equal to a second preset threshold value, determining that the lithium precipitation amount of the battery to be detected reaches a second lithium precipitation degree. The second lithium precipitation level is used for representing serious lithium precipitation, and the lithium precipitation amount is larger than that of the first lithium precipitation level, namely the lithium precipitation amount of the battery to be tested reaches the limit value of penetrating through the isolating membrane, and the isolating membrane is penetrated.

The embodiment of the application can determine the point positions of a large amount of lithium precipitation and serious lithium precipitation of the battery to be detected, so that the detection of the lithium precipitation degree of the battery to be detected provides a basis for more timely alarm in order to improve the safety of the battery.

As shown in fig. 3, based on the voltage change curve, a point where the voltage difference suddenly increases can be determined, specifically, whether the change amount of the voltage difference is greater than a preset threshold value or not can be judged, if so, the phenomenon that the voltage difference suddenly increases is described, and then the lithium precipitation phenomenon of the first lithium precipitation degree of the battery to be detected can be determined.

When the voltage difference reaches the maximum value, the relaxation voltage is indicated to be dominated by the open-circuit voltage of lithium metal, and the battery to be tested belongs to the phenomenon of severely lithium precipitation, namely the lithium precipitation phenomenon of the second lithium precipitation degree.

In the embodiment of the application, since the battery is subjected to a large amount of lithium precipitation, the corresponding lithium stripping and lithium re-intercalation reactions are balanced, and the voltage difference is represented as the mixed voltage of the two reactions, the voltage difference is obviously increased, and therefore, the accuracy of detecting whether the large amount of lithium precipitation occurs can be improved by judging whether the variation of the voltage difference is larger than the preset threshold value.

On the basis of the above embodiment, it may be determined that the variation of the voltage difference is greater than the preset threshold by at least one of:

1. the difference value between the voltage differences corresponding to the adjacent two times of charge and discharge is larger than a preset difference value;

2. generating a voltage difference curve based on the voltage differences respectively corresponding to the multiple charge-discharge cycles, wherein the slope of the voltage difference curve is larger than a preset slope;

3. Differential calculation is carried out based on voltage differences corresponding to the charge and discharge cycles, and the obtained differential value is larger than a preset differential value.

In a specific implementation process, each charge-discharge cycle corresponds to a voltage difference, a voltage change curve can be generated by the voltage difference corresponding to each charge-discharge cycle and the corresponding cycle times, as shown in fig. 3, based on the voltage change curve, the voltage difference corresponding to the current charge-discharge and the voltage difference corresponding to the previous charge-discharge can be compared to obtain a difference value, if the difference value is greater than a preset difference value, the situation that the voltage difference is suddenly increased is described, and the situation that a large amount of lithium is separated from the battery to be tested is determined. It should be noted that the minimum cycle number corresponding to the abrupt increase of the voltage difference is the starting point of the battery to be tested for generating a large amount of lithium. And then, with the continuous charge and discharge of the battery to be tested, the lithium precipitation amount is gradually increased. In addition, when the electronic device acquires the voltage difference in the relaxation period after the completion of charging, the electronic device can acquire the voltage difference at intervals, the interval number can be 1,2,5,10, the smaller the interval number is, the more accurate the lithium precipitation detection of the battery to be detected is, and the correspondingly larger the calculated amount is; the larger the interval number is, the smaller the calculated amount is, and accordingly the accuracy of lithium analysis detection of the battery to be detected is reduced. The specific value of the interval number is not infinite, and an upper limit value, for example, a maximum value of 50 or 100, may be given based on practical situations. Taking the interval number as 10 as an example, the electronic device may obtain the voltage differences corresponding to the 10 th, 20 th and 30 th charging and discharging cycles, where the difference between the voltage difference corresponding to the 10 th charging and discharging cycle and the voltage difference corresponding to the 20 th charging and discharging cycle is called the difference between the voltage differences corresponding to the adjacent two charging and discharging cycles. The difference between the voltage difference corresponding to the 20 th charge-discharge cycle and the voltage difference corresponding to the 30 th charge-discharge cycle is referred to as the difference between the voltage differences corresponding to the adjacent two charge-discharge cycles.

After the electronic device obtains the voltage differences corresponding to the charge-discharge cycles, a voltage difference curve is generated based on the voltage differences and the cycle times, as shown in fig. 3, and the slope of any point on the curve can be calculated. The minimum cycle times corresponding to the slope larger than the preset slope are the starting points of a large amount of lithium precipitation of the battery to be detected, and then the lithium precipitation amount is gradually increased along with the continuous charge and discharge of the battery to be detected.

And differential calculation can be performed based on the voltage differences corresponding to the charge and discharge cycles respectively to obtain differential values corresponding to the cycle times respectively, and the minimum cycle times with the differential values larger than the preset differential values are used as starting points of the battery to be tested for generating a large amount of lithium precipitation. And then, with the continuous charge and discharge of the battery to be tested, the lithium precipitation amount is gradually increased.

On the basis of the above embodiment, the method for obtaining the voltage difference during relaxation of the battery to be tested after each charge is completed during the charge-discharge cycle includes:

And determining the voltage difference of the battery to be tested during relaxation according to the voltage difference between the first voltage and the second voltage.

In a specific implementation process, a charging and discharging device is utilized to charge a battery to be tested, so that the state of charge of the battery to be tested reaches a preset state of charge, wherein the range of the preset state of charge can be (0, 100% ], preferably, the range of the preset state of charge can be [50%,100% ], taking the preset state of charge as an example, when the battery to be tested is charged to 100% SOC, stopping charging, and recording the first voltage of the battery to be tested in the current time, then standing the battery to be tested, so that the battery to be tested is kept stand for a preset time length, and after the preset time length of standing, recording the second voltage of the battery to be tested, wherein the range of the preset time length can be [10 minutes, 60 minutes ], preferably, the range of the preset time length of the value can be [10 minutes, 30 minutes ]. The embodiment of the application refers to the battery to be tested in the standing period, the battery to be recovered from the polar state to the steady state or approximate steady state. Therefore, when the preset duration is determined, the charging rate, the temperature, the aging degree and other factors of the battery to be measured can be determined.

After the first voltage and the second voltage are obtained, the voltage difference between the first voltage and the second voltage is calculated, and the calculated voltage difference is used as the voltage difference of the battery to be tested during relaxation.

According to the embodiment of the application, the lithium precipitation detection of the battery to be detected is performed through calculating the voltage difference between two points after each charge is completed and through the change condition of the voltage difference corresponding to multiple charge and discharge cycles, so that the acquired data volume is smaller, and the calculated volume is reduced.

On the basis of the above embodiment, charging the battery to be tested so that the charged state of the battery to be tested reaches a preset state of charge, including:

constant-current charging is carried out on the battery to be tested, so that the voltage of the battery to be tested after constant-current charging reaches the cut-off voltage;

In a specific implementation process, when the battery to be tested is charged, constant current charging can be performed on the battery to be tested, for example, the battery to be tested can be charged by adopting a constant current with a charging rate of 1C, so that the voltage of the battery to be tested reaches a cut-off voltage. It is understood that the cut-off voltage refers to a voltage corresponding to a preset state of charge to be reached by the battery to be measured. After the constant current charging of the battery to be tested reaches the cut-off voltage, the actual voltage of the battery to be tested is smaller than the cut-off voltage due to the internal polarization of the battery, which indicates that the actual state of charge of the charged battery to be tested does not reach the preset state of charge. Therefore, the constant-voltage charging can be performed on the battery after constant-current charging, so that the charge state of the battery to be measured after charging reaches the preset charge state.

In addition, the battery to be measured can be charged with a small current and a constant current, so that the state of charge of the battery to be measured reaches a preset state of charge. The polarization reaction inside the battery to be tested is small due to the small current charge, and can be ignored. When the battery to be tested is charged, constant voltage charging can be adopted, so that the state of charge of the battery to be tested reaches a preset state of charge.

On the basis of the embodiment, the method further comprises:

And inputting the charge and discharge parameters into a lithium precipitation prediction model to obtain the charge and discharge cycle times of the lithium precipitation amount of the first lithium precipitation degree of the battery to be detected, which is output by the lithium precipitation prediction model.

In a specific implementation process, the lithium analysis prediction model is obtained through pre-training, and the training method is as follows:

And charging and discharging the test battery by adopting a plurality of different charging and discharging parameters, and acquiring a training voltage difference in a relaxation period after each charging is completed, wherein the charging and discharging parameters can comprise a charging multiplying power, a discharging multiplying power, a standing time after each charging is completed and a SOC (state of charge) corresponding to each charging completion. It should be noted that the training voltage difference is similar to that in the above embodiment, except that the corresponding battery is different, and will not be described here again.

The method for determining whether the lithium precipitation amount reaches the first lithium precipitation degree based on the training voltage difference can be referred to the method for determining whether the lithium precipitation amount reaches the first lithium precipitation degree based on the voltage difference in the above embodiment, and will not be described herein.

After the lithium-precipitation prediction model is obtained, charge and discharge parameters of the battery to be measured can be acquired for the battery to be measured, then the charge and discharge parameters are input into the trained lithium-precipitation prediction model, and the charge and discharge cycle times of the lithium-precipitation amount of the battery to be measured, which is output by the lithium-precipitation prediction model and has the first lithium-precipitation degree, are obtained.

On the basis of the embodiment, the method further comprises:

In a specific implementation, besides the determination based on the voltage difference during relaxation after each charge is completed, the temperature of the battery and the internal pressure information of the battery can also be used to characterize the lithium precipitation of the battery. The method comprises the step of acquiring battery temperature and battery internal pressure information of the battery to be measured in a relaxation period after each charge is completed in a charge-discharge cycle process. It is understood that the battery temperature may be the average temperature of the battery during relaxation, the highest temperature, or an intermediate value of temperature. The battery internal pressure information may be the average pressure of the battery during relaxation, the maximum pressure, or an intermediate value of the pressure.

And comparing the voltage difference, the battery temperature and the internal pressure of the battery by adopting corresponding thresholds respectively, namely comparing the voltage difference with a first voltage threshold to obtain a first comparison result, and if the voltage difference is larger than the first voltage threshold, primarily considering that the lithium precipitation amount of the first lithium precipitation degree exists in the battery to be detected. And if the battery temperature is greater than the temperature threshold, primarily considering that the lithium precipitation amount of the first lithium precipitation degree appears in the battery to be detected. And comparing the internal pressure information of the battery with a pressure threshold value to obtain a third comparison result, and if the internal pressure information of the battery is larger than the pressure threshold value, primarily considering that the lithium precipitation amount of the first lithium precipitation degree appears in the battery to be detected. The first voltage threshold, the temperature threshold and the pressure threshold can be set according to actual conditions.

After the first comparison result, the second comparison result and the third comparison result are obtained, if two or more comparison results indicate that the lithium precipitation amount of the first lithium precipitation degree appears in the battery to be tested, the lithium precipitation amount of the first lithium precipitation degree of the battery to be tested can be finally determined. Otherwise, the lithium precipitation amount of the battery to be tested does not reach the first lithium precipitation degree. Or the weighted average can be performed based on the first comparison result, the second comparison result and the third comparison result, so as to obtain the score of the lithium precipitation amount of the battery to be measured reaching the first lithium precipitation degree, and if the score is higher than the preset score, the lithium precipitation amount of the battery to be measured reaching the first lithium precipitation degree is determined. The weight corresponding to each comparison result can be set according to the actual situation.

The embodiment of the application provides a lithium separation detection process of a comparison example and six embodiments, wherein:

Example 1 except that the charge-discharge ratio was 2C, the conditions were the same as in the comparative example.

Example 2 except that the charge-discharge ratio was 0.5C, the conditions were the same as in the comparative example.

Example 3 the conditions were the same as in the comparative example except that the standing time period was 60 minutes.

Example 4 the conditions were the same as in the comparative example except that the standing time period was 120 min.

Example 5 the conditions were the same as in example except that the charge was to 80% SOC.

Example 6 the conditions were the same as in example except that the charge was to 50% SOC.

After charging and discharging the comparative example and the example in the above manner, the following results were obtained:

From the above table it can be derived that:

by comparing example 1 and example 2 with comparative example, the larger the charging rate, the faster the battery ages (see cycle corresponding to 85% soh), example 1 shows a large amount of lithium precipitation around 600 cycles, and at this time shows a battery jump phenomenon, which indicates that the cycle with sudden voltage change during charging can realize jump early warning.

The effect of the rest period on the charge-discharge cycle is illustrated by comparing example 3 and example 4 with the comparative example. I.e., a long standing time, may cause degradation in battery performance.

By comparing the embodiment 5 and the embodiment 6 with the comparative example, the jump pre-warning can be realized by the voltage change sudden cycle in the charging process when the battery is charged to different SOCs, so the embodiment of the application is suitable for lithium precipitation detection of the battery charged to (0, 100 percent SOCs), and can realize the purpose of lithium precipitation detection of the battery to be detected by respectively testing the battery to be detected to 10 percent SOCs, 30 percent SOCs and 75 percent SOCs besides the battery to be detected to 50 percent SOCs and 100 percent SOCs.

Fig. 4 is a schematic structural diagram of a lithium analysis detection device for a battery according to an embodiment of the present application, where the device may be a module, a program segment, or a code on an electronic device. It should be understood that the apparatus corresponds to the embodiment of the method of fig. 1 described above, and is capable of performing the steps involved in the embodiment of the method of fig. 1, and specific functions of the apparatus may be referred to in the foregoing description, and detailed descriptions thereof are omitted herein as appropriate to avoid redundancy. The device comprises a voltage difference acquisition module 401 and a detection module 402, wherein:

The voltage difference acquisition module 401 is configured to acquire a voltage difference during a relaxation period of the battery to be tested after each charge is completed in a charge-discharge cycle process, where the relaxation period refers to a period of time from the completion of charge to the restoration of the battery to be tested to a steady state;

The detection module 402 is configured to perform lithium analysis detection on the battery to be tested based on voltage differences during relaxation periods corresponding to the charge-discharge cycles.

Based on the above embodiments, the detection module 402 is specifically configured to:

On the basis of the above embodiment, the preset thresholds include a first preset threshold and a second preset threshold, where the first preset threshold is smaller than the second preset threshold, and the detection module 402 is specifically configured to:

On the basis of the above embodiment, it is judged that the variation of the voltage difference is larger than the preset threshold by at least one of:

Generating a voltage difference curve based on voltage differences respectively corresponding to the multiple charge-discharge cycles, wherein the slope of the voltage difference curve is larger than a preset slope;

Based on the above embodiment, the voltage difference acquisition module 401 is specifically configured to:

On the basis of the above embodiment, the value range of the preset duration is [10 minutes, 60 minutes ].

On the basis of the above embodiment, the device further includes an early warning module for:

On the basis of the above embodiment, the apparatus further includes a model analysis module for:

Collecting charge and discharge parameters of the battery to be tested, wherein the charge and discharge parameters comprise charge and discharge multiplying power, standing time length and SOC (state of charge) corresponding to charge and discharge completion respectively;

On the basis of the above embodiment, the detection module 402 is further configured to:

Fig. 5 is a schematic diagram of an entity structure of an electronic device according to an embodiment of the present application, as shown in fig. 5, where the electronic device includes a processor (processor) 501, a memory (memory) 502, and a bus 503,

The processor 501 and the memory 502 complete communication with each other via the bus 503;

The processor 501 is configured to invoke the program instructions in the memory 502 to execute the method provided in the above embodiments of the method, for example, includes obtaining a voltage difference between a relaxation period of a battery to be tested after each charge is completed in a charge-discharge cycle, where the relaxation period refers to a period from the completion of the charge to the restoration of the battery to be tested to a steady state, the voltage difference between the voltage corresponding to the completion of the charge of the battery to be tested and the voltage restored to the steady state, and performing lithium analysis detection on the battery to be tested based on the voltage differences between the relaxation periods corresponding to the multiple charge-discharge cycles, respectively.

The processor 501 may be an integrated circuit chip having signal processing capabilities. The processor 501 may be a general-purpose processor including a central processing unit (Central Processing Unit, CPU), a network processor (Network Processor, NP), etc., or may be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components. Which may implement or perform the various methods, steps, and logical blocks disclosed in embodiments of the application. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

Memory 502 may include, but is not limited to, random access Memory (Random Access Memory, RAM), read Only Memory (ROM), programmable Read Only Memory (Programmable Read-Only Memory, PROM), erasable Read Only Memory (Erasable Programmable Read-Only Memory, EPROM), electrically erasable Read Only Memory (ELECTRICALLY ERASABLE PROGRAMMABLE READ-Only Memory, EEPROM), and the like.

The embodiment discloses a computer program product, which comprises a computer program stored on a non-transitory computer readable storage medium, wherein the computer program comprises program instructions, when the program instructions are executed by a computer, the computer can execute the method provided by the method embodiments, for example, the method comprises the steps of acquiring a voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the charge completion to the restoration to a steady state of the battery to be tested, the voltage difference in the relaxation period is a difference between a voltage corresponding to the charge completion of the battery to be tested and a voltage restoration to the steady state of the battery to be tested, and performing lithium analysis detection on the battery to be tested based on the voltage differences in the relaxation periods corresponding to the charge-discharge cycles.

The embodiment provides a non-transitory computer readable storage medium, which stores computer instructions for causing a computer to execute the methods provided in the above embodiments, for example, including obtaining a voltage difference between a relaxation period of a battery to be tested after each charge is completed in a charge-discharge cycle, where the relaxation period refers to a period from the completion of charge to the restoration of the battery to be tested to a steady state, the voltage difference between the relaxation period is a difference between a voltage corresponding to the completion of charge of the battery to be tested and a voltage corresponding to the restoration of the battery to the steady state, and performing lithium analysis detection on the battery to be tested based on the voltage differences between the relaxation periods corresponding to the respective charge-discharge cycles.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other manners. The above-described apparatus embodiments are merely illustrative, for example, the division of the units is merely a logical function division, and there may be other manners of division in actual implementation, and for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be through some communication interface, device or unit indirect coupling or communication connection, which may be in electrical, mechanical or other form.

Further, the units described as separate units may or may not be physically separate, and units displayed as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

Furthermore, functional modules in various embodiments of the present application may be integrated together to form a single portion, or each module may exist alone, or two or more modules may be integrated to form a single portion.

In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and variations will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A lithium analysis detection method for a battery, comprising:

The method comprises the steps of obtaining a voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the completion of the charge of the battery to be tested to the restoration of the battery to be tested to a steady state;

and performing lithium precipitation detection on the battery to be detected based on the voltage difference during the relaxation period corresponding to the multiple charge-discharge cycles.

2. The method according to claim 1, wherein the lithium analysis detection of the battery to be measured based on the voltage difference during the relaxation corresponding to the plurality of charge-discharge cycles includes:

3. The method of claim 2, wherein the preset thresholds comprise a first preset threshold and a second preset threshold, the first preset threshold being less than the second preset threshold;

When the change of the voltage difference is larger than or equal to the first preset threshold value, determining that the lithium precipitation amount of the battery to be detected is a first lithium precipitation degree;

when the change of the voltage difference is larger than or equal to the second preset threshold value, determining that the lithium precipitation amount of the battery to be detected is a second lithium precipitation degree;

4. A method according to claim 3, wherein the change in the voltage difference is determined to be greater than a predetermined threshold by at least one of:

Generating a voltage difference curve based on the voltage difference corresponding to the multiple charge-discharge cycles, wherein the slope of the voltage difference curve is larger than a preset slope;

And performing differential calculation based on the voltage difference corresponding to the multiple charge-discharge cycles, wherein the obtained differential value is larger than a preset differential value.

5. The method of claim 1, wherein the step of obtaining the voltage difference during relaxation of the battery under test after each charge is completed during the charge-discharge cycle comprises:

Charging the battery to be tested, so that the charged state of the battery to be tested reaches a preset state of charge, and recording the first voltage of the battery to be tested after the charging is completed;

a voltage difference during the relaxation is determined from a voltage difference between the first voltage and the second voltage.

6. The method of claim 5, wherein charging the battery under test such that the state of charge of the charged battery under test reaches a preset state of charge comprises:

7. The method of claim 5, wherein the predetermined time period is in the range of [10 minutes, 60 minutes ].

8. A method according to claim 3, characterized in that the method further comprises:

9. The method according to claim 1, wherein the method further comprises:

Inputting the charge and discharge parameters into a lithium precipitation prediction model to obtain the charge and discharge cycle times of the lithium precipitation amount of the battery to be detected, which is output by the lithium precipitation prediction model and has a first lithium precipitation degree;

determining the charge and discharge cycle times corresponding to the lithium precipitation amount of the test battery reaching a first lithium precipitation degree based on the training voltage difference;

And taking the charge and discharge parameters as a model input, and taking the charge and discharge cycle times as a label to perform model training to obtain a lithium analysis prediction model.

10. The method according to any one of claims 1 to 9, further comprising acquiring battery temperature and battery internal pressure information during relaxation after each charge completion of the battery under test during a charge-discharge cycle;

The lithium analysis detection is performed on the battery to be detected based on the voltage difference during the relaxation period corresponding to the multiple charge-discharge cycles, and the lithium analysis detection comprises the following steps:

And judging whether the battery to be tested reaches the lithium precipitation amount of the first lithium precipitation degree or not according to the first comparison result, the second comparison result and the third comparison result.

11. A lithium separation detection device for a battery, comprising:

The device comprises a voltage difference acquisition module, a voltage difference acquisition module and a voltage difference judgment module, wherein the voltage difference acquisition module is used for acquiring the voltage difference of a battery to be tested in a relaxation period after each charge is completed in a charge-discharge cycle process, wherein the relaxation period refers to a period from the completion of the charge of the battery to be tested to the restoration of the battery to be tested to a steady state;

and the detection module is used for carrying out lithium precipitation detection on the battery to be detected based on the voltage difference during the relaxation period corresponding to the multiple charge-discharge cycles.

12. An electronic device comprising a processor, a memory and a bus, wherein,

The processor and the memory complete communication with each other through the bus;

the memory stores program instructions executable by the processor, the processor invoking the program instructions to perform the method of any of claims 1-10.

13. A non-transitory computer readable storage medium storing computer instructions which, when executed by a computer, cause the computer to perform the method of any of claims 1-10.

14. A computer program product comprising computer program instructions which, when read and executed by a processor, perform the method of any of claims 1-10.