Method for calculating pre-tightening force of battery assembly and assembly method of battery module

Abstract

The application provides a battery assembly pre-tightening force calculation method and a battery module assembly method, relates to the technical field of batteries, and aims to solve the technical problem of excessive or insufficient pre-tightening force applied to the battery module. First, a battery assembly is provided. The battery assembly comprises n battery monomers, n+1 buffer pads and two end plates. The battery monomers and the buffer pads are arranged between the two end plates. The battery monomers and the buffer pads are arranged alternately. The buffer pads are arranged between the end plates and the battery monomers. Second, the maximum extrusion force f0 that can be borne by the buffer pad is calculated and obtained. Third, the maximum design extrusion force f1 that can be borne by the buffer pad is calculated and obtained. Fourth, the maximum pressure f2 that can be borne by the battery monomer is obtained. Finally, the initial pre-tightening force of the battery assembly is calculated. The method of the application can solve the technical problem of excessive or insufficient pre-tightening force applied to the battery assembly.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a method for calculating the preload of a battery assembly and a method for assembling a battery module. Background Technology

[0002] With the development of modern society, people's travel efficiency is constantly improving. New energy vehicles, as an indispensable means of daily transportation, are being used more and more widely. Batteries serve as the power components of new energy vehicles. A battery includes a casing and battery modules located within the casing. A battery module includes battery packs. A battery pack includes individual battery cells, buffer pads, and end plates. During charging and discharging, individual battery cells expand. This not only affects the cycle charging and discharging performance and lifespan of the individual cells but also significantly impacts the capacity and size design of the battery module. To better utilize the performance of individual battery cells, buffer pads are typically placed between the battery cells during battery module design. Furthermore, a certain preload force needs to be applied to the battery pack during application.

[0003] However, if the preload of the battery assembly is too high, the buffer pad may not be able to recover after compression. This would prevent the buffer pad from being further compressed when the battery expands, leading to insufficient expansion space for individual battery cells and causing the battery module assembly to fail. If the preload of the battery assembly is too low, the compression of the buffer pad will be too large, failing to effectively restrain the individual battery cells. This could result in excessive expansion of the individual battery cells, potentially leading to a decrease in performance. Alternatively, if the preload of the battery assembly is too low, the individual battery cells may not be securely fixed, resulting in an excessively large overall size (e.g., length) of the battery module, making it difficult to install into the housing. Summary of the Invention

[0004] This application provides a method for calculating the preload of a battery module and a method for assembling a battery module, in order to solve the technical problem of applying too large or too small a preload to the battery module.

[0005] In a first aspect, this application provides a method for calculating the preload of a battery assembly, comprising:

[0006] Step S10: Provide a battery assembly, which includes n battery cells, n+1 buffer pads and two end plates. Battery cells and buffer pads are arranged between the two end plates. Battery cells and buffer pads are arranged alternately. Buffer pads are arranged between the end plates and battery cells.

[0007] Step S20: Calculate the maximum compressive force f0 that the buffer pad can withstand;

[0008] Step S30: Calculate the maximum design compressive force f1 that the buffer pad can withstand, where f1 < f0;

[0009] Step S40: Obtain the maximum pressure f2 that a single battery cell can withstand;

[0010] Step S50: Calculate the initial preload of the battery assembly:

[0011] When the condition (n+1)×f1≤f2 is satisfied, the initial preload force applied to the battery assembly is determined to be F1, where f0≤F1≤(n+1)×f1+f2;

[0012] When the condition (n+1)×f1>f2 is satisfied, the initial preload applied to the battery assembly is determined to be F2, where f2≤F2≤(n+1)×f1.

[0013] The method for calculating the preload of the battery module in this application determines the maximum compressive force f0 that the buffer pad can withstand based on the effective compression of the buffer pad, thus preventing the buffer pad from failing due to excessive pressure. The maximum design compressive force that the buffer pad can withstand is determined based on the design dimensions of the battery module, and this maximum design compressive force is used to determine the maximum compressive force that the buffer pad can withstand while ensuring its effectiveness. When the compressive force borne by all the buffer pads is less than or equal to the maximum pressure f2 that the battery cell can withstand, the minimum initial preload applied to the battery module is determined to be f0, and the maximum initial preload applied to the battery module is the sum of the compressive force borne by all the buffer pads and f2. When the compressive force borne by all the buffer pads is greater than the maximum pressure f2 that the battery cell can withstand, the minimum initial preload applied to the battery module is determined to be f2, and the maximum initial preload applied to the battery module is the compressive force borne by all the buffer pads. This ensures that the preload applied to the battery module is neither too large nor too small, thereby ensuring the efficiency of the battery module design and the reliability of the product.

[0014] In some embodiments that may include the above-described embodiments, the maximum pressure f2 is equal to 3000 Newtons.

[0015] In some embodiments that may include the above-described embodiments, the maximum extrusion force f0 is equal to 3000 Newtons.

[0016] In some embodiments that may include the above embodiments, when the buffer pad bears the maximum compressive force f0, the corresponding length of the battery assembly is L0, and when the buffer pad bears the maximum design compressive force f1, the corresponding length of the battery assembly is L1, wherein L1 is greater than L0.

[0017] In some embodiments that may include the above embodiments, pressure is applied to the buffer pad to compress it, and the pressure corresponding to the compression of the buffer pad to a thickness equal to 50% of the initial thickness of the buffer pad is the maximum compressive force f0.

[0018] In some embodiments that may include the above embodiments, the cushioning pad is foam.

[0019] Secondly, this application provides a method for assembling a battery module, comprising:

[0020] Step S100: Provide n battery cells, n+1 buffer pads and two end plates. The battery cells and buffer pads are set between the two end plates. The battery cells and buffer pads are set alternately. The buffer pads are set between the end plates and the battery cells. The battery cells, buffer pads and end plates form a battery assembly.

[0021] Step S200: Determine the preload force of the battery assembly using the above calculation method;

[0022] Step S300: Provide a fastener, use the fastener to secure the battery cell, buffer pad and end plate, and apply a preload force to the battery assembly from the outside of the end plate.

[0023] In some embodiments that may include the above-described embodiments, the fastener is a cable tie. The cable tie is fitted around the outer periphery of the battery assembly.

[0024] In some embodiments that may include the above-described embodiments, the number of cable ties is two. The two cable ties are spaced apart along the height direction of the battery cell.

[0025] In some embodiments that may include the above embodiments, after step S300, step S400 is further included: providing a bus. The bus is electrically connected to the terminals of the individual battery cells to enable series or parallel connection between the individual battery cells. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. It is obvious that the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a partial structural diagram of a battery module according to an embodiment of this application;

[0028] Figure 2 This is a partial structural diagram of a battery module according to an embodiment of this application;

[0029] Figure 3 This is a flowchart illustrating a method for calculating the preload force of a battery assembly according to an embodiment of this application.

[0030] Figure 4 This is a schematic flowchart illustrating a battery module assembly method according to an embodiment of this application.

[0031] Figure 5This is a schematic flowchart illustrating the assembly method of a battery module according to another embodiment of this application.

[0032] Explanation of reference numerals in the attached figures:

[0033] 10. Battery module;

[0034] 101. Battery assembly; 1011. Battery cell; 1012. Buffer pad; 1013. End plate;

[0035] 102. Fasteners;

[0036] 103. Busbar. Detailed Implementation

[0037] The embodiments of this application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of this application by way of example, but should not be used to limit the scope of this application, that is, this application is not limited to the described embodiments.

[0038] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. "Vertical" is not vertical in the strict sense, but within the allowable tolerance range. "Parallel" is not parallel in the strict sense, but within the allowable tolerance range.

[0039] In this application, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments.

[0040] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application depending on the specific circumstances.

[0041] This application provides an electrical device that uses a battery as a power source. This electrical device can be, but is not limited to, vehicles, ships, or aircraft. The vehicle can be a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. The battery can serve as the vehicle's driving power source, replacing or partially replacing fuel or natural gas to provide driving power. Exemplarily, the battery can be used to meet the vehicle's starting, navigation, and operating power needs. Exemplarily, the vehicle in this application can be a pure electric vehicle.

[0042] A vehicle may include a battery. The battery may include a housing and battery modules. The type of housing is not limited. The housing can be a frame-shaped housing, a disc-shaped housing, or a box-shaped housing, etc. The housing includes a cover and the space formed after the housing is closed. The cover and housing can be connected by adhesive bonding. The housing serves to house the battery modules and provide support and fixation for them, preventing the battery modules from moving back and forth, which could reduce battery safety and create safety hazards. The battery modules are housed within the space of the housing.

[0043] In some embodiments, the battery may include two or more battery modules. The two or more battery modules are arranged in a housing.

[0044] See Figure 1 and Figure 2 As shown, the battery module 10 includes a battery assembly 101. The battery assembly 101 includes multiple battery cells 1011. The battery cells 1011 are arranged side-by-side. After a certain period of operation, each battery cell 1011 may expand during charging and discharging. When the battery cells 1011 expand, their opposite surfaces may bulge along the arrangement direction. The battery assembly 101 can be pre-tightened by the fastener 102, and then the pre-tightened battery module 10 is placed inside the housing. Applying a certain pre-tightening force to the battery assembly 101 allows for expansion space for the battery cells 1011 and slows down the performance degradation rate of the battery cells 1011 during their service life.

[0045] The battery assembly 101 also includes a buffer pad 1012. Among the multiple battery cells 1011, a buffer pad 1012 is provided between two adjacent battery cells 1011. When a battery cell 1011 expands, the battery cell 1011 can squeeze the buffer pad 1012 to compress the buffer pad 1012, so that the overall length of the battery module 10 does not increase due to the expansion of the battery cells 1011.

[0046] The battery assembly 101 also includes end plates 1013. Multiple battery cells 1011 are disposed between two end plates 1013. A buffer pad 1012 is disposed between the end plate 1013 and the adjacent battery cell 1011. Along the arrangement direction of the battery cells 1011, compressive stress is applied to the end plates 1013 from the outer side away from the battery cells 1011, thereby pressing the battery cells 1011 and the buffer pad 1012 together. The compressive stress applied to the end plates 1013 is the preload force.

[0047] As described in the background section, excessive or insufficient preload applied to the battery assembly 101 in related technologies can affect the overall performance of the battery module 10. Excessive preload can cause the buffer pad 1012 to be unable to recover after compression, thus losing its cushioning effect. Insufficient preload can lead to increased expansion of the battery cells 1011, thereby reducing their performance. Alternatively, insufficient preload can result in the battery cells 1011 not being securely fixed, leading to an oversized battery module 10 that is difficult to fit into the housing.

[0048] Based on the problems identified above, this application provides a method for calculating the preload of a battery module 101. The method for calculating the preload of the battery module 101 provided in this application can obtain a reasonable preload of the battery module 101, which can help the individual battery cells 1011 operate in an optimal state, thereby extending the overall service life of the battery module 10.

[0049] This application describes a method for calculating the preload of a battery assembly 101. See also... Figure 3 As shown, the method for calculating the preload of the battery assembly 101 in this application includes:

[0050] Step S10: Provide a battery assembly 101, which includes n battery cells 1011, n+1 buffer pads 1012 and two end plates 1013. The battery cells 1011 and the buffer pads 1012 are arranged between the two end plates 1013. The battery cells 1011 and the buffer pads 1012 are arranged alternately. The buffer pads 1012 are arranged between the end plates 1013 and the battery cells 1011.

[0051] Step S20: Calculate the maximum compressive force f0 that the buffer pad 1012 can withstand;

[0052] Step S30: Calculate the maximum design compressive force f1 that the buffer pad 1012 can withstand, where f1 < f0;

[0053] Step S40: Obtain the maximum pressure f2 that the battery cell 1011 can withstand;

[0054] Step S50: Calculate the initial preload of battery assembly 101:

[0055] When the condition (n+1)×f1≤f2 is met, the initial preload force applied to the battery assembly 101 is determined to be F1, where f0≤F1≤(n+1)×f1+f2;

[0056] When the condition (n+1)×f1>f2 is satisfied, the initial preload force applied to the battery assembly 101 is determined to be F2, where f2≤F2≤(n+1)×f1.

[0057] The method for calculating the preload of the battery module 101 in this embodiment calculates the initial preload applied to the battery module 101 by using the maximum compressive force f0 that the buffer pad 1012 can bear, the maximum design compressive force f1 that the buffer pad 1012 can bear, the maximum pressure f2 that the battery cell 1011 can bear, the number of battery cells 1011, and the number of buffer pads 1012. This method yields a reasonable preload for the battery module 101, ensuring that the initial preload of the battery module 101 better meets product requirements. The preload calculated using this method is neither too large nor too small, which helps ensure that the battery cells 1011 maintain good performance during use, thereby extending the overall lifespan of the battery module 101, improving its reliability, and ensuring that the battery cells 1011 are securely fixed, allowing the battery module 10 to be easily placed into the housing.

[0058] In some possible implementations, the maximum compressive force f0 that the buffer pad 1012 can withstand is determined by the effective compression amount of the buffer pad 1012, in order to prevent the buffer pad 1012 from failing due to excessive pressure and being unable to rebound. The maximum design compressive force f1 that the buffer pad 1012 can withstand is determined based on the design dimensions (e.g., length) of the battery assembly 101 and while ensuring the effectiveness of the buffer pad 1012.

[0059] In some embodiments, the maximum pressure f2 that a single battery cell 1011 can withstand is equal to 3000 N, meaning that the maximum pressure f2 that a single battery cell 1011 can withstand is 3000 N. Compressive stress is applied to the battery cell 1011 from both sides along the arrangement direction of the battery cells 1011. If the compressive stress on the battery cell 1011 exceeds 3000 N, the pressure borne by the battery cell 1011 is too high, which will adversely affect the performance of the battery cell 1011, potentially reducing its service life and causing it to deform under pressure. Therefore, limiting the maximum pressure f2 that a single battery cell 1011 can withstand to 3000 N is beneficial in ensuring that the battery cell 1011 maintains good performance and ensures a relatively long service life.

[0060] In some examples, the battery cell 1011 can be a prismatic cell. The maximum pressure f2 that the prismatic battery cell 1011 can withstand is 3000 N. When the actual pressure that the prismatic battery cell 1011 withstands is less than 3000 N, the service life of the battery cell 1011 is relatively long and its performance can be maximized.

[0061] For example, the maximum pressure f2 that the battery cell 1011 can withstand is equal to 3000 Newtons. When the condition (n+1)×f1≤3000 is satisfied, the initial preload force applied to the battery assembly 101 is determined to be F1, where f0≤F1≤(n+1)×f1+3000; when the condition (n+1)×f1>3000 is satisfied, the initial preload force applied to the battery assembly 101 is determined to be F2, where 3000≤F2≤(n+1)×f1.

[0062] In some embodiments, the maximum compressive force f0 that the buffer pad 1012 can withstand is equal to 3000 N. A compressive force is applied to the buffer pad 1012 along the arrangement direction of the battery cells 1011, i.e., the thickness direction of the buffer pad 1012. The buffer pad 1012, in its initial state, can be compressed after being compressed. When the compressive force applied to the buffer pad 1012 disappears, the buffer pad 1012 can rebound from the compressed state to its initial state. When the compressive force borne by the buffer pad 1012 exceeds 3000 N, the buffer pad 1012, in its initial state, is compressed, but when the compressive force borne by the buffer pad 1012 disappears, the buffer pad 1012 cannot rebound from the compressed state to its initial state; that is, the buffer pad 1012 is over-compressed and fails, unable to rebound.

[0063] In some examples, the maximum compressive force f0 that the buffer pad 1012 can withstand is equal to 3000 N, and the maximum pressure f2 that the battery cell 1011 can withstand is equal to 3000 N. When the condition (n+1)×f1≤3000 N is met, the initial preload applied to the battery assembly 101 is determined to be F1, where 3000 N≤F1≤(n+1)×f1+3000 N; when the condition (n+1)×f1>3000 N is met, the initial preload applied to the battery assembly 101 is determined to be F2, where 3000 N≤F2≤(n+1)×f1.

[0064] For example, the maximum design compressive force f1 that the buffer pad 1012 can withstand is equal to 1000 N. When the condition (n+1)×1000≤3000 is satisfied, the initial preload force applied to the battery assembly 101 is determined to be F1, where 3000 N≤F1≤(n+1)×1000 N+3000 N; when the condition (n+1)×1000 N>3000 N is satisfied, the initial preload force applied to the battery assembly 101 is determined to be F2, where 3000 N≤F2≤(n+1)×1000 N.

[0065] For example, n equals 2, meaning the battery assembly 101 includes 2 battery cells 1011, 3 buffer pads 1012, and 2 end plates 1013. Since (n+1)×f1 = (2+1)×1000 N = 3000 N, the condition (n+1)×f1 ≤ f2 is satisfied, thus the initial preload F1 applied to the battery assembly 101 can be determined to be 3000 N ≤ F1 ≤ 6000 N. For example, when the battery assembly 101 includes 2 battery cells 1011, 3 buffer pads 1012, and 2 end plates 1013, the initial preload F1 applied to the battery assembly 101 can be determined to be 4500 N.

[0066] For example, n equals 3, meaning the battery assembly 101 includes 3 battery cells 1011, 4 buffer pads 1012, and two end plates 1013. Since (n+1)×f1 = (3+1)×1000 N = 4000 N, the condition (n+1)×f1 > f2 is satisfied, thus the initial preload F2 applied to the battery assembly 101 can be determined to be 3000 N ≤ F2 ≤ 4000 N. For example, when the battery assembly 101 includes 3 battery cells 1011, 4 buffer pads 1012, and two end plates 1013, the initial preload F2 applied to the battery assembly 101 can be determined to be 3500 N.

[0067] In some embodiments, when the buffer pad 1012 bears the maximum compressive force f0, the corresponding length of the battery assembly 101 is L0, and when the buffer pad 1012 bears the maximum design compressive force f1, the corresponding length of the battery assembly 101 is L1, wherein L1 is greater than L0.

[0068] When the buffer pad 1012 bears the maximum compressive force f0, the buffer pad 1012 can be compressed, and the amount of compression of the buffer pad 1012 reaches its maximum, that is, the actual thickness of the buffer pad 1012 is minimum. At this time, the length L0 of the battery assembly 101 is equal to the sum of the thickness of each battery cell 1011, the actual thickness of each buffer pad 1012, and the thickness of the two end plates 1013. The thickness of the battery cell 1011 refers to the dimension measured along the arrangement direction of the battery cells 1011. The thickness of the end plate 1013 refers to the dimension measured along the arrangement direction of the battery cells 1011.

[0069] When the buffer pad 1012 bears the maximum design compressive force f1, the buffer pad 1012 can be compressed, but the amount of compression of the buffer pad 1012 does not reach the maximum. The actual thickness of the buffer pad 1012 is greater than the actual thickness of the buffer pad 1012 when bearing the maximum compressive force f0. The length L1 of the battery assembly 101 is equal to the sum of the thickness of each battery cell 1011, the actual thickness of each buffer pad 1012, and the thickness of the two end plates 1013. Since the thickness of the battery cell 1011 and the thickness of the end plate 1013 remain unchanged, and the actual thickness of the buffer pad 1012 when bearing the maximum design compressive force f1 is greater than the actual thickness of the buffer pad 1012 when bearing the maximum compressive force f0, the actual designed length L1 of the battery assembly 101 is greater than the aforementioned length L0 of the battery assembly 101.

[0070] In some examples, n equals 3, meaning that the battery assembly 101 includes 3 battery cells 1011, 4 buffer pads 1012, and two end plates 1013. When the buffer pads 1012 bear the maximum compressive force f0, the length L0 of the battery assembly 101 is equal to the sum of the thickness of the 3 battery cells 1011, the actual thickness of the 4 buffer pads 1012, and the thickness of the two end plates 1013.

[0071] When the buffer pads 1012 bear the maximum design compressive force f1, the length L1 of the battery assembly 101 is equal to the sum of the thickness of the three battery cells 1011, the actual thickness of the four buffer pads 1012, and the thickness of the two end plates 1013. The thickness of the three battery cells 1011 and the thickness of the two end plates 1013 remain unchanged. Therefore, the actual thickness of the four buffer pads 1012 bearing the maximum design compressive force f1 is greater than the actual thickness of the four buffer pads 1012 bearing the maximum compressive force f0, thus making L1 greater than L0.

[0072] In some embodiments, see Figure 2As shown, the maximum compressive force f0 is the pressure applied to the buffer pad 1012 to compress it, and the pressure corresponding to the thickness of the buffer pad 1012 after compression being equal to 50% of its initial thickness. Correspondingly, when the maximum compressive force f0 is applied to the buffer pad 1012, the thickness of the buffer pad 1012 after compression is equal to 50% of its initial thickness.

[0073] In some embodiments, the cushioning pad 1012 is foam. Foam has good elasticity and can be compressed or rebound. When compressive force is applied to the foam in its initial state, the foam can deform and transform into a compressed state. After the compressive force applied to the foam disappears, the foam can return from the compressed state to its initial state. The foam can reduce pressure and provide shock absorption for the battery cell 1011, thereby helping to reduce the pressure borne by the battery cell 1011 and reducing the possibility of significant vibration in the battery cell 1011 due to external impacts to the battery module 10.

[0074] This application also provides a method for assembling a battery module 10, see [link to relevant documentation]. Figure 4 As shown, it includes:

[0075] Step S100: Provide n battery cells 1011, n+1 buffer pads 1012 and two end plates 1013. The battery cells 1011 and buffer pads 1012 are arranged between the two end plates 1013. The battery cells 1011 and buffer pads 1012 are arranged alternately. The buffer pads 1012 are arranged between the end plates 1013 and the battery cells 1011. The battery cells 1011, buffer pads 1012 and end plates 1013 form a battery assembly 101.

[0076] Step S200: Determine the preload of battery module 101 using the calculation method for preload of battery module 101;

[0077] Step S300: Provide a fastener 102, use the fastener 102 to fix the battery cell 1011, the buffer pad 1012 and the end plate 1013, and apply the preload force described above to the battery assembly 101 from the outside of the end plate 1013.

[0078] The calculation method for the preload of the battery assembly 101 mentioned in step S200 refers to the calculation method for the preload of the battery assembly 101 in the above embodiment.

[0079] The assembly method of the battery module 10 in this application embodiment calculates and determines the initial preload applied to the battery assembly 101, thereby obtaining a reasonable preload for the battery assembly 101. This helps ensure that the initial preload of the battery assembly 101 meets product requirements. The preload calculated using the preload calculation method for the battery assembly 101 is neither too large nor too small, which helps ensure that the battery cells 1011 maintain good performance during use and also helps to securely fix the battery cells 1011. The buffer pad 1012 in the battery assembly 101 has a compressible amount reserved, thereby reserving expansion space for the battery cells 1011. This not only helps the buffer pad 1012 to buffer the vibration of the battery cells 1011, but also helps to ensure that the pressure borne by the battery cells 1011 is moderate, ensuring that the performance of the battery cells 1011 can be effectively utilized, extending the service life of the battery cells 1011, but also helps to fix the end plate 1013, making the end plate 1013 less likely to fall off. With the preload of the battery assembly 101 effectively controlled, the overall dimensions (e.g., length) of the battery assembly 101 can also be effectively controlled, making it easier for the battery module 10, including the battery assembly 101, to be easily installed into the housing and secured. The fastener 102 secures the battery cell 1011, the buffer pad 1012, and the end plate 1013, ensuring that the battery cell 1011, the buffer pad 1012, and the end plate 1013 are not prone to misalignment, facilitating the transfer and transportation of the battery module 10, and reducing the possibility of the battery module 10 failing due to shaking of the battery cell 1011 under complex road conditions.

[0080] In some embodiments, see Figure 2 As shown, the fastener 102 is a cable tie. The cable tie is sleeved around the outer periphery of the battery assembly 101. The initial preload of the battery assembly 101 is less than the maximum tensile force that the fastener 102 can withstand, which ensures that the fastener 102 is not prone to breakage during the use of the battery module 10. The cable tie sleeved around the outer periphery of the battery assembly 101 can effectively fix the battery cell 1011, the buffer pad 1012, and the end plate 1013, avoiding the safety hazard of the battery cell 1011 or the end plate 1013 falling off.

[0081] Since the initial preload applied by the fastener 102 to the battery assembly 101 is appropriate in the initial state, the buffer pad 1012 can be compressed to absorb the expansion of the battery cell 1011 after the battery cell 1011 expands during subsequent use. This prevents the size of the battery assembly 101 from increasing due to the expansion of the battery cell 1011, and thus the tensile stress borne by the fastener 102 will not increase due to the expansion of the battery cell 1011. This helps to reduce the possibility of the fastener 102 breaking due to excessive tensile stress caused by the expansion of the battery cell 1011.

[0082] In some embodiments, see Figure 2 As shown, there are two cable ties. The two cable ties are spaced apart along the height of the battery cell 1011. The spaced arrangement of the two cable ties can more effectively secure the battery cell 1011, the buffer pad 1012, and the two end plates 1013, thereby keeping the battery assembly 101 in an integral state and preventing it from falling off.

[0083] In some embodiments, see Figure 5 As shown, after step S300, step S400 is also included:

[0084] A busbar 103 is provided. The busbar 103 is electrically connected to the terminals of the battery cells 1011 so that the individual battery cells 1011 can be connected in series or in parallel.

[0085] In some examples, the busbar 103 can be connected to the terminal post of the battery cell 1011 by laser welding, thereby further improving the overall robustness of the battery module 10.

[0086] In this embodiment, the fixing member 102 fixes the battery cell 1011, the buffer pad 1012, and the end plate 1013, ensuring that the battery cell 1011, the buffer pad 1012, and the end plate 1013 are not prone to misalignment. This ensures that the busbar 103 and the terminal post of the battery cell 1011 are aligned, effectively avoiding welding misalignment and reducing the possibility of safety hazards in the battery cell 1011 due to welding misalignment of the busbar 103.

[0087] In some examples, bus 103 can be an aluminum bus. Bus 103 can also be a copper bus.

[0088] The various embodiments or implementation methods described in this specification are presented in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for calculating the preload of a battery assembly, characterized in that, include: Step S10: Provide a battery assembly, the battery assembly including n battery cells, n+1 buffer pads and two end plates, the battery cells and the buffer pads are disposed between the two end plates, the battery cells and the buffer pads are disposed alternately, and the buffer pads are disposed between the end plates and the battery cells; Step S20: Calculate the maximum compressive force f0 that the buffer pad can withstand; Step S30: Calculate the maximum design compressive force f1 that the buffer pad can withstand, where f1 < f0; Step S40: Obtain the maximum pressure f2 that the battery cell can withstand; Step S50: Calculate the initial preload of the battery assembly: When the condition (n+1)×f1≤f2 is satisfied, the initial preload force applied to the battery assembly is determined to be F1, where f0≤F1≤(n+1)×f1+f2; When the condition (n+1)×f1>f2 is met, the initial preload applied to the battery assembly is determined to be F2, where f2≤F2≤(n+1)×f1; pressure is applied to the buffer pad to compress the buffer pad, and the pressure corresponding to the thickness of the buffer pad after compression being equal to 50% of the initial thickness of the buffer pad is the maximum compressive force f0.

2. The method for calculating the preload of the battery assembly according to claim 1, characterized in that, The maximum pressure f2 is equal to 3000 Newtons.

3. The method for calculating the preload of the battery assembly according to claim 1, characterized in that, The maximum compressive force f0 is equal to 3000 Newtons.

4. The method for calculating the preload of the battery assembly according to claim 1, characterized in that, When the buffer pad bears the maximum compressive force f0, the corresponding length of the battery assembly is L0. When the buffer pad bears the maximum design compressive force f1, the corresponding length of the battery assembly is L1, where L1 is greater than L0.

5. The method for calculating the preload of a battery assembly according to any one of claims 1 to 4, characterized in that, The cushioning pad is made of foam.

6. A method for assembling a battery module, characterized in that, include: Step S100: Provide n battery cells, n+1 buffer pads and two end plates. The battery cells and the buffer pads are disposed between the two end plates. The battery cells and the buffer pads are disposed alternately. The buffer pads are disposed between the end plates and the battery cells. The battery cells, the buffer pads and the end plates form a battery assembly. Step S200: Determine the preload force of the battery assembly using the calculation method described in any one of claims 1 to 5; Step S300: Provide a fastener, use the fastener to fix the battery cell, the buffer pad and the end plate, and the fastener applies the preload force to the battery assembly from the outside of the end plate.

7. The assembly method of the battery module according to claim 6, characterized in that, The fastener is a cable tie, which is sleeved around the outer periphery of the battery assembly.

8. The assembly method of the battery module according to claim 7, characterized in that, The number of cable ties is two, and the two cable ties are spaced apart along the height direction of the battery cell.

9. The assembly method of the battery module according to claim 6, characterized in that, Following step S300, step S400 is also included: A busbar is provided, which is electrically connected to the terminals of the individual battery cells to enable series or parallel connection between the individual battery cells.

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