Test structure for pouch battery airbag design and application thereof

Abstract

The present application relates to a kind of soft package battery air bag design test structure and its application, it is related to lithium ion battery technical field, the soft package battery air bag design test structure includes two main pressure plates for extruding sample to be measured, first vice pressure plate and second vice pressure plate are arranged on the main pressure plate, pressure sensor is arranged on the first vice pressure plate, the pressure sensor is connected with pressure display by wire, the second vice pressure plate is heating plate.The present application provides a kind of soft package battery air bag design test structure and its application, soft package battery aluminum plastic film air bag size can be simply, quickly, effectively and safely designed, and the test structure and method process involved are simple, effective, practical and strong.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a test structure for designing a pouch for a soft-pack battery and its application. Background Technology

[0002] Lithium-ion batteries, as a new generation of green and environmentally friendly energy products, possess advantages such as high energy density, high specific power, long lifespan, small size, light weight, high safety performance, and no memory effect. They are widely used in many fields, including 3C consumer electronics, power batteries, and energy storage. With the continuous development of the global economy and the increasingly serious energy shortage problem, the market share of lithium-ion batteries is constantly increasing, gradually becoming an important component of future green energy. Among them, polymer soft-pack lithium-ion batteries have higher energy density, more flexible shape, and higher safety, resulting in an increasingly larger market share.

[0003] During the formation of polymer soft-pack lithium batteries, side reactions between the electrolyte and the electrodes generate a large amount of gas. To ensure normal cell production, a portion of aluminum-plastic film is reserved during cell packaging to store the gas generated during the formation process. This reserved portion of aluminum-plastic film is called the cell gas bag. In the degassing process, the equipment punctures the gas bag, extracts the formation gas, performs a second sealing of the cell, and finally cuts off the gas bag to obtain the finished cell.

[0004] Traditional air bag design mainly relies on engineers' practical experience to estimate the width of the air bag based on the design capacity of the battery cell, rather than quantitative design, which leads to the following problems: (1) If the air bag design is too large, it will cause waste of aluminum-plastic film and increase the material cost of battery cell packaging; (2) If the air bag design is insufficient, it will affect the secondary sealing of the battery cell, causing poor sealing, resulting in the battery cell swelling or poor appearance during use.

[0005] In the prior art, patent application number CN201911293461.1 relates to a design method for an air bag in polymer soft-pack battery cells. This method determines the gas production coefficient of the battery cell during formation and then calculates the width of the air bag for effective gas storage space, thereby achieving the air bag design for polymer soft-pack battery cells. This overcomes the problems of unsuitable air bag design in traditional soft-pack battery cell packaging, which can lead to waste of aluminum-plastic film or affect the secondary sealing of the battery cell, resulting in poor sealing. The air bag design method described in this invention can effectively reduce the packaging cost of polymer soft-pack battery cells without affecting the battery cell seal and avoiding gas expansion or poor appearance during battery cell use. However, the air bag opening angle changes continuously with different gas production rates, leading to wrinkles or expansion of the aluminum-plastic film at the sealing point during battery cell packaging. Furthermore, the air bag opening angle needs to be measured experimentally, which is a very cumbersome process.

[0006] In the prior art, patent application number CN202011492598.2 discloses a design method for airbags in soft-pack battery cells. This method involves measuring the gas tolerance coefficient λ of the initial battery cell's airbag and using it as a bridge to apply to the airbag of the battery cell under test. This ensures that the internal coefficients of the airbags in both cells are the same. The volume of the airbag cavity in the battery cell under test is then calculated using a formula. This ensures that the aluminum-plastic film at the sealing point of the battery cell under test will not wrinkle or be stretched during the packaging process, thus guaranteeing the battery cell packaging effect. Although the measurement process involved in this patent is very simple and improves the design efficiency of the airbag to some extent, this method heavily relies on the gas tolerance coefficient λ = X1 / V1 of the initial battery cell's airbag. If the initial formation gas production X1 and the airbag volume V1 do not match, resulting in an unreasonable selection of the coefficient λ, the subsequently calculated airbag size becomes meaningless.

[0007] In conclusion, evaluating the packaging performance of pouch cells is crucial for the new energy industry, as it affects the cell's cycle life and safety. Therefore, a simple, rapid, effective, and safe solution for designing the gas bag size for pouch batteries is urgently needed. Summary of the Invention

[0008] This application provides a test structure for designing air bags for pouch batteries and its application, aiming to solve the problem of how to design the size of aluminum-plastic film air bags for pouch battery cells simply, quickly, effectively and safely.

[0009] In a first aspect, this application provides a test structure for designing a pouch cell air bag. The test structure includes two main pressure plates for compressing the sample to be tested. A first secondary pressure plate and a second secondary pressure plate are provided on the main pressure plates. A pressure sensor is provided on the first secondary pressure plate. The pressure sensor is connected to a pressure display via a wire. The second secondary pressure plate is a heating plate.

[0010] Furthermore, the main pressure plate, the first auxiliary pressure plate, and the second auxiliary pressure plate are all fixed to the extrusion equipment that can move left and right through bolt holes.

[0011] Furthermore, the main pressure plates are symmetrically arranged, and the first and second auxiliary pressure plates are spaced apart on opposite sides of the main pressure plates.

[0012] Furthermore, the heating temperature range of the second auxiliary pressure plate is 25℃~70℃; the pressure sensor has a range of 0.2~0.3MPa and an accuracy of 0.1%~1%FS.

[0013] Secondly, this application provides the application of the test structure for designing pouch cell air bags as described in any of the first aspects in the design of pouch cell air bag dimensions.

[0014] Thirdly, this application provides a method for designing the size of the air bag in a pouch battery, the method comprising the following steps:

[0015] S1: Obtain the battery cell after liquid injection;

[0016] S2: After adding a preset mass m of vaporizing agent to the injected battery cell, pre-seal it with an aluminum-plastic film to obtain a battery cell sample containing a preset air bag size.

[0017] S3: Place the battery cell sample to be tested between the second auxiliary pressure plates in the test structure for the design of the soft-pack battery air bag as described in any one of claims 1 to 4. At a preset experimental temperature T, pressurize and heat the battery cell sample to be tested to a preset value through the main pressure plate and the second auxiliary pressure plate. At the same time, record the force exerted on the first auxiliary pressure plate by the preset-sized air bag in the battery cell sample to be tested during the expansion process of the air bag of the preset size displayed by the pressure display.

[0018] S4: Plot the pressure curve of the first sub-pressure plate based on the force exerted on the first sub-pressure plate during the expansion of the air bag in the battery cell sample under test, which is displayed in real time by the pressure display.

[0019] S5: Change the preset mass m of the gasifying agent and the preset experimental temperature T, and repeat steps S2 to S4 to obtain the pressure curve of the first pressure plate under different preset mass m and preset experimental temperature T conditions.

[0020] S6: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset mass m and preset experimental temperature T conditions, select data points and calculate the critical gas production V0 of the preset size air bag according to Formula 1;

[0021] Formula 1: V0=m*R*T / (P*M); where V0 is the critical gas production rate, m is the mass of the gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent.

[0022] S7: Based on the actual gas production fluctuation range V(1±a%) of the battery cell sample to be tested, take k=1-a%, and calculate the actual gas production V1 of the applicable preset size air bag according to Formula 2;

[0023] Formula 2: V1 = k * V0; where V1 is the actual gas production, k is the correction coefficient, and V0 is the critical gas production.

[0024] S8: The gas production of the battery cell sample under test is fixed. The preset gas bag size of the battery cell sample under test is adjusted. Steps S2 to S4 are repeated to obtain the pressure curve of the first pressure plate under different preset gas bag sizes.

[0025] S9: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset air bag size conditions, select data points to obtain the critical air bag width dimension value H0 of the battery cell sample to be tested;

[0026] S10: Based on the k-value coefficient selected in S7, calculate the design value H1 of the air bag width of the battery cell sample to be tested according to Formula 3;

[0027] Formula 3: H1 = H0 / k; where H0 is the critical airbag width dimension, k is the correction coefficient, and H1 is the design value of the airbag width dimension.

[0028] Furthermore, the design method also includes:

[0029] S11: If the selected gap is large, take a new point near the critical condition to conduct the experiment, and repeat S1-S10 to obtain the actual gas production V1 of the gas bag of the battery cell sample to be tested and the design value H1 of the gas bag width of the battery cell sample to be tested.

[0030] Furthermore, the design standard line used for selecting data points can be adjusted according to the actual sealing strength of the air bag used.

[0031] Furthermore, the air bag sealing strength ranges from 0 to 30 kPa.

[0032] The technical solutions provided in this application have at least the following advantages compared with the prior art:

[0033] 1. The process of the cell air bag expansion acting on the pressure plate can simulate the effect of the cell air bag expansion on the adjacent air bags during the pre-charging process of the formation process. The design value obtained by this method can effectively ensure that the force between adjacent air bags is small or non-existent during the pre-charging process, while ensuring process safety.

[0034] 2. The design of the pre-sealed seal on the air bag is mainly based on the area of ​​the action area of ​​the clamp on the aluminum-plastic film air bag during the process of the equipment grabbing the battery cell. At the same time, the position and size can be adjusted according to the actual gripping position and the size of the clamp. The design value obtained by this method fully considers the process and can ensure the effective gripping of the aluminum-plastic film air bag by the equipment clamp during the manufacturing process.

[0035] 3. This method is applicable to all sizes and types of battery cells, including single-sided or double-sided tabs, consumer or power battery cells, and various types of air bag designs;

[0036] 4. This method takes into account the safety of the cell expansion process and effectively combines the manufacturing process design based on reality. It is operable and practical, and at the same time effectively reduces the packaging cost of polymer soft-pack cells.

[0037] 5. The vaporizing agent used in this method is a safe reagent such as dry ice and liquid nitrogen, and the testing process is safe, reliable and pollution-free;

[0038] 6. This method can quickly, effectively and safely design the gas bag for soft-pack batteries. At the same time, the cell structure, test structure and process methods involved are simple, effective and highly practical.

[0039] In summary, this invention provides a test structure for designing air bags for soft-pack batteries and its application, which can design the size of aluminum-plastic film air bags for soft-pack battery cells simply, quickly, effectively, and safely. At the same time, the test structure and method involved are simple, effective, and highly practical. Attached Figure Description

[0040] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0041] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of the front structure of the battery cell sample under test in an embodiment of this application;

[0043] Figure 2 This is a schematic diagram of the side structure of the battery cell sample under test in an embodiment of this application;

[0044] Figure 3 This is a schematic diagram of the test structure for the soft-pack battery gas bag design after adding the sample of the battery cell to be tested in the embodiments of this application;

[0045] Figure 4 This is a schematic diagram of the expansion and testing process of the battery cell sample under test in an embodiment of this application;

[0046] Figure 5 This is a force curve of the cell gas bag on the pressure plate under different temperature / vaporizing agent dosage conditions in Example 2 of this application;

[0047] Figure 6 This is a force curve of the cell air bag on the pressure plate under different temperature / air bag width dimensions in Embodiment 3 of this application;

[0048] Among them, 1 is the battery cell sample to be tested; 11 is the aluminum-plastic film; 111 is the aluminum-plastic film and the top seal of the electrode tab; 112 is the battery cell body; 113 is the aluminum-plastic film pre-seal first; 114 is the aluminum-plastic film pre-seal second; 115 is the battery cell air bag; 12 is the electrode tab; 13 is the stacked core package; 2 is the test structure component; 21 is the main pressure plate; 22 is the first auxiliary pressure plate; 23 is the second auxiliary pressure plate; 24 is the bolt hole first; 25 is the bolt hole second; 26 is the bolt hole third; 27 is the pressure sensor; 28 is the wire; 29 is the pressure display. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0051] Firstly, this application provides a test structure for the design of a pouch for soft-pack batteries, such as... Figure 3 As shown, the test structure for the soft-pack battery gas bag design includes two main pressure plates 21 for squeezing the sample to be tested. The main pressure plates 21 are provided with a first secondary pressure plate 22 and a second secondary pressure plate 23. The first secondary pressure plate 22 is provided with a pressure sensor 27. The pressure sensor 27 is connected to a pressure display 29 through a wire 28. The second secondary pressure plate 22 is a heating plate.

[0052] This application provides a test structure for designing air bags for soft-pack batteries. The test structure is simple in structure and highly practical, and can easily, quickly, effectively and safely design the size of aluminum-plastic film air bags for soft-pack battery cells.

[0053] In some specific embodiments, the main pressure plate, the first auxiliary pressure plate 22 and the second auxiliary pressure plate 23 are all fixed to the extrusion equipment that can move left and right through bolt holes (specifically bolt hole one 24, bolt hole two 25 and bolt hole three 26).

[0054] In some specific embodiments, the main pressure plate 21 is symmetrically arranged, and the first auxiliary pressure plate 22 and the second auxiliary pressure plate 23 are spaced apart on opposite sides of the main pressure plate 21.

[0055] In some specific embodiments, the pressure plate can be made of steel plate, or other materials such as silicone plate, and the bolt holes can be other fixing holes.

[0056] In some specific embodiments, the heating temperature range of the second auxiliary pressure plate 23 is 25℃~70℃; the pressure sensor has a range of 0.2~0.3MPa and an accuracy of 0.1%~1%FS.

[0057] In this application, the heating principle of the heating plate is as follows: the heating plate contains a resistance wire, which generates heat when current passes through it, and the amount of heat generated is directly proportional to the current intensity. Therefore, by controlling the current intensity, the heat generated by the resistance wire can be controlled, thereby achieving the purpose of heating and temperature regulation of the battery cell.

[0058] Secondly, based on a general inventive concept, this application provides the application of the test structure for designing pouch battery airbags as described in any of the first aspects in the design of pouch battery airbag dimensions.

[0059] The test structure provided in this application is simple in structure and highly practical. It can easily, quickly, effectively and safely design the size of the aluminum-plastic film air bag for soft-pack battery cells. At the same time, the test structure and method involved are simple, effective and highly practical.

[0060] Thirdly, based on a general inventive concept, this application provides a design method for the heat sealing effect of pouch cells, the design method comprising the following steps:

[0061] This application provides a method for designing the size of the air bag in a pouch battery, the method comprising the following steps:

[0062] S1: Obtain the battery cell after liquid injection;

[0063] S2: After adding a preset mass m of vaporizing agent to the injected battery cell, pre-seal it with an aluminum-plastic film to obtain a battery cell sample containing a preset air bag size.

[0064] S3: Place the battery cell sample to be tested between the second auxiliary pressure plates in the test structure for the design of the soft-pack battery air bag as described in any one of claims 1 to 4. At a preset experimental temperature T, pressurize and heat the battery cell sample to be tested to a preset value through the main pressure plate and the second auxiliary pressure plate. At the same time, record the force exerted on the first auxiliary pressure plate by the preset-sized air bag in the battery cell sample to be tested during the expansion process of the air bag of the preset size displayed by the pressure display.

[0065] S4: Plot the pressure curve of the first sub-pressure plate based on the force exerted on the first sub-pressure plate during the expansion of the air bag in the battery cell sample under test, which is displayed in real time by the pressure display.

[0066] S5: Change the preset mass m of the gasifying agent and the preset experimental temperature T, and repeat steps S2 to S4 to obtain the pressure curve of the first pressure plate under different preset mass m and preset experimental temperature T conditions.

[0067] S6: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset mass m and preset experimental temperature T conditions, select data points and calculate the critical gas production V0 of the preset size air bag according to Formula 1;

[0068] Formula 1: V0=m*R*T / (P*M); where V0 is the critical gas production rate, m is the mass of the gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent.

[0069] S7: Based on the actual gas production fluctuation range V(1±a%) of the battery cell sample to be tested, take k=1-a%, and calculate the actual gas production V1 of the applicable preset size air bag according to Formula 2;

[0070] Formula 2: V1 = k * V0; where V1 is the actual gas production, k is the correction coefficient, and V0 is the critical gas production.

[0071] S8: The gas production of the battery cell sample under test is fixed. The preset gas bag size of the battery cell sample under test is adjusted. Steps S2 to S4 are repeated to obtain the pressure curve of the first pressure plate under different preset gas bag sizes.

[0072] S9: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset air bag size conditions, select data points to obtain the critical air bag width dimension value H0 of the battery cell sample to be tested;

[0073] S10: Based on the k-value coefficient selected in S7, calculate the design value H1 of the air bag width of the battery cell sample to be tested according to Formula 3;

[0074] Formula 3: H1 = H0 / k; where H0 is the critical airbag width dimension, k is the correction coefficient, and H1 is the design value of the airbag width dimension.

[0075] This application provides a design method for the heat sealing effect of pouch cells, which has at least the following advantages compared to existing design methods:

[0076] 1. The process of the cell air bag expansion acting on the pressure plate can simulate the effect of the cell air bag expansion on the adjacent air bags during the pre-charging process of the formation process. The design value obtained by this method can effectively ensure that the force between adjacent air bags is small or non-existent during the pre-charging process, while ensuring process safety.

[0077] 2. The design of the pre-sealed seal on the air bag is mainly based on the area of ​​the action area of ​​the clamp on the aluminum-plastic film air bag during the process of the equipment grabbing the battery cell. At the same time, the position and size can be adjusted according to the actual gripping position and the size of the clamp. The design value obtained by this method fully considers the process and can ensure the effective gripping of the aluminum-plastic film air bag by the equipment clamp during the manufacturing process.

[0078] 3. This method is applicable to all sizes and types of battery cells, including single-sided or double-sided tabs, consumer or power battery cells, and various types of air bag designs;

[0079] 4. This method takes into account the safety of the cell expansion process and effectively combines the manufacturing process design based on reality. It is operable and practical, and at the same time effectively reduces the packaging cost of polymer soft-pack cells.

[0080] 5. The vaporizing agent used in this method is a safe reagent such as dry ice and liquid nitrogen, and the testing process is safe, reliable and pollution-free;

[0081] 6. This method can quickly, effectively and safely design the gas bag for soft-pack batteries. At the same time, the cell structure, test structure and process methods involved are simple, effective and highly practical.

[0082] In summary, this invention provides a test structure for designing air bags for soft-pack batteries and its application, which can design the size of aluminum-plastic film air bags for soft-pack battery cells simply, quickly, effectively, and safely. At the same time, the test structure and method involved are simple, effective, and highly practical.

[0083] In this application, the design standard line is designed based on the range of force exerted on the upper pressure plate during the inflation process of the air bag. Ideally, there is no force (i.e., the standard line ≤ 0) to ensure that there is no squeezing effect between the air bags of different cells during the pre-charging process of the battery cells, thereby avoiding safety issues caused by the rupture of the air bags during the squeezing process. However, since the battery cell packaging shell itself has a certain pressure resistance, it can be allowed to be subjected to slight squeezing, and the standard line can be slightly relaxed (i.e., the standard line ≤ 0~30KPa).

[0084] In this application, the method of selecting data points can be as follows: select points based on experimental data curves and design standard lines (≤ a certain standard value). As long as the air bag width dimension corresponding to the curve below the design standard line is met, the largest air bag width among those that meet the requirements is selected as the critical air bag width dimension, and then proceed to the next step of calculation.

[0085] Furthermore, the design method also includes:

[0086] S11: If the selected gap is large, take a new point near the critical condition to conduct the experiment, and repeat S1-S10 to obtain the actual gas production V1 of the gas bag of the battery cell sample to be tested and the design value H1 of the gas bag width of the battery cell sample to be tested.

[0087] In some specific embodiments, the intervals are relatively large: the design values ​​of initial gasifying agent dosage of 40, 80, and 120 on the vertical axis of the table differ significantly (interval of 40). To obtain more accurate data, the intervals can be reduced, such as 40, 60, 80, 100, and 120 (interval of 20).

[0088] Furthermore, the design standard line used for selecting data points can be adjusted according to the actual sealing strength of the air bag used.

[0089] Furthermore, the air bag sealing strength ranges from 0 to 30 kPa.

[0090] In some specific embodiments, the above testing process may specifically include the following steps:

[0091] S1: The laminated core package and the tab are pre-welded and final-welded to obtain the welded core package;

[0092] S2: Punch the aluminum-plastic film according to the designed pit depth, and then seal the core package after welding to obtain the battery cell before liquid injection.

[0093] S3: Inject a certain amount of solvent according to the design value to obtain the battery cell after liquid injection;

[0094] S4: After adding a vaporizing agent of mass m, quickly pre-seal with aluminum-plastic film to obtain the battery cell to be tested;

[0095] S5: Fix the upper and lower auxiliary pressure plates to the surface of the main pressure plate through the bolt holes, and then install the test structure onto the extrusion equipment through the bolt holes;

[0096] S6: Place the battery cell under test in the test structure, pressurize the battery cell body to the set value through the main pressure plate and the lower auxiliary pressure plate, and at the same time, the pressure display records the force on the upper auxiliary pressure plate during the expansion of the battery cell air bag.

[0097] S7: Plot the S-curve using real-time data from the pressure display;

[0098] S8: Conduct experiments according to different preset amounts of gasifying agent and pre-charge temperatures, and plot the pressure curves of the pressure plate under different conditions;

[0099] S9: Based on the pressure curve of the pressure plate under different conditions and the design standard line, select appropriate data points and calculate the critical gas production V0 applicable to the gas bag of this size: V0 = m*R*T / (P*M), where m is the mass of the added gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent.

[0100] S10: Based on the actual fluctuation of gas production in the battery cell, take the k value coefficient and calculate the design value of the actual gas production applicable to the gas bag of this size, V1 = k * V0.

[0101] S11: After the internal system of the battery cell (i.e., gas production) is fixed, adjust the size of the gas bag according to S1-S7, and draw the pressure plate stress curve under different conditions.

[0102] S12: Based on the pressure curve of the pressure plate under different conditions and the design standard line, select appropriate data points to obtain the critical aluminum-plastic film air bag width dimension H0 under this cell system;

[0103] S13: Based on the k value coefficient taken in S10, calculate the design value H1 = H0 / k of the width of the aluminum-plastic film air bag under this battery cell system.

[0104] S14: If the selected gap is large, the experiment can be repeated near the critical condition, and S1-S13 can be repeated to finally obtain the gas production capacity that the cell gas bag can accommodate or the suitable gas bag width size for the cell system.

[0105] In some specific embodiments, the front and side structural schematic diagrams of the battery cell sample under test are respectively as shown in the figure. Figure 1 and Figure 2 As shown in the diagram, the expansion of the battery cell sample under test and the testing process are illustrated in the figure below. Figure 4 As shown; where 1 is the battery cell sample to be tested; 11 is the aluminum-plastic film; 111 is the aluminum-plastic film and top seal of the electrode tab; 112 is the battery cell body; 113 is the aluminum-plastic film pre-seal first; 114 is the aluminum-plastic film pre-seal second; 115 is the battery cell air bag; 12 is the electrode tab; 13 is the stacked core package; 2 is the test structure component; 21 is the main pressure plate; 22 is the first auxiliary pressure plate; 23 is the second auxiliary pressure plate; 24 is the bolt hole first; 25 is the bolt hole second; 26 is the bolt hole third; 27 is the pressure sensor; 28 is the wire; 29 is the pressure display.

[0106] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0107] Example 1

[0108] This application provides a test structure for designing a pouch cell for a soft-pack battery. A schematic diagram of the test structure for designing a pouch cell for a soft-pack battery with a sample of the battery cell to be tested inserted is shown below. Figure 3As shown, the test structure for the soft-pack battery gas bag design includes two main pressure plates 21 for compressing the sample to be tested. A first auxiliary pressure plate 22 and a second auxiliary pressure plate 23 are mounted on the main pressure plate 21. A pressure sensor 27 is mounted on the first auxiliary pressure plate 22, and the pressure sensor 27 is connected to a pressure display 29 via a wire 28. The second auxiliary pressure plate 22 is a heating plate. The main pressure plates, the first auxiliary pressure plate 22, and the second auxiliary pressure plate 23 are all fixed to a left-right movable extrusion device via bolt holes (specifically bolt hole 1 24, bolt hole 25, and bolt hole 3 26). The main pressure plates 21 are symmetrically arranged, and the first auxiliary pressure plate 22 and the second auxiliary pressure plate 23 are spaced apart on opposite sides of the main pressure plates 21. The heating temperature range of the second auxiliary pressure plate 23 is 25℃~70℃. The pressure sensor has a range of 0.2~0.3MPa and an accuracy of 0.1%~1%FS.

[0109] Example 2

[0110] This embodiment provides a method for designing the size of the air bag for a soft-pack battery, the method comprising the following steps:

[0111] S1: The laminated core package and the tab are pre-welded and final-welded to obtain the welded core package;

[0112] S2: The aluminum-plastic film is punched and cut (450mm*340mm) according to the design pit depth of 5.2mm, and then sealed with the core package after welding to obtain the battery cell before liquid injection;

[0113] S3: Inject a certain amount of electrolyte according to the design value of 150g to obtain the electrolyte-filled battery cell. The battery cell body thickness is 11.2mm, the length is 322mm, the width is 105mm, and the air bag width is 120mm.

[0114] S4: After adding a certain amount of dry ice vaporizing agent, quickly pre-seal with aluminum-plastic film to obtain the battery cell to be tested;

[0115] S5: Fix the upper and lower auxiliary pressure plates to the surface of the main pressure plate through the bolt holes, and then install the test structure onto the extrusion equipment through the bolt holes;

[0116] S6: Place the battery cell under test in the test structure, pressurize and heat the battery cell body to the set value through the main pressure plate and the lower auxiliary pressure plate, and at the same time, the pressure display records the force on the upper auxiliary pressure plate during the expansion of the battery cell air bag.

[0117] S7: Plot the S-curve using real-time data from the pressure display;

[0118] S8: Conduct experiments according to the different amounts of gasifying agent and temperatures preset in Table 1, and plot the pressure curves of the pressure plate under different conditions;

[0119] S9: Based on the corresponding curves of different gasifying agents at 25℃ and the design standard line (≤20KPa), select a suitable data point m of 200mg, and calculate the critical gas production rate applicable to this size gas bag, as shown below:

[0120] V 10 =m*R*T / (P*M)=200*8.314*(273.15+25) / (100*44)=112.67ml;

[0121] Where m is the mass of the gasifying agent added, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent;

[0122] S10: Based on the actual gas production fluctuation range of 50ml (1±15%) of the battery cell, and taking k = 1 - 15% = 0.85, calculate the actual gas production capacity applicable to this size of air bag, as shown below:

[0123] V 11 =k*V 10 =0.85 * 112.67 = 95.76 ml

[0124] S11: Based on the corresponding curves of different gasifying agents at 45℃ and the design standard line (≤20KPa), select a suitable data point m of 160mg, and calculate the critical gas production rate applicable to this size gas bag, as shown below:

[0125] V 20 =m*R*T / (P*M)=160*8.314*((273.15+45)) / (100*44)=96.18ml;

[0126] Where m is the mass of the gasifying agent added, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent;

[0127] S12: Based on the actual fluctuations in gas production from the battery cell, take k = 0.85 and calculate the actual gas production applicable to this gas bag size.

[0128] As shown below: V 21 =k*V 20＝ 0.85 * 96.18 = 81.75 ml;

[0129] S13: Test results show that the applicable gas production values ​​for this size airbag under pre-charging conditions of 25℃ and 45℃ are 95.76ml and 81.75ml, respectively. If the dimensions of the battery cell (length, width, thickness, etc.) and the airbag size are adjusted, the experiment needs to be repeated for verification.

[0130] Table 1 shows the force exerted by the cell gas bag on the pressure plate under different temperatures / agent dosages. Figure 5The force curves of the cell gas bag on the pressure plate under different temperatures / agent dosages are shown.

[0131] Table 1. Force exerted by the cell gas bag on the pressure plate under different temperatures / vaporizer dosages.

[0132]

[0133]

[0134] Note: The pressure plate force data in the table are selected partial test data.

[0135] Example 3

[0136] This embodiment provides a method for designing the size of the air bag for a soft-pack battery, the method comprising the following steps:

[0137] S1: After lamination, the core package and the tab are pre-welded and final-welded to obtain the welded core package;

[0138] S2: The aluminum-plastic film is punched and cut (450mm*340mm) according to the design pit depth of 5.2mm, and then sealed with the core package after welding to obtain the battery cell before liquid injection;

[0139] S3: Inject a certain amount of electrolyte according to the design value of 150g to obtain the electrolyte-filled battery cell. The battery cell body thickness is 11.2mm, the length is 322mm, the width is 105mm, and the air bag width is 120mm.

[0140] S4: Given that the gas production of the battery cell in this system is 50ml, after theoretical calculation, 90mg of dry ice vaporizing agent was added and the aluminum-plastic film was quickly pre-sealed to obtain the battery cell to be tested.

[0141] S5: Fix the upper and lower auxiliary pressure plates to the surface of the main pressure plate through the bolt holes, and then install the test structure onto the extrusion equipment through the bolt holes;

[0142] S6: Place the battery cell under test in the test structure, pressurize the battery cell body to the set value through the main pressure plate and the lower auxiliary pressure plate, and at the same time, the pressure display records the force on the upper auxiliary pressure plate during the expansion of the battery cell air bag.

[0143] S7: Plot the S-curve using real-time data from the pressure display;

[0144] S8: Adjust the aluminum-plastic film punching size according to the preset value in Table 2, conduct experiments on the battery cell samples with different air bag widths, and plot the pressure curve of the pressure plate under different conditions.

[0145] S9: Based on the curves corresponding to different air bag height dimensions at 25℃ and the design standard line (≤20KPa), select appropriate data points to obtain the critical aluminum-plastic film air bag dimension H under this cell system.10 =60mm, where m is the mass of the added gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent;

[0146] S10: Based on the actual fluctuations in gas production from the battery cell, taking k = 0.85, calculate the required actual aluminum-plastic film gas bag design dimensions for this battery cell system, as shown below:

[0147] H 11 =H 10 / k=60 / 0.85=70.58mm;

[0148] S11: Based on the curves corresponding to different air bag height dimensions at 25℃, design a standard line (≤20KPa), select appropriate data points, and obtain the critical aluminum-plastic film air bag dimension H under this cell system. 20 =70mm, where m is the mass of the added gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent;

[0149] S12: Based on the actual gas production fluctuation range of 50ml (1±15%) of the battery cell, and taking k = 1 - 15% = 0.85, calculate the actual design size of the aluminum-plastic film gas bag required for this battery cell system, as shown below:

[0150] H 21 =H 20 / k=70 / 0.85=82.35mm;

[0151] S13: Test results show that the width of the air bag of this size can be reduced to 70.58mm and 82.35mm respectively under pre-charging conditions at 25℃ and 45℃. If the dimensions of the battery cell, such as length, width, and thickness, are adjusted, the experiment needs to be repeated for verification.

[0152] Table 2 shows the force exerted by the cell air bag on the pressure plate under different temperatures and air bag widths. Figure 6 The force curves of the cell air bag on the pressure plate under different temperatures and air bag widths are shown.

[0153] Table 2. Force exerted by cell air bags on pressure plates under different temperatures and air bag widths.

[0154]

[0155] In summary, this invention provides a test structure and process method for designing air bags for flexible battery cells. This method enables simple, rapid, effective, and safe design of the dimensions of aluminum-plastic film air bags for flexible battery cells. Furthermore, the cell structure, test structure, and process involved are simple, effective, and highly practical.

[0156] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0157] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0158] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for designing the size of a pouch for a soft-pack battery, characterized in that, A test structure for a soft-pack battery air bag design is adopted. The test structure for a soft-pack battery air bag design includes two main pressure plates for compressing the sample to be tested. The main pressure plates are provided with a first secondary pressure plate and a second secondary pressure plate. The first secondary pressure plate is provided with a pressure sensor, which is connected to a pressure display through a wire. The second secondary pressure plate is a heating plate. The design method for the size of the pouch cell in the soft-pack battery includes the following steps: S1: Obtain the battery cell after liquid injection; S2: After adding a preset mass m of vaporizing agent to the injected battery cell, pre-seal it with an aluminum-plastic film to obtain a battery cell sample containing a preset air bag size. S3: Place the battery cell sample to be tested between the second auxiliary pressure plates in the test structure for the design of the soft-pack battery air bag. At a preset experimental temperature T, pressurize and heat the battery cell sample to be tested to a preset value through the main pressure plate and the second auxiliary pressure plate. At the same time, record the force exerted on the first auxiliary pressure plate by the preset size air bag in the battery cell sample to be tested during the expansion process of the preset size air bag in the battery cell sample to be tested, which is displayed in real time by the pressure display. S4: Plot the pressure curve of the first sub-pressure plate based on the force exerted on the first sub-pressure plate during the expansion of the air bag in the battery cell sample under test, which is displayed in real time by the pressure display. S5: Change the preset mass m of the gasifying agent and the preset experimental temperature T, and repeat steps S2~S4 to obtain the pressure curve of the first pressure plate under different preset mass m and preset experimental temperature T conditions. S6: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset mass m and preset experimental temperature T conditions, select data points and calculate the critical gas production V0 of the preset size air bag according to Formula 1; Formula 1: Where V0 is the critical gas production rate, m is the mass of the gasifying agent, T is the experimental temperature, P is the atmospheric pressure at the experimental site, and M is the molar mass of the gasifying agent. S7: Based on the actual gas production fluctuation range V (1±a%) of the battery cell sample to be tested, take... And calculate the actual gas production V1 of the applicable preset size air bag according to Formula 2; Formula 2: Where V1 is the actual gas production, k is the correction coefficient, and V0 is the critical gas production. S8: The actual gas production of the battery cell sample under test is fixed. Adjust the preset gas bag size of the battery cell sample under test and repeat steps S2~S4 to obtain the first pressure plate pressure curve under different preset gas bag size conditions. S9: Based on the pressure curve of the first auxiliary pressure plate and the design standard line under different preset air bag size conditions, select data points to obtain the critical air bag width dimension value H0 of the battery cell sample to be tested; S10: Based on the k-value coefficient selected in S7, calculate the design value H1 of the air bag width of the battery cell sample to be tested according to Formula 3; Formula 3: Where H0 is the critical airbag width dimension, k is the correction coefficient, and H1 is the design value of the airbag width dimension.

2. The design method for the size of the pouch for a soft-pack battery according to claim 1, characterized in that, The main pressure plate, the first auxiliary pressure plate, and the second auxiliary pressure plate are all fixed to the extrusion equipment that can move left and right through bolt holes.

3. The design method for the size of the pouch for a soft-pack battery according to claim 1, characterized in that, The main pressure plates are symmetrically arranged, and the first and second auxiliary pressure plates are spaced apart on opposite sides of the main pressure plates.

4. The design method for the size of the pouch for a soft-pack battery according to claim 1, characterized in that, The heating temperature range of the second auxiliary pressure plate is 25℃~70℃; the pressure sensor has a range of 0.2~0.3MPa and an accuracy of 0.1%~1%FS.

5. The design method for the size of the pouch for a soft-pack battery according to claim 1, characterized in that, The design method further includes: S11: If the gap between different gasifying agent dosage designs or different gas bag width designs is large, redesign the experiment near the critical data points obtained in steps S6 and S8, and repeat S1-S10 to obtain the actual gas production V1 of the gas bag of the battery cell sample to be tested and the designed value H1 of the gas bag width of the battery cell sample to be tested.

6. The method for designing the size of the pouch for a soft-pack battery according to claim 1 or 5, characterized in that, The design standard line used for selecting data points can be adjusted according to the actual sealing strength of the air bag.

7. The method for designing the size of the pouch for a soft-pack battery according to claim 6, characterized in that, The design standard line ranges from 0 to 30 kPa.

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