Method and device for determining solid-phase diffusion coefficient of battery material and electronic equipment

Abstract

The invention discloses a method and a device for determining a solid-phase diffusion coefficient of a battery material and electronic equipment, and belongs to the technical field of batteries. The method for determining the solid-phase diffusion coefficient of the battery material comprises the following steps: obtaining a first solid-phase diffusion coefficient based on obtained test parameters corresponding to a to-be-tested battery material; based on the first solid phase diffusion coefficient and a preset association relationship, determining a correction parameter corresponding to the first solid phase diffusion coefficient; the preset association relationship is pre-constructed according to the material particle sizes of various materials and a first diffusion coefficient calculation formula; and correcting the first solid phase diffusion coefficient according to the correction parameter. According to the method for determining the solid-phase diffusion coefficient of the battery material, the first solid-phase diffusion coefficient can be corrected into the solid-phase diffusion coefficient closer to a true value according to the correction parameter, so that the accuracy of a test result of the battery material is improved, and the method is simple to operate and easy to implement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, and more particularly, to a method and device for determining a solid-phase diffusion coefficient of a battery material and an electronic device. BACKGROUND

[0002] In the battery material testing scenario, the GITT measurement method is commonly used in the related art to measure the electrical performance data of the spherical particle material in the battery under the semi-infinite diffusion premise. There are approximation assumptions in the derivation process of the calculation formula based on the GITT measurement. The actual measurement process usually deviates from these assumption premises, resulting in a large calculation error, thereby affecting the accuracy of the measurement value. SUMMARY

[0003] The present application provides a method and device for determining a solid-phase diffusion coefficient of a battery material, which modifies the first solid-phase diffusion coefficient to a solid-phase diffusion coefficient closer to the true value according to a correction parameter, thereby improving the accuracy of the battery material test results and being simple and easy to implement.

[0004] In a first aspect, the embodiments of the present application provide a method for determining a solid-phase diffusion coefficient of a battery material, comprising: obtaining a first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested; determining a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation relationship; the preset correlation relationship is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials; correcting the first solid-phase diffusion coefficient according to the correction parameter; The test parameters are parameters related to the solid-phase diffusion coefficient of the battery electrode material, and the test method is the constant current intermittent titration method. The preset correlation relationship is used to represent the correlation relationship between the calculated value of the diffusion coefficient obtained by solving the approximate solution of the first diffusion coefficient calculation formula and the theoretical value of the solid-phase diffusion coefficient. The first diffusion coefficient calculation formula is an original equation used to represent the change of the surface concentration with time.

[0005] In the above technical solution, the preset correlation relationship between the calculated value of the solid-phase diffusion coefficient of the spherical particle under the semi-infinite diffusion premise and the theoretical value is constructed in advance, so that the correction parameter can be determined according to the currently obtained solid-phase diffusion coefficient in combination with the preset correlation relationship in the actual testing process, to correct the error between the approximate solution and the original solution in the process of calculating the solid-phase diffusion coefficient. The first solid-phase diffusion coefficient can be modified to a solid-phase diffusion coefficient closer to the true value according to the correction parameter, thereby improving the accuracy of the battery material test results and being simple and easy to implement.

[0006] In some embodiments, the preset correlation relationship is obtained according to the material particle size of each type of material and a first diffusion coefficient calculation formula, and includes: obtaining a material particle size of a target type of material and at least one second solid-phase diffusion coefficient corresponding to the material particle size; obtaining a surface concentration change amount corresponding to each time step based on the second solid-phase diffusion coefficient and a first analytical expression in the first diffusion coefficient calculation formula; substituting the surface concentration change amount into the first diffusion coefficient calculation formula, and obtaining a third solid-phase diffusion coefficient corresponding to each surface concentration change amount according to an approximate solution equation of the first analytical expression; constructing the preset correlation relationship based on the third solid-phase diffusion coefficient corresponding to the surface concentration change amount and the second solid-phase diffusion coefficient corresponding to the surface concentration change amount.

[0007] In the above technical solution, the preset correlation relationship is set according to the spherical particles of different material types, so that the correction value is obtained by selecting the corresponding preset correlation relationship according to the current material type to be tested in the actual test process, which can further improve the accuracy of the obtained correction value, thereby improving the correction effect, making the finally obtained solid-phase diffusion coefficient closer to the true value, and having high flexibility.

[0008] In some embodiments, the obtaining of the surface concentration change amount corresponding to each time step based on the second solid-phase diffusion coefficient and the first analytical expression in the first diffusion coefficient calculation formula includes: substituting the second solid-phase diffusion coefficient into the first analytical expression to obtain an analytical value of the first analytical expression corresponding to each time step; substituting the analytical value, the material particle size and the current flux into the first diffusion coefficient calculation formula to obtain the surface concentration change amount corresponding to each time step.

[0009] In some embodiments, the obtaining of the at least one second solid-phase diffusion coefficient corresponding to the material particle size includes: determining a theoretical range of the solid-phase diffusion coefficient corresponding to the target type of material; setting a plurality of different numerical values as the second solid-phase diffusion coefficient within the theoretical range.

[0010] In the above technical solution, the second solid-phase diffusion coefficient corresponding to the material particle size is set through the theoretical range of the solid-phase diffusion coefficient corresponding to the target type of material, which has high authenticity and calculation accuracy.

[0011] In some embodiments, the determining the correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and the preset correlation relationship comprises: determining a preset correlation relationship corresponding to the material type of the battery material to be tested based on the material type of the battery material to be tested; processing the first solid-phase diffusion coefficient according to the preset correlation relationship to obtain the correction parameter.

[0012] In the above technical solution, the preset correlation relationship is set according to the spherical particles of different material categories, so that the correction value is obtained according to the corresponding preset correlation relationship of the current material type to be tested in the actual test process, which can further improve the accuracy of the obtained correction value, thereby improving the correction effect, making the finally obtained solid-phase diffusion coefficient closer to the true value, and having high flexibility.

[0013] In some embodiments, before the first solid-phase diffusion coefficient is obtained based on the obtained test parameter corresponding to the battery material to be tested, the method further comprises: performing GITT testing on a battery prepared from the battery material to be tested to obtain the test parameter.

[0014] In some embodiments, the first solid-phase diffusion coefficient is obtained based on the obtained test parameter corresponding to the battery material to be tested, comprising: substituting the test parameter into a second diffusion coefficient calculation formula to obtain the first solid-phase diffusion coefficient; the second diffusion coefficient calculation formula is obtained based on the first diffusion coefficient calculation formula.

[0015] In some embodiments, the test parameter comprises a linear slope of pulse voltage and time square root, a thermodynamic equilibrium potential difference before and after the pulse, a pulse time, and a material particle size.

[0016] In a second aspect, the embodiments of the present application provide a determination device of a solid-phase diffusion coefficient of a battery material.

[0017] In a third aspect, the embodiments of the present application provide an electronic device.

[0018] In a fourth aspect, the embodiments of the present application provide a non-transitory computer readable storage medium.

[0019] In a fifth aspect, the embodiments of the present application provide a computer program product. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 One of the flowcharts of the determination method of the solid-phase diffusion coefficient of the battery material provided by some embodiments of the present application; Figure 2Flowchart II of a method for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 3 Flowchart III of a method for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 4 Intermediate result diagram I of a method for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 5 Intermediate result diagram II of a method for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 6 Result diagram of a method for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 7 Structure diagram of a device for determining a solid-phase diffusion coefficient of a battery material according to some embodiments of the present application; Figure 8 Structure diagram of an electronic device according to some embodiments of the present application. DETAILED DESCRIPTION

[0021] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0022] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used in the specification of the present application are only for the purpose of describing specific embodiments of the present application, and are not intended to limit the present application; the terms “include” and “have” and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion. The terms “first”, “second” and the like in the specification and claims of the present application and the above description of drawings are used to distinguish different objects, and are not intended to describe a particular order or primary and secondary relationships.

[0023] Reference to an "embodiment" in this application means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are they necessarily mutually exclusive of one another. As will be apparent to those of ordinary skill in the art, embodiments described in this application can be combined with one another.

[0024] In the description of the application, it needs to be explained that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "attaching" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0025] The term "and / or" in this application is only to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in this application generally represents that the front and rear associated objects have an "or" relationship.

[0026] "Multiple" appearing in this application means two or more (including two), and similarly, "multiple groups" means two or more groups (including two groups), and "multiple pieces" means two or more pieces (including two pieces).

[0027] The battery material solid-phase diffusion coefficient determination method, the battery material solid-phase diffusion coefficient determination device, the electronic equipment and the readable storage medium provided by the embodiments of the application will be described in detail below in combination with the specific embodiments and their application scenarios.

[0028] The battery material solid-phase diffusion coefficient determination method can be applied to a terminal, and can be executed by hardware or software in the terminal.

[0029] The battery material solid-phase diffusion coefficient determination method provided by the embodiments of the application, the execution subject of the battery material solid-phase diffusion coefficient determination method can be an electronic device or a function module or function entity in the electronic device that can realize the battery material solid-phase diffusion coefficient determination method. The electronic device mentioned in the embodiments of the application includes but is not limited to mobile phones, tablet computers, computers, cameras and wearable devices, etc. The battery material solid-phase diffusion coefficient determination method provided by the embodiments of the application will be described below with the electronic device as an example.

[0030] In the related art, the GITT technique is the most commonly used method for measuring Ds. In order to simplify the calculation, assumptions are usually introduced in the formula derivation process. The actual measurement process usually deviates from these assumptions, resulting in a large calculation error. The derivation of the Ds formula is based on the second Fick's law and meets the premise of semi-infinite diffusion, and the general formula of the surface concentration and time can be obtained: ; wherein, and respectively represent the Li+concentration on the surface of the particle at time t and time t=0, j is the Li+flux, is the particle radius, and F is the Faraday constant. Since the analytical expression of is relatively complex, it cannot be directly solved for Ds. In the actual calculation process, an approximate solution is taken: ; however, this approximate assumption has a prerequisite: . In fact, even if , the error between the approximate solution and the original solution exceeds 5%, and the error is further amplified after power calculation, thereby affecting the accuracy of the finally measured solid-phase diffusion coefficient.

[0031] Based on the above considerations, in order to solve the problem of low accuracy of the finally measured solid-phase diffusion coefficient of the battery material, a method for determining the solid-phase diffusion coefficient of a battery material is designed, including obtaining a first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested; determining a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation; and correcting the first solid-phase diffusion coefficient according to the correction parameter; wherein the preset correlation is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials.

[0032] In this method for determining the solid-phase diffusion coefficient of the battery material, the correlation between the calculated value and the theoretical value of the solid-phase diffusion coefficient is pre-established, so that the correction parameter can be determined according to the currently obtained solid-phase diffusion coefficient in combination with the pre-established correlation during the actual test process, to correct the error between the approximate solution and the original solution in the process of calculating the solid-phase diffusion coefficient. The first solid-phase diffusion coefficient can be corrected to a solid-phase diffusion coefficient closer to the true value according to the correction parameter, thereby improving the accuracy of the battery material test results and being simple and easy to implement.

[0033] As shown in Figure 1 , the method for determining the solid-phase diffusion coefficient of the battery material includes steps 110, 120, and 130.

[0034] Step 110, obtaining a first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested; In this step, the first solid-phase diffusion coefficient is the solid-phase diffusion coefficient obtained by solving the equation approximately.

[0035] The test parameter is a parameter involved in testing the solid-phase diffusion coefficient of the battery electrode material, including material intrinsic parameters, test condition parameters, and electrode structure parameters, etc.

[0036] The constant current intermittent titration technique (GITT) or the potential intermittent titration technique (PITT) can be used.

[0037] Taking the constant current intermittent titration technique as an example, a small current pulse is applied to the battery for a short time, and then the system is allowed to recover to equilibrium for a period of time. By analyzing the voltage change during the current pulse and the resting period, key information can be extracted, and the test parameter can be obtained.

[0038] In some embodiments, the test parameter includes the linear slope of the pulse voltage and the square root of time, the thermodynamic equilibrium potential difference before and after the pulse, the pulse time, and the material particle size.

[0039] In this embodiment, the material particle size is the radius r of the active particle s (unit: cm), and the pulse time is the current pulse time (unit: s).

[0040] The thermodynamic equilibrium potential difference before and after the pulse (unit: V), that is, the steady-state voltage change after a single pulse, can be obtained by subtracting the thermodynamic potential after relaxation twice.

[0041] The linear slope of the pulse voltage and the square root of time , can be obtained by linear fitting of the measured pulse voltage and the square root of time within a certain time range.

[0042] In some embodiments, before step 110, the method further includes: performing GITT testing on the battery prepared from the battery material to be tested to obtain the test parameter.

[0043] In this embodiment, as shown in Figure 2 , the electrode sheet can be prepared first, the battery can be assembled, and then the GITT test can be performed to obtain the test parameter.

[0044] The electrode sheet preparation method includes but is not limited to conventional wet coating, dry process, etc.

[0045] The assembled battery can include but is not limited to a full battery or a half battery of a button type, a stacked type, and a soft package type, and can also be assembled into a three-electrode battery.

[0046] After the battery is assembled, formation and pre-cycling steps can be performed. The formation activates the battery, enabling the battery to have the first charge and discharge capability and forming an SEI film on the negative electrode. After formation and exhaust, the battery is subjected to a certain number (such as 1-3 times) of complete charge and discharge cycles to complete pre-cycling.

[0047] Then the battery is charged to full capacity and subjected to GITT testing.

[0048] In some embodiments, the GITT test is performed on a battery prepared from a battery material to be tested, including: A pulse current is applied to the battery for a first duration; After resting for a second duration, test parameters are collected.

[0049] In this embodiment, the pulse current is generally less than 4C, and the rate can be appropriately reduced according to the actual rate performance of the battery, such as 0.5C-0.1C at a lower SOC.

[0050] The first duration can be determined based on the number of obtained solid-phase diffusion coefficients and test time, etc. A shorter pulse time can ensure that solid-phase diffusion coefficients are obtained at more SOCs, and a longer pulse can shorten the overall test time.

[0051] The second duration can be determined based on the effect of electrode equilibrium recovery and test time, etc. A longer relaxation time can ensure that the electrode recovers to equilibrium, and a shorter relaxation time can also shorten the test. In some embodiments, the second duration can be set to between 300s and 7200s.

[0052] In some embodiments, the battery can also be subjected to multiple pulse-rest cycles. The cycle test can be determined according to the SOC variation range of a single pulse to ensure that the electrode reaches full discharge after GITT testing, such as setting the cycle number to 30 times for a pulse rate of 4C and a pulse time of 30s.

[0053] In some embodiments, a voltage cutoff condition can also be set to end the GITT test when the voltage of the battery is less than the cutoff voltage, in order to reduce the risk of over-discharge of the battery. The cutoff voltage can be set according to the battery material, such as 2.5V-2.8V for ternary materials (including lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, etc.).

[0054] Continuing with the GITT test as an example, in the process of using GITT to test the solid-phase diffusion coefficient, assumptions are usually introduced in the formula derivation process to simplify the calculation. The derivation of the solid-phase diffusion coefficient formula is based on Fick's second law, and the general solution formula of the surface concentration and time can be obtained under the premise of semi-infinite diffusion as follows:

[0055] wherein, is the Li+ concentration on the surface of the particle at time t; is the Li+ concentration on the surface of the particle at time t = 0; j is the Li+ flux, i.e. the given pulse current, which can be determined according to the real test scenario; is the particle size of the material; F is the Faraday constant; is the solid-phase diffusion coefficient; t is time.

[0056] Since the analytical expression of is relatively complex, cannot be directly solved , in the actual calculation process, its approximate solution will be taken, and the approximate solution expression is as follows:

[0057] In the actual test process, after obtaining the test parameters, the test parameters can be substituted into the above approximate solution formula to obtain the first solid-phase diffusion coefficient.

[0058] In some embodiments, step 110 comprises: substituting the test parameters into the second diffusion coefficient calculation formula to obtain the first solid-phase diffusion coefficient; the second diffusion coefficient calculation formula is obtained based on the deformation of the first diffusion coefficient calculation formula.

[0059] In this embodiment, the second diffusion coefficient calculation formula is as follows:

[0060] wherein, is the first solid-phase diffusion coefficient; is the linear slope of the pulse voltage and the square root of time; is the particle size of the material; is the difference between the thermodynamic equilibrium potential before and after the pulse; is the pulse time.

[0061] The second diffusion coefficient calculation formula is obtained based on the deformation of the first diffusion coefficient calculation formula.

[0062] wherein, the first diffusion coefficient calculation formula is an original equation for characterizing the change of surface concentration with time, and the first diffusion coefficient calculation formula is as follows:

[0063] wherein, is the change value of the Li+ concentration on the surface of the particle within time t; j is the Li+ flux; is the particle size of the material; F is the Faraday constant; is the solid-phase diffusion coefficient; the real analytical expression of, i.e. the original solution, is as follows:

[0064] wherein, is ; is the nth positive root of the equation .

[0065] When the time is short, the approximate solution expression can be substituted into the original equation, and the original equation is simplified to the following approximate solution solving simplified equation:

[0066] By , the approximate solution solving simplified equation is converted into a stoichiometric number expression, wherein is expressed as:

[0067] The data of the change of voltage E with time can be obtained during the GITT test, and in the case where the stoichiometric number x is difficult to directly measure, the relationship between the stoichiometric number x and the voltage E can be established, as follows:

[0068] wherein, is the linear slope of the pulse voltage and the square root of time.

[0069] The above formula can be arranged as follows:

[0070] The potential change caused by the change of the stoichiometric number of the material in a short time is linear, and then the voltage change before and after the pulse can be used to calculate:

[0071]

[0072] wherein, A and V are the surface area and volume of the material respectively, is the voltage change amount; is the duration; the formula can be understood as the change of the stoichiometric number caused by the current passing through the surface of the material into the material, and for a general particle material, a sphere is used for calculation, and then , the integrated formula can obtain the second diffusion coefficient calculation formula as follows:

[0073] Step 120, determining a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation relationship; ​In this step, the preset correlation relationship is used to represent the correlation relationship between the calculated value of the solid-phase diffusion coefficient obtained according to the approximate solution of the solid-phase diffusion coefficient calculation formula and the theoretical value of the solid-phase diffusion coefficient. The preset correlation relationship can be in the form of a correlation table, a functional relationship or other forms, which are not limited in the present application.

[0074] The correction parameter is used to correct the error between the approximate solution and the original solution. The correction parameter can be a theoretical value corresponding to the first solid-phase diffusion coefficient, or a parameter value that can correct the first solid-phase diffusion coefficient to a theoretical value by a certain calculation method, which is not limited in the present application.

[0075] Figure 4 An example of a preset correlation relationship is shown in the figure, which is used to represent the ratio of the calculated value Ds_test of the solid-phase diffusion coefficient to the theoretical value Ds_real of the solid-phase diffusion coefficient. The abscissa is the theoretical value Ds_real of the solid-phase diffusion coefficient, and the ordinate is the ratio of the calculated value Ds_test of the solid-phase diffusion coefficient to the theoretical value Ds_real.

[0076] The preset correlation relationship is constructed in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials, and the specific construction method will be described in the embodiments below, which will not be described here.

[0077] In some embodiments, the preset correlation relationship can also be constructed according to different categories of materials.

[0078] In some embodiments, step 120 comprises: Based on the material type corresponding to the battery material to be tested, a preset correlation relationship corresponding to the material type is determined; The first solid-phase diffusion coefficient is processed according to the preset correlation relationship to obtain a correction parameter.

[0079] In this embodiment, the preset correlation relationship corresponding to different categories of materials can be constructed in advance. In actual application process, according to the current material type to be tested, the matching preset correlation relationship is selected to obtain the corresponding correction value according to the calculated value of the solid-phase diffusion coefficient actually measured and the preset correlation relationship.

[0080] According to the method for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application, the preset correlation relationship is set according to different material categories under spherical particles, so that the correction value is obtained by selecting the corresponding preset correlation relationship according to the current material type to be tested in actual test process, which can further improve the accuracy of the obtained correction value, thereby improving the correction effect, making the finally obtained solid-phase diffusion coefficient closer to the true value, and having high flexibility.

[0081] Step 130, according to the correction parameter, correct the first solid phase diffusion coefficient.

[0082] In this step, the first solid phase diffusion coefficient is corrected according to the correction parameter, and the final target solid phase diffusion coefficient is closer to the true value.

[0083] Taking the preset correlation as an example, the correction value obtained by the first solid phase diffusion coefficient and the preset correlation is approximately considered as the theoretical value corresponding to the first solid phase diffusion coefficient, and then the first solid phase diffusion coefficient can be directly corrected to the correction parameter.

[0084] Figure 5 An example of the calculation result of the solid phase diffusion coefficient of a ternary material at different lithium insertion amounts is shown in the following table, Figure 6 An example of a sampling preset correlation is shown in the following table, Figure 5 The target solid phase diffusion coefficient obtained by correcting the calculation result of the solid phase diffusion coefficient is shown in the following table, wherein, Figure 6 The lower curve in the middle is the solid phase diffusion coefficient before correction, and the upper curve is the solid phase diffusion coefficient after correction.

[0085] In the related art, there is also a method of obtaining the solid phase diffusion coefficient by comparing the measured electrical performance data with the simulation results and adjusting and optimizing the simulation parameters. However, this method obtains the solid phase diffusion coefficient by simulating the reverse correction of the parameters, which leads to the dependence of the calculation result on the accuracy of the simulation model and the accuracy of other parameters in the model, thereby affecting the accuracy of the final obtained solid phase diffusion coefficient.

[0086] According to the method for determining the solid phase diffusion coefficient of the battery material provided in the embodiments of the present application, the preset correlation between the calculation value and the theoretical value of the solid phase diffusion coefficient of the spherical particles under the condition of semi-infinite diffusion is constructed in advance, so that the correction parameter can be determined according to the currently obtained solid phase diffusion coefficient in combination with the preset correlation during the actual test process, to correct the error between the approximate solution and the original solution in the process of calculating the solid phase diffusion coefficient. The first solid phase diffusion coefficient can be corrected to a solid phase diffusion coefficient closer to the true value according to the correction parameter, thereby improving the accuracy of the test result of the battery material, and the operation is simple and easy to implement.

[0087] The specific construction method of the preset correlation will be described below.

[0088] In some embodiments, the preset correlation is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials, including: Obtain the material particle size of the target material and at least one second solid phase diffusion coefficient corresponding to the material particle size; The surface concentration change amount corresponding to each time step is obtained based on the second solid-phase diffusion coefficient and the first analytical expression in the first diffusion coefficient calculation formula; The third solid-phase diffusion coefficient corresponding to each surface concentration change amount is obtained by substituting the surface concentration change amount into the first diffusion coefficient calculation formula and according to the approximate solution equation of the first analytical expression. The preset correlation relationship is constructed based on the third solid-phase diffusion coefficient corresponding to the surface concentration change amount and the second solid-phase diffusion coefficient corresponding to the surface concentration change amount.

[0089] In this embodiment, the target material can be any type of material.

[0090] The second solid-phase diffusion coefficient is a theoretical solid-phase diffusion coefficient of the target material under the current material particle size, which can be approximately considered as a true value. The theoretical value can be determined according to prior knowledge or theoretical knowledge.

[0091] The third solid-phase diffusion coefficient is a calculated value of the solid-phase diffusion coefficient obtained by using the first diffusion coefficient calculation formula containing the approximate solution.

[0092] The same material particle size of the same target material can correspond to one or more second solid-phase diffusion coefficients.

[0093] Taking the GITT test as an example, the first analytical expression is:

[0094] The approximate solution equation of the first analytical expression is:

[0095] The time step is a shorter time interval, which can be defined by the user. It should be noted that the time step can be consistent with the time step in the subsequent actual measurement process.

[0096] The surface concentration change amount is the Li+ concentration change value of the particle surface.

[0097] The method for measuring the material particle size can include but is not limited to spectroscopy, electron microscopy, sedimentation, specific surface area method, etc. In some embodiments, for a material system with a certain particle size distribution, a statistically meaningful particle size such as D50 / 2 can also be used.

[0098] According to the method for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application, the preset correlation relationship is set according to different material categories of spherical particles, so that the correction value is obtained by selecting the corresponding preset correlation relationship according to the current material type to be measured in the actual test process, which can further improve the accuracy of the obtained correction value, thereby improving the correction effect, making the finally obtained solid-phase diffusion coefficient closer to the true value, and having high flexibility.

[0099] In some embodiments, obtaining at least one second solid-phase diffusion coefficient corresponding to the material particle size includes: Determine the theoretical range of the solid-phase diffusion coefficient corresponding to the target material type; Within the theoretical range, several different values ​​are set as the second solid-phase diffusion coefficient.

[0100] In this embodiment, the theoretical range can be set according to the specific category of the target material to improve the accuracy and comprehensiveness of the obtained second solid-phase diffusion coefficient, while reducing unnecessary calculations; for example, for ternary materials, the theoretical range can be set to 10. -10 ~10 -20 m 2 s -1 .

[0101] The numerical values ​​within this theoretical range are extracted as the second solid-phase diffusion coefficient. It is understandable that the number of extracted second solid-phase diffusion coefficients can be set based on a combination of computational accuracy and computational speed; a larger number corresponds to higher computational accuracy, while a smaller number results in relatively faster computational efficiency.

[0102] In some embodiments, a first number of second solid-phase diffusion coefficients can be set for each order of magnitude within the theoretical range to balance computational speed and accuracy. The first number can be 100 or 110, etc. In some embodiments, multiple different values ​​can be collected within the theoretical range as the second solid-phase diffusion coefficients using a random or interval extraction method, which is not limited herein.

[0103] like Figure 2 As shown, for target materials, the particle size r can be measured first. s For material particle size r s Multiple theoretical values ​​for the second solid-phase diffusion coefficient Ds are set accordingly, and then the material particle size r is considered. s A preset correlation is generated between the theoretical value of the second solid-phase diffusion coefficient Ds and the first solid-phase diffusion coefficient. This preset correlation is used to correct the first solid-phase diffusion coefficient when subsequently measuring the solid-phase diffusion coefficient of materials of the same type as the target material.

[0104] According to the method for determining the solid-phase diffusion coefficient of battery materials provided in the embodiments of this application, a second solid-phase diffusion coefficient corresponding to the particle size of the material is set by using the theoretical range of the solid-phase diffusion coefficient corresponding to the spherical particles of the target material, which has high realism and calculation accuracy.

[0105] In some embodiments, the surface concentration change corresponding to each time step is obtained based on the first analytical expression in the formula for calculating the second solid-phase diffusion coefficient and the first diffusion coefficient, including: The second solid-phase diffusion coefficient is substituted into the first analytical expression, and a solution of the first analytical expression corresponding to each time step is obtained; The analytical value, the material particle size, and the current flux are substituted into the first diffusion coefficient calculation formula to obtain the surface concentration change amount corresponding to each time step.

[0106] In this embodiment, the analytical value is a numerical value obtained by solving the real first analytical expression, and is a value obtained by substituting the second solid-phase diffusion coefficient into the first analytical expression .

[0107] The obtained analytical value, the material particle size, and the current flux are then substituted into the first diffusion coefficient calculation formula to obtain the surface concentration change amount corresponding to each time step.

[0108] In the following Figure 3 , the specific implementation manner of generating the preset correlation relationship according to the material particle size r s and the second solid-phase diffusion coefficient Ds_theory is described.

[0109] In the actual execution process, for a given theoretical range and quantity, a group of Ds_theory values can be generated.

[0110] Each Ds_theory value is substituted into the first diffusion coefficient calculation formula to generate a group of data pairs of (C )~t, that is, the surface concentration change amount corresponding to each time step: first, the time range and quantity are given according to the single pulse time and the time interval set in the actual test process, for example, t can be set as a group of time sequence data of 1-30s with an interval of 0.1s; the Ds_theory value is substituted into the first analytical expression to calculate the (C ) value corresponding to each time step t, respectively, to obtain a group of (C )~t data.

[0111] Each group of (C )~t data is substituted into the diffusion coefficient calculation formula to calculate the corresponding Ds_cal value. The Cs-t data are substituted into the third solid-phase diffusion coefficient Ds_cal value.

[0112] The above steps are repeated, all given Ds_theory values are brought into the analytical expression to obtain (C )~t, and then brought into the approximate solution simulation to obtain Ds_cal value, so as to obtain a plurality of groups of Ds_theory value~Ds_cal value. Then, the plurality of groups of data are fitted to obtain the preset correlation relationship for characterizing the correlation relationship between Ds_theory value and Ds_cal value.

[0113] The fitting processing can further include interpolation processing. ​

[0114] According to the method for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application, the preset correlation relationship between the calculated value and the theoretical value of the solid-phase diffusion coefficient of the spherical particles under the premise of semi-infinite diffusion is constructed in advance, so that the correction parameter is determined according to the currently obtained solid-phase diffusion coefficient in combination with the preset correlation relationship in the actual testing process, to correct the error between the approximate solution and the original solution in the process of calculating the solid-phase diffusion coefficient, so that the first solid-phase diffusion coefficient can be corrected to a solid-phase diffusion coefficient closer to the true value according to the correction parameter, thereby improving the accuracy of the test result of the battery material, and the operation is simple and easy to implement.

[0115] The method for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application can be executed by the device for determining the solid-phase diffusion coefficient of the battery material. The device for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application is described by taking the device for determining the solid-phase diffusion coefficient of the battery material as an example.

[0116] The embodiments of the present application also provide a device for determining the solid-phase diffusion coefficient of the battery material.

[0117] As shown in Figure 7 The device for determining the solid-phase diffusion coefficient of the battery material includes a first processing module 710, a second processing module 720 and a third processing module 730.

[0118] The first processing module 710 is configured to obtain a first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested. The second processing module 720 is configured to determine a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation relationship; the preset correlation relationship is obtained in advance according to the material particle size of various materials and a first diffusion coefficient calculation formula. The third processing module 730 is configured to correct the first solid-phase diffusion coefficient according to the correction parameter.

[0119] According to the device for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present application, the preset correlation relationship between the calculated value and the theoretical value of the solid-phase diffusion coefficient of the spherical particles under the premise of semi-infinite diffusion is constructed in advance, so that the correction parameter is determined according to the currently obtained solid-phase diffusion coefficient in combination with the preset correlation relationship in the actual testing process, to correct the error between the approximate solution and the original solution in the process of calculating the solid-phase diffusion coefficient, so that the first solid-phase diffusion coefficient can be corrected to a solid-phase diffusion coefficient closer to the true value according to the correction parameter, thereby improving the accuracy of the test result of the battery material, and the operation is simple and easy to implement.

[0120] In some embodiments, the device further includes a fourth processing module configured to: obtain a material particle size of the target material and at least one second solid-phase diffusion coefficient corresponding to the material particle size; obtain a surface concentration change amount corresponding to each time step based on the second solid-phase diffusion coefficient and the first analytical expression in the first diffusion coefficient calculation formula; substitute the surface concentration change amount into the first diffusion coefficient calculation formula, and obtain a third solid-phase diffusion coefficient corresponding to each surface concentration change amount according to an approximate solution equation of the first analytical expression; construct a preset correlation relationship based on the third solid-phase diffusion coefficient corresponding to the surface concentration change amount and the second solid-phase diffusion coefficient corresponding to the surface concentration change amount.

[0121] In some embodiments, the fourth processing module is configured to: substitute the second solid-phase diffusion coefficient into the first analytical expression to obtain an analytical value of the first analytical expression corresponding to each time step; substitute the analytical value, the material particle size and the current flux into the first diffusion coefficient calculation formula to obtain the surface concentration change amount corresponding to each time step.

[0122] In some embodiments, the fourth processing module is configured to: determine a theoretical range of the solid-phase diffusion coefficient corresponding to the target material; set a plurality of different numerical values as the second solid-phase diffusion coefficient within the theoretical range.

[0123] In some embodiments, the second processing module 720 is configured to: determine a preset correlation relationship corresponding to a material type of the battery material to be tested based on the material type; process the first solid-phase diffusion coefficient according to the preset correlation relationship to obtain a correction parameter.

[0124] In some embodiments, the apparatus further includes a fifth processing module configured to: perform GITT testing on a battery prepared from the battery material to be tested to obtain the test parameter before obtaining the first solid-phase diffusion coefficient based on the obtained test parameter corresponding to the battery material to be tested.

[0125] In some embodiments, the first processing module 710 is configured to: substitute the test parameter into a second diffusion coefficient calculation formula to obtain the first solid-phase diffusion coefficient; the second diffusion coefficient calculation formula is obtained based on a transformation of the first diffusion coefficient calculation formula.

[0126] The device for determining the solid-phase diffusion coefficient of the battery material in the embodiments of the present applicationapplicationbe an electronic device or a component in an electronic device, such as an integrated circuit or a chip. The electronic deviceapplicationbe a terminal or another device other than a terminal. For example, the electronic deviceapplicationbe a mobile phone, a tablet computer, a notebook computer, a palm computer, a vehicle-mounted electronic device, a Mobile Internet Device (MID), an augmented reality (AR) / virtual reality (VR) device, a robot, a wearable device, an ultra-mobile personal computer (UMPC), a netbook, or a personal digital assistant (PDA), andapplicationbe a server, a Network Attached Storage (NAS), a personal computer (PC), a television (TV), a teller machine, or a self-service machine, without any specific limitation in the embodiments of the present application.

[0127] The device for determining the solid-phase diffusion coefficient of the battery material in the embodiments of the present applicationapplicationbe a device having an operating system. The operating systemapplicationbe an Android operating system, an IOS operating system, or another possible operating system, without any specific limitation in the embodiments of the present application.

[0128] The device for determining the solid-phase diffusion coefficient of the battery material provided in the embodiments of the present applicationapplicationbe capable of implementing the method embodiments. Figures 1 to 6 The processes implemented by the method embodimentsapplicationbe described above, and thus will not be described here again.

[0129] In some embodiments, as shown in Figure 8 The embodiments of the present application also provide an electronic device 800, whichapplicationinclude a processor 801, a memory 802, and a computer program stored in the memory 802 and capable of running on the processor 801. The programapplicationbe executed by the processor 801 to implement the processes of the above method embodiments for determining the solid-phase diffusion coefficient of the battery material and achieve the same technical effects. The processesapplicationnot be described here again to avoid repetition.

[0130] It should be noted that the electronic device in the embodiments of the present applicationapplicationinclude the above-mentioned mobile electronic device and non-mobile electronic device.

[0131] The embodiment of the present application further provides a non-transitory computer readable storage medium, which stores a computer program. The computer program is executed by a processor to implement each process of the method for determining the solid-phase diffusion coefficient of battery material and achieve the same technical effects. To avoid repetition, details are not described herein.

[0132] The embodiment of the present application further provides a computer program product, which comprises a computer program. The computer program is executed by a processor to implement the method for determining the solid-phase diffusion coefficient of battery material.

[0133] The processor is the processor in the electronic device described in the above embodiment. The readable storage medium comprises a computer readable storage medium, such as a computer readable only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, etc.

[0134] The embodiment of the present application further provides a chip, which comprises a processor and a communication interface. The communication interface is coupled to the processor. The processor is configured to run a program or an instruction to implement each process of the method for determining the solid-phase diffusion coefficient of battery material and achieve the same technical effects. To avoid repetition, details are not described herein.

[0135] It should be understood that the chip mentioned in the embodiment of the present application can also be referred to as a system-level chip, a system chip, a chip system or a system-on-chip, etc.

[0136] It should be noted that, in this document, the term "comprising" or "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article or apparatus including the element. In addition, it should be pointed out that the scope of the method and apparatus in the embodiment of the present application is not limited to the order of performing the functions shown or discussed, but can also include performing the functions in a substantially simultaneous manner or in a reverse order, for example, the described method can be performed in an order different from that described, and various steps can be added, omitted or combined. In addition, the features described with reference to certain examples can be combined in other examples.

[0137] Through the above description of the embodiments, those skilled in the art can clearly understand that the above-mentioned example methods can be realized by means of software and necessary general hardware platforms, and of course, can also be realized by hardware, but in many cases, the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a computer software product in essence or in the form of a part of the prior art that makes a contribution. The computer software product is stored in a storage medium (such as a ROM / RAM, a magnetic disc, an optical disc), and includes a plurality of instructions for causing a terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application.

[0138] The embodiments of the present application are described above in combination with the accompanying drawings, but the present application is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative and not restrictive. Those skilled in the art can make many forms under the inspiration of the present application without departing from the scope of the present application and the scope of protection of the claims.

[0139] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an illustrative embodiment", "an example", "a specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0140] Although the embodiments of the present application have been shown and described, those skilled in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A method for determining a solid phase diffusion coefficient of a battery material, the method comprising: The method comprises the following steps: ​ obtaining a first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested; determining a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation relationship; the preset correlation relationship is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials; correcting the first solid-phase diffusion coefficient according to the correction parameter; the test parameter is a parameter related to the solid-phase diffusion coefficient of the battery electrode material, and the test mode is a constant current intermittent titration mode; the preset correlation relationship is used to represent the correlation relationship between the calculated value of the diffusion coefficient obtained according to the approximate solution of the first diffusion coefficient calculation formula and the theoretical value of the solid-phase diffusion coefficient; the first diffusion coefficient calculation formula is an original equation used to represent the change of surface concentration with time.

2. The method for determining the solid-phase diffusion coefficient of the battery material according to claim 1, characterized in that, The preset correlation relationship is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials, comprising: obtaining the material particle size of the target material and at least one second solid-phase diffusion coefficient corresponding to the material particle size; obtaining the surface concentration change amount corresponding to each time step based on the second solid-phase diffusion coefficient and the first analytical expression in the first diffusion coefficient calculation formula; obtaining the third solid-phase diffusion coefficient corresponding to each surface concentration change amount based on the first analytical expression of the approximate solution equation of the first diffusion coefficient calculation formula by substituting the surface concentration change amount into the first diffusion coefficient calculation formula; constructing the preset correlation relationship based on the third solid-phase diffusion coefficient corresponding to the surface concentration change amount and the second solid-phase diffusion coefficient corresponding to the surface concentration change amount.

3. The method for determining the solid-phase diffusion coefficient of the battery material according to claim 2, characterized in that, The method comprises the following steps: substituting the second solid-phase diffusion coefficient into the first analytical expression to obtain the analytical value of the first analytical expression corresponding to each time step; obtaining the surface concentration change amount corresponding to each time step by substituting the analytical value, the material particle size and the current flux into the first diffusion coefficient calculation formula.

4. The method for determining the solid-phase diffusion coefficient of the battery material according to claim 2, characterized in that, obtaining at least one second solid-phase diffusion coefficient corresponding to the material particle size, comprising: determining the theoretical range of the solid-phase diffusion coefficient corresponding to the target material; setting a plurality of different numerical values as the second solid-phase diffusion coefficient within the theoretical range.

5. The method of determining the solid phase diffusion coefficient of a battery material according to any one of claims 1 to 4, wherein The method comprises the following steps: determining the preset correlation relationship corresponding to the material type based on the material type corresponding to the battery material to be tested; obtaining the correction parameter by processing the first solid-phase diffusion coefficient according to the preset correlation relationship.

6. The method of determining the solid phase diffusion coefficient of a battery material according to any one of claims 1 to 4, wherein Before the step of obtaining the first solid-phase diffusion coefficient based on the obtained test parameters corresponding to the battery material to be tested, the method further comprises: performing GITT test on the battery prepared by the battery material to be tested to obtain the test parameters.

7. The method of determining the solid phase diffusion coefficient of a battery material according to any one of claims 1 to 4, wherein The method comprises the following steps: The test parameter is substituted into a second diffusion coefficient calculation formula to obtain the first solid-phase diffusion coefficient; the second diffusion coefficient calculation formula is obtained based on deformation of the first diffusion coefficient calculation formula.

8. The method of determining the solid phase diffusion coefficient of a battery material according to any one of claims 1 to 4, wherein The test parameter includes a linear slope of pulse voltage and square root of time, a thermodynamic equilibrium potential difference before and after the pulse, a pulse time and a material particle size.

9. A device for determining the solid-phase diffusion coefficient of a battery material, characterized in that, The method comprises: The first processing module is configured to obtain a first solid-phase diffusion coefficient based on the obtained test parameter corresponding to the battery material to be tested; The second processing module is configured to determine a correction parameter corresponding to the first solid-phase diffusion coefficient based on the first solid-phase diffusion coefficient and a preset correlation relationship; The preset correlation relationship is obtained in advance according to the material particle size and the first diffusion coefficient calculation formula of various materials; The third processing module is configured to correct the first solid-phase diffusion coefficient according to the correction parameter; The test parameter is a parameter related to the solid-phase diffusion coefficient of the battery electrode material, and the test mode is a constant current intermittent titration mode; The preset correlation relationship is used to represent the correlation relationship between a calculated value of the diffusion coefficient obtained according to an approximate solution of the first diffusion coefficient calculation formula and a theoretical value of the solid-phase diffusion coefficient; The first diffusion coefficient calculation formula is an original equation used to represent the change of surface concentration with time.

10. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the method for determining the solid-phase diffusion coefficient of the battery material according to any one of claims 1-8.

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