Battery simulation method for winding battery, storage medium and electronic device

Abstract

The application provides a battery simulation method for a wound battery, a storage medium and an electronic device, and the method comprises the following steps: obtaining the lithium ion flux of a curved area and the lithium ion flux of a flat area in the wound battery respectively; establishing a solid-phase lithium ion mass transfer description equation and a liquid-phase lithium ion mass transfer description equation based on the lithium ion flux of the curved area and the lithium ion flux of the flat area respectively; obtaining the solid-phase lithium ion potential and the liquid-phase lithium ion potential, and obtaining the overpotential of the curved area and the overpotential of the flat area based on the solid-phase lithium ion potential and the liquid-phase lithium ion potential; and obtaining the output voltage of the wound battery based on the overpotential of the curved area, the overpotential of the flat area and the open-circuit potential of the wound battery. The application simulates and analyzes the curved part and the flat part of the wound battery respectively, solves the problems jointly, analyzes the risk of lithium precipitation, and effectively solves the technical problem of poor battery simulation performance of the existing lithium battery analysis model.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to the field of lithium battery simulation technology. Background Technology

[0002] In recent years, due to the depletion of fossil fuels and the increasing environmental problems, new energy sources have developed rapidly. Because of the time-dependent nature of these new energy sources (i.e., wind and solar power), energy storage systems are frequently introduced into power systems to maintain stable power output. Among these, energy storage power stations using ultra-large battery packs for power storage have experienced rapid development as a crucial supporting technology. Lithium-ion batteries, with their significant advantages such as high stability, large capacity, long lifespan, and environmental friendliness, have become the mainstream battery technology for energy storage power stations in my country. However, due to material and structural issues, lithium-ion batteries are prone to over-discharge, overcharge, overheating, and degradation during practical applications, ultimately leading to reduced battery performance or even failure. To ensure the safe operation and effective energy management of lithium batteries, it is necessary to identify the internal parameters of lithium-ion batteries and effectively and accurately monitor their internal physical and chemical changes. The quasi-two-dimensional (P2D) model of lithium-ion batteries is a relatively practical and accurate electrochemical model for scientific research and practical engineering, effectively reflecting the internal physical and chemical processes during the use of lithium-ion batteries. The P2D model encompasses all the basic components of a lithium-ion battery, including electrodes (positive and negative), separator, electrolyte, and current collector. The P2D model consists of a set of numerous partial differential equations. Its advantage lies in its ability to clearly describe the battery's internal working mechanism, including diffusion transport, ion migration, and electrochemical reactions. Therefore, using the P2D model allows for a better understanding of the battery's working mechanism, correlating the battery's internal state with its external behavior. However, current P2D models assume that the area ratio of the positive and negative electrodes is equal and that there are no differences in three dimensions.

[0003] However, in practical applications, for battery cells produced using the winding process, the cross-section includes a flat portion and curved portions at both ends. For the flat portion of the battery, the curvature is 0, and the positive and negative electrode areas are basically the same. However, for the curved portion, the curvature is not 0, and the curvature decreases sequentially from the inside to the outside. This causes several effects: 1) The inner layer curvature is greater than the outer layer curvature, resulting in a larger area for the outer positive electrode corresponding to the inner negative electrode, leading to an inconsistent area ratio; 2) Because the inner layer is compressed and the outer layer is stretched, for the same electrode, the inner layer is denser with greater mechanical stress, while the outer layer is looser with less mechanical stress, resulting in inconsistent active material volume fraction and porosity. These inconsistencies make it more prone to lithium deposition at the bending points. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a battery simulation method, storage medium and electronic device for wound batteries, in order to solve the technical problem of poor battery simulation performance of existing lithium battery analysis models.

[0005] To achieve the above and other related objectives, the present invention provides a battery simulation method for wound batteries. The method includes: obtaining the lithium-ion flux in a curved region and the lithium-ion flux in a flat region of the wound battery; establishing a solid-phase lithium-ion mass transfer description equation and a liquid-phase lithium-ion mass transfer description equation based on the lithium-ion flux in the curved region and the lithium-ion flux in the flat region, respectively; obtaining the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential, and obtaining the overpotential of the curved region and the overpotential of the flat region based on the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential; and obtaining the output voltage of the wound battery based on the overpotential of the curved region, the overpotential of the flat region, and the open-circuit potential of the wound battery.

[0006] In one embodiment of the present invention, the lithium-ion flux in the curved region and the lithium-ion flux in the flat region are calculated as follows: Among them, J h，K Indicates lithium-ion flux, i L Indicates external current, L electrode thickness, a h，K Indicates the specific surface area of ​​active particles. ∈ h，K R represents the volume fraction of the solid phase. h S represents the particle radius of the positive and negative electrode active materials. h，K Let H represent the electrode area, h∈{p, n}, where n represents the negative electrode and p represents the positive electrode, K∈{CRV, FLAT}, where CRV represents the curved region and FLAT represents the flat region, and F represents the Faraday constant.

[0007] In one embodiment of the present invention, the solid-phase lithium-ion mass transfer description equation is expressed in the following form:

[0008] For the curved region, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows: For flat regions, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows: Among them, c s，h，K D represents the lithium-ion solid phase concentration. s denoted by , r represents the solid-phase diffusion coefficient, r represents the particle radius, and t represents time.

[0009] In one embodiment of the present invention, the liquid-phase lithium-ion mass transfer description equation is expressed in the following form:

[0010] Where, ε e，K c represents the liquid volume fraction. e D represents the concentration in the liquid phase. e Indicates the liquid phase diffusion coefficient. The value represents the lithium-ion liquid phase transfer coefficient, t represents time, and x represents the electrode thickness direction.

[0011] In one embodiment of the present invention, the overpotential η of the curved region h，CRV and the overpotential η of the flat region h，FLAT The joint solution is:

[0012]

[0013] Where, φ s，h，K φ represents the solid-state potential of lithium ions. e，h，K OCP represents the liquid phase potential of lithium ions. h，CRV OCP represents the open-circuit potential of the curved region. h，FLAT This represents the open-circuit potential of a flat region.

[0014] In one embodiment of the present invention, the lithium-ion solid-state potential φ s，h，K One calculation method is as follows:

[0015] And φ s，h，CRV =φ s，h，FLAT ;

[0016] The lithium-ion liquid phase potential φ eh，K One calculation method is as follows:

[0017] And φ e，h，CRV =φ e，h，FLAT ;

[0018] Among them, i s σ represents the solid-state current density. s φ represents the solid-state conductivity. e，h，CRV φ represents the solid-state potential in the curved region. e，h,FLAT κ represents the solid-state potential in a flat region. e Indicates the liquid phase ionic conductivity, i e c represents the liquid phase current density. e D represents the concentration in the liquid phase. e Indicates the liquid phase diffusion coefficient. R represents the lithium-ion liquid phase transfer coefficient, R represents the ideal gas constant, and T represents the temperature.

[0019] In one embodiment of the present invention, the method further includes establishing an electrochemical reaction description equation at the solid-liquid interface, wherein one form of the electrochemical reaction description equation is:

[0020]

[0021] Where i0 represents the exchange current density, n represents the lithium-ion charge number, and a a a c η represents the transfer coefficients of the cathode and anode, respectively. h，K It represents overpotential.

[0022] In one embodiment of the present invention, the output voltage U of the wound battery t One calculation method is as follows:

[0023] U t =OCP p -OCP n +η p -η n +φ e ;

[0024] Among them, OCP p OCP represents the positive electrode potential. n η represents the potential of the negative electrode. p η represents the positive electrode overpotential. n φ represents the negative electrode overpotential. e This represents the liquid phase potential of lithium ions.

[0025] To achieve the above and other related objectives, the present invention also provides a storage medium storing program instructions that, when executed, implement the steps of the battery simulation method for winding batteries as described above.

[0026] To achieve the above and other related objectives, the present invention also provides an electronic device, including a memory for storing a computer program; and a processor for running the computer program to implement the steps of the battery simulation method for winding a battery as described above.

[0027] As described above, the battery simulation method, storage medium, and electronic device for wound batteries of the present invention have the following characteristics:

[0028] Beneficial effects:

[0029] This invention simulates and solves the curved and flat portions of a wound battery separately, and analyzes the risk of lithium plating by combining the results. This effectively solves the technical problem of poor battery simulation performance in existing lithium battery analysis models. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 The diagram shown is a schematic flowchart of a battery simulation method for winding batteries according to an embodiment of this application.

[0032] Figure 2 The diagram shows the principle process of a battery simulation method for winding batteries according to an embodiment of this application.

[0033] Figure 3 The diagram shown is a schematic block diagram of an electronic device according to an embodiment of this application.

[0034] Component designation explanation

[0035] 101 Electronic Devices

[0036] 1001 processor

[0037] 1002 Memory

[0038] S100~S400 Steps Detailed Implementation

[0039] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0040] The purpose of this embodiment is to provide a battery simulation method, storage medium, and electronic device for wound batteries, in order to solve the technical problem of poor battery simulation performance of existing lithium battery analysis models.

[0041] The battery simulation method for wound batteries in this embodiment establishes electrode unit cells with two different compositions based on a quasi-two-dimensional model solution: portions with curvature greater than 0 and portions with curvature = 0. For the curved and flat regions of a lithium battery, the difference in area and porosity leads to different solid phase concentrations. Simultaneously, the consistent solid phase potential results in inconsistent overpotentials. Based on this inconsistency in overpotentials, the overpotentials of the curved and flat regions can be calculated. If the overpotential exceeds a certain value, the risk of lithium plating can be analyzed.

[0042] The following will describe in detail the principles and implementation methods of the battery simulation method, storage medium, and electronic device for wound batteries of the present invention, so that those skilled in the art can understand the battery simulation method, storage medium, and electronic device for wound batteries of the present invention without creative effort.

[0043] Example 1

[0044] This embodiment provides a battery simulation method for wound batteries. Specifically, as shown in the example... Figure 1 As shown, the battery simulation method for winding batteries in this embodiment includes the following steps S100 to S400.

[0045] Step S100: Obtain the lithium-ion flux in the curved region and the lithium-ion flux in the flat region of the wound battery, respectively.

[0046] Step S200: Based on the lithium-ion flux in the curved region and the lithium-ion flux in the flat region, establish solid-phase lithium-ion mass transfer description equations and liquid-phase lithium-ion mass transfer description equations, respectively.

[0047] Step S300: Obtain the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential respectively, and obtain the overpotential of the curved region and the overpotential of the flat region based on the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential.

[0048] Step S400: Obtain the output voltage of the wound battery based on the overpotential of the curved region, the overpotential of the flat region, and the open-circuit potential of the wound battery.

[0049] The following describes in detail steps S100 to S400 of the battery simulation method for winding batteries in this embodiment.

[0050] Step S100: Obtain the lithium-ion flux in the curved region and the lithium-ion flux in the flat region of the wound battery, respectively.

[0051] In this embodiment, one method for calculating the lithium-ion flux in the curved region and the lithium-ion flux in the flat region is as follows:

[0052]

[0053] Among them, J h，K Indicates lithium-ion flux, i L Indicates external current, L electrode thickness, a h，K Indicates the specific surface area of ​​active particles. ∈ h，K R represents the volume fraction of the solid phase. h S represents the particle radius of the positive and negative electrode active materials. h，K Let H represent the electrode area, h∈{p, n}, where n represents the negative electrode and p represents the positive electrode, K∈{CRV, FLAT}, where CRV represents the curved region and FLAT represents the flat region, and F represents the Faraday constant.

[0054] In this embodiment, the lithium battery region is divided into two types: curved region (the part with curvature greater than 0) and flat region (the part with curvature = 0). The lithium ion flux is calculated for the curved region (the part with curvature greater than 0) and the flat region (the part with curvature = 0) of the lithium battery respectively.

[0055] Where, when K = CRV, through Calculate the lithium-ion flux in the curved region when K = FLAT, through Calculate the lithium-ion flux in the flat region.

[0056] In this embodiment, S h，K This represents the electrode area. For the flat area of ​​a lithium battery (the part with curvature = 0), the area ratio between the positive and negative electrodes is 1:1, and the porosity is basically the same as the overall area.

[0057] For the curved region (the part with curvature greater than 0), the area ratio of the inner and outer sides is inconsistent, and the area ratio is:

[0058]

[0059] Wherein: S n，CRV S represents the area of ​​the negative electrode bending region. p，CRV The area of ​​the positive electrode bending region is represented by W, and the length of the wound cell electrode sheet is represented by L. n and L p These represent the thickness of the positive electrode and the thickness of the negative electrode, respectively, with the inner layer having a higher porosity than the outer layer.

[0060] Step S200: Based on the lithium-ion flux in the curved region and the lithium-ion flux in the flat region, establish solid-phase lithium-ion mass transfer description equations and liquid-phase lithium-ion mass transfer description equations, respectively.

[0061] In this embodiment, according to Fick's second law, one form of the solid-phase lithium-ion mass transfer description equation is:

[0062]

[0063] Among them, c s，h，K D represents the lithium-ion solid phase concentration. s denoted by , r represents the solid-phase diffusion coefficient, r represents the particle radius, and t represents time.

[0064] In this embodiment, different boundary conditions are set for the curved region (the part with curvature greater than 0) and the flat region (the part with curvature = 0) of the lithium battery.

[0065] Specifically, for the curved region, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows:

[0066]

[0067] For flat regions, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows:

[0068]

[0069] In this embodiment, the lithium-ion concentration distribution in the liquid phase is calculated according to the Nernst-Planck equation. Specifically, in this embodiment, one expression of the liquid-phase lithium-ion mass transfer description equation is as follows:

[0070]

[0071] Where, ε e，K c represents the liquid volume fraction. e D represents the concentration in the liquid phase. e Indicates the liquid phase diffusion coefficient. The value represents the lithium-ion liquid phase transfer coefficient, t represents time, and x represents the electrode thickness direction.

[0072] Step S300: Obtain the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential respectively, and obtain the overpotential of the curved region and the overpotential of the flat region based on the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential.

[0073] In this embodiment, the electric field is decoupled to determine the overpotential.

[0074] In this embodiment, the lithium-ion solid-state potential φ s，h，K One calculation method is as follows:

[0075] And φ s，h，CRV =φ s，h，FLAT ;

[0076] The lithium-ion liquid phase potential φe，h，K One calculation method is as follows:

[0077] And φ e，h，CRV =φ e，h，FLAT ;

[0078] Among them, i s σ represents the solid-state current density. s φ represents the solid-state conductivity. e，h，CRV φ represents the solid-state potential in the curved region. e，h，FLAT κ represents the solid-state potential in a flat region. e Indicates the liquid phase ionic conductivity, i e c represents the liquid phase current density. e D represents the concentration in the liquid phase. e Indicates the liquid phase diffusion coefficient. R represents the lithium-ion liquid phase transfer coefficient, R represents the ideal gas constant, and T represents the temperature.

[0079] Among them, i=i s +i e , i = i L / S, where i represents the total current density, i L This represents the external current, and S represents the total area of ​​the lithium-ion battery.

[0080] In this embodiment, the electrochemical reaction at the solid-liquid interface is described using the Butler-Volmer kinetic equation. Specifically, this embodiment also includes establishing a descriptive equation for the electrochemical reaction at the solid-liquid interface, one form of which is:

[0081]

[0082] Where i0 represents the exchange current density, n represents the lithium-ion charge number, and a a a c η represents the transfer coefficients of the cathode and anode, respectively. h，K It represents overpotential.

[0083] For the CRV and FLAT regions of the lithium battery, we solve them together to find the overpotential in each region.

[0084] Specifically, in this embodiment, the overpotential η of the curved region h，CRV and the overpotential η of the flat region h，FLAT The joint solution is:

[0085]

[0086] Where, φ s，h，K φ represents the solid-state potential of lithium ions.e，h，K OCP represents the liquid phase potential of lithium ions. h，CRV OCP represents the open-circuit potential of the curved region. h，FLAT This represents the open-circuit potential in a flat region. The open-circuit potential (OCR) of the electrode material. h，K (c s，surf The value is determined by the surface concentration of lithium ions.

[0087] In lithium-ion batteries, the differences in area and porosity between curved and flat regions lead to varying solid-phase concentrations. Simultaneously, the uniform solid-phase potential results in inconsistent overpotentials. Based on these inconsistencies, the overpotentials of the curved and flat regions can be calculated. If the overpotential exceeds a certain value, the risk of lithium plating can be analyzed.

[0088] Step S400: Obtain the output voltage of the wound battery based on the overpotential of the curved region, the overpotential of the flat region, and the open-circuit potential of the wound battery.

[0089] In this embodiment, the output voltage U of the wound battery t One calculation method is as follows:

[0090] U t =OCP p -OCP n +η p -η n +φ e ;

[0091] Among them, OCP p OCP represents the positive electrode potential. n η represents the potential of the negative electrode. p η represents the positive electrode overpotential. n φ represents the negative electrode overpotential. e This represents the liquid phase potential of lithium ions.

[0092] Figure 2 This diagram illustrates the principle process of a battery simulation method for winding a battery according to an embodiment of this application. Figure 2As shown, in this embodiment, the lithium-ion flux is calculated in the initial state of the lithium battery, specifically for the curved region (curvature greater than 0) and the flat region (curvature = 0) of the lithium battery. Then, solid-phase mass transfer is calculated according to the solid-phase lithium-ion mass transfer description equation, with different boundary conditions set for the curved and flat regions. Next, liquid-phase mass transfer is calculated according to the Nernst-Planck equation. Then, the overpotential is calculated by electric field decoupling, jointly solving for the curved and flat regions to obtain the overpotential in each region. Finally, the output voltage of the wound battery is obtained based on the overpotential in the curved region, the overpotential in the flat region, and the open-circuit potential of the wound battery.

[0093] like Figure 3 As shown, this embodiment provides an electronic device 101, which includes a processor 1001 and a memory 1002. The memory 1002 stores a computer program. The processor 1001 executes the computer program stored in the memory 1002 to cause the electronic device 101 to perform the steps of the battery simulation method for winding a battery as described in Embodiment 1. Since the specific implementation process of the battery simulation method for winding a battery has been described in detail in Embodiment 1, it will not be repeated here.

[0094] Processor 1001 is a Central Processing Unit (CPU). Memory 1002 is connected to processor 1001 via a system bus and communicates with it. Memory 1002 stores computer programs, and processor 1001 runs the computer programs to execute the battery simulation method for winding batteries. Memory 1002 may include random access memory (RAM) and may also include non-volatile memory, such as at least one disk drive.

[0095] Furthermore, this embodiment also provides a computer-readable storage medium storing a computer program thereon. When executed by the processor 1001, the computer program implements the steps in the battery simulation method for winding batteries described in Embodiment 1. Embodiment 1 has already provided a detailed description of the battery simulation method for winding batteries, and will not be repeated here.

[0096] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented using computer program-related hardware. The aforementioned computer program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0097] In summary, this invention simulates and solves the curved and flat portions of a wound battery separately, and then analyzes the risk of lithium plating, effectively solving the technical problem of poor battery simulation performance in existing lithium battery analysis models. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0098] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A battery simulation method for wound batteries, characterized in that: The method includes: The lithium-ion flux in the curved region and the lithium-ion flux in the flat region of the wound battery were obtained respectively. Based on the lithium-ion flux in the curved region and the lithium-ion flux in the flat region, solid-phase lithium-ion mass transfer description equations and liquid-phase lithium-ion mass transfer description equations are established respectively. The lithium-ion solid-phase potential and lithium-ion liquid-phase potential are obtained respectively, and the overpotential of the curved region and the overpotential of the flat region are obtained based on the lithium-ion solid-phase potential and the lithium-ion liquid-phase potential. The output voltage of the wound battery is obtained based on the overpotential of the curved region, the overpotential of the flat region, and the open-circuit potential of the wound battery. The lithium-ion flux in the curved region and the lithium-ion flux in the flat region are calculated as follows: ； in, This indicates the lithium-ion flux. L represents the external current. h Indicates electrode thickness. Indicates the specific surface area of ​​active particles. , Indicates the volume fraction of the solid phase. This indicates the particle radius of the positive and negative electrode active materials. Indicates the electrode area. n represents the negative electrode, and p represents the positive electrode. , Indicates the curved area. Let F represent a flat region; The solid-phase lithium-ion mass transfer description equation is expressed in the following form: ； For the curved region, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows: ； For flat regions, the boundary conditions established for the solid-phase lithium-ion mass transfer description equation are as follows: ； in, Indicates the lithium-ion solid phase concentration. Let represent the solid-phase diffusion coefficient, r represent the particle radius, and t represent time; The liquid-phase lithium-ion mass transfer description equation is expressed in the following form: ； in, Indicates the liquid volume fraction. Indicates the concentration of the liquid phase. Indicates the liquid phase diffusion coefficient. The value represents the lithium-ion liquid phase transfer coefficient, and t represents time. Indicates the direction of electrode thickness; The overpotential of the curved region and the overpotential of the flat region The joint solution is: ； in, This represents the solid-state potential of lithium ions. This represents the liquid phase potential of lithium ions. This represents the open-circuit potential of the curved region. This represents the open-circuit potential of a flat region; The lithium-ion solid-state potential The calculation method is as follows: ； The lithium-ion liquid phase potential The calculation method is as follows: ； in, Represents solid-state current density. Indicates the solid-state conductivity. This represents the solid-state potential in the curved region. This represents the solid-state potential in a flat region. Indicates the ionic conductivity of the liquid phase. Represents liquid phase current density. Indicates the concentration of the liquid phase. Indicates the liquid phase diffusion coefficient. denoted by the lithium-ion liquid phase transfer coefficient, R represents the ideal gas constant, and T represents the temperature; It also includes establishing an electrochemical reaction description equation at the solid-liquid interface, wherein the electrochemical reaction description equation is expressed in the following form: ； in, Represents the exchange current density Indicates the number of lithium-ion charges. , These represent the transfer coefficients of the cathode and anode, respectively. Indicates overpotential; The output voltage of the wound battery The calculation method is as follows: ； in, This represents the positive electrode potential. This represents the potential of the negative electrode. Indicates the positive electrode overpotential. Indicates the overpotential at the negative electrode. This represents the liquid phase potential of lithium ions.

2. A storage medium storing program instructions, characterized in that: When the program instructions are executed, they implement the steps of the battery simulation method for wound batteries as described in claim 1.

3. An electronic device, characterized in that: It includes a memory for storing computer programs; and a processor for running the computer programs to implement the steps of the battery simulation method for winding batteries as described in claim 1.

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