Electrochemical simulation method and device for multi-layer coated reduced-order model

Abstract

The invention relates to an electrochemical simulation method and device for a multi-layer coated reduced-order model, and belongs to the technical field of battery simulation, the method comprises the following steps: respectively dividing a positive electrode and a negative electrode of a simulation model of a multi-layer coated battery cell into a plurality of simulation areas, each simulation area being in one-to-one correspondence with a plurality of layers of coatings of the battery cell; establishing a reduced-order model based on the area simulation parameters corresponding to the simulation areas so as to perform electrochemical simulation on the battery cell; the problem that a traditional order reduction model cannot perform electrochemical simulation on a multi-layer coated battery cell can be solved; and the electrochemical simulation of the multi-layer coated battery cell on the basis of the reduced-order model is realized.

Description

Technical Field

[0001] The present application relates to a reduced-order model electrochemical simulation method and device for multi-layer coating, and belongs to the technical field of battery simulation. Background Art

[0002] The multi-layer coating process of the battery is a process of coating one or more layers of slurry on the current collector. The coated electrode materials include basic materials of the battery such as active materials, conductive agents, and binders.

[0003] When performing electrochemical simulation on battery cells, it is necessary to simulate the coating of the battery cells. Traditional simulation methods include simulating the coating of the battery cells through reduced-order models, such as simulating the coating of the battery cells through single particle models (SPM) and pseudo-two-dimensional models (P2D).

[0004] However, both SPM and P2D can only perform electrochemical simulation on single-layer coated cells, but cannot perform electrochemical simulation on multi-layer coated cells. Summary of the invention

[0005] The present application provides a multi-layer coated reduced-order model electrochemical simulation method and device, which can realize electrochemical simulation of multi-layer coated battery cells based on reduced-order models. The present application provides the following technical solutions: In a first aspect, a reduced-order model electrochemical simulation method for multilayer coating is provided, the method comprising: The positive and negative electrodes of the simulation model of the multi-layer coated battery cell are respectively divided into a plurality of simulation regions, each simulation region corresponding to the multi-layer coating of the battery cell; A reduced-order model is established based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell.

[0006] Optionally, the method further comprises: Multiple simulated active substances are arranged in each simulation area; and / or, A plurality of coating parameters of the coating corresponding to the simulation area are set for each simulation area.

[0007] Optionally, the plurality of simulated active substances include: a plurality of active substance particles, and / or a plurality of active substance particle sizes; The various coating parameters include: various coating porosities, various active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity.

[0008] Optionally, establishing a reduced-order model based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell includes: Determine the reaction current density in each simulation area, the sum of the reaction current densities is equal to the external circuit current of the battery cell; Solving diffusion equations in active material particles in each simulation region to obtain lithium ion concentrations in the active material particles; The source terms in the solid phase potential equation, liquid phase potential equation and electrolyte lithium ion concentration equation are modified from the reaction current density of active materials in one simulation area to the reaction current density of active materials in multiple simulation areas.

[0009] Optionally, the external circuit current is expressed by the following formula: ; ; ; Where i represents the i-th layer of coating, dx is the length element in the thickness direction of the battery cell, represents the integral in the i-layer coating area, is the reaction current density of each active substance in the i-th coating layer, F is the Faraday constant, is the reaction rate constant of each active substance in the i-th coating layer, is the lithium ion concentration of the electrolyte, is the reference electrolyte lithium ion concentration, is the transfer coefficient, is the maximum lithium ion concentration of the active material in the i-th coating layer, is the lithium ion concentration on the surface of the active material particles in the i-th coating layer, R is the ideal gas constant, T is the temperature, is the overvoltage, where is the solid phase potential, is the liquid phase potential, is the equilibrium potential of the active materials in each layer; is the radius of the active material particle in the i-th coating layer, is the volume fraction of active material particles in the i-th coating layer, is the specific surface area of ​​the active material particles in the i-th coating layer.

[0010] Optionally, the source terms in the solid phase potential equation and the liquid phase potential equation are: the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating ; The source term of the liquid phase lithium ion concentration diffusion equation is: the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating The corresponding lithium ion flux; Set the boundary flux to the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating , based on the boundary flux, the solid phase lithium ion diffusion equation is solved in the active material particle sub-region within the simulation region corresponding to the i-th layer of coating.

[0011] In a second aspect, a multi-layer coated reduced-order model electrochemical simulation device is provided, the device comprising: A region division module, used to divide the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into a plurality of simulation regions, each simulation region corresponding to the multi-layer coating of the battery cell; The electrochemical simulation module is used to establish a reduced-order model based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell.

[0012] Optionally, the device further comprises: A first setting module is used to set a plurality of simulated active substances in each simulation area; and / or, The second setting module is used to set, for each simulation area, a plurality of coating parameters of the coating corresponding to the simulation area.

[0013] Optionally, the plurality of simulated active substances include: a plurality of active substance particles, and / or a plurality of active substance particle sizes; The various coating parameters include: various coating porosities, various active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity.

[0014] Optionally, the electrochemical simulation module is used to: Determine the reaction current density in each simulation area, the sum of the reaction current densities is equal to the external circuit current of the battery cell; Solving diffusion equations in active material particles in each simulation region to obtain lithium ion concentrations in the active material particles; The source terms in the solid phase potential equation, liquid phase potential equation and electrolyte lithium ion concentration equation are modified from the reaction current density of active materials in one simulation area to the reaction current density of active materials in multiple simulation areas.

[0015] In a third aspect, a reduced-order model electrochemical simulation device for multilayer coating is provided, the device comprising a processor and a memory; a program is stored in the memory, and the program is loaded and executed by the processor to implement the reduced-order model electrochemical simulation method for multilayer coating described in the first aspect.

[0016] In a fourth aspect, a computer-readable storage medium is provided, wherein a program is stored in the storage medium, and the program is loaded and executed by the processor to implement the reduced-order model electrochemical simulation method of multilayer coating described in the first aspect.

[0017] The beneficial effects of the present application are: by dividing the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into multiple simulation areas respectively, each simulation area corresponds one-to-one to the multi-layer coating of the battery cell; a reduced-order model is established based on the regional simulation parameters corresponding to each simulation area to perform electrochemical simulation of the battery cell; the problem that the traditional reduced-order model cannot perform electrochemical simulation of the multi-layer coated battery cell can be solved; and the electrochemical simulation of the multi-layer coated battery cell based on the reduced-order model can be realized.

[0018] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present application in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a flow chart of a reduced-order model electrochemical simulation method for multilayer coating provided by one embodiment of the present application; Figure 2 It is a block diagram of a reduced-order model electrochemical simulation device for multilayer coating provided in one embodiment of the present application. DETAILED DESCRIPTION

[0020] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present application but are not intended to limit the scope of the present application.

[0021] Figure 1 This is a flow chart of a reduced-order model electrochemical simulation method for multilayer coating provided by an embodiment of the present application. This embodiment is described by taking the method applied to an electronic device as an example. The electronic device may be a user terminal or server with computing capabilities. This embodiment does not limit the implementation of the electronic device. The method includes at least the following steps: Step 101 , dividing the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into a plurality of simulation regions, respectively, and each simulation region corresponds to the multi-layer coating of the battery cell one by one.

[0022] The traditional single particle model and quasi-two-dimensional model divide the simulation model of the battery cell into one region in the positive and negative electrodes, and the material, particle size, volume fraction of the active material, and porosity of the coating in this region are all the same. At this time, the traditional single particle model and quasi-two-dimensional model can only perform electrochemical simulation on single-layer coated battery cells. In this embodiment, by dividing the positive and negative electrodes into multiple simulation regions based on the multi-layer coating of the battery cell, each simulation region can simulate the electrochemical characteristics of a layer of coating, and electrochemical simulation of multi-layer coated battery cells can be achieved.

[0023] Optionally, in this embodiment, a plurality of simulated active substances may be set in each simulation area; and / or a plurality of coating parameters of the coating corresponding to the simulation area may be set for each simulation area.

[0024] In one example, the multiple simulated active materials include: multiple active material particles, multiple active material particle sizes; the multiple coating parameters include but are not limited to: multiple coating porosities, multiple active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity, etc. This embodiment does not limit the content of the coating parameters.

[0025] Step 102 : establishing a reduced-order model based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell.

[0026] In one example, a reduced-order model is established based on regional simulation parameters corresponding to each simulation area to perform electrochemical simulation on a battery cell, including: determining the reaction current density in each simulation area, the sum of the reaction current densities being equal to the external circuit current of the battery cell; solving the diffusion equation within the active material particles within each simulation area to obtain the lithium ion concentration within the active material particles; and modifying the source terms in the solid phase potential equation, the liquid phase potential equation, and the electrolyte lithium ion concentration equation from the reaction current density of the active material within one simulation area to the reaction current density of the active material within multiple simulation areas.

[0027] Among them, the external circuit current is expressed by the following formula: ; ; ; Where i represents the i-th layer of coating, dx is the length element in the thickness direction of the battery cell, represents the integral in the i-layer coating area, is the reaction current density of each active substance in the i-th coating layer, F is the Faraday constant, is the reaction rate constant of each active substance in the i-th coating layer, is the lithium ion concentration of the electrolyte, is the reference electrolyte lithium ion concentration, is the transfer coefficient, schematically, , in other embodiments, and The value of may also be other values. This embodiment is not and The value of is limited. is the maximum lithium ion concentration of the active material in the i-th coating layer, is the lithium ion concentration on the surface of the active material particles in the i-th coating layer, and is obtained by solving the solid phase lithium ion diffusion equation. R is the ideal gas constant. T is the temperature, and is obtained by solving the heat transfer equation. is the overvoltage, where is the solid potential and is obtained by solving the solid potential equation. is the liquid phase potential, which is obtained by solving the liquid phase potential equation. is the equilibrium potential of the active materials in each layer; is the radius of the active material particle in the i-th coating layer, is the volume fraction of active material particles in the i-th coating layer, is the specific surface area of ​​the active material particles in the i-th coating layer. , , , Preset input data for external circuit current.

[0028] Among them, the liquid phase lithium ion diffusion equation is: .in, is the liquid phase lithium ion concentration, For time, is the liquid phase lithium ion diffusion coefficient, is the ion migration number, is the Faraday constant, is the reaction current density, is the specific surface area. Solid phase lithium ion diffusion equation: .in, is the solid phase lithium ion concentration, For time, is the solid phase lithium ion diffusion coefficient. Solid phase potential equation: .in, is the solid phase potential, is the solid phase conductivity. Liquid phase potential equation: .in, is the liquid phase potential, is the liquid conductivity, R is the ideal gas constant, T is the temperature, is the activity coefficient correction factor, which is usually 1. When solving, the parameters corresponding to each region are used in each region, among which only the source term in the equation needs to be determined during the solution process, and the remaining parameters are input values. The solution method is the conventional method for solving partial differential equations.

[0029] Schematically, the source terms in the solid phase potential equation and the liquid phase potential equation are: The reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating ; The source term of the liquid phase lithium ion concentration diffusion equation is: the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating The corresponding lithium ion flux; set the boundary flux to the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating , the solid phase lithium ion diffusion equation is solved in the active material particle sub-region within the simulation region corresponding to the i-th layer of coating based on the boundary flux.

[0030] To summarize, the electrochemical simulation method of the reduced-order model of the multi-layer coating provided in the present embodiment divides the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into multiple simulation areas respectively, and each simulation area corresponds one-to-one to the multi-layer coating of the battery cell; a reduced-order model is established based on the regional simulation parameters corresponding to each simulation area to perform electrochemical simulation on the battery cell; the problem that the traditional reduced-order model cannot perform electrochemical simulation on the multi-layer coated battery cell can be solved; and the electrochemical simulation of the multi-layer coated battery cell based on the reduced-order model can be realized.

[0031] In order to more clearly understand the reduced-order model electrochemical simulation method of the above-mentioned multi-layer coating, two examples are given below to illustrate the method.

[0032] In one example, assume that two layers of active material particles of different materials are coated in the positive electrode of the simulation model. Specifically, the positive electrode is coated with two layers, lithium iron phosphate (LFP) is coated near the current collector side, and ternary lithium (NCM) is coated near the diaphragm side. Assuming that the two layers of coating have the same thickness, the radius of the NCM particles is 5 microns, the radius of the LFP particles is 0.5 microns, the volume fraction of NCM is 0.48, and the volume fraction of LFP is also 0.48. The simulation area corresponding to each layer of coating in the thickness direction of the positive electrode is divided into 10 grids, and a sub-region of the active material particles in the corresponding coating is set on each grid, representing the NCM particles and LFP particles in the two layers, respectively, and the geometric size of each sub-region is set to the size of the corresponding particle.

[0033] During the solution process, ensure Satisfy the external circuit current equation ; Here, i represents the i-th coating layer.

[0034] ; ; In the positive electrode region, the source terms in the solid phase potential equation and the liquid phase potential equation are the reaction current density of the active material particles in the corresponding regions. In the positive electrode region, the source terms of the liquid phase lithium ion diffusion equation in the two regions are the reaction current density of the active material particles The solid-phase lithium ion diffusion equation is solved in the sub-regions of the active material particles in the two regions, and the boundary flux is the reaction current density of the corresponding active material particles. . Solve all electrochemical equations.

[0035] In another example, suppose that the two layers in the positive electrode are coated with the same material, and the porosity of the two layers is different. Specifically, the positive electrode active material selects two layers of ternary lithium (NCM), the coating porosity is smaller at 25% near the current collector side, and the coating porosity is larger at 30% near the diaphragm side. The two layers of coating have the same thickness, the radius of the NCM particles is 5 microns, and the volume fraction is 0.48. The simulation area corresponding to each layer of coating in the thickness direction of the positive electrode is divided into 10 grids, and an active material particle sub-region is set on each grid to represent the NCM particles in the two layers. The geometric size of each sub-region is set to the size of the corresponding particle.

[0036] During the solution process, ensure Satisfy the external circuit current equation ; Here, i represents the i-th coating layer.

[0037] ; When solving the liquid phase potential equation and the liquid phase lithium ion diffusion equation, the porosity in the two coating regions of the positive electrode is set to the corresponding values. Solve all electrochemical equations.

[0038] Figure 2 1 is a block diagram of a reduced-order model electrochemical simulation device for multilayer coating provided in one embodiment of the present application. The device comprises at least the following modules: a region division module 210 and an electrochemical simulation module 220 .

[0039] A region division module 210, for dividing the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into a plurality of simulation regions, each simulation region corresponding to the multi-layer coating of the battery cell; The electrochemical simulation module 220 is used to establish a reduced-order model based on the regional simulation parameters corresponding to each simulation region, so as to perform electrochemical simulation on the battery cell.

[0040] Optionally, the device further comprises: a first setting module for setting a plurality of simulated active substances in each simulation area; and / or a second setting module for setting a plurality of coating parameters of the coating corresponding to the simulation area for each simulation area.

[0041] Optionally, the multiple simulated active materials include: multiple active material particles, and / or multiple active material particle sizes; the multiple coating parameters include: multiple coating porosities, multiple active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity.

[0042] For relevant details, refer to the above method embodiment.

[0043] It should be noted that: the multi-layer coated reduced-order model electrochemical simulation device provided in the above embodiment only uses the division of the above-mentioned functional modules as an example when performing multi-layer coated reduced-order model electrochemical simulation. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the multi-layer coated reduced-order model electrochemical simulation device is divided into different functional modules to complete all or part of the functions described above. In addition, the multi-layer coated reduced-order model electrochemical simulation device provided in the above embodiment and the multi-layer coated reduced-order model electrochemical simulation method embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment, which will not be repeated here.

[0044] Optionally, the present application also provides a computer-readable storage medium, in which a program is stored, and the program is loaded and executed by a processor to implement the reduced-order model electrochemical simulation method of multilayer coating of the above method embodiment.

[0045] Optionally, the present application also provides a computer product, which includes a computer-readable storage medium, in which a program is stored, and the program is loaded and executed by a processor to implement the reduced-order model electrochemical simulation method of multilayer coating of the above method embodiment.

[0046] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0047] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A reduced-order model electrochemical simulation method for multilayer coating, characterized in that: The method comprises: The positive and negative electrodes of the simulation model of the multi-layer coated battery cell are respectively divided into a plurality of simulation regions, each simulation region corresponding to the multi-layer coating of the battery cell; Establishing a reduced-order model based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell; Also includes: A plurality of simulated active substances are arranged in each simulation area; the plurality of simulated active substances include: a plurality of active substance particles and / or a plurality of active substance particle sizes; and / or, Setting, for each simulation area, a plurality of coating parameters of the coating corresponding to the simulation area; The various coating parameters include: various coating porosities, various active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity.

2. The method according to claim 1, characterized in that: The step of establishing a reduced-order model based on regional simulation parameters corresponding to each simulation region to perform electrochemical simulation on the battery cell includes: Determine the reaction current density in each simulation area, the sum of the reaction current densities is equal to the external circuit current of the battery cell; Solving diffusion equations in active material particles in each simulation region to obtain lithium ion concentrations in the active material particles; The source terms in the solid phase potential equation, liquid phase potential equation and electrolyte lithium ion concentration equation are modified from the reaction current density of active materials in one simulation area to the reaction current density of active materials in multiple simulation areas.

3. The method according to claim 2, characterized in that The external circuit current is expressed by the following formula: ； ； ； Where i represents the i-th layer of coating, dx is the length element in the thickness direction of the battery cell, represents the integral in the i-layer coating area, is the reaction current density of each active substance in the i-th coating layer, F is the Faraday constant, is the reaction rate constant of each active substance in the i-th coating layer, is the lithium ion concentration of the electrolyte, is the reference electrolyte lithium ion concentration, is the transfer coefficient, is the maximum lithium ion concentration of the active material in the i-th coating layer, is the lithium ion concentration on the surface of the active material particles in the i-th coating layer, R is the ideal gas constant, T is the temperature, is the overvoltage, where is the solid phase potential, is the liquid phase potential, is the equilibrium potential of the active materials in each layer; is the radius of the active material particle in the i-th coating layer, is the volume fraction of active material particles in the i-th coating layer, is the specific surface area of ​​the active material particles in the i-th coating layer.

4. The method according to claim 3, characterized in that The source terms in the solid phase potential equation and the liquid phase potential equation are: ; The source term of the liquid phase lithium ion concentration diffusion equation is: the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating The corresponding lithium ion flux; Set the boundary flux to the reaction current density of the active material particles in the simulation area corresponding to the i-th layer of coating , based on the boundary flux, the solid phase lithium ion diffusion equation is solved in the active material particle sub-region within the simulation region corresponding to the i-th layer of coating.

5. A multi-layer coated reduced-order model electrochemical simulation device, characterized in that: The device comprises: A region division module, used to divide the positive and negative electrodes of the simulation model of the multi-layer coated battery cell into a plurality of simulation regions, each simulation region corresponding to the multi-layer coating of the battery cell; An electrochemical simulation module, used for establishing a reduced-order model based on regional simulation parameters corresponding to each simulation region, so as to perform electrochemical simulation on the battery cell; A first setting module is used to set a plurality of simulated active substances in each simulation area; the plurality of simulated active substances include: a plurality of active substance particles and / or a plurality of active substance particle sizes; and / or, A second setting module is used to set, for each simulation area, a plurality of coating parameters of the coating corresponding to the simulation area; The various coating parameters include: various coating porosities, various active material volume fractions, conductive agent and binder volume fractions, and / or tortuosity.

6. The device according to claim 5, characterized in that The electrochemical simulation module is used to: Determine the reaction current density in each simulation area, the sum of the reaction current densities is equal to the external circuit current of the battery cell; Solving diffusion equations in active material particles in each simulation region to obtain lithium ion concentrations in the active material particles; The source terms in the solid phase potential equation, liquid phase potential equation and electrolyte lithium ion concentration equation are modified from the reaction current density of active materials in one simulation area to the reaction current density of active materials in multiple simulation areas.

Images