Electrochemical model acquisition method, device, terminal and storage medium considering stress

Abstract

The present disclosure relates to the technical field of battery energy storage system modeling, and in particular to a method, device, terminal, and storage medium for acquiring an electrochemical model that takes stress into account. The method for acquiring an electrochemical model that takes stress into account includes: acquiring an initial electrochemical model corresponding to a target battery; determining a stress model and an overpotential model corresponding to the initial electrochemical model; and coupling the stress model and overpotential model with the initial electrochemical model to obtain a target electrochemical model. The present disclosure can improve the accuracy of electrochemical model acquisition.

Description

Technical Field

[0001] The present disclosure relates to the field of computer technology, and in particular to a method, device, terminal, and storage medium for acquiring an electrochemical model taking stress into consideration. Background Art

[0002] With the development of science and technology, the widespread application of energy storage technology has enriched people's production and life. The main energy storage methods can be divided into mechanical energy storage, electrochemical energy storage, and electromagnetic energy storage. Among them, battery energy storage technology is relatively mature, and electrochemical energy storage is currently developing well. Batteries are widely used in electrochemical energy storage systems due to their advantages such as high energy density, long cycle life, and low self-discharge. In order to accurately describe battery characteristics, design reliable battery state estimation algorithms, and accurately modeling are essential. Therefore, how to improve the accuracy of the electrochemical model corresponding to the battery has become a key focus. Summary of the Invention

[0003] The present disclosure provides a method, device, terminal and storage medium for acquiring an electrochemical model taking stress into consideration, the main purpose of which is to improve the accuracy of acquiring the electrochemical model.

[0004] According to one aspect of the present disclosure, a method for obtaining an electrochemical model considering stress is provided, comprising:

[0005] Obtain the initial electrochemical model corresponding to the target battery;

[0006] Determining a stress model and an overpotential model corresponding to the initial electrochemical model;

[0007] The stress model and the overpotential model are coupled with the initial electrochemical model to obtain a target electrochemical model.

[0008] Optionally, obtaining an initial electrochemical model corresponding to the target battery includes:

[0009] Constructing an initial electrochemical model control equation, wherein the initial electrochemical model control equation includes a lithium solid phase diffusion equation, a solid electrode potential change equation, an electrolyte species conservation equation, an electrolyte charge conservation equation, a lithium flux equation through a solid electrolyte interface, an overpotential equation, and a battery voltage equation;

[0010] The control equations of the initial electrochemical model are combined to obtain a terminal voltage equation;

[0011] An initial electrochemical model corresponding to the target battery is determined according to the terminal voltage equation.

[0012] Optionally, determining a stress model and an overpotential model corresponding to the initial electrochemical model includes:

[0013] Analyzing the stress of the target battery to obtain a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a net water stress equation on the particle surface;

[0014] The stress model and the overpotential model are determined according to the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation on the particle surface.

[0015] Optionally, coupling the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model includes:

[0016] Transfer-functioning the initial electrochemical model to obtain a transfer-functioned electrochemical model;

[0017] The stress model and the overpotential model are coupled with the transfer function electrochemical model to obtain the target electrochemical model.

[0018] Optionally, converting the initial electrochemical model into a transfer function to obtain a transfer function electrochemical model includes:

[0019] Converting the initial electrochemical model into a transfer function to obtain a transfer function between solid surface concentration and lithium flux density and an electrolyte potential transfer function;

[0020] Determining a negative electrode transfer function and a lithium concentration transfer function according to the transfer function between the solid surface concentration and the lithium flux density;

[0021] The transfer function electrochemical model is determined according to the negative electrode transfer function, the lithium concentration transfer function and the electrolyte potential transfer function.

[0022] Optionally, after coupling the stress model and the overpotential model with the transfer function electrochemical model to obtain the target electrochemical model, the method further includes:

[0023] Parameter identification is performed on the target electrochemical model to obtain a target electrochemical model after parameter identification.

[0024] Optionally, performing parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification includes:

[0025] Obtaining a first terminal voltage corresponding to the target battery and a second terminal voltage corresponding to the target electrochemical model at any moment;

[0026] If the first terminal voltage and the second terminal voltage meet the parameter identification condition, determining that the target electrochemical model is the target electrochemical model after the parameter identification;

[0027] If the first terminal voltage and the second terminal voltage do not satisfy the parameter identification condition, the model parameters corresponding to the target electrochemical model are adjusted until the first terminal voltage and the second terminal voltage satisfy the parameter identification condition.

[0028] According to another aspect of the present disclosure, there is provided a device for acquiring an electrochemical model taking stress into consideration, comprising:

[0029] A model acquisition unit, used to obtain an initial electrochemical model corresponding to the target battery;

[0030] A model determination unit, configured to determine a stress model and an overpotential model corresponding to the initial electrochemical model;

[0031] A model coupling unit is used to couple the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model.

[0032] Optionally, when the model acquisition unit is used to acquire the initial electrochemical model corresponding to the target battery, it is specifically used to:

[0033] Constructing an initial electrochemical model control equation, wherein the initial electrochemical model control equation includes a lithium solid phase diffusion equation, a solid electrode potential change equation, an electrolyte species conservation equation, an electrolyte charge conservation equation, a lithium flux equation through a solid electrolyte interface, an overpotential equation, and a battery voltage equation;

[0034] The control equations of the initial electrochemical model are combined to obtain a terminal voltage equation;

[0035] An initial electrochemical model corresponding to the target battery is determined according to the terminal voltage equation.

[0036] Optionally, when the model determination unit is used to determine the stress model and overpotential model corresponding to the initial electrochemical model, it is specifically used to:

[0037] Analyzing the stress of the target battery to obtain a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a net water stress equation on the particle surface;

[0038] The stress model and the overpotential model are determined according to the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation on the particle surface.

[0039] Optionally, the model coupling unit is used to couple the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model, specifically to:

[0040] Transfer-functioning the initial electrochemical model to obtain a transfer-functioned electrochemical model;

[0041] The stress model and the overpotential model are coupled with the transfer function electrochemical model to obtain the target electrochemical model.

[0042] Optionally, the model coupling unit is used to transfer function the initial electrochemical model to obtain the transfer function electrochemical model, specifically for:

[0043] Converting the initial electrochemical model into a transfer function to obtain a transfer function between solid surface concentration and lithium flux density and an electrolyte potential transfer function;

[0044] Determining a negative electrode transfer function and a lithium concentration transfer function according to the transfer function between the solid surface concentration and the lithium flux density;

[0045] The transfer function electrochemical model is determined according to the negative electrode transfer function, the lithium concentration transfer function and the electrolyte potential transfer function.

[0046] Optionally, the device further includes a model identification unit configured to, after coupling the stress model and the overpotential model with the transfer function electrochemical model to obtain the target electrochemical model:

[0047] The model identification unit is used to perform parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification.

[0048] Optionally, the model identification unit is used to perform parameter identification on the target electrochemical model, and when obtaining the target electrochemical model after parameter identification, is specifically used to:

[0049] Obtaining a first terminal voltage corresponding to the target battery and a second terminal voltage corresponding to the target electrochemical model at any moment;

[0050] If the first terminal voltage and the second terminal voltage meet the parameter identification condition, determining that the target electrochemical model is the target electrochemical model after the parameter identification;

[0051] If the first terminal voltage and the second terminal voltage do not satisfy the parameter identification condition, the model parameters corresponding to the target electrochemical model are adjusted until the first terminal voltage and the second terminal voltage satisfy the parameter identification condition.

[0052] According to another aspect of the present disclosure, there is provided a terminal, including:

[0053] at least one processor; and

[0054] a memory communicatively connected to the at least one processor; wherein,

[0055] The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform any one of the methods described in the above aspect.

[0056] According to another aspect of the present disclosure, a non-transitory computer-readable storage medium storing computer instructions is provided, wherein the computer instructions are used to enable the computer to execute any one of the methods described in the aforementioned aspect.

[0057] According to another aspect of the present disclosure, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a processor, the computer program implements the method according to any one of the aforementioned aspects.

[0058] In one or more embodiments of the present disclosure, a target electrochemical model is obtained by obtaining an initial electrochemical model corresponding to a target battery; determining a stress model and an overpotential model corresponding to the initial electrochemical model; and coupling the stress model and the overpotential model with the initial electrochemical model. Therefore, by coupling the stress model and the stress-induced overpotential model with the initial electrochemical model, an electrochemical model can be constructed that takes into account the overpotential caused by the solid-state stress of the electrode, thereby reducing model inaccuracies and improving the accuracy of obtaining the target electrochemical model.

[0059] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are used to better understand the present invention and do not constitute a limitation of the present invention.

[0061] Figure 1 A schematic flow chart illustrating a first method for acquiring an electrochemical model taking stress into consideration provided by an embodiment of the present disclosure is shown;

[0062] Figure 2 A schematic structural diagram of a DFN model provided by an embodiment of the present disclosure is shown;

[0063] Figure 3 A schematic flow chart illustrating a second method for acquiring an electrochemical model taking stress into consideration provided by an embodiment of the present disclosure is shown;

[0064] Figure 4 A schematic diagram showing the net water stress on a particle provided by an embodiment of the present disclosure is shown;

[0065] Figure 5A schematic diagram of a parameter identification process provided by an embodiment of the present disclosure is shown;

[0066] Figure 6 A schematic structural diagram of a first electrochemical model acquisition device considering stress provided by an embodiment of the present disclosure is shown;

[0067] Figure 7 A schematic structural diagram of a second electrochemical model acquisition device considering stress provided by an embodiment of the present disclosure is shown;

[0068] Figure 8 It is a block diagram of a terminal used to implement the stress-considered electrochemical model acquisition method according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0069] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0070] The present disclosure is described in detail below with reference to specific embodiments.

[0071] In the first embodiment, if Figure 1 As shown, Figure 1 A schematic flow chart illustrating a first stress-considered electrochemical model acquisition method provided by an embodiment of the present disclosure is provided. This method can be implemented using a computer program and run on a device performing the stress-considered electrochemical model acquisition method. The computer program can be integrated into an application or run as a standalone tool application.

[0072] The device for obtaining an electrochemical model taking into account stress may be a terminal having a function of obtaining an electrochemical model taking into account stress, and the terminal includes but is not limited to a wearable device, a handheld device, a personal computer, a tablet computer, an in-vehicle device, a smart phone, a computing device, or other processing device connected to a wireless modem. In different networks, the terminal may be called by different names, such as user equipment, access terminal, subscriber unit, subscriber station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, cellular phone, cordless phone, personal digital assistant (PDA), a terminal in a fifth generation mobile communication technology (5G) network, a fourth generation mobile communication technology (4G) network, a third generation mobile communication technology (3G) network, or a future evolution network, etc.

[0073] Specifically, the method for obtaining the electrochemical model considering stress includes:

[0074] S101, obtaining an initial electrochemical model corresponding to the target battery;

[0075] According to some embodiments, the target battery refers to the battery targeted when the terminal acquires the electrochemical model. The target battery is not specifically a fixed battery. For example, the target battery may be an energy storage battery.

[0076] In some embodiments, the initial electrochemical model is the Doyle-Fuller-Newman (DFN) model. The DFN model is the foundation for the development of electrochemical mechanism models. It is a pseudo-two-dimensional model that can simulate the solid and electrolyte dynamics of lithium-ion batteries based on porous electrode theory. However, its core also contains complex partial differential equations and numerous electrochemical parameters, which places high demands on the computing power of the battery management system.

[0077] In some embodiments, Figure 2 FIG. 1 shows a schematic diagram of the structure of a DFN model provided by an embodiment of the present disclosure. Figure 2 As shown, the DFN model includes a positive electrode region, a negative electrode region, and a separator between the positive electrode region and the negative electrode region. In the DFN model, an x-axis is established from the outside of the negative electrode region to the outside of the positive electrode region. The electrolyte passes through the positive electrode region, the separator, and the negative electrode region in sequence along the x-axis direction; wherein, the negative electrode region is 0≤x≤L n , the diaphragm is L n≤x≤L n + m , the area corresponding to the positive electrode is L n + m ≤x≤L n + m + p , subscript “n” represents the variable in the negative electrode, subscript “m” represents the variable in the separator (sep), subscript “p” represents the variable in the positive electrode, subscript “s” represents the solid phase, subscript “e” represents the solid phase, superscript “surf” represents the surface, and c is the lithium ion concentration.

[0078] In some embodiments, as Figure 2 As shown, the positive electrode region is a positive electrode porous electrode, and the negative electrode region is a negative electrode porous electrode. Both the positive electrode porous electrode and the negative electrode porous electrode include spherical electrode particles. In the domain of the spherical electrode particles, R s,k is the radius of particle k, k∈{n=negative,p=positive}.

[0079] In some embodiments, Table (1) is a parameter table of the DFN model.

[0080]

[0081] Table (1)

[0082] It is easy to understand that when the terminal acquires the electrochemical model, the terminal can acquire the initial electrochemical model corresponding to the target battery.

[0083] S102, determining a stress model and an overpotential model corresponding to the initial electrochemical model;

[0084] According to some embodiments, stress refers to stress generated in the electrode during lithium insertion. A stress model is used to indicate the relationship between stress, lithium ion concentration, and electrode properties.

[0085] In some embodiments, an overpotential model is used to indicate the relationship between overpotential and lithium ion concentration and electrode properties.

[0086] It is easy to understand that when the terminal obtains the initial electrochemical model corresponding to the target battery, the terminal can determine the stress model and overpotential model corresponding to the initial electrochemical model.

[0087] S103 , coupling the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model.

[0088] According to some embodiments, the target electrochemical model refers to the electrochemical model obtained by coupling the stress model and the overpotential model with the initial electrochemical model. The target electrochemical model is not specifically a fixed model. For example, when the stress model changes, the target electrochemical model can change. When the overpotential model changes, the target electrochemical model can also change.

[0089] In some embodiments, in a battery management system (BMS) or a cloud platform of an energy storage power station, the target electrochemical model can be used for battery modeling and battery state calculation.

[0090] It is easy to understand that when the terminal obtains the stress model and overpotential model corresponding to the initial electrochemical model, the terminal can couple the stress model and overpotential model with the initial electrochemical model to obtain the target electrochemical model.

[0091] In summary, the method provided by the embodiments of the present disclosure obtains an initial electrochemical model corresponding to the target battery; determines the stress model and overpotential model corresponding to the initial electrochemical model; and couples the stress model and overpotential model with the initial electrochemical model to obtain the target electrochemical model. Therefore, considering the overpotential caused by stress of lithium iron phosphate batteries at low temperatures, by coupling the stress model and the overpotential model caused by stress with the initial electrochemical model, an electrochemical model that takes into account the overpotential caused by the solid-state stress of the electrode can be constructed, which can reduce the possibility of model inaccuracy and improve the accuracy of obtaining the target electrochemical model.

[0092] See Figure 3 , Figure 3 A schematic flow chart of a second method for obtaining an electrochemical model taking into account stress provided by an embodiment of the present disclosure is shown. This method can be executed by a terminal. Specifically, the method for obtaining an electrochemical model taking into account stress includes:

[0093] S201, constructing the initial electrochemical model control equation;

[0094] According to some embodiments, the governing equations of the initial electrochemical model refer to the equations in the initial electrochemical model that describe mass conversion, charge conservation, and lithium flux density in the solid and electrolyte. The governing equations of the initial electrochemical model do not specifically refer to a fixed equation. The governing equations of the initial electrochemical model include, but are not limited to, the lithium solid phase diffusion equation, the solid electrode potential change equation, the electrolyte species conservation equation, the electrolyte charge conservation equation, the lithium flux equation through the solid electrolyte interface, the overpotential equation, the battery voltage equation, and the like.

[0095] In some embodiments, the mathematical expression of the lithium solid phase diffusion equation is as follows:

[0096]

[0097] Where t is time, r is from 0 to particle radius R s The coefficient between .

[0098] The mathematical expression of the boundary condition corresponding to the lithium solid phase diffusion equation is as follows:

[0099]

[0100] Where j is the reaction flux across the solid phase boundary, F is the Faraday constant, and a s is the specific surface area.

[0101] In some embodiments, the mathematical expression of the solid electrode potential change equation is as follows:

[0102]

[0103] Here, the superscript “eff” stands for effective, and φ is the charge potential.

[0104] In some embodiments, the mathematical expression of the electrolyte material conservation equation is as follows:

[0105]

[0106] in, The Bruggeman coefficient is expressed as brug, and brug can be 1.5, for example. is the lithium transfer number, For example, 0.363 can be taken.

[0107] The mathematical expression of the boundary condition corresponding to the electrolyte material conservation equation is as follows:

[0108]

[0109]

[0110] c e ((L n +L m ) - )=c e ((L n +L m ) + ) (7)

[0111]

[0112]

[0113] As shown in formulas (5) to (9), continuity can be achieved by applying internal boundary conditions at the connection of the three regions of the unit.

[0114] In some embodiments, the mathematical expression of the electrolyte charge conservation equation is as follows:

[0115]

[0116] in, yes R is the universal gas constant and T is the preset time.

[0117] The mathematical expressions of the boundary conditions of the two current collectors in the electrolyte charge conservation equation are as follows:

[0118]

[0119] In some embodiments, the mathematical expression of the lithium flux equation through the solid electrolyte interface is as follows:

[0120]

[0121] Where i0 is the exchange current density, c s,e is the lithium ion concentration on the surface of solid particles, α a is the conversion coefficient of the positive electrode reaction, α c is the conversion coefficient of the negative electrode reaction, and η is the overpotential, that is, η is the additional force required to overcome the surface reaction.

[0122] In some embodiments, the mathematical expression of the overpotential equation is as follows:

[0123] η k =φ s,k -φ w,k -U ocp,k ,k∈{n,p} (13)

[0124] Among them, U ocp is the open circuit potential of the electrode, U ocp is the lithium ion concentration c on the surface of solid particles s, function.

[0125] In some embodiments, the mathematical expression of the battery voltage equation is as follows:

[0126] Ucell(t)=φ s (L,t)-φ s (0,t)-R f I (14)

[0127] Where, Ucell(t) is the output voltage, φs (L,t) is the positive electrode collector potential, φ s (0,t) is the negative electrode collector potential, R f is the membrane DC resistance, and I is the input current.

[0128] It is easy to understand that when the terminal acquires the electrochemical model, the terminal can construct an initial electrochemical model control equation.

[0129] S202, combining the control equations of the initial electrochemical model to obtain a terminal voltage equation;

[0130] According to some embodiments, the terminal may combine formulas (1) to (14) to obtain a mathematical expression of the terminal voltage equation:

[0131]

[0132] It is easy to understand that when the terminal obtains the initial electrochemical model control equation, the terminal can combine the initial electrochemical model control equation to obtain the terminal voltage equation.

[0133] S203, determining an initial electrochemical model corresponding to the target battery according to the terminal voltage equation;

[0134] It is easy to understand that when the terminal obtains the terminal voltage equation, the terminal can determine the initial electrochemical model corresponding to the target battery based on the terminal voltage equation.

[0135] S204, analyzing the stress of the target battery to obtain a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a net water stress equation on the particle surface;

[0136] According to some embodiments, considering that stress may cause overpotential and thus model inaccuracy, stress needs to be analyzed first when obtaining a target electrochemical model. To quantify stress, stress analysis can be limited to electrode particles and particle stress can be modeled to obtain a stress model.

[0137] In some embodiments, Figure 4 Schematic diagram of the net water stress on a particle provided by an embodiment of the present disclosure is shown. Figure 4 As shown in the figure, the stress on the particles is related to the diffusion stress and the inter-particle stress. Therefore, the terminal can construct a model of the electrode solid phase stress and the overpotential caused by it, that is, a stress model and an overpotential model.

[0138] According to some embodiments, the mathematical expression of the stress-strain relationship equation is as follows:

[0139]

[0140] Among them, σ θθ is the tangential stress, is the normal stress, τ 0 is the deformation-independent surface tension, K s is the “surface modulus”, ε θθ is the tangential strain.

[0141] In some embodiments, the mathematical expression for the concentration-dependent stress-strain relationship is as follows:

[0142]

[0143]

[0144] The superscript “c” indicates concentration-related, ε rr is the radial strain, σ rr is the radial stress, is the molar concentration of lithium ions in the solid active material.

[0145] in, and The calculation formula is as follows:

[0146]

[0147] Where u is the function of radial displacement.

[0148] According to some embodiments, the mathematical expression of the static mechanical equilibrium equation of the solid active material is as follows:

[0149]

[0150] According to some embodiments, the mathematical expression of the net water stress equation on the particle surface is as follows:

[0151]

[0152] Among them, σ h is the net water stress on the particle surface, c ave is the particle surface concentration, is the average concentration.

[0153] It is easy to understand that when the terminal acquires the electrochemical model, the terminal can analyze the stress of the target battery to obtain the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation of the particle surface.

[0154] S205, determining a stress model and an overpotential model based on a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a net water stress equation on the particle surface;

[0155] According to some embodiments, the terminal may determine the stress model according to formula (16) to formula (21). At the same time, the terminal may also combine formula (16) to formula (21) to obtain the mathematical expression of the overpotential equation:

[0156] μ=-Ωσ h (twenty two)

[0157] Where μ is the overpotential.

[0158] It is easy to understand that when the terminal obtains the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active substance, and the net water stress equation on the particle surface, the terminal can determine the stress model and the overpotential model based on the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active substance, and the net water stress equation on the particle surface.

[0159] S206, converting the initial electrochemical model into a transfer function to obtain a transfer function-converted electrochemical model;

[0160] According to some embodiments, when the terminal transfer functions the initial electrochemical model to obtain the transfer function electrochemical model, the terminal may first transfer function the initial electrochemical model to obtain the transfer function between the solid surface concentration and the lithium flux density and the electrolyte potential transfer function. Next, the terminal may determine the negative electrode transfer function and the lithium concentration transfer function based on the transfer function between the solid surface concentration and the lithium flux density. Finally, the terminal may determine the transfer function electrochemical model based on the negative electrode transfer function, the lithium concentration transfer function, and the electrolyte potential transfer function.

[0161] In some embodiments, when the terminal transfer functions the initial electrochemical model to obtain the transfer function between the solid surface concentration and the lithium flux density and the electrolyte potential transfer function, the terminal can use mathematical methods to find the analytical solution of the internal variables of the battery, that is, use Laplace transform and Padé approximation to transfer function the DFN model, thereby obtaining the transfer function between the solid surface concentration and the lithium flux density and the electrolyte potential transfer function.

[0162] In some embodiments, the mathematical expression of the transfer function between solid surface concentration and lithium flux density is as follows:

[0163]

[0164] Among them, the s in the non-label is the Laplace operator.

[0165] Next, to further refine the model, the terminal can use the third-order Padé approximation to convert Equation (23) into a polynomial transfer function as follows:

[0166]

[0167] Among them, "+" applies to the positive electrode and "-" applies to the negative electrode.

[0168] In some embodiments, when the terminal obtains the electrolyte potential transfer function, first, the terminal may perform Laplace transform on the electrolyte material conservation equation, that is, formula (4), to obtain:

[0169]

[0170]

[0171]

[0172] Among them, formulas (25), (26), and (27) meet the following conditions:

[0173]

[0174]

[0175]

[0176] C e,m (( n +L m ) - )=C e, (( n +L m ) + )

[0177]

[0178]

[0179] Among them, it can be seen from formulas (25), (26), and (27) that after Laplace transformation, the conservation of matter in the electrolyte is a standard parabolic partial differential equation with homogeneous boundary conditions.

[0180] Then, the terminal can calculate the transfer function of the negative electrode at x=0:

[0181]

[0182] At the same time, the terminal can calculate the transfer function of lithium concentration at x = L:

[0183]

[0184] At the same time, similar to the solid phase, the terminal can use the Padé approximation to convert the transfer function of the lithium concentration of the negative electrode at x = 0 and the positive electrode at x = L into a reduced-order rational expression. Specifically, first, the terminal can be linearly defined as Then, the terminal can perform Taylor expansion on it get:

[0185]

[0186] Among them, c e,0 is the initial concentration of the electrolyte.

[0187] Then, the terminal can integrate formula (30) with respect to x to obtain the ion current i flowing through the electrolyte. e Definition:

[0188]

[0189] Thus, the terminal can obtain the new mathematical expression corresponding to formula (30):

[0190]

[0191] Secondly, the terminal can integrate formula (32) from 0 to x to obtain:

[0192]

[0193] Among them, φ e The calculation formula is as follows:

[0194]

[0195] Finally, the terminal can determine the electrolyte potential transfer function, that is, the electrolyte potential transfer function at x = L is as follows:

[0196]

[0197] The overpotential can be solved by inverting formula (12):

[0198]

[0199] According to some embodiments, the solid phase diffusion coefficient D taking into account stress sT = s (aln ave +bc ave ) 2 +cc ave ), therefore, the terminal can convert the solid phase diffusion coefficient D in formula (1) into s Replace with D sT . Where a, b, and c are constants.

[0200] It is easy to understand that when the terminal obtains the initial electrochemical model, since the initial electrochemical model control equation corresponding to the initial electrochemical model contains complex partial differential equations and numerous electrochemical parameters, in order to reduce the computational burden, the terminal can transfer function the initial electrochemical model to obtain a transfer function electrochemical model. After a series of transfer function transformations, each term of the initial electrochemical model control equation can be calculated as a function of current, which can greatly reduce the amount of calculation.

[0201] S207, coupling the stress model and the overpotential model with the transfer function electrochemical model to obtain a target electrochemical model;

[0202] According to some embodiments, when the terminal couples the stress model and the overpotential model with the transfer function electrochemical model, the terminal can obtain the electrode potential equation:

[0203] U=U ref (c s )-Ωσ h (37)

[0204] Among them, Ωσ h is the overpotential caused by stress.

[0205] It is easy to understand that when the terminal obtains the transfer function electrochemical model, the terminal can couple the stress model and the overpotential model with the transfer function electrochemical model to obtain the target electrochemical model.

[0206] S208 , performing parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification.

[0207] According to some embodiments, when the terminal performs parameter identification on the target electrochemical model and obtains the target electrochemical model after parameter identification, first, the terminal can obtain the first terminal voltage corresponding to the target battery and the second terminal voltage corresponding to the target electrochemical model at any time. If the terminal determines that the first terminal voltage and the second terminal voltage meet the parameter identification conditions, the terminal can determine that the target electrochemical model is the target electrochemical model after parameter identification. If the terminal determines that the first terminal voltage and the second terminal voltage do not meet the parameter identification conditions, the terminal can adjust the model parameters corresponding to the target electrochemical model until the first terminal voltage and the second terminal voltage meet the parameter identification conditions.

[0208] In some embodiments, when the terminal obtains the target electrochemical model, the terminal can obtain the operating data at time t and use an intelligent algorithm (GA) to perform parameter identification on the target electrochemical model. Figure 5 FIG. 1 is a flow chart showing a parameter identification process provided by an embodiment of the present disclosure. Figure 5As shown in FIG, when the terminal obtains the target electrochemical model, the terminal can obtain the operating condition data corresponding to the target battery at time t to obtain the first terminal voltage U. At the same time, the terminal can input a preset current value into the dimensional transfer function model to obtain the second terminal voltage Um. Then, the terminal can input the first terminal voltage U and the second terminal voltage Um into the objective function to obtain the voltage error between the first terminal voltage U and the second terminal voltage Um: e(θ)=(U m -) 2 If the voltage error satisfies the parameter identification conditions, the terminal may determine that the increased-dimensional transfer function model is the target electrochemical model and terminate the parameter identification. If the voltage error does not satisfy the parameter identification conditions, the terminal may adjust the model parameter θ corresponding to the increased-dimensional transfer function model according to the identification algorithm until the voltage error satisfies the parameter identification conditions.

[0209] In some embodiments, the model parameter θ includes but is not limited to all parameters involved in formulas (1) to (37).

[0210] In some embodiments, the parameter identification condition is not specifically a fixed condition. For example, the parameter identification condition may be that the voltage error is less than an error threshold ε. The error threshold is not specifically a fixed threshold. For example, when a threshold modification instruction for the error threshold is obtained, the error threshold may change.

[0211] It is easy to understand that when the terminal obtains the target electrochemical model, the terminal can perform parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification.

[0212] In summary, the method provided by the embodiment of the present disclosure first constructs the initial electrochemical model control equation, and the initial electrochemical model control equation is combined to obtain the terminal voltage equation. According to the terminal voltage equation, the initial electrochemical model corresponding to the target battery is determined, and the stress of the target battery is analyzed to obtain the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation of the particle surface. According to the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation of the particle surface, the stress model and the overpotential model are determined, the initial electrochemical model is transfer-functionalized to obtain the transfer-functionalized electrochemical model, and the stress model and The overpotential model is coupled with the transfer function electrochemical model to obtain the target electrochemical model. Therefore, considering that the overpotential caused by stress in lithium iron phosphate batteries at low temperatures causes model inaccuracy, by coupling the stress model and the stress-induced overpotential model with the initial electrochemical model, an electrochemical model that takes into account the overpotential caused by the electrode solid phase stress can be constructed. This can reduce model inaccuracy and improve the accuracy of the target electrochemical model. At the same time, by using mathematical methods to obtain analytical solutions for the internal variables of the battery and using mathematical order reduction methods to establish a reduced-order electrochemical model that accurately approximates the full-order model but has a computational complexity close to that of the equivalent circuit, the computational burden can be reduced and the calculation speed can be increased. Then, by performing parameter identification on the target electrochemical model, the target electrochemical model after parameter identification is obtained. Therefore, the model error can be reduced, the model parameters are closest to physical reality, the model accuracy can be improved, and the model robustness can be increased.

[0213] In the technical solutions disclosed herein, the collection, storage, use, processing, transmission, provision and disclosure of user personal information involved comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0214] The following are embodiments of the apparatus disclosed herein, which can be used to implement the method embodiments disclosed herein. For details not disclosed in the apparatus embodiments disclosed herein, please refer to the method embodiments disclosed herein.

[0215] See Figure 6 , which shows a schematic structural diagram of the first stress-considered electrochemical model acquisition device provided by an embodiment of the present disclosure. The stress-considered electrochemical model acquisition device can be implemented as all or part of a device through software, hardware, or a combination of both. The stress-considered electrochemical model acquisition device 600 includes a model acquisition unit 601, a model determination unit 602, and a model coupling unit 603, wherein:

[0216] A model acquisition unit 601 is used to acquire an initial electrochemical model corresponding to a target battery;

[0217] A model determination unit 602 is used to determine a stress model and an overpotential model corresponding to the initial electrochemical model;

[0218] The model coupling unit 603 is used to couple the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model.

[0219] Optionally, when the model acquisition unit 601 is used to acquire the initial electrochemical model corresponding to the target battery, it is specifically used to:

[0220] Constructing the initial electrochemical model control equations, wherein the initial electrochemical model control equations include the lithium solid phase diffusion equation, the solid electrode potential change equation, the electrolyte species conservation equation, the electrolyte charge conservation equation, the lithium flux equation through the solid electrolyte interface, the overpotential equation, and the battery voltage equation;

[0221] The control equations of the initial electrochemical model are combined to obtain the terminal voltage equation;

[0222] According to the terminal voltage equation, the initial electrochemical model corresponding to the target battery is determined.

[0223] Optionally, when the model determination unit 602 is used to determine the stress model and the overpotential model corresponding to the initial electrochemical model, it is specifically used to:

[0224] Analyze the stress of the target battery to obtain the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation on the particle surface;

[0225] The stress model and overpotential model are determined based on the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material and the net water stress equation on the particle surface.

[0226] Optionally, the model coupling unit 603 is used to couple the stress model and the overpotential model with the initial electrochemical model to obtain a target electrochemical model, specifically for:

[0227] The initial electrochemical model is converted into a transfer function to obtain a transfer function electrochemical model;

[0228] The stress model and overpotential model are coupled with the transfer function electrochemical model to obtain the target electrochemical model.

[0229] Optionally, the model coupling unit 603 is used to transfer function the initial electrochemical model to obtain the transfer function electrochemical model, specifically for:

[0230] The initial electrochemical model is transformed into a transfer function to obtain the transfer function between the solid surface concentration and the lithium flux density, and the electrolyte potential transfer function;

[0231] Determining the negative electrode transfer function and the lithium concentration transfer function based on the transfer function between the solid surface concentration and the lithium flux density;

[0232] A transfer function electrochemical model is determined based on the negative electrode transfer function, the lithium concentration transfer function and the electrolyte potential transfer function.

[0233] Optional, Figure 7 FIG. 1 is a schematic diagram showing the structure of a second electrochemical model acquisition device considering stress provided by an embodiment of the present disclosure. Figure 7 As shown, the stress-considered electrochemical model acquisition device 600 further includes a model identification unit 604, which is used to couple the stress model and the overpotential model with the transfer function electrochemical model to obtain the target electrochemical model:

[0234] The model identification unit 604 is used to perform parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification.

[0235] Optionally, the model identification unit 604 is used to perform parameter identification on the target electrochemical model. When obtaining the target electrochemical model after parameter identification, it is specifically used to:

[0236] Obtaining a first terminal voltage corresponding to a target battery and a second terminal voltage corresponding to a target electrochemical model at any moment;

[0237] If the first terminal voltage and the second terminal voltage meet the parameter identification condition, determining the target electrochemical model to be the target electrochemical model after parameter identification;

[0238] If the first terminal voltage and the second terminal voltage do not satisfy the parameter identification condition, the model parameters corresponding to the target electrochemical model are adjusted until the first terminal voltage and the second terminal voltage satisfy the parameter identification condition.

[0239] It should be noted that the device for acquiring an electrochemical model taking into account stress provided in the above embodiment only uses the division of the above-mentioned functional modules as an example when executing the method for acquiring an electrochemical model taking into account stress. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device for acquiring an electrochemical model taking into account stress provided in the above embodiment and the embodiment of the method for acquiring an electrochemical model taking into account stress belong to the same concept. The implementation process thereof is detailed in the method embodiment and will not be repeated here.

[0240] In summary, the device provided by the embodiment of the present disclosure obtains the initial electrochemical model corresponding to the target battery through the model acquisition unit; the model determination unit determines the stress model and overpotential model corresponding to the initial electrochemical model; and the model coupling unit couples the stress model and overpotential model with the initial electrochemical model to obtain the target electrochemical model. Therefore, considering the overpotential caused by stress of lithium iron phosphate batteries at low temperatures, by coupling the stress model and the overpotential model caused by stress with the initial electrochemical model, an electrochemical model that takes into account the overpotential caused by the solid-state stress of the electrode can be constructed, which can reduce the possibility of model inaccuracy and improve the accuracy of obtaining the target electrochemical model.

[0241] In the technical solutions disclosed herein, the collection, storage, use, processing, transmission, provision and disclosure of user personal information involved comply with the provisions of relevant laws and regulations and do not violate public order and good morals.

[0242] According to an embodiment of the present disclosure, the present disclosure also provides a terminal, a readable storage medium, and a computer program product.

[0243] Figure 8 A schematic block diagram of an example terminal 800 that can be used to implement embodiments of the present disclosure is shown. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit implementations of the present disclosure described and / or claimed herein.

[0244] like Figure 8 As shown, terminal 800 includes a computing unit 801, which can perform various appropriate actions and processes according to a computer program stored in a read-only memory (ROM) 802 or a computer program loaded from a storage unit 808 into a random access memory (RAM) 803. Various programs and data required for the operation of terminal 800 can also be stored in RAM 803. Computing unit 801, ROM 802, and RAM 803 are connected to each other via a bus 804. An input / output (I / O) interface 805 is also connected to bus 804.

[0245] Multiple components in terminal 800 are connected to I / O interface 805, including: an input unit 806, such as a keyboard, mouse, etc.; an output unit 807, such as various types of displays, speakers, etc.; a storage unit 808, such as a magnetic disk, optical disk, etc.; and a communication unit 809, such as a network card, modem, wireless communication transceiver, etc. The communication unit 809 allows terminal 800 to exchange information / data with other devices via a computer network such as the Internet and / or various telecommunication networks.

[0246] The computing unit 801 can be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the computing unit 801 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various dedicated artificial intelligence (AI) computing chips, various computing units for running machine learning model algorithms, digital signal processors (DSPs), and any appropriate processors, controllers, microcontrollers, etc. The computing unit 801 performs the various methods and processes described above, such as the electrochemical model acquisition method considering stress. For example, in some embodiments, the electrochemical model acquisition method considering stress can be implemented as a computer software program, which is tangibly contained in a machine-readable medium, such as a storage unit 808. In some embodiments, part or all of the computer program can be loaded and / or installed on the terminal 800 via ROM 802 and / or communication unit 809. When the computer program is loaded into RAM 803 and executed by the computing unit 801, one or more steps of the electrochemical model acquisition method considering stress described above can be performed. Alternatively, in other embodiments, the computing unit 801 may be configured to execute the electrochemical model acquisition method considering stress in any other appropriate manner (for example, by means of firmware).

[0247] Various embodiments of the systems and techniques described herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system-on-chip systems (SOCs), programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments can include being implemented in one or more computer programs that are executable and / or interpreted on a programmable system that includes at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0248] The program code for implementing the method of the present disclosure can be written in any combination of one or more programming languages. These program codes can be provided to a processor or controller of a general-purpose computer, a special-purpose computer, or other programmable data processing device so that when the program code is executed by the processor or controller, the functions / operations specified in the flow chart and / or block diagram are implemented. The program code can be executed entirely on the machine, partially on the machine, as a stand-alone software package, partially on the machine and partially on a remote machine, or entirely on a remote machine or server.

[0249] In the context of the present disclosure, a machine-readable medium can be a tangible medium that can contain or store a program for use by or in conjunction with an instruction execution system, device or equipment. A machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium can include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium can include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0250] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user can provide input to the computer. Other types of devices can also be used to provide interaction with the user; for example, the feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including acoustic input, voice input, or tactile input).

[0251] The systems and techniques described herein can be implemented in a computing system that includes back-end components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes front-end components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such back-end components, middleware components, or front-end components. The components of the system can be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), the Internet, and a blockchain network.

[0252] A computer system may include a client and a server. The client and server are generally remote from each other and typically interact via a communication network. This client-server relationship is established by computer programs running on the respective computers, establishing a client-server relationship. The server may be a cloud server, also known as a cloud computing server or cloud host, a host product within the cloud computing service ecosystem that addresses the management difficulties and limited scalability of traditional physical hosts and VPS services ("Virtual Private Servers" or simply "VPS"). The server may also be a server in a distributed system or a server integrated with blockchain.

[0253] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved. This is not a limitation herein.

[0254] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

Claims

1. A method for obtaining an electrochemical model considering stress, characterized in that: include: Constructing an initial electrochemical model control equation, wherein the initial electrochemical model control equation includes a lithium solid phase diffusion equation, a solid electrode potential change equation, an electrolyte species conservation equation, an electrolyte charge conservation equation, a lithium flux equation through a solid electrolyte interface, an overpotential equation, and a battery voltage equation; The control equations of the initial electrochemical model are combined to obtain a terminal voltage equation; Determining an initial electrochemical model corresponding to the target battery according to the terminal voltage equation; Analyzing the stress of the target battery to obtain a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a net water stress equation on the particle surface; Determining a stress model and an overpotential model based on the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the net water stress equation on the particle surface; Transfer-functioning the initial electrochemical model to obtain a transfer-functioned electrochemical model; The stress model and the overpotential model are coupled with the transfer function electrochemical model to obtain a target electrochemical model.

2. The method according to claim 1, characterized in that The transferring function of the initial electrochemical model to obtain the transferred function electrochemical model includes: Converting the initial electrochemical model into a transfer function to obtain a transfer function between solid surface concentration and lithium flux density and an electrolyte potential transfer function; Determining a negative electrode transfer function and a lithium concentration transfer function according to the transfer function between the solid surface concentration and the lithium flux density; The transfer function electrochemical model is determined according to the negative electrode transfer function, the lithium concentration transfer function and the electrolyte potential transfer function.

3. The method according to claim 1, characterized in that After coupling the stress model and the overpotential model with the transfer function electrochemical model to obtain the target electrochemical model, the method further includes: Parameter identification is performed on the target electrochemical model to obtain a target electrochemical model after parameter identification.

4. The method according to claim 3, characterized in that The performing parameter identification on the target electrochemical model to obtain the target electrochemical model after parameter identification includes: Obtaining a first terminal voltage corresponding to the target battery and a second terminal voltage corresponding to the target electrochemical model at any moment; If the first terminal voltage and the second terminal voltage meet the parameter identification condition, determining that the target electrochemical model is the target electrochemical model after the parameter identification; If the first terminal voltage and the second terminal voltage do not satisfy the parameter identification condition, the model parameters corresponding to the target electrochemical model are adjusted until the first terminal voltage and the second terminal voltage satisfy the parameter identification condition.

5. A device for acquiring an electrochemical model taking stress into consideration, characterized in that: include: A model acquisition unit is used to construct an initial electrochemical model control equation, wherein the initial electrochemical model control equation includes a lithium solid phase diffusion equation, a solid electrode potential change equation, an electrolyte material conservation equation, an electrolyte charge conservation equation, a lithium flux equation through a solid electrolyte interface, an overpotential equation, and a battery voltage equation; the initial electrochemical model control equations are combined to obtain a terminal voltage equation; and based on the terminal voltage equation, an initial electrochemical model corresponding to a target battery is determined; a model determination unit, configured to analyze the stress of the target battery to obtain a stress-strain relationship equation, a static mechanical equilibrium equation of the solid active material, and a particle surface net water stress equation; and determine a stress model and an overpotential model based on the stress-strain relationship equation, the static mechanical equilibrium equation of the solid active material, and the particle surface net water stress equation; A model coupling unit, configured to convert the initial electrochemical model into a transfer function to obtain a transfer function electrochemical model; The stress model and the overpotential model are coupled with the transfer function electrochemical model to obtain a target electrochemical model.

6. A terminal comprising: at least one processor; as well as a memory communicatively connected to the at least one processor; wherein, The memory stores instructions that can be executed by the at least one processor, and the instructions are executed by the at least one processor to enable the at least one processor to perform the method according to any one of claims 1 to 4.

7. A non-transitory computer-readable storage medium storing computer instructions, wherein: The computer instructions are used to cause the computer to execute the method according to any one of claims 1-4.

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