Flow battery stack packaging design method and flow battery stack

Abstract

The application discloses a flow battery stack packaging design method and a flow battery stack. The method comprises the following steps: establishing a flow battery stack model, wherein the flow battery stack model at least comprises two polar plates, a diaphragm arranged between the two polar plates, positive and negative electrode battery pieces arranged on the sides of the two polar plates away from the diaphragm, and two special-shaped permanent magnets arranged on the sides of the positive and negative electrode battery pieces away from the diaphragm; calculating the magnetization intensity of the special-shaped permanent magnets; calculating the magnetization current density of the special-shaped permanent magnets and the surface magnetization current surface density of the special-shaped permanent magnets according to the magnetization intensity; calculating the initial magnetic field force between the two special-shaped permanent magnets according to the magnetization current density and the surface magnetization current surface density; and correcting the initial magnetic field force according to a preset condition, so that the clamping force borne by the flow battery stack model reaches the packaging requirement. The application can provide uniform clamping force for the flow battery stack and improve the stability of the flow battery stack under the premise of ensuring the performance of the flow battery stack.

Description

Technical Field

[0001] This application relates to the field of flow battery packaging technology, specifically to a flow battery stack packaging design method and a flow battery stack. Background Technology

[0002] During the assembly process of flow battery stacks, the final clamping force is a crucial factor affecting their operating efficiency and system stability. If the local clamping force is too high, it may cause excessive deformation or even cracking of the sealing material. If the local clamping force is too low, it will not be able to seal effectively, leading to end plate deformation, altering the electrode compression state, and consequently affecting the uniformity of electrolyte distribution within the electrodes.

[0003] In existing technologies, bolts are used to apply force to the nuts on both sides, resulting in a difference in locking torque between the two sides. Current processes rely heavily on manual tightening or experience-based adjustments, making it difficult to quantify the clamping force. Furthermore, to meet mechanical performance requirements, traditional designs require the use of coarse screws. However, coarse screws increase the end plate area, exacerbating end plate deformation and thus worsening uneven pressure distribution inside the battery.

[0004] Therefore, how to provide a flow battery stack packaging design method and flow battery stack that can provide uniform clamping force to the flow battery stack while ensuring its performance, thereby improving the stability of the flow battery stack, has become an urgent problem to be solved. Summary of the Invention

[0005] This application provides a flow battery stack packaging design method and a flow battery stack, which aims to provide a uniform clamping force to the flow battery stack while ensuring its performance, thereby improving the stability of the flow battery stack.

[0006] On one hand, embodiments of this application provide a flow battery stack packaging design method, including the following steps: establishing a flow battery stack model, the flow battery stack model including at least: two electrode plates, a separator disposed between two adjacent electrode plates, positive and negative electrode cells respectively disposed on the side of the two electrode plates away from the separator, and two irregularly shaped permanent magnets respectively disposed on the side of the positive and negative electrode cells away from the separator; calculating the magnetization intensity of the irregularly shaped permanent magnets; calculating the magnetization current fluid density and the surface magnetization current density of the irregularly shaped permanent magnets based on the magnetization intensity; calculating the initial magnetic field force between the two irregularly shaped permanent magnets based on the magnetization current fluid density and the surface magnetization current density; and correcting the initial magnetic field force according to preset conditions so that the clamping force on the flow battery stack model meets the packaging requirements.

[0007] Optionally, in some embodiments of this application, the flow battery stack model further includes 2N electrode plates, 2N magnetic pads, and N separators, wherein any one of the separators is disposed between two adjacent electrode plates, and any one of the magnetic pads is disposed between an adjacent electrode plate and a separator, where N is a positive integer greater than or equal to 1.

[0008] Optionally, in some embodiments of this application, the magnetization M of the irregular permanent magnet is calculated according to the following formula:

[0009] ,

[0010] Where B is the magnetic flux density. The permeability of free space, denoted as ρ, where ρ is the relative permeability of the magnetic medium.

[0011] Optionally, in some embodiments of this application, the magnetization current density δv of the irregular permanent magnet is calculated according to the following formula:

[0012] ,

[0013] in, M is the magnetization intensity of the irregular permanent magnet per unit volume;

[0014] And calculate the surface magnetization current density δs of the irregularly shaped permanent magnet according to the following formula:

[0015] ,

[0016] Where n is the surface normal vector and M is the magnetization intensity of the irregular permanent magnet.

[0017] Optionally, in some embodiments of this application, the initial magnetic field force between the two irregularly shaped permanent magnets is calculated according to the following formula. :

[0018] ,

[0019] in, The relative permeability of the magnetic medium. denoted as vacuum permeability, s as the effective projected area of ​​the magnetic material and the magnetic field, B as the magnetic induction intensity at the magnetic material and the magnetic field, and ds as the area element.

[0020] Optionally, in some embodiments of this application, the flow battery stack packaging design method further includes:

[0021] The initial magnetic field force is corrected based on the magnetic field distribution and permeability of the magnetic material to obtain the corrected magnetic field force. ;

[0022] Corrected magnetic force The calculation formula is:

[0023] ,

[0024] Where B is the magnetic induction intensity at the point where the magnetic material is in contact with the magnetic field, H is the magnetic field intensity at the point where the magnetic material is in contact with the magnetic field, and S is the effective projected area of ​​the magnetic material and the magnetic field.

[0025] Optionally, in some embodiments of this application, the flow battery stack packaging design method further includes:

[0026] The magnetic flux density B is corrected based on the performance parameters of the two irregularly shaped permanent magnets to obtain the corrected magnetic flux density. ;

[0027] Corrected magnetic flux density The calculation formula is:

[0028] ,

[0029] in, X is the remanent magnetic induction intensity, L is the gap between the irregularly shaped permanent magnets, H is the side length of the irregularly shaped permanent magnets, and H is the thickness of the irregularly shaped permanent magnets.

[0030] Optionally, in some embodiments of this application, the flow battery stack model further includes a screw and a nut, the screw passing through the two irregularly shaped permanent magnets, and the nut used to fasten the screw to apply a clamping force to the flow battery stack model. ;

[0031] ,

[0032] Where T is the tightening torque of a single nut, and d is the nominal diameter of the screw;

[0033] The clamping force on the flow battery stack model is calculated using the following formula. :

[0034] ,

[0035] in, The clamping force applied by the screw and nut to the flow battery stack model. The magnetic force between the two irregularly shaped permanent magnets.

[0036] Optionally, in some embodiments of this application, the flow battery stack model further includes two end plates, which are respectively disposed on the side of the two irregular permanent magnets away from the electrode plates. The screw passes through the two end plates, and the nut is used to fasten the screw. The end plates are made of wood or aluminum.

[0037] On the other hand, this application provides a flow battery stack, which is packaged using the flow battery stack packaging design method described above.

[0038] Compared with the prior art, the flow battery stack packaging design method and flow battery stack provided in this application provide a non-contact, uniform initial magnetic field force to the component between the two irregular permanent magnets by setting two irregular permanent magnets at both ends of the flow battery stack. This is achieved by applying a uniform clamping force to the flow battery stack and by correcting the initial magnetic field force to ensure that the clamping force on the flow battery stack meets the packaging requirements and is within the optimal clamping force range. This improves the sealing performance and performance stability of the flow battery stack. Attached Figure Description

[0039] Figure 1 This is a flowchart of the flow battery stack packaging design method provided in this application;

[0040] Figure 2 This is a schematic diagram of the first type of flow battery stack model provided in this application;

[0041] Figure 3 This is a second schematic diagram of the flow battery stack model provided in this application;

[0042] Figure 4 This is a schematic diagram of the permanent magnet model inside the COMSOL in the flow battery stack packaging design method provided in this application;

[0043] Figure 5 This is a schematic diagram of the permanent magnet model and gas model inside the COMSO in the flow battery stack packaging design method provided in this application;

[0044] Figure 6 This is a schematic diagram of the magnetic induction intensity distribution between permanent magnets in the COMSOL simulation of the flow battery stack packaging design method provided in this application;

[0045] Figure 7 This is a schematic diagram of the change of clamping force between permanent magnets with distance in the COMSOL simulation of the flow battery stack packaging design method provided in this application;

[0046] Figure 8 This is a schematic diagram comparing the EIS of the battery with and without permanent magnet clamping in the flow battery stack packaging design method provided in this application.

[0047] Components and their designations:

[0048] The flow battery stack model 100 / 200 includes: electrode plate 10, separator 20, positive and negative electrode cells 30, irregular permanent magnet 40, end plate 50, magnetic gasket 60, screw 71, and nut 72. Detailed Implementation

[0049] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings. The described technical solutions are for illustrative purposes only and should not be construed as limiting the scope of protection of this application.

[0050] The various embodiments provided in this application are similar, and features in different embodiments can be combined with each other.

[0051] like Figure 1 As shown, an embodiment of this application provides a flow battery stack packaging design method, including the following steps:

[0052] S10. Establish a flow battery stack model.

[0053] like Figure 2 As shown, the flow battery stack model 100 includes at least: two electrode plates 10, a separator 20 disposed between two adjacent electrode plates 10, positive and negative electrode cells 30 disposed on the side of the two electrode plates 10 away from the separator 20, and two irregular permanent magnets 40 disposed on the side of the positive and negative electrode cells 30 away from the separator 20.

[0054] In the embodiments of this application, the flow battery stack model 100 further includes two gaskets (not shown in the figure), which are respectively disposed on opposite sides of the separator 20 near the electrode plate 10, that is, the gaskets are located between the electrode plate 10 and the separator 20.

[0055] In the embodiments of this application, the flow battery stack model 100 further includes two end plates 50, which are respectively disposed on the side of the two irregular permanent magnets 40 away from the electrode plate 10. The screw passes through the two end plates 50, and the nut is used to fasten the screw. The material of the end plates 50 includes wood.

[0056] like Figure 3As shown, the flow battery stack model 200 includes at least: 2N electrode plates 10, 2N magnetic pads 60, and N separators 20. Any separator 20 is disposed between two adjacent electrode plates 10, any magnetic pad 60 is disposed between an adjacent electrode plate 10 and a separator 20, positive and negative electrode cells 30 are respectively disposed on the side of the two electrode plates 10 away from the separator 20, and two irregularly shaped permanent magnets 40 are respectively disposed on the side of the positive and negative electrode cells 30 away from the separator 20. N is a positive integer greater than or equal to 1. The value of N includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.

[0057] In embodiments of this application, the flow battery stack model further includes a screw 71 and a nut 72, the screw 71 passing through two irregular permanent magnets 40, and the nut 72 used to fasten the screw 71.

[0058] In the embodiments of this application, the flow battery stack model further includes two end plates 50, which are respectively disposed on the side of the two irregular permanent magnets 40 away from the electrode plate 10. The screw 71 passes through the two end plates 50, and the nut 72 is used to fasten the screw 71. The material of the end plate 50 includes aluminum plate.

[0059] S20. Calculate the magnetization intensity of the irregular permanent magnet.

[0060] In the embodiments of this application, the magnetization M of the irregularly shaped permanent magnet is calculated according to the following formula:

[0061] ;

[0062] Where B is the magnetic flux density. The permeability of free space, denoted as ρ, where ρ is the relative permeability of the magnetic medium.

[0063] S30. Calculate the magnetization current density and surface magnetization current density of the irregular permanent magnet based on the magnetization intensity.

[0064] In the embodiments of this application, the magnetic force generated by the irregularly shaped permanent magnet is a force produced by the interaction of charged particles or magnetic objects with magnetic field lines in a magnetic field. The magnetic force generated by the irregularly shaped permanent magnet can change the motion state or path of charged particles or magnetic objects.

[0065] In the embodiments of this application, the volumetric magnetization current density δv and the surface magnetization current density δs are two very important parameters in electromagnetic theory describing magnetization phenomena. δv represents the intensity of the magnetization current per unit volume, reflecting the distribution of magnetic moments in the material, i.e., the sum of microscopic current loops. δs refers to the intensity of the magnetization current per unit area, used to describe the magnetization of the material surface.

[0066] In the embodiments of this application, the magnetization current density δv of the irregularly shaped permanent magnet is calculated according to the following formula:

[0067] ;

[0068] in, M is the magnetization intensity of the irregular permanent magnet per unit volume.

[0069] And calculate the surface magnetization current density δs of the irregularly shaped permanent magnet according to the following formula:

[0070] ;

[0071] Where n is the surface normal vector and M is the magnetization intensity of the irregular permanent magnet.

[0072] In the embodiments of this application, the unit of magnetic flux density B is T. Vacuum permeability Units are Relative permeability of magnetic media The unit is .in, equal .

[0073] S40. Calculate the initial magnetic force between two irregular permanent magnets based on the magnetization current density and the surface magnetization current density.

[0074] In the embodiments of this application, the initial magnetic force between two irregularly shaped permanent magnets is calculated according to the following formula. :

[0075] ;

[0076] When the magnetic material is an isotropic medium:

[0077] ;

[0078] At this point, the initial magnetic force is the magnetic clamping force. for:

[0079] ;

[0080] Substituting into the vector gradient integral formula:

[0081] ;

[0082] The initial magnetic field force of the magnetic material can be obtained. Calculation formula:

[0083] ;

[0084] The initial magnetic force between two irregularly shaped permanent magnets can be calculated using the following formula. :

[0085] ;

[0086] in, The relative permeability of the magnetic medium. denoted as vacuum permeability, s as the effective projected area of ​​the magnetic material and the magnetic field, B as the magnetic induction intensity at the magnetic material and the magnetic field, and ds as the area element.

[0087] S50. The initial magnetic field force is modified according to the preset conditions so that the clamping force on the flow battery stack model meets the packaging requirements.

[0088] Step S50 specifically includes: based on the magnetic field distribution of the magnetic material and the effect of the magnetic permeability of the magnetic material on the initial magnetic field force. After making corrections, the corrected magnetic force is obtained. .

[0089] In the embodiments of this application, it is assumed that the magnetic field distribution of the magnetically conductive material is uniform and the permeability u of the magnetically conductive material is... r Much greater than 1, therefore the initial magnetic force can be corrected. The calculation formula is simplified to facilitate the direct calculation of the magnetic field force of magnetic materials.

[0090] Specifically:

[0091] ;

[0092] That is, the corrected magnetic field force The calculation formula is:

[0093] ;

[0094] Where B is the magnetic induction intensity at the point where the magnetic material is in contact with the magnetic field, H is the magnetic field intensity at the point where the magnetic material is in contact with the magnetic field, and S is the effective projected area of ​​the magnetic material and the magnetic field.

[0095] In the embodiments of this application, the unit of the effective projected area S of the magnetic material and the magnetic field is m. 2 The unit of the magnetic field strength H at the point where a magnetically conductive material interacts with a magnetic field is A / m. The unit of the magnetic field strength B at the point where a magnetically conductive material interacts with a magnetic field is T.

[0096] This application obtains the modified magnetic field force. This helps to accurately and quickly determine the optimal clamping force range of the flow battery stack, thereby improving design efficiency, shortening the design cycle, and reducing computational costs.

[0097] In embodiments of this application, the flow battery stack packaging design method further includes:

[0098] The magnetic flux density B is corrected based on the performance parameters of the two irregularly shaped permanent magnets to obtain the corrected magnetic flux density. .

[0099] In the embodiments of this application, the irregularly shaped permanent magnet is a neodymium iron boron permanent magnet.

[0100] In the embodiments of this application, the effective projected area S in the formula for calculating the magnetic field force of a neodymium iron boron permanent magnet is related to its shape. For example... Figure 4 As shown, the sample of the irregularly shaped NdFeB permanent magnet is a square permanent magnet with side length L on both the upper and lower surfaces, and four bolt holes. Its magnetization direction is axial, meaning it passes through the center point of the square and points vertically upwards. The upper and lower surfaces (two square faces) of the permanent magnet are the N and S poles, respectively. To calculate the magnetic force of the irregularly shaped permanent magnet, the magnetic induction intensity B generated by the permanent magnet at the magnetic conductive material must first be calculated. To calculate the magnetic induction intensity B generated by the permanent magnet at the magnetic conductive material, the leakage flux of the magnetic circuit formed by the permanent magnet and the magnetic conductive material in the actual magnetic circuit must first be obtained. Excessive leakage flux will affect the calculation error of the final magnetic force calculation result. Therefore, it is assumed that the coercivity of the permanent magnet is along its magnetization direction to simplify the magnetic circuit. Based on the above assumption, the magnetic induction intensity at a distance from the center of the square NdFeB permanent magnet surface is calculated. The corrected magnetic induction intensity is then... The calculation formula is:

[0101] ;

[0102] in, Where X is the remanent magnetization intensity, L is the gap between irregularly shaped permanent magnets, H is the side length of the irregularly shaped permanent magnet, and H is the thickness of the irregularly shaped permanent magnet.

[0103] In the embodiments of this application, the square NdFeB sample is 80 mm long, 80 mm wide, and 10 mm high. The sintered NdFeB permanent magnet material is manufactured using powder metallurgy. The smelted NdFeB alloy is made into powder and pressed into a compact in a magnetic field. The compact is then sintered in an inert gas or vacuum to achieve densification. To improve the coercivity of the magnet, tempering heat treatment is usually required. According to the national standard GB / T13560-2017, its performance parameters are: grade N52, N45, N38; maximum energy product 50, 44, 37 MGOe; and remanence Br 1.44, 1.35, 1.23 T. Based on the performance parameters of the square NdFeB irregular permanent magnet, these parameters are substituted into the corrected magnetic induction Br. The calculation formula can be used to calculate the magnetic induction intensity B / at the center of the surface of a square NdFeB irregular permanent magnet with zero gap under this size and parameters. Then, the magnetic induction intensity B / Substituting magnetic force The magnetic force of the square face of the square neodymium iron boron shaped permanent magnet can be obtained from the calculation formula. By fully utilizing the magnetic force of mutual attraction between irregularly shaped permanent magnets, a uniform clamping force can be provided for the battery.

[0104] In embodiments of this application, the flow battery stack model further includes a screw and a nut. The screw passes through two irregularly shaped permanent magnets, and the nut is used to fasten the screw to apply a clamping force to the flow battery stack model. .

[0105] ;

[0106] Where T is the tightening torque of a single nut, and d is the nominal diameter of the screw.

[0107] Calculate the clamping force on the flow battery stack model using the following formula. :

[0108] ;

[0109] in, The clamping force applied by the screw and nut to the flow battery stack model. It represents the magnetic force between two irregularly shaped permanent magnets.

[0110] In the embodiments of this application, the magnetic induction intensity distribution of the two irregularly shaped permanent magnets added to the flow battery stack is simulated using the COMSOL software. Based on the actual magnetic pole distribution of the irregularly shaped permanent magnets, the magnetization direction of the magnets is set to axial magnetization, and the solution is obtained through the "Magnetic Field" physical field under the AC / DC module of the COMSOL software. The external environment is assumed to be: room temperature, T=293.15K, and absolute pressure of 1 atmosphere. The change in magnetic induction intensity distribution between the irregularly shaped permanent magnets with varying distance is simulated using formulas.

[0111] In the embodiments of this application, the simulation software COMSOL is used to simulate the change in magnetic clamping force of irregular permanent magnets as the distance between them changes, according to the formula.

[0112] Finite element simulation includes the following steps:

[0113] (1) Select the problem type. For the magnetic field simulation problem of neodymium iron boron irregular permanent magnet, select the "Magnetic Field" physical field under the AC / DC module.

[0114] (2) Establish a model. For example... Figure 5As shown, two cuboids and a sphere enclosing a rectangle are set by directly inputting coordinates in the COMSOL software. The radius of the sphere is set to be much larger than that of the cuboids, taking into account both the computational load and the magnetic force distribution range. The cuboids and the sphere are models of an irregular permanent magnet and air, respectively.

[0115] (3) Add materials. Add materials for neodymium iron boron shaped permanent magnets and air. Both of these materials can be found in the material library built into the COMSOL software.

[0116] (4) Set boundary conditions. The relative permeability of the magnet is 1.05, the relative permeability of air is 1, and the magnetization intensity is set to be the same and equal in direction.

[0117] (5) Grid generation. Click on grid generation to automatically generate the grid.

[0118] The permanent magnet is modeled as follows: a square permanent magnet with a side length of 80mm and a height of 10mm, surrounded by an argon gas field. For example... Figures 6 to 8 As shown, the magnet material is NdFeB, with magnet strengths of N52, N45, and N38. The relative permeability of the magnet is 1.05, while the relative permeability of air is 1. NdFeB magnets are strong magnets, with remanent magnetic induction of 1.44T, 1.35T, and 1.23T for N52, N45, and N38, respectively. Steady-state solutions for the magnets are obtained using a standardized mesh, and then the magnitude of the magnetic field around the magnet is displayed using 3D and 1D plotting tools in COMSOL software post-processing.

[0119] For permanent magnets, the magnetic field around the magnet is difficult to measure accurately. However, COMSOL software can quantitatively display the surrounding magnetic field. COMSOL's post-processing program includes a 3D plotting group, which displays slices of the magnetic field around the magnet. This shows that the magnetic induction intensity is greatest and the magnetic field is strongest at the two sides of the magnet, gradually decreasing outwards, while the magnetic field distribution is more uniform from the sides inwards. Therefore, it can provide a relatively uniform attractive force from the sides inwards.

[0120] The attractive force between two irregularly shaped permanent magnets can also be quantitatively calculated using COMSOL software. According to simulation results, N52, N45, and N38 can provide forces of 149.24N, 131.17N, and 108.88N respectively at a spacing of 33mm, which can assist in clamping the flow battery to a certain extent. The design of irregularly shaped NdFeB permanent magnets as end plates for the flow battery utilizes the principle of attraction between opposite magnets to provide additional non-contact, uniform clamping force to clamp the battery. This partially replaces the non-uniform bolt clamping force, which helps improve battery sealing performance, reduce the risk of graphite plate crushing, reduce local deformation, and lower battery contact resistance.

[0121] In the embodiments of this application, irregularly shaped neodymium iron boron permanent magnets are used as end plates of flow batteries or disposed near both ends of flow battery stacks. The additional non-contact clamping force provided by the principle of attraction between opposite poles of irregularly shaped permanent magnets is used to clamp the battery. Furthermore, since the magnetic field distribution between the irregularly shaped permanent magnets is uniform, the clamping force provided is also a uniformly distributed clamping force.

[0122] The flow battery stack packaging design method provided in this application provides a non-contact uniform magnetic field force to the component between the two irregular permanent magnets by setting two irregular permanent magnets at both ends of the flow battery stack. This is achieved by applying a uniform clamping force to the flow battery stack, thereby improving the sealing performance and performance stability of the flow battery stack.

[0123] On the other hand, this application provides a flow battery stack, which is packaged using the flow battery stack packaging design method described above.

[0124] Specifically, the flow battery stack includes at least: two plates, a separator disposed between two adjacent plates, positive and negative electrode cells disposed on the side of the two plates away from the separator, and two irregularly shaped permanent magnets disposed on the side of the positive and negative electrode cells away from the separator.

[0125] The flow battery stack provided in this application provides a non-contact, uniform initial magnetic field force by setting two irregularly shaped permanent magnets at both ends of the flow battery stack. Utilizing the principle of attraction between opposite poles of the irregularly shaped permanent magnets, a uniform clamping force is applied to the component between the two irregularly shaped permanent magnets. This applies a uniform clamping force to the flow battery stack. By correcting the initial magnetic field force, the clamping force on the flow battery stack is ensured to meet the encapsulation requirements and be within the optimal clamping force range, thereby improving the sealing performance and performance stability of the flow battery stack.

[0126] The above provides a detailed description of a flow battery stack packaging design method and a flow battery stack as described in the embodiments of this application. The description of the above embodiments is only for the purpose of helping to understand the core idea of ​​this application, and the above description should not be construed as a limitation on the scope of protection of this application.

Claims

1. A flow battery stack packaging design method, characterized in that, Includes the following steps: A flow battery stack model is established, which includes at least: two electrode plates, a separator disposed between two adjacent electrode plates, positive and negative electrode cells respectively disposed on the side of the two electrode plates away from the separator, and two irregularly shaped permanent magnets respectively disposed on the side of the positive and negative electrode cells away from the separator; Calculate the magnetization of the irregularly shaped permanent magnet; Calculate the magnetization current density of the irregular permanent magnet and the surface magnetization current density of the irregular permanent magnet based on the magnetization intensity. The initial magnetic force between the two irregular permanent magnets is calculated based on the magnetization current density and the surface magnetization current density. The initial magnetic field force is modified according to preset conditions so that the clamping force on the flow battery stack model meets the encapsulation requirements. The flow battery stack model also includes 2N electrode plates, 2N magnetic pads, and N separators. Each separator is disposed between two adjacent electrode plates, and each magnetic pad is disposed between an adjacent electrode plate and a separator. N is a positive integer greater than or equal to 1. The flow battery stack model also includes a screw and a nut. The screw passes through the two irregularly shaped permanent magnets, and the nut is used to fasten the screw to apply a clamping force to the flow battery stack model. ; ， Where T is the tightening torque of a single nut, and d is the nominal diameter of the screw; The clamping force on the flow battery stack model is calculated using the following formula. : ， in, The clamping force applied by the screw and nut to the flow battery stack model. The magnetic force between the two irregularly shaped permanent magnets.

2. The flow battery stack packaging design method according to claim 1, characterized in that, The magnetization M of the irregularly shaped permanent magnet is calculated using the following formula: ， Where B is the magnetic flux density. The permeability of free space, denoted as ρ, where ρ is the relative permeability of the magnetic medium.

3. The flow battery stack packaging design method according to claim 2, characterized in that, The magnetization current density δv of the irregular permanent magnet is calculated using the following formula: ， in, M is the magnetization intensity of the irregular permanent magnet per unit volume; And calculate the surface magnetization current density δs of the irregularly shaped permanent magnet according to the following formula: ， Where n is the surface normal vector and M is the magnetization intensity of the irregular permanent magnet.

4. The flow battery stack packaging design method according to claim 1, characterized in that, The flow battery stack model also includes two end plates, which are respectively disposed on the side of the two irregular permanent magnets away from the electrode plates. The screw passes through the two end plates, and the nut is used to fasten the screw. The end plates are made of wood or aluminum.

5. A flow battery stack, characterized in that, The battery stack is packaged using the flow battery stack packaging design method as described in any one of claims 1 to 4.

Images