Accelerated thermal aging detection method for aluminum plastic film

Abstract

The invention belongs to the technical field of aluminum plastic film performance detection, and particularly relates to an aluminum plastic film accelerated thermal aging detection method which comprises the following steps: S1, testing the initial stripping force performance of an aluminum plastic film test sample; s2, importing an acceleration factor calculation formula according to an ASTM standard; s3, calculating normal corresponding normal working time L1 according to the acceleration factor AF; l2 is the working time at high temperature; l3 is the working time under high temperature and high humidity; s4, accelerated aging temperature and humidity are designed, and acceleration factors AF and corresponding L2 and L3 in the placement environment and the normal working environment are calculated respectively; and S5, directly placing the aluminum-plastic film test sample in a high-temperature and high-humidity box and a high-temperature box soaked in a polytetrafluoroethylene bottle containing electrolyte respectively, testing the electrolysis-resistant stripping force performance of the aged inner layer according to L2, testing the stripping force performance of the aged outer layer according to L3, and determining that the aluminum-plastic film test sample is qualified when the stripping force for accelerated aging meets the set requirement.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum-plastic film performance detection, and particularly relates to an aluminum-plastic film accelerated heat aging detection method. BACKGROUND

[0002] With the rapid development of the electric vehicle industry in the past two years, the technical requirements for lithium ion batteries, especially power lithium ion batteries, have been significantly improved, and the industry has also put forward more stringent requirements for aluminum-plastic film. However, the performance testing in the aluminum-plastic film industry is still at the level of routine testing, and the long-term performance of aluminum-plastic film is often lagging behind, which can only be determined by the feedback from the after-sales market of finished lithium batteries.

[0003] Therefore, how to predict the long-term performance of aluminum-plastic film under accelerated aging based on the initial performance of aluminum-plastic film is a technical problem that needs to be solved in the field.

[0004] It should be noted that the above information disclosed in the background section is only used to understand the background of the present application, and therefore, the above description is not considered to constitute prior art information. SUMMARY

[0005] The embodiments of the present disclosure at least provide an aluminum-plastic film accelerated heat aging detection method.

[0006] In a first aspect, the embodiments of the present disclosure provide an aluminum-plastic film accelerated heat aging detection method, which comprises the following steps: S1, testing the initial peel force performance of an aluminum-plastic film test sample; S2, introducing an acceleration factor calculation formula according to the ASTM standard, wherein the acceleration factor calculation formula comprises: a temperature acceleration factor T1 is the absolute temperature under normal working condition, T2 is the absolute temperature under accelerated high temperature, Ea is the activation energy of the product, and k is the Boltzmann constant; a humidity acceleration factor RH1 is the humidity under normal working condition, RH2 is the humidity under accelerated heat and humidity, and n is 2 or 3; a temperature and humidity total acceleration factor S3, calculating the high-temperature aging time L2 and the high-temperature and high-humidity aging time L3 according to the acceleration factors TAF / AF and the normal working time L1, respectively, and the calculation formula is as follows: L1=L2*TAF; L1=L3*AF; L2 is the working time under high temperature; L3 is the working time under high temperature and high humidity; S4, designing the accelerated aging temperature and temperature and humidity, and obtaining the acceleration factors TAF and AF under the placement environment and the normal working environment and the corresponding L2 and L3; S5, respectively placing the aluminum-plastic film test sample in a high-temperature and high-humidity box and a high-temperature box immersed in a polytetrafluoroethylene bottle containing electrolyte, testing the aged inner layer electrolyte peel force performance according to L2, and testing the aged outer layer peel force performance according to L3, and the aluminum-plastic film is qualified when the peel force under accelerated aging meets the set requirements.

[0007] In an alternative embodiment, the thickness of the aluminum-plastic film test sample is 100-200 μm.

[0008] In an alternative embodiment, the absolute temperature T1 of the lithium battery placement temperature is set to 25 DEG C, i.e. 273+25K; and the absolute temperature T1 of the normal working temperature of the lithium battery is set to 40 DEG C, i.e. 273+40K.

[0009] In an alternative embodiment, the absolute temperature T2 of the accelerated high temperature is set to a range of M DEG C, i.e. 273+MK, wherein M is greater than 40.

[0010] In an alternative embodiment, the product activation energy Ea is set to 0.6 eV, and the Boltzmann constant k = 8.6*10 -5 eV / K.

[0011] In an alternative embodiment, the normal working time L1 is set to a range of 3-5 years, i.e. 26280-43800 h.

[0012] In an alternative embodiment, the humidity RH1 under the normal working temperature is set to 50%.

[0013] In an alternative embodiment, the humidity RH2 under the accelerated aging is set to a range of N%, wherein N is greater than 50.

[0014] In an alternative embodiment, the peeling force performance includes the electrolyte peeling force of ONY / AL and PP / AL.

[0015] In an alternative embodiment, the electrolyte includes DMC, DEC, EC and lithium salt.

[0016] The aluminum-plastic film accelerated thermal aging detection method has the advantages that the accelerated model is established according to the daily working temperature and humidity of the lithium battery and the design service life, the reaction time of the lithium battery under the design service life in the equal ratio normal environment is calculated under the experimental accelerated environment by using the total acceleration factor of the temperature and humidity, and the aging performance of the aluminum-plastic film is quickly evaluated to determine whether it is qualified.

[0017] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art upon examination of the following or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the description and the drawings.

[0018] In order to make the above objectives, features and advantages of the present application more apparent, the following preferred embodiments are described in detail, and the accompanying drawings are referred to, and the detailed description is as follows. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the specific embodiments or prior art of the present application, the drawings required to be used in the description of the specific embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0020] Figure 1 The outer layer ONY / AL peeling force performance data graph provided by the embodiment of the present disclosure;

[0021] Figure 2 The inner layer PP / AL electrolyte solution resistance peeling force performance data graph provided by the embodiment of the present disclosure;

[0022] Figure 3 The photo of the aluminum-plastic film peeled from the outer layer ONY / AL after placing the example B in the 85°C oven 111D provided by the embodiment of the present disclosure;

[0023] Figure 4 The photo of the inner layer PP / AL aluminum-plastic film after placing the example F in the 85°C, 85%RH high temperature and high humidity box provided by the embodiment of the present disclosure. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the present application will be described clearly and completely below in combination with the drawings. Obviously, the described embodiments are some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0025] As used herein, the phrases "in an embodiment", "according to an embodiment", "in some embodiments", and the like generally mean the fact that a particular feature, structure, or characteristic described after the phrase can be included in at least one embodiment of the present disclosure. Therefore, the particular feature, structure or characteristic can be included in more than one embodiment of the present disclosure, so that these phrases do not necessarily refer to the same embodiment. As used herein, the terms "example", "exemplary", and the like are used as an example, instance, or illustration. Any implementation, aspect or design described herein as "example" or "exemplary" is not necessarily interpreted as preferred or superior to other implementations, aspects or designs. On the contrary, the use of the terms "example", "exemplary" and the like is intended to present the concept in a specific manner.

[0026] In this document, example embodiments of the disclosure will be described in greater detail. As used herein, expressions such as "at least one of," when preceding the term "comprising," "including," or "having," denotes the existence of at least one or more of the stated features and / or objects. For example, the expression "at least one of a, b, and c" should be construed to mean a, b, or c individually or any two or more of the a, b, and c, for example, a or b, or a or c, or a or d, and so forth, but not a+b+c.

[0027] The terminology used herein is for the purpose of describing particular example configurations only and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order in which they are discussed or illustrated, unless specifically identified as an order of performance. Additional or alternative steps can be employed.

[0028] It is to be noted that like-numbers and like-letters refer to like items throughout the drawings, and once an item is defined in one drawing, that definition should be applied to all like- numbered and like-lettered items in the other drawings.

[0029] Some embodiments of the present application will now be described in detail in connection with the accompanying drawings. The following embodiments and features are not mutually exclusive and can be combined with each other.

[0030] The aluminum-plastic film accelerated heat aging detection method provided by the embodiments of the present disclosure comprises the following steps: S1, testing the initial peeling force performance of an aluminum-plastic film test sample; S2, establishing an acceleration model, and importing an acceleration factor calculation formula according to an ASTM standard, wherein the acceleration factor calculation formula comprises: a temperature acceleration factor T1 is an absolute temperature under normal operation, T2 is an absolute temperature under accelerated high temperature, Ea is a product activation energy, and k is a Boltzmann constant; a humidity acceleration factor RH1 is humidity under normal operation, RH2 is humidity under accelerated heat and humidity, and n is 2 or 3; a temperature and humidity total acceleration factor S3, according to the acceleration factor TAF / AF and normal working time L1, respectively calculate the high temperature aging time L2, the high temperature and high humidity aging time L3, the formula is as follows: L1=L2*TAF; L1=L3*AF; L2 is the working time under high temperature; L3 is the working time under high temperature and high humidity; S4, design the acceleration aging temperature and temperature and humidity, and obtain the placement environment and the acceleration factor TAF, AF and corresponding L2, L3 under normal working environment; S5, respectively, the aluminum plastic film test sample is directly placed in the high temperature and high humidity box and immersed in the polytetrafluoroethylene bottle containing electrolyte, according to L2 test aging inner layer electrolyte stripping force performance, according to L3 test aging outer layer stripping force performance, when the stripping force of acceleration aging meets the set requirements, it is qualified.

[0031] Specifically, the working temperature range of lithium battery is usually between-20℃ to 60℃, in high temperature environment, the chemical reaction in the lithium battery will accelerate, causing the temperature rise in the battery, high temperature will also accelerate the aging of the materials in the battery, in high temperature, it is convenient to obtain the aging performance data of aluminum plastic film.

[0032] Specifically, for the humidity requirement, the storage environment humidity of lithium battery should be controlled below 50%RH, and the use environment humidity should also be kept at a lower level as much as possible. Too high humidity will cause the battery to produce electrochemical reaction, and then cause the battery to leak, corrosion and other problems, which seriously affect the performance and safety of the battery, in high humidity, it is convenient to obtain the aging performance data of aluminum plastic film.

[0033] In some embodiments, specifically, the thickness specification of the aluminum plastic film test sample is 100μm-200μm.

[0034] In some embodiments, specifically, the absolute temperature T1 of the lithium battery placement temperature is set to 25℃, that is, 273+25K; the absolute temperature T1 of the normal working temperature of the lithium battery is set to 40℃, that is, 273+40K.

[0035] In some embodiments, specifically, the absolute temperature T2 under the acceleration high temperature is set to the range of M℃, that is, 273+MK, and M is greater than 40.

[0036] In some embodiments, specifically, the product activation energy Ea is set to 0.6eV, and the Boltzmann constant k=8.6*10 -5 eV / K.

[0037] In some embodiments, specifically, the normal working time L1 is set to range from 3 to 5 years, i.e. 26280 to 43800 hours; the service life of the lithium battery is affected by various factors, including the number of charging cycles, usage habits, environmental conditions, etc. Generally, the service life of the lithium battery is 3-5 years, so when the service life is 5 years, L1 = 5*365*24 = 43800 hours.

[0038] In some embodiments, specifically, the humidity RH1 under normal working is set to 50%.

[0039] In some embodiments, specifically, the humidity RH2 under accelerated aging is set to range from N%, and the N is greater than 50.

[0040] In some embodiments, specifically, the peeling force performance includes the electrolyte resistance of ONY / AL and PP / AL.

[0041] In some embodiments, specifically, the electrolyte includes DMC, DEC, EC and lithium salt, specifically, the DMC is dimethyl carbonate, the DEC is diethyl carbonate, the EC is ethylene carbonate, the ratio of DMC:DEC:EC is preferably 1:1:1, and the content of the lithium salt is preferably 1 mol.

[0042] Embodiment 1

[0043] S1, test the initial peeling force performance of the aluminum plastic film test sample ABCDEFG, the specification of the aluminum plastic film test sample is ABCD specification: thickness 113 μm* width 15 mm* length 120 mm; EFG specification: thickness 153 μm* width 15 mm* length 120 mm;

[0044] S2, according to the ASTM standard, the accelerated factor calculation formula is introduced, and the accelerated factor calculation formula includes:

[0045] Temperature acceleration factor T1 is the absolute temperature under normal working, the absolute temperature T1 of the lithium battery placement temperature is set to 25℃, i.e. 273+25K; the absolute problem T1 of the normal working temperature of the lithium battery is set to 40℃, i.e. 273+40K, T2 is the absolute temperature under accelerated high temperature, the absolute temperature T2 under accelerated high temperature is set to 85℃, i.e. 273+85K, Ea is the product activation energy 0.6Ev, k is the Boltzmann constant 8.6*10 -5 eV / K;

[0046] Humidity acceleration factor RH1 is the humidity under normal working and is set to 50%, RH2 is the humidity under accelerated heat and humidity and is set to 85%, and n is 2.

[0047] Temperature and humidity total acceleration factor

[0048] S3, according to the acceleration factor AF and normal working time L1, 43800h, respectively, calculate the high temperature aging time L2, high temperature and humidity aging time L3; formula as follows: L1=L2*TAF; L1=L3*AF; L2 is the working time under high temperature; L3 is the working time under high temperature and humidity;

[0049] S4, design the acceleration aging temperature, temperature and humidity, and obtain the placement environment and normal working environment under the acceleration factor TAF, AF and the corresponding L2, L3;

[0050] The high temperature acceleration factor TAF is calculated as follows:

[0051] The lithium battery is placed in

[0052] The lithium battery is normally working in

[0053]

[0054] The high temperature and humidity acceleration factor AF is calculated as follows:

[0055] The lithium battery is placed in

[0056] The lithium battery is normally working in

[0057] The working time L2 under high temperature is calculated as follows:

[0058] The lithium battery is placed in L2=L1 / 50.52=43800 / 50.52=866.98H≈36D;

[0059] The lithium battery is normally working in L2=L1 / 16.47=43800 / 16.47=2659.38H≈111D;

[0060] The working time L3 under high temperature and humidity is calculated as follows:

[0061] The lithium battery is placed in L3=L1 / 146.21=43800 / 146.21=299.57H=12.48D;

[0062] The lithium battery is normally working in L3=L1 / 47.61=43800 / 47.61=919.97H=38.33D;

[0063] (1) that is, the aluminum plastic film inner layer electrolytic resistance is verified at temperature 85℃ for 36D, which is equivalent to the aluminum plastic film normally placed at temperature 25℃ for 5 years; the aluminum plastic film is placed at temperature 85℃ for 111D, which is equivalent to the aluminum plastic film normally working at temperature 40℃ for 5 years;

[0064] (2) i.e. verifying the outer layer of the aluminum-plastic film against electrolyte resistance at a temperature of 85°C for 36D, which is equivalent to the normal placement of the aluminum-plastic film at a temperature of 25°C for 5 years; and the aluminum-plastic film at a temperature of 85°C for 111D, which is equivalent to the normal operation of the aluminum-plastic film at a temperature of 40°C for 5 years;

[0065] S5, respectively, the ABCDEFG (ABCD specification: 113 μm thick * 15 mm wide * 120 mm long; EFG specification: 153 μm thick * 15 mm wide * 120 mm long) aluminum-plastic film test sample is directly placed in a high temperature and humidity chamber, soaked in a high temperature chamber containing an electrolyte in a polytetrafluoroethylene bottle, and the inner layer electrolyte resistance peeling force performance is tested according to L2, and the outer layer peeling force performance is tested according to L3, and when the peeling force of the accelerated aging meets the set requirements, it is qualified.

[0066] Specifically, on the basis of Example 1, other samples ABCDEFG were tested, and the test data results are shown in Tables 1 and 2.

[0067] Table 1 Example sample data - high temperature aging condition outer layer peeling force test

[0068]

[0069] Table 2 Example sample data - high temperature and humidity aging condition inner layer electrolyte resistance peeling force test

[0070]

[0071] Specifically, the performance data is shown in Figure 1 and Figure 2 According to the accelerated aging test, it is concluded that the ONY / AL peeling force of B is significantly lower at 85°C for 36D / 111D, and the PP / AL peeling force of F is significantly lower at 85°C, 85% RH for 13D / 39D.

[0072] The market feedback of B has an abnormal outer layer delamination, and the conclusion that F has an abnormal inner layer delamination is consistent with the results of the accelerated aging test, i.e. the aluminum-plastic film accelerated thermal aging test method is feasible.

[0073] In summary, the aluminum-plastic film accelerated thermal aging test method establishes an acceleration model according to the daily operating temperature and humidity of the lithium battery and the designed service life, calculates the reaction time of the lithium battery in the experimental acceleration environment under the designed service life in the normal environment using the total humidity acceleration factor, and thus quickly evaluates whether the aging performance of the aluminum-plastic film is qualified.

[0074] With the above ideal embodiments according to the present application as the inspiration, through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. A method for accelerating thermal aging detection of aluminum-plastic film, characterized in that, Includes the following steps: S1, testing the initial peel force performance of the aluminum-plastic film test sample; S2, The acceleration factor calculation formula is imported according to the ASTM standard. The acceleration factor calculation formula includes: Temperature acceleration factor T1 is the absolute temperature under normal operating conditions, T2 is the absolute temperature under accelerated high temperature, Ea is the activation energy of the product, and k is the Boltzmann constant. Humidity Accelerator RH1 is the humidity under normal operating conditions, RH2 is the humidity under accelerated heat and humidity conditions, and n is 2 or 3; Total Accelerator Factor of Temperature and Humidity S3, based on the acceleration factor AF and the normal working time L1, calculate L2 and L3 respectively as follows: L1 = L2 * TAF; L2 is the working time at high temperature; L1 = L3 * AF; L3 is the working time under high temperature and high humidity. S4, design accelerated aging temperature and humidity, and obtain the acceleration factors TAF,AF and corresponding aging times L2,L3 under the placement environment and normal working environment. S5. The aluminum-plastic film test samples are placed directly in a high-temperature and high-humidity chamber and in a high-temperature chamber immersed in a polytetrafluoroethylene bottle containing electrolyte, respectively. The peel strength resistance of the inner layer under aging is tested according to L2, and the peel strength resistance of the outer layer under aging is tested according to L3. The sample is considered qualified when the peel strength under accelerated aging meets the set requirements.

2. The detection method as described in claim 1, characterized in that: The thickness of the aluminum-plastic film test samples ranges from 100 μm to 200 μm.

3. The detection method as described in claim 1, characterized in that: The absolute temperature T1 of the lithium battery placement temperature is set to 25℃, i.e., 273+25K. The absolute temperature T1 of the normal operating temperature of the lithium battery is set to 40℃, i.e., 273+40K.

4. The detection method as described in claim 1, characterized in that: The absolute temperature T2 under accelerated high temperature is set within the range of M℃, i.e., 273+MK, where M is greater than 40.

5. The detection method as described in claim 1, characterized in that: The activation energy Ea of the product is set to 0.6 eV, and the Boltzmann constant k = 8.6 * 10⁻⁶. -5 eV / K.

6. The detection method as described in claim 1, characterized in that: The normal working time L1 is set within a range of 3 to 5 years, i.e., 26,280 to 43,800 hours.

7. The detection method as described in claim 1, characterized in that: The humidity RH1 under normal operating conditions is set to 50%.

8. The detection method as described in claim 1, characterized in that: The humidity RH2 setting range under accelerated aging is N%, where N is greater than 50.

9. The detection method as described in claim 1, characterized in that: The peel strength properties include the electrolyte peel strength of ONY / AL and PP / AL.

10. The detection method as described in claim 1, characterized in that: The electrolyte includes DMC, DEC, EC, and lithium salt.

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