Lithium ion battery external short circuit simulation method
By building an electrochemical-thermal coupled external short circuit simulation model, the current and temperature changes of lithium-ion batteries under external short circuit conditions are simulated, and the problem of insufficient prediction capabilities in the existing technology is solved, and more accurate battery state prediction and optimization design is achieved.
Patent Information
- Application Number
- CN202411736849.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-29
- Publication Date
- 2025-03-25
AI Technical Summary
The existing external short circuit simulation method of lithium-ion batteries uses constant current and linear resistivity for simulation, and cannot accurately simulate the actual external short circuit current fluctuations and battery behavior at high temperatures, resulting in insufficient prediction capabilities.
The electrochemical-thermal coupled external short circuit simulation model is adopted, and the electrochemical and thermal test of lithium-ion battery samples is performed, geometric, electrochemical and thermal parameters are obtained, the electrochemical-thermal coupling model is built, boundaries and initial conditions are set, grid division and simulation calculation are carried out, and the distribution and changes of current and temperature are simulated.
This method can accurately simulate the fuse process of lithium-ion batteries under external short circuit conditions, improve battery state prediction capabilities, save experimental costs, improve development efficiency, and guide the optimized design of the battery.
Smart Images
Figure CN119692101A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of new energy technology, and in particular to a lithium-ion battery external short-circuit simulation method. Background Art
[0002] The massive consumption of traditional energy has caused serious air pollution, resource scarcity and environmental pollution. In this environment, new energy technologies have been continuously developed, and lithium-ion batteries have been widely used due to their advantages such as high specific energy, long cycle life, no memory and low self-discharge rate.
[0003] The current development of lithium-ion batteries still faces certain problems and challenges, especially safety issues. External short circuit of lithium-ion batteries is a relatively common type of failure. At the moment when an external short circuit occurs in a lithium-ion battery, an overcurrent phenomenon of ultra-large current will occur between the positive and negative electrodes, which will cause local overheating, leading to leakage, explosion, and spontaneous combustion of the battery cells, which will trigger a chain reaction and cause more battery damage.
[0004] Generally, a combination of testing and simulation is used to verify the overcurrent capacity of lithium-ion batteries. There are some lithium-ion battery external short-circuit simulation methods in the prior art, but these methods usually use a constant current to simulate the actual external short-circuit current. For the ohmic heat of the positive and negative electrode structures, linear resistivity is usually used for calculation. This calculation method has the following defects: First, the actual external short-circuit current is not a constant value, it will fluctuate within a certain range, and there is a certain deviation between the simulation and the actual value using a constant current; secondly, the temperature application range of the linear resistivity is small, about 0 to 100°C, and when the battery has an external short circuit, the temperature rises instantly, and the fuse temperature reaches above 645°C, at which time the linear resistivity is no longer applicable.
[0005] Therefore, it is necessary to study new lithium-ion battery external short-circuit simulation methods to improve the prediction ability of lithium-ion battery external short-circuit behavior. Summary of the invention
[0006] In view of the above problems, the purpose of the present invention is to provide a lithium-ion battery external short-circuit simulation method, which can simulate the external short-circuit behavior of the battery when carrying ultra-large current, solve the temperature distribution and changes of each component of the battery during the external short-circuit process, and estimate and predict the melting time of the positive electrode connecting piece. Using this model for external short-circuit simulation can save experimental costs, improve development efficiency, guide the optimal design of the battery, and significantly improve the battery state prediction ability under external short-circuit conditions.
[0007] To achieve the above object, the present invention adopts the following technical solutions:
[0008] In a first aspect, the present application provides a lithium-ion battery external short-circuit simulation method, comprising:
[0009] S10, performing electrochemical testing and thermal testing on the sample of the lithium ion battery to obtain geometric parameters, electrochemical parameters and thermal parameters of the lithium ion battery;
[0010] S20, building an electrochemical-thermal coupled external short-circuit simulation model of the lithium-ion battery based on the geometric parameters, the electrochemical parameters, and the thermal parameters, wherein the electrochemical-thermal coupled external short-circuit simulation model includes an associated electrochemical model and a thermal model;
[0011] S30, setting boundary conditions and initial conditions of the electrochemical-thermal coupled external short circuit simulation model, and meshing components of the lithium-ion battery;
[0012] S40, executing simulation calculation of the electrochemical-thermal coupled external short circuit simulation model according to the boundary conditions and initial conditions, and solving the distribution and change of current and / or temperature in each grid.
[0013] The above scheme tests the sample to obtain geometric parameters, electrochemical parameters and thermal parameters, and then builds the electrochemical-thermal coupled external short circuit simulation model of the lithium-ion battery based on the parameters, further sets the boundary conditions and initial conditions, and performs meshing; according to the boundary conditions and initial conditions, performs simulation calculations to solve the distribution and changes of current and / or temperature in each grid. This method can be used for estimating, predicting and analyzing the results of battery external short circuit tests. It has high reliability and low cost. It can simulate the fusing process of the battery under external short circuit conditions, solve the changes of the temperature of each battery component with time and space during the external short circuit process, and predict the time when the fusing occurs.
[0014] In one implementation, the electrochemical test includes:
[0015] Within a set wide temperature range, the conductivity of the positive and negative electrode structures of the lithium ion battery sample is tested, and the functional relationship between the conductivity and temperature is fitted, and the fitting result is assigned to the thermal model as a material property.
[0016] In one implementation manner, the set wide range temperature is 0-700°C.
[0017] In one implementation manner, the fitting calculation method adopts polynomial fitting.
[0018] In one implementation, the electrochemical model and the thermal model are associated with each other, specifically including:
[0019] The temperature of the thermal model is associated with the input temperature of the electrochemical model; the current of the electrochemical model is associated with the input heat source of the thermal model.
[0020] In one implementation, the mesh division method includes triangular mesh, quadrilateral mesh, tetrahedral mesh, hexahedral mesh, pyramid mesh, wedge mesh and a hybrid mesh composed of the above mesh types.
[0021] In one implementation, the method further includes: performing a real external short-circuit test on the sample of the lithium-ion battery to obtain a real test result, and comparing and verifying the real test result with a result obtained by simulation calculation.
[0022] In one implementation, the real external short circuit test includes:
[0023] External short-circuit tests are carried out under multiple preset temperature conditions and multiple preset current sizes, during which the changes in the surface and internal temperature of the lithium-ion battery and the changes in the voltage of the lithium-ion battery over time are collected.
[0024] In one implementation, the geometric parameters include the length and width of the battery electrode, the battery current collector The length and width of the battery, the location parameters of the battery tabs, the thickness of the battery tabs, the number of battery tabs, and the battery one or more of length, width and height;
[0025] The electrochemical related parameters include one or more of the solid phase material electronic conductivity, initial lithium ion concentration, solid phase volume fraction, liquid phase volume fraction, solid phase material particle radius, liquid phase material effective conductivity, initial lithium concentration of electrolyte, electrochemical reaction rate constant, charge transfer coefficient, solid phase lithium ion diffusion coefficient and liquid phase lithium ion diffusion coefficient of the test sample;
[0026] The thermal related parameters include one or more of the mass, density, specific heat capacity, thermal conductivity, and thermal decomposition temperature of the test sample.
[0027] In one implementation, the electrochemical model is composed of an electrochemical equation group and an electrochemical heat generation equation group; the electrochemical equation group includes one or more of a solid phase mass conservation equation, a liquid phase mass conservation equation, a solid phase charge conservation equation, a liquid phase charge conservation equation, and an electrode reaction kinetic equation, and is used to solve the electric potential, Li+ concentration, and concentration distribution and change of side reaction substances in the solid / liquid phase of the battery; the electrochemical heat generation equation group includes one or more of an Ohmic heat equation, a reversible entropy heat equation, and an electrochemical polarization heat equation, and is used to solve the size of each heat-generating component of the battery;
[0028] The thermal model is composed of energy conservation equations, which are used to simulate the temperature distribution and changes in the battery; the energy conservation equations contain heat transfer terms, heat generation terms and heat dissipation terms; the heat transfer terms are used to describe the heat transfer phenomenon caused by the temperature gradient inside the battery; the heat sources included in the heat generation terms include electrochemical polarization heat, reversible entropy heat, ohmic heat, internal short circuit heat and thermal runaway side reaction heat; the heat sources of the heat generation terms are all transferred to the thermal model by other physical models through real-time parameter transfer; the heat dissipation terms are composed of convective heat transfer and radiative heat transfer, which are used to describe the heat exchange caused by convection and radiative heat transfer between the battery and the environment;
[0029] The coupling mode of the real-time parameter transmission is that the above-mentioned electrochemical model and thermal model are solved simultaneously, and each model transmits the parameters obtained by the current solution to the corresponding physical model in real time and carries out the next solution calculation, so as to realize the mutual influence between the models.
[0030] The present invention has the following advantages due to the adoption of the above technical scheme: by testing the sample, the geometric parameters, electrochemical parameters and thermal parameters are obtained, and then based on the parameters, the electrochemical-thermal coupling external short circuit simulation model of the lithium ion battery is built, the boundary conditions and initial conditions are further set, and the grid is divided; according to the boundary conditions and initial conditions, the simulation calculation is performed to solve the distribution and change of the current and / or temperature in each grid. The method can be used for the estimation, prediction and analysis of the battery external short circuit test results, with high reliability and low cost, and can simulate the fusing process of the battery under the external short circuit working condition, solve the temperature change of each component of the battery with time and space during the external short circuit process, and predict the time when the fusing occurs. The method of the present invention breaks through the limitations that the general model is only applicable to short-time current, the current input is a constant value, and the temperature prediction is low, and can adapt to and predict the external short circuit phenomenon caused by long-term large current, and accordingly provides the battery connector fuse (fuse) structure and the optimization design method of plastic parts, which has important application value. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 A schematic diagram of a flow chart of a lithium-ion battery external short-circuit simulation method in one embodiment of the present invention;
[0032] Figure 2 It is a schematic diagram of model coupling in an embodiment of the present invention. DETAILED DESCRIPTION
[0033] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.
[0034] The model simulation of the prior art has the problem of low accuracy and the prediction ability needs to be strengthened. This application specifically proposes a lithium-ion battery external short-circuit simulation method, including: S10, performing electrochemical tests and thermal tests on the samples of the lithium-ion battery to obtain the geometric parameters, electrochemical parameters and thermal parameters of the lithium-ion battery; S20, based on the geometric parameters, the electrochemical parameters and the thermal parameters, building an electrochemical-thermal coupled external short-circuit simulation model of the lithium-ion battery, the electrochemical-thermal coupled external short-circuit simulation model includes associated electrochemical models and thermal models; S30, setting the boundary conditions and initial conditions of the electrochemical-thermal coupled external short-circuit simulation model, and meshing the components of the lithium-ion battery; S40, performing simulation calculations of the electrochemical-thermal coupled external short-circuit simulation model according to the boundary conditions and initial conditions, and solving the distribution and changes of current and / or temperature in each grid. This method can simulate the external short-circuit behavior of the battery when carrying ultra-large current, solve the temperature distribution and changes of each component of the battery during the external short-circuit process, and estimate and predict the melting time of the positive electrode connector. Using this model for external short-circuit simulation can save experimental costs, improve development efficiency, guide the optimal design of the battery, and significantly improve the battery state prediction ability under external short-circuit conditions.
[0035] The process of the method of the present application and its technical effects are explained below in more detailed embodiments in conjunction with more drawings of the present application.
[0036] like Figure 1 , the overall process of the method is provided in a more detailed embodiment.
[0037] The method for constructing an external short-circuit model of an electrochemical-thermal coupling of a lithium-ion battery comprises the following steps:
[0038] S1. Perform electrochemical and thermal tests on the samples to obtain relevant physicochemical parameters, including geometric parameters, electrochemical related parameters, and thermal related parameters;
[0039] Specifically, the geometric parameters include the length and width of the battery pole piece, the length and width of the battery current collector, the position parameters of the battery pole ear, the thickness of the battery pole piece, the number of battery pole pieces, and one or more of the length, width and height of the battery;
[0040] The electrochemical parameters include the electronic conductivity of the solid phase material of the test sample, the initial concentration of lithium ions, the solid phase volume fraction, the liquid phase volume fraction, the solid phase material particle radius, the effective conductivity of the liquid phase material, the initial electrolyte concentration, the solid phase volume fraction, the solid phase material particle radius, the liquid phase material effective conductivity, the electrolyte initial concentration, the solid phase volume fraction, the liquid ... liquid phase volume fraction, the solid phase material particle radius, the liquid phase material effective conductivity, the electrolyte initial concentration, the solid phase volume fraction, the liquid phase volume fraction, the liquid phase volume fraction, the liquid phase volume fraction, the liquid phase volume fraction, the liquid phase volume fraction, the liquid phase volume fraction Lithium concentration, Electrochemical reaction rate constant, charge transfer coefficient, solid-phase lithium ion diffusion coefficient and liquid-phase lithium ion diffusion coefficient One or more of the dispersion coefficients;
[0041] The thermal related parameters include one or more of the mass, density, specific heat capacity, thermal conductivity, and thermal decomposition temperature of the test sample.
[0042] S2. Use finite element software to construct an electrochemical model and a thermal model respectively, build an electrochemical-thermal coupled external short-circuit simulation model of a lithium-ion battery, and assign the relevant parameters obtained in S1 to the constructed model;
[0043] Specifically, the coupling association in the model includes: the temperature of the thermal model is associated with the input temperature of the electrochemical model; the current of the electrochemical model is associated with the input heat source of the thermal model. Through the above coupling association, the impact of the battery under external short-circuit conditions can be successfully transmitted in real time and accurately in the model, and reflected through parameters such as temperature change and heat generation, thereby improving the simulation accuracy, sensitivity and prediction ability of the model.
[0044] The coupling relationship between the electrochemical model and the thermal model can be achieved by establishing the following specific models.
[0045] The electrochemical model consists of an electrochemical equation group and an electrochemical heat generation equation group; the electrochemical equation group includes one or more of the solid phase mass conservation equation, the liquid phase mass conservation equation, the solid phase charge conservation equation, the liquid phase charge conservation equation and the electrode reaction kinetics equation, which are used to solve the electric potential, Li+ concentration and concentration distribution and changes of side reaction substances in the solid / liquid phase of the battery; the electrochemical heat generation equation group includes one or more of the Ohmic heat equation, the reversible entropy heat equation and the electrochemical polarization heat equation, which solve the size of each heat generating component of the battery.
[0046] The thermal model is composed of energy conservation equations, which are used to simulate the temperature distribution and changes in the battery; the energy conservation equations contain heat transfer terms, heat generation terms and heat dissipation terms; the heat transfer terms are used to describe the heat transfer phenomenon caused by the temperature gradient inside the battery; the heat generation terms include heat sources such as electrochemical polarization heat, reversible entropy heat, ohmic heat, internal short circuit heat and thermal runaway side reaction heat; the heat sources of the heat generation terms are all transferred to the thermal model by other physical models through real-time parameter transfer; the heat dissipation terms are composed of convective heat transfer and radiative heat transfer, which are used to describe the heat exchange caused by convection and radiative heat transfer between the battery and the environment.
[0047] The coupling mode of the real-time parameter transmission is that the electrochemical model and the thermal model are solved at the same time, and each model transmits the parameters obtained by the current solution to the corresponding physical model in real time and carries out the next step of solution calculation, so as to realize the mutual influence between the physical models, that is, coupling. The schematic diagram can be seen in Figure 2 .
[0048] S3. According to the actual external short circuit simulation requirements, set the boundary conditions and initial conditions of the physical model and divide the grid;
[0049] Specifically, the meshing uses one or more of a triangular mesh, a quadrilateral mesh, a tetrahedral mesh, a hexahedral mesh, a pyramid mesh, a wedge mesh, and a hybrid mesh consisting of the above mesh types.
[0050] S4. Based on the metal conductivity test data, perform polynomial fitting on the metal conductivity of the positive and negative electrode structural parts in the range of 0 to 700°C, and assign the fitting results as material property parameters to the thermal model.
[0051] S5. Perform an external short-circuit test on the sample, compare the measured data with the results of the external short-circuit simulation model, and verify the accuracy of the model.
[0052] Specifically, the test conditions for testing the samples include: testing under multiple temperature conditions, multiple current sizes of External short circuit test, during which the changes of battery surface and internal temperature over time and battery voltage over time are collected change.
[0053] In summary, the method provided by the present application can be used for estimating, predicting and analyzing the test results of the external short circuit of the battery, with high reliability and low cost, and can simulate the fusing process of the battery under the external short circuit condition, solve the temperature change of each component of the battery with time and space during the external short circuit, and predict the time of the fusing. The method of the present invention breaks through the limitations that the general model is only applicable to short-time current, the current input is a constant value, and the temperature prediction is low. It can adapt to and predict the external short circuit phenomenon caused by long-term large current, and accordingly provide the optimization design method of the battery connecting piece fuse structure and plastic parts, which has important application value.
[0054] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.
[0055] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the above units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.
[0056] The above-mentioned integrated unit implemented in the form of a software functional unit can be stored in a computer-readable storage medium. The above-mentioned software functional unit is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor (Processor) to perform some steps of the above-mentioned method of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), disk or optical disk and other media that can store program codes.
[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A lithium-ion battery external short circuit simulation method, characterized in that: The method comprises: S10, performing electrochemical testing and thermal testing on the sample of the lithium ion battery to obtain geometric parameters, electrochemical parameters and thermal parameters of the lithium ion battery; S20, building an electrochemical-thermal coupled external short-circuit simulation model of the lithium-ion battery based on the geometric parameters, the electrochemical parameters, and the thermal parameters, wherein the electrochemical-thermal coupled external short-circuit simulation model includes an associated electrochemical model and a thermal model; S30, setting boundary conditions and initial conditions of the electrochemical-thermal coupled external short circuit simulation model, and meshing components of the lithium-ion battery; S40, executing simulation calculation of the electrochemical-thermal coupled external short circuit simulation model according to the boundary conditions and initial conditions, and solving the distribution and change of current and / or temperature in each grid.
2. The lithium-ion battery external short-circuit simulation method according to claim 1, characterized in that: The electrochemical test includes: Within a set wide temperature range, the conductivity of the positive and negative electrode structures of the lithium ion battery sample is tested, and the functional relationship between the conductivity and temperature is fitted, and the fitting result is assigned to the thermal model as a material property.
3. The lithium-ion battery external short-circuit simulation method according to claim 2, characterized in that: The set wide temperature range is 0-700°C.
4. The lithium-ion battery external short-circuit simulation method according to claim 2, characterized in that: The fitting calculation method adopts polynomial fitting.
5. The lithium-ion battery external short-circuit simulation method according to claim 2, characterized in that: The association method of the electrochemical model and the thermal model specifically includes: The temperature of the thermal model is associated with the input temperature of the electrochemical model; the current of the electrochemical model is associated with the input heat source of the thermal model.
6. The lithium-ion battery external short-circuit simulation method according to claim 5, characterized in that: The grid division methods include triangular grid, quadrilateral grid, tetrahedral grid, hexahedral grid, pyramid grid, wedge grid and a hybrid grid composed of the above grid types.
7. The lithium-ion battery external short-circuit simulation method according to claim 1, characterized in that: The method further comprises: performing a real external short circuit test on the sample of the lithium ion battery to obtain a real test result, and comparing and verifying the real test result with a result obtained by simulation calculation.
8. The lithium-ion battery external short-circuit simulation method according to claim 7, characterized in that: The real external short circuit test comprises: External short-circuit tests are carried out under multiple preset temperature conditions and multiple preset current sizes, during which the changes in the surface and internal temperature of the lithium-ion battery and the changes in the voltage of the lithium-ion battery over time are collected.
9. The lithium-ion battery external short-circuit simulation method according to claim 1, characterized in that: The geometric parameters include the length and width of the battery pole piece, the length and width of the battery current collector, the position parameters of the battery pole ear, the thickness of the battery pole piece, the number of battery pole pieces, and one or more of the length, width and height of the battery; The electrochemical related parameters include one or more of the solid phase material electronic conductivity, initial lithium ion concentration, solid phase volume fraction, liquid phase volume fraction, solid phase material particle radius, liquid phase material effective conductivity, initial lithium concentration of electrolyte, electrochemical reaction rate constant, charge transfer coefficient, solid phase lithium ion diffusion coefficient and liquid phase lithium ion diffusion coefficient of the test sample; The thermal related parameters include one or more of the mass, density, specific heat capacity, thermal conductivity, and thermal decomposition temperature of the test sample.
10. The lithium-ion battery external short-circuit simulation method according to claim 9, characterized in that: The electrochemical model consists of an electrochemical equation group and an electrochemical heat generation equation group; the electrochemical equation group includes one or more of the solid phase mass conservation equation, the liquid phase mass conservation equation, the solid phase charge conservation equation, the liquid phase charge conservation equation and the electrode reaction kinetics equation, which are used to solve the electric potential, Li+ concentration and the concentration distribution and change of the side reaction substances in the solid / liquid phase of the battery; the electrochemical heat generation equation group includes one or more of the Ohmic heat equation, the reversible entropy heat equation and the electrochemical polarization heat equation, which solve the size of each heat generating component of the battery; The thermal model is composed of energy conservation equations, which are used to simulate the temperature distribution and changes in the battery; the energy conservation equations contain heat transfer terms, heat generation terms and heat dissipation terms; the heat transfer terms are used to describe the heat transfer phenomenon caused by the temperature gradient inside the battery; the heat sources included in the heat generation terms include electrochemical polarization heat, reversible entropy heat, ohmic heat, internal short circuit heat and thermal runaway side reaction heat; the heat sources of the heat generation terms are all transferred to the thermal model by other physical models through real-time parameter transfer; the heat dissipation terms are composed of convective heat transfer and radiative heat transfer, which are used to describe the heat exchange caused by convection and radiative heat transfer between the battery and the environment; The coupling mode of the real-time parameter transmission is that the above-mentioned electrochemical model and thermal model are solved simultaneously, and each model transmits the parameters obtained by the current solution to the corresponding physical model in real time and carries out the next solution calculation, so as to realize the mutual influence between the models.