Thermal simulation analysis method for annular insulating film of lithium battery

Abstract

A thermal simulation analysis method for an annular insulating film of a lithium battery comprises the steps that insulating film parameters are obtained, and the insulating film parameters comprise the thickness delta 1 and the thermal conductivity k1; the method comprises the following steps: constructing a geometric model of a lithium battery module through three-dimensional modeling software, importing the geometric model into thermal simulation software, and establishing a contact area between battery cells by setting material parameters and dividing finite element grids; calculating the thickness delta 2 of the equivalent simplified model of the double-layer insulating film; calculating a heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film; setting parameters of the contact area; the method comprises the following steps: setting a thermal simulation boundary condition, carrying out thermal simulation solution on a geometric model of a battery module, obtaining the local highest temperature of the geometric model and the temperature gradient distribution condition of each component of the geometric model, and judging whether the local overheating condition occurs to the local part and each component of the battery module or not. According to the method, the establishment of a geometric model and a finite element grid of the insulating film is omitted, the solving process is simple, the solving time is short, and the solving precision can be ensured.

Description

Technical Field

[0001] This invention relates to the field of lithium battery thermal simulation technology, specifically to a thermal simulation analysis method for a ring-shaped insulating film of a lithium battery. Background Technology

[0002] Batteries consume a lot of heat when discharging at high power. If the thermal design is not proper, the temperature difference between individual cells in the battery module will be large during operation, which will lead to poor performance consistency of individual cells. In severe cases, it may even cause safety problems such as combustion due to local overheating. Therefore, it is necessary to use thermal simulation analysis technology in the battery module design to iteratively optimize the thermal design of battery products, provide important data support for designing safe and reliable products, significantly shorten the product development cycle, and significantly reduce the testing cost.

[0003] Lithium-ion battery modules are typically composed of many cells connected in series and parallel. The surface of each cell casing is generally designed with a PVC insulating film with a thickness of approximately 0.05mm to 0.10mm. Because the insulating film has relatively poor thermal conductivity, it cannot be ignored in thermal simulations; otherwise, it will significantly affect the accuracy of the simulation results. However, due to the thinness of the insulating film, if a geometric model is created according to actual dimensions, the mesh size of the insulating film must be set very small to obtain high mesh quality when using mainstream simulation software for finite element mesh generation. This results in a large number of meshes and a significant computational burden during thermal simulations.

[0004] With the widespread application of lithium batteries in the new energy field, the requirements for battery energy and power are getting higher and higher. The number of cells that make up battery modules has increased dramatically, with some cells exceeding 1,000. This results in a huge amount of computational workload for thermal simulation analysis of the insulating film, excessive consumption of server resources, and long simulation analysis and solution time. In addition, mainstream simulation software has a maximum mesh number limit, and calculations cannot be performed if the limit is exceeded.

[0005] Therefore, there is an urgent need to design a thermal simulation analysis technology for lithium battery annular insulating films that is simple to solve, has a short solution time, low server resource consumption, requires few meshes, and can guarantee solution accuracy. Summary of the Invention

[0006] To address the technical problems of existing technologies, such as excessive computational demands, high server resource consumption, long simulation and analysis times, and limitations on the maximum number of mesh elements, this application provides a thermal simulation analysis method for a ring-shaped insulating film in lithium batteries, including the following: Obtain the insulating film parameters, including the thickness δ1 and the thermal conductivity k1; A geometric model of the lithium battery module is constructed using 3D modeling software, imported into thermal simulation software, and contact areas between battery cells are created by setting material parameters, dividing finite element meshes, and then creating the contact areas between the cells. Among them, the thickness δ2 of the equivalent simplified model of the double-layer insulating film is calculated based on the thickness δ1; The heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is generated based on the thermal conductivity k1 and the thickness δ2 of the equivalent simplified model of the double-layer insulating film. The contact area parameters are set based on the thickness δ2 and heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film. Set thermal simulation boundary conditions, perform thermal simulation solution on the geometric model of the battery module, obtain the local maximum temperature of the geometric model and the temperature gradient distribution of each component of the geometric model, and complete the thermal simulation analysis of the annular insulating film of the lithium battery. The thermal simulation analysis of the lithium battery annular insulating film refers to the analysis of the temperature differences of the local area and each component of the battery module to determine whether the local area and each component of the battery module have experienced local overheating.

[0007] Furthermore, the formula for calculating the thickness δ2 of the equivalent simplified model of the double-layer insulating film is expressed as: δ2=2×δ1.

[0008] Furthermore, the formula for calculating the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is: k2 = k1 ÷ δ2.

[0009] Furthermore, the contact area parameters include trimming tolerance and thermal conductivity value; Furthermore, the trimming tolerance is greater than or equal to the thickness δ2 of the equivalent simplified model of the double-layer insulating film.

[0010] Furthermore, the thermal conductivity value is the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film.

[0011] Furthermore, the thermal simulation boundary conditions include the initial temperature of the environment during thermal simulation, the volumetric heat of the battery, the convection coefficient, and the emissivity.

[0012] The beneficial effects of this invention are as follows: By establishing an equivalent simplified model of the double-layer insulating film and calculating the heat transfer coefficient of the equivalent simplified model, only the geometric model of the battery cell needs to be created and the trimming tolerance and heat transfer coefficient of the contact area between the battery cells need to be set during thermal simulation analysis. This eliminates the need to create the geometric model of the insulating film and the finite element mesh, which greatly reduces the number of meshes while ensuring high solution accuracy, saves solution time, simplifies the solution process, shortens the solution time, consumes low server resources, uses fewer meshes, and can ensure solution accuracy, thus significantly reducing the cost of thermal simulation analysis. Attached Figure Description

[0013] Figure 1 This is a flowchart of the thermal simulation analysis method for the annular insulating film of a lithium battery provided in an embodiment of the present invention; Figure 2 This is a simplified schematic diagram of the annular insulating film for lithium batteries provided in this embodiment of the invention. Figure 3 This is a simplified schematic diagram of the annular insulating film for lithium batteries provided in an embodiment of the present invention. Detailed Implementation

[0014] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0015] This invention provides a thermal simulation analysis method for a ring-shaped insulating film in lithium batteries, such as... Figure 1 As shown, it includes the following: Step S100: Obtain insulating film parameters, including thickness δ1 and thermal conductivity k1; Step S200: Construct a geometric model of the lithium battery module using 3D modeling software, import it into thermal simulation software, and create contact areas between battery cells by setting material parameters, dividing the mesh into finite element models; wherein, the geometric model of the battery module is a simplified equivalent model of a double-layer insulating film; the insulating film does not need to be modeled; the thermal simulation software is such as ANSYS. The lithium battery annular insulating film before simplification is as follows: Figure 2 As shown, the simplified ring-shaped insulating film of a lithium battery is as follows: Figure 3 As shown.

[0016] Among them, the thickness δ2 of the equivalent simplified model of the double-layer insulating film is calculated based on the thickness δ1; The formula for calculating the thickness δ2 of the equivalent simplified model of the double-layer insulating film is: δ2 = 2 × δ1.

[0017] The heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is generated based on the thermal conductivity k1 and the thickness δ2 of the equivalent simplified model of the double-layer insulating film. The formula for calculating the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is: k2 = k1 ÷ δ2.

[0018] Step S300: Set the contact area parameters according to the thickness δ2 and heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film. The contact area parameters include trimming tolerance and thermal conductivity.

[0019] The trimming tolerance is greater than or equal to the thickness δ2 of the equivalent simplified model of the double-layer insulating film.

[0020] The thermal conductivity value is the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film.

[0021] Step S400: Set thermal simulation boundary conditions, perform thermal simulation on the geometric model of the battery module, obtain the local maximum temperature of the geometric model and the temperature gradient distribution of each component of the geometric model, and complete the thermal simulation analysis of the annular insulating film of the lithium battery. The thermal simulation boundary conditions include the initial temperature of the environment during thermal simulation, the volumetric heat of the battery, the convection coefficient, and the emissivity.

[0022] The thermal simulation analysis of the lithium battery annular insulating film refers to the analysis of the temperature differences of the local area and each component of the battery module to determine whether the local area and each component of the battery module have experienced local overheating.

[0023] This invention establishes an equivalent simplified model of a double-layer insulating film and calculates the heat transfer coefficient of the equivalent simplified model. During thermal simulation analysis, only the geometric model of the battery cell needs to be created and the trimming tolerance and heat transfer coefficient of the contact area between the battery cells need to be set. This eliminates the need to create a geometric model of the insulating film and a finite element mesh. While ensuring high solution accuracy, this greatly reduces the number of meshes, saves solution time, simplifies the solution process, consumes low server resources, uses fewer meshes, and can ensure solution accuracy, thus significantly reducing the cost of thermal simulation analysis.

[0024] Taking a lithium battery module composed of 8 cells as an example, the simulation analysis efficiency comparison between the present invention and the original scheme is shown in Table 1, and the solution results are shown in Table 2.

[0025] Table 1 Comparison of Simulation Analysis Efficiency

[0026] Table 2 Comparison of Solution Results

[0027] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the present invention is not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A thermal simulation analysis method for a ring-shaped insulating film of a lithium battery, characterized in that, Includes the following: Obtain the insulating film parameters, including the thickness δ1 and the thermal conductivity k1; A geometric model of the lithium battery module is constructed using 3D modeling software, imported into thermal simulation software, and contact areas between battery cells are created by setting material parameters, dividing finite element meshes, and then creating the contact areas between the cells. Among them, the thickness δ2 of the equivalent simplified model of the double-layer insulating film is calculated based on the thickness δ1; The heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is generated based on the thermal conductivity k1 and the thickness δ2 of the equivalent simplified model of the double-layer insulating film. The contact area parameters are set based on the thickness δ2 and heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film. Set thermal simulation boundary conditions, perform thermal simulation solution on the geometric model of the battery module, obtain the local maximum temperature of the geometric model and the temperature gradient distribution of each component of the geometric model, and complete the thermal simulation analysis of the annular insulating film of the lithium battery. The thermal simulation analysis of the lithium battery annular insulating film refers to the analysis of the temperature differences of the local area and each component of the battery module to determine whether the local area and each component of the battery module have experienced local overheating.

2. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 1, characterized in that, The formula for calculating the thickness δ2 of the equivalent simplified model of the double-layer insulating film is: δ2 = 2 × δ1.

3. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 1, characterized in that, The formula for calculating the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film is: k2 = k1 ÷ δ2.

4. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 1, characterized in that, The contact area parameters include trimming tolerance and thermal conductivity.

5. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 4, characterized in that, The trimming tolerance is greater than or equal to the thickness δ2 of the equivalent simplified model of the double-layer insulating film.

6. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 4, characterized in that, The thermal conductivity value is the heat transfer coefficient k2 of the equivalent simplified model of the double-layer insulating film.

7. The thermal simulation analysis method for the annular insulating film of a lithium battery as described in claim 1, characterized in that, The thermal simulation boundary conditions include the initial temperature of the environment during thermal simulation, the volumetric heat of the battery, the convection coefficient, and the emissivity.

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