A high-precision pressure uniformity clamp and formation device
By using a high-precision pressure uniformity fixture and formation device, the surface pressure of the battery cell is detected and adjusted in real time, which solves the problem of uneven pressure during the formation process and improves the consistency of the battery cell.
Patent Information
- Application Number
- CN202521110859.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-30
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2035-05-30
AI Technical Summary
In the existing battery cell formation process, the pressure applied to the cells by the clamping plates is uneven, resulting in poor cell consistency.
A high-precision pressure uniformity fixture was designed. Through the sandwich plate assembly and pressure adjustment component, the surface pressure of the battery cell is detected in real time, and the spacing of the sandwich plates is adjusted by the telescopic rod and the drive device to ensure that each battery cell is uniformly pressurized.
This improves the consistency of battery cell products, ensuring that each cell is subjected to uniform stress during the formation process, thus enhancing the consistency of battery batches.
Smart Images
Figure CN224683125U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of battery processing technology, and more specifically, to a high-precision pressure uniformity fixture and a formation device. Background Technology
[0002] During the formation of battery cells, the cells need to be pressurized. Currently, the pressurization device uses two clamps to hold multiple cells. The pressure applied by the pressurization device to different cells often varies, which can lead to uneven pressure values among cells in a batch during formation, resulting in poor consistency of the batch of cells. Utility Model Content
[0003] The purpose of this invention is to provide a high-precision pressure uniformity fixture and formation device, which can improve the consistency of each batch of battery cells.
[0004] The embodiments of this utility model are implemented as follows: In a first aspect, embodiments of this application provide a high-precision pressure uniformity fixture, comprising: A sandwich panel assembly, comprising a plurality of sandwich panels arranged in sequence, wherein each pair of adjacent sandwich panels has a first cell contact surface and a second cell contact surface respectively; the space between the first cell contact surface and the second cell contact surface is used to place a cell product, and the spacing between the two is adjustable; Each of the first cell contact surfaces and / or the corresponding second cell contact surfaces is provided with a pressure detection structure, which is used to collect the pressure borne by the surface of the cell product. Each pair of adjacent sandwich panels is provided with a pressure regulating assembly. Each group of pressure regulating assemblies includes a first driving device and a telescopic rod. The first driving device is connected to one end of the telescopic rod. The other end of the telescopic rod passes through the first cell contact surface and is connected to the corresponding second cell contact surface. The first driving device is used to adjust the distance between the first battery cell contact surface and the second battery cell contact surface by means of the telescopic rod based on the pressure on the surface of the battery cell product.
[0005] In a possible implementation, in each pair of adjacent sandwich panels, the number of the first drive device and the telescopic rod in the pressure regulating assembly is matched and is even, and the even number of the first drive device and the telescopic rod are symmetrically arranged with respect to the first cell contact surface. In a possible implementation, limit blocks are symmetrically arranged at both ends of each second cell contact surface, and limit grooves are provided on the opposite sides of the limit blocks; the shape of the limit groove matches the shape of the end of the cell product, and the end of the cell product is limited and installed in the corresponding limit groove. In a possible implementation, a first mounting groove is provided on each of the first cell contact surfaces and / or the corresponding second cell contact surfaces, the first mounting groove being located between the corresponding limiting blocks, and the pressure detection structure being a strain gauge and disposed within the corresponding first mounting groove. In a possible implementation, each of the first cell contact surfaces and / or the corresponding second cell contact surfaces is further provided with a second mounting groove, each of the second mounting grooves is provided with an elastic buffer structure, and each of the elastic buffer structures is used to contact the surface of the cell product. In a possible implementation, each of the elastic buffer structures includes a spring and a plunger, the spring being disposed within a corresponding second mounting slot; one end of the plunger is connected to the corresponding spring, and the other end extends from the corresponding second mounting slot for contact with the surface of the battery cell product.
[0006] Secondly, embodiments of this application also provide a formation apparatus, including a pressure application component and the aforementioned high-precision pressure uniformity fixture, wherein the pressure application component is used to apply a set pressure to the battery cell product held by the sandwich plate assembly through the sandwich plate assembly.
[0007] In a possible implementation, the pressure application assembly further includes: a frame, a pressing plate, and a second drive device; The sandwich panel assembly is mounted on the frame, and both ends of each sandwich panel are slidably connected to the frame. The extrusion plate is disposed on the frame relative to the sandwich panel assembly; The second driving device is connected to the extrusion plate and drives the extrusion plate to move in a direction toward or away from the sandwich panel assembly; the extrusion plate can move to a set position, and the extrusion plate at the set position is in contact with the side of the outermost sandwich panel in the sandwich panel assembly.
[0008] In a possible implementation, the second drive device includes: a plurality of lead screws and a driver; Each of the lead screws is arranged on the frame along the arrangement direction of the sandwich plates and is also located on both sides of the sandwich plate assembly. Each of the lead screws is threadedly connected to the extrusion plate. The driver is connected to the lead screw drive.
[0009] In a possible implementation, the formation apparatus further includes a control device and a plurality of control valves, the control device being electrically connected to each of the control valves; the number of control valves matching the number of the first drive devices; the control valves being electrically connected to the corresponding first drive device and the pressure detection structure, respectively, and used to control the corresponding first drive device to adjust the distance between the first cell contact surface and the second cell contact surface via the telescopic rod based on the pressure on the surface of the cell product.
[0010] The beneficial effects of this utility model embodiment are: The pressure detection structure can detect the pressure borne by the corresponding battery cell in real time. Based on the detected pressure data, the pressure adjustment component can selectively adjust the distance between the contact surfaces of the first and second battery cells via the first drive device and the telescopic rod, thereby changing the pressure borne by the corresponding battery cell and achieving uniform pressure distribution, thus improving the consistency of the battery cell products. Attached Figure Description
[0011] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0012] Figure 1 This is a structural diagram of one embodiment of the high-precision pressure uniformity fixture of this utility model; Figure 2 for Figure 1 Structural diagram of the sandwich panel located at the bottom; Figure 3 This is a structural diagram of one embodiment of the high-precision pressure uniformity fixture of this utility model; Figure 4 for Figure 3 Structural diagram of the sandwich panel located at the bottom; Figure 5 This is a structural diagram of the high-precision pressure uniformity fixture according to an embodiment of the present invention; Figure 6 This is a structural diagram of the formation apparatus according to an embodiment of the present invention.
[0013] Icons: 1. Sandwich panel assembly; 101. Sandwich panel; 102. First cell contact surface; 103. Second cell contact surface; 104. Cell extrusion zone; 2. Pressure detection structure; 3. Pressure regulating assembly; 301. First drive device; 302. Telescopic rod; 4. Limit block; 401. Limit groove; 5. Control valve assembly; 501. Control valve; 6. Plunger; 7. Frame; 8. Extrusion plate; 9. Second drive device; 901. Lead screw; 902. Driver. Detailed Implementation
[0014] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0015] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
[0016] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
[0017] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use. They are only for the convenience of describing this utility model 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. Therefore, they should not be construed as limitations on this utility model. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0018] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.
[0019] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" 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 mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0020] First Embodiment This application provides a high-precision pressure uniformity fixture, comprising: a sandwich panel assembly 1, wherein the sandwich panel assembly 1 includes a plurality of sandwich panels 101 arranged in sequence, each pair of adjacent sandwich panels 101 having a first cell contact surface 102 and a second cell contact surface 103 respectively; the space between the first cell contact surface 102 and the second cell contact surface 103 is used to place a cell product, and the distance between them is adjustable. The sandwich panel assembly 1 is a structure composed of a plurality of sandwich panels 101 arranged in sequence, and a cell compression zone 104 is formed between adjacent sandwich panels 101 for placing cell products (such as lithium battery cells). The relative movement of two adjacent sandwich panels 101 achieves clamping and pressure application on the cell products, and its sequential arrangement allows a single power source to simultaneously apply pressure to multiple cell products.
[0021] refer to Figures 1 to 5 , Figure 1 The fixture shown contains two sandwich panels 101. Figure 3 The fixture shown includes at least three interlayer plates 101. A pressure detection structure 2 is provided on each of the first cell contact surfaces 102 and / or the corresponding second cell contact surfaces 103. The pressure detection structure 2 is used to collect the pressure exerted on the surface of the cell product. The pressure detection structure 2 is used to collect the pressure value exerted on the surface of the cell product in real time and to provide real-time feedback of the pressure data.
[0022] Each pair of adjacent sandwich panels 101 is equipped with a pressure regulating component 3. The pressure regulating component 3 is used to adjust the distance between the first cell contact surface 102 and the second cell contact surface 103. When different cell products bear different pressures, the pressure regulating component 3 adjusts the distance between the first cell contact surface 102 and the second cell contact surface 103 clamping the corresponding cell product, thereby adjusting the pressure borne by the cell product. For example, if the pressure detection structure 2 detects that the pressure borne by a cell product at a certain location is greater than that of other cell products in the same batch, and the pressure difference exceeds a preset threshold, then the pressure regulating component 3 needs to increase the distance between the first cell contact surface 102 and the second cell contact surface 103, thereby reducing the pressure applied to the cell product by the corresponding first cell contact surface 102 and the second cell contact surface 103, achieving a more consistent pressure among cell products in the same batch, and achieving a uniform pressure effect.
[0023] In some embodiments, the pressure regulating component 3 may be selected as a linear drive mechanism. Taking the selection of an electric actuator as an example, referring to... Figure 1 , Figure 2 , Figure 3 and Figure 5 The pressure regulating assembly 3 includes a first driving device 301 and a telescopic rod 302. The first driving device 301 is connected to one end of the telescopic rod 302; the other end of the telescopic rod 302 passes through the first cell contact surface 102 and is connected to the corresponding second cell contact surface 103. The first driving device 301 is used to adjust the distance between the corresponding first cell contact surface 102 and the corresponding second cell contact surface 103 based on the pressure on the surface of the cell product, via the corresponding telescopic rod 103.
[0024] Generally, when the telescopic rod 302 extends, the distance between the first cell contact surface 102 and the second cell contact surface 103 increases, thereby reducing the pressure borne by the cell product between the first cell contact surface 102 and the second cell contact surface 103. When the telescopic rod 302 retracts, the distance between the first cell contact surface 102 and the second cell contact surface 103 decreases, thereby increasing the pressure borne by the cell product between the first cell contact surface 102 and the second cell contact surface 103. By collecting the pressure information borne by the cell product from the correspondingly set pressure detection structure 2, the corresponding telescopic rod 302 is extended or shortened, thereby adjusting the pressure borne by the surface of the cell product, achieving the effect of uniform pressure on the cell product, and improving the consistency of the cell product.
[0025] In some embodiments, in each pair of adjacent sandwich panels 101, the number of the first driving device 301 and the telescopic rod 302 in each pressure regulating assembly 3 is matched and is even. The even number of the first driving devices 301 and telescopic rods 302 are symmetrically arranged with respect to the first cell contact surface 102. (Reference) Figure 1 or Figure 3 The number of the first driving device 301 and the telescopic rod 302 are set to four, and they are symmetrically arranged along the center of the first cell contact surface 102, that is, they are respectively distributed at the four corners of the first cell contact surface 102, so that the telescopic rod 302 can abut against the four corners of the cell product when it is extended, thereby ensuring that the cell product bears uniform pressure to ensure performance consistency.
[0026] In some embodiments, limiting blocks 4 are symmetrically arranged at both ends of each of the second cell contact surfaces 103, and limiting grooves 401 are provided on opposite sides of the limiting blocks 4; the shape of the limiting grooves 401 matches the shape of the end of the cell product, and the end of the cell product is limited and installed within the corresponding limiting grooves 401. (Reference) Figure 2 or Figure 4 Two limiting blocks 4 are provided and symmetrically arranged on the second cell contact surface 103. Each limiting block 4 has a limiting groove 401 on its side. The shape of the limiting groove 401 matches the shape of both ends of the cell product. For example, if both ends of the cell product are sheet-like, the limiting groove 401 is also a slightly larger three-dimensional shape, thus enabling the limiting installation of the cell product. In addition, the top surface of each limiting block 4 can contact the first cell contact surface 102. When the cell product moves beyond the maximum value through the first cell contact surface 102, the top surface of each limiting block 4 contacts the first cell contact surface 102, thereby preventing the first cell contact surface 102 from continuing to apply pressure and preventing the cell product from being damaged due to excessive pressure, thus protecting the cell product.
[0027] In some embodiments, a first mounting groove is provided on each of the first cell contact surfaces 102 and / or the corresponding second cell contact surfaces 103. The first mounting groove is located between the corresponding limiting blocks 4. The pressure detection structure 2 is a strain gauge and is disposed within the corresponding first mounting groove. During the compression process, the strain gauge indirectly obtains the pressure borne by the cell product through the deformation of the cell product surface. The number of pressure detection structures 2 can be set to multiple, such as being respectively disposed on the first cell contact surface 102 and the second contact surface 103, thereby realizing the acquisition of force information on both sides of the cell product.
[0028] In some embodiments, each of the first cell contact surfaces 102 and / or the corresponding second cell contact surfaces 103 is further symmetrically provided with a second mounting groove, each of the second mounting grooves being provided with an elastic buffer structure, and each of the elastic buffer structures being used to contact the surface of the cell product. (Reference) Figure 1 or Figure 3 Each of the elastic buffer structures includes a spring and a plunger 6. The spring is disposed within the corresponding second mounting groove. One end of the plunger 6 is connected to the corresponding spring, and the other end extends out of the corresponding second mounting groove to contact the surface of the battery cell product. During compression, the battery cell product contacts the elastic buffer structure, which then activates its buffering function to achieve a flexible clamping effect.
[0029] Second Embodiment This application also provides a formation apparatus, including a pressure application component and the aforementioned high-precision pressure uniformity fixture. The pressure application component can apply a set pressure to the battery cell product held by the sandwich plate assembly 1 through the sandwich plate assembly 1. The high-precision pressure uniformity fixture can selectively adjust the distance between the corresponding first battery cell contact surface 102 and second battery cell contact surface 103 according to the magnitude of the pressure borne by the battery cell product, thereby responding to and changing the pressure borne by the battery cell product, achieving the purpose of uniformly pressurizing the battery cell product, and improving the consistency of the battery cell product.
[0030] In some embodiments, the pressure application assembly further includes: a frame 7, a pressing plate 8, and a second drive device 9.
[0031] refer to Figure 6 The sandwich panel assembly 1 is mounted on the frame 7, and both ends of each sandwich panel 101 are slidably connected to the frame 7. The extrusion plate 8 is mounted on the frame 7 relative to the sandwich panel assembly 1. The second driving device 9 is connected to the extrusion plate 8 and drives the extrusion plate 8 to move toward or away from the sandwich panel assembly 1. The extrusion plate 8 can move to a set position, and the extrusion plate 8 at the set position is in contact with the side of the outermost sandwich panel 101 in the sandwich panel assembly 1. By driving the extrusion plate 8 with the second driving device 9 to apply pressure to the first sandwich panel 101, and the sandwich panel 101 is slidably connected to the frame 7, a single power unit can simultaneously apply pressure to multiple sandwich panels 101. Combined with the pressure regulating component 3, the pressure values on the surfaces of multiple battery cell products are made consistent, thereby improving the consistency of the battery cell products.
[0032] In some embodiments, the second drive device 9 can be selected from at least one of a screw drive mechanism, a ball screw mechanism, a linkage mechanism, and an electric push rod mechanism. Taking the screw drive mechanism as an example, the second drive device 9 includes: a plurality of screws 901 and a driver 902; each screw 901 is arranged on the frame 7 along the arrangement direction of the sandwich panel assembly 1 and is also located on both sides of the sandwich panel assembly 1, and each screw 901 is threadedly connected to the extrusion plate 8; the driver 902 is drivenly connected to the screw 901. The extrusion plate 8 moves on the drive screw 901 so that the extrusion plate 8 is slidably connected to the frame 7, so that the extrusion plate 8 approaches and extrudes the first sandwich panel 101. Since the plurality of sandwich panels 101 are arranged sequentially, the extrusion plate 8 can apply pressure to the plurality of sandwich panels 101, and the pressure adjustment component 3 can adjust the pressure value on the surface of the cell between the sandwich panels 101, so that the batch of cell products are subjected to uniform force during formation, thereby improving the consistency of the cell products.
[0033] In some embodiments, the formation apparatus further includes a control device and a plurality of control valves 501, the number of which matches the number of the first drive devices 301, so that one control valve 501 controls one first drive device 301, thereby improving the accuracy of control; the control valves 501 are electrically connected to the corresponding first drive device 301 and the pressure detection structure 2 respectively, and are used to control the corresponding first drive device 301 to adjust the distance between the first cell contact surface 102 and the second cell contact surface 103 through the telescopic rod 302 based on the pressure on the surface of the cell product.
[0034] First, the control device controls the second driver 902 to drive the lead screw 901 to rotate rapidly. The lead screw 901 then drives the extrusion plate 8 to move rapidly to a set position, causing the extrusion surface of the extrusion plate 8 to contact the side of the outermost sandwich plate 102. Afterward, the control device controls the second driver 902 to reduce its rotation speed, and the extrusion plate 8 slowly compresses the battery cells between the sandwich plates 101.
[0035] During the compression process, each pressure detection structure 2 collects the pressure on the surface of the corresponding battery cell in real time. The control device obtains the real-time pressure information and determines whether the current pressure difference is less than a first preset value. If it is less than the first preset value, the control plate 101 is controlled to achieve constant compression of the battery cell. If it is greater than or equal to the first preset value, the control device adjusts the rotation speed of the driver 902 until the current pressure difference is less than the first preset value.
[0036] Then, control valve 501 is adjusted. The control device acquires real-time pressure information and determines whether the current pressure difference is less than a first preset value. If it is less than the first preset value, the control device controls control valve 501 to open the constant pressure. If it is greater than or equal to the first preset value, control valve 501 adjusts the length of the corresponding telescopic rod 302 until the current pressure difference is less than the first preset value.
[0037] Finally, after the extrusion of the battery cell is completed, the second drive device 9 controls the extrusion plate to reset.
[0038] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A high-precision pressure uniformity fixture, characterized in that, include: A sandwich panel assembly, comprising a plurality of sandwich panels arranged in sequence, wherein each pair of adjacent sandwich panels has a first cell contact surface and a second cell contact surface respectively; the space between the first cell contact surface and the second cell contact surface is used to place a cell product, and the spacing between the two is adjustable; Each of the first cell contact surfaces and / or the corresponding second cell contact surfaces is provided with a pressure detection structure, which is used to collect the pressure borne by the surface of the cell product. Each pair of adjacent sandwich panels is provided with a pressure regulating assembly. Each group of pressure regulating assemblies includes a first driving device and a telescopic rod. The first driving device is connected to one end of the telescopic rod. The other end of the telescopic rod passes through the first cell contact surface and is connected to the corresponding second cell contact surface. The first driving device is used to adjust the distance between the first battery cell contact surface and the second battery cell contact surface by means of the telescopic rod based on the pressure on the surface of the battery cell product.
2. The high-precision pressure uniformity fixture according to claim 1, characterized in that, In each pair of adjacent sandwich panels, the number of the first drive device and the telescopic rod is matched and is even. The even number of the first drive device and the telescopic rod are symmetrically arranged with respect to the first cell contact surface.
3. The high-precision pressure uniformity fixture according to claim 1, characterized in that, Each of the second cell contact surfaces is provided with limit blocks symmetrically at both ends, and the opposite sides of the limit blocks are provided with limit grooves; the shape of the limit groove matches the shape of the end of the cell product, and the end of the cell product is limited and installed in the corresponding limit groove.
4. The high-precision pressure uniformity fixture according to claim 3, characterized in that, A first mounting groove is provided on each of the first battery cell contact surfaces and / or on the corresponding second battery cell contact surfaces. The first mounting groove is located between the corresponding limiting blocks, and the pressure detection structure is a strain gauge and is disposed in the corresponding first mounting groove.
5. The high-precision pressure uniformity fixture according to claim 1, characterized in that, Each of the first battery cell contact surfaces and / or the corresponding second battery cell contact surfaces is further provided with a second mounting groove, each of the second mounting grooves is provided with an elastic buffer structure, and each of the elastic buffer structures is used to contact the surface of the battery cell product.
6. The high-precision pressure uniformity fixture according to claim 5, characterized in that, Each of the elastic buffer structures includes a spring and a plunger, the spring being disposed within the corresponding second mounting slot; one end of the plunger is connected to the corresponding spring, and the other end extends from the corresponding second mounting slot for contacting the surface of the battery cell product.
7. A formation apparatus, characterized in that, The device includes a pressure-applying assembly and a high-precision pressure uniformity clamp as described in any one of claims 1 to 6, wherein the pressure-applying assembly is used to apply a set pressure to the battery cell product held by the sandwich panel assembly.
8. The formation apparatus according to claim 7, characterized in that, The pressure application assembly also includes: a frame, an extrusion plate, and a second drive device; The sandwich panel assembly is mounted on the frame, and both ends of each sandwich panel are slidably connected to the frame. The extrusion plate is disposed on the frame relative to the sandwich panel assembly; The second driving device is connected to the extrusion plate and drives the extrusion plate to move in a direction toward or away from the sandwich panel assembly; the extrusion plate can move to a set position, and the extrusion plate at the set position is in contact with the side of the outermost sandwich panel in the sandwich panel assembly.
9. The formation apparatus according to claim 8, characterized in that, The second drive device includes: multiple lead screws and a driver; Each of the lead screws is arranged on the frame along the arrangement direction of the sandwich plates and is also located on both sides of the sandwich plate assembly. Each of the lead screws is threadedly connected to the extrusion plate. The driver is connected to the lead screw drive.
10. The formation apparatus according to claim 7, characterized in that, The formation device further includes a control device and a plurality of control valves, wherein the control device is electrically connected to each of the control valves; the number of control valves matches the number of the first drive devices; the control valves are respectively electrically connected to the corresponding first drive device and the pressure detection structure, and are used to control the corresponding first drive device to adjust the distance between the first battery cell contact surface and the second battery cell contact surface through the telescopic rod based on the pressure on the surface of the battery cell product.