Method for testing temperature stability of sodium-nickel battery module

Abstract

The invention discloses a method for testing the temperature stability of a sodium-nickel battery module, and belongs to the technical field of sodium-nickel battery tests.The method comprises the steps that formation activation is conducted on the sodium-nickel battery module at a certain temperature, and the initial battery capacity of the sodium-nickel battery module is recorded; then the sodium-nickel battery module is subjected to multiple freezing and thawing treatment, the final battery capacity is recorded, the freezing and thawing treatment is used for simulating the influence of an extreme environment on the battery, and finally the temperature stability of the sodium-nickel battery module to be detected is judged by calculating the battery capacity retention ratio of the sodium-nickel battery module before and after freezing and thawing. The working performance of the sodium-nickel battery module is judged; namely, according to the method, the temperature stability of the sodium-nickel battery module is evaluated by testing the change of the battery capacity before and after the sodium-nickel battery module is frozen and thawed for multiple times, the testing period is shorter than that of a traditional method, the temperature stability of the sodium-nickel battery module is rapidly and effectively tested, the testing efficiency is improved, and meanwhile, the quality of the sodium-nickel battery is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of sodium-nickel battery testing, and in particular relates to a temperature stability testing method for a sodium-nickel battery module. Background Art

[0002] Sodium-nickel battery is a high-temperature energy storage battery. The electrolyte is a solid Na-β"-Al2O3 solid electrolyte. During charging and discharging, sodium ions migrate between the positive and negative electrodes through the solid electrolyte.

[0003] When evaluating the performance of sodium-nickel battery modules, it is usually necessary to focus on multiple key performance indicators, including energy density, power density, cycle life, internal resistance, and temperature stability. Since sodium-nickel batteries are high-temperature energy storage batteries, that is, they work in high-temperature environments, ensuring the stability of sodium-nickel battery modules in extreme environments is the basic prerequisite for ensuring battery quality.

[0004] Since different performance indicators of a battery can usually be reflected by different components in the battery, the existing traditional method generally adopts performance testing of each component before battery production and assembly. Among them, temperature stability is usually reflected by the hot pressing and sealing components and diaphragms in the battery. For the testing of hot pressing and sealing components, random sampling is usually used. This will result in incomplete testing. In addition, the performance test of the factory batteries in the existing traditional method also adopts random sampling and the detection cycle is long, usually about 2-6 months, which affects the normal production and sales of the battery. At the same time, there is no effective method for performance testing of battery modules in the traditional method.

[0005] In this regard, the present application designs a temperature stability testing method for a sodium-nickel battery module. Summary of the invention

[0006] The purpose of the present invention is to provide a method for testing the temperature stability of a sodium-nickel battery module to solve the existing deficiencies. The method of the present application can quickly and effectively test the temperature stability performance of the sodium-nickel battery module, thereby improving the test efficiency and providing a guarantee for the quality of the sodium-nickel battery module.

[0007] The present invention provides a method for testing the temperature stability of a sodium-nickel battery module, comprising the following steps:

[0008] S1, placing the sodium-nickel battery module in a heating device and gradually heating it to a target temperature and then keeping it warm; during the heating process or the keeping warm process, performing a formation activation treatment on the sodium-nickel battery module, and recording the initial battery capacity C1 of the current sodium-nickel battery module;

[0009] S2, after the heat preservation time is reached, the heating device stops heating and cools the sodium-nickel battery module until the room temperature of the sodium-nickel battery module is less than or equal to 80° C.;

[0010] S3, gradually heating the heating device to the target temperature and then keeping it warm;

[0011] S4, repeating the above steps S2 and S3 20-25 times;

[0012] S5, discharging the sodium-nickel battery module again to a termination voltage, and recording its final battery capacity C2;

[0013] S6, calculating the battery capacity retention rate of the sodium-nickel battery module according to the initial battery capacity C1 and the final battery capacity C2 and determining whether it is within a preset range.

[0014] As the preferred solution of this application:

[0015] In step S1, the specific method of performing formation treatment on the sodium-nickel battery module comprises:

[0016] S11, charging the sodium-nickel battery module until a constant voltage is reached, and stopping charging when the charging current of the battery module drops to 0.1-0.5A;

[0017] S12, let stand for 2-6 minutes;

[0018] S13, discharging the sodium-nickel battery module until a termination voltage is reached, and recording the battery capacity C2 of the sodium-nickel battery.

[0019] As the preferred solution of this application:

[0020] The sodium-nickel battery module is charged or discharged using a 0.2C or 0.5C current.

[0021] As the preferred solution of this application:

[0022] In step S1 and step S3, the heating device is gradually heated to a target temperature at a heating rate of 0.3-1°C / min, and the target temperature is 285±10°C.

[0023] As the preferred solution of this application:

[0024] In step S6, when the calculated battery capacity retention rate is not within a preset range, voltage tests are performed on multiple sodium-nickel battery cells in the sodium-nickel battery module to locate abnormal sodium-nickel battery cells, and the abnormal battery cells in the sodium-nickel battery module are replaced.

[0025] As the preferred solution of this application:

[0026] The test method for abnormal sodium-nickel battery cells includes: at least one of a capacity test, a voltage test, a temperature test and an internal resistance test.

[0027] As the preferred solution of this application:

[0028] The insulation time is 1-2h.

[0029] Compared with the prior art, the advantages of this application are:

[0030] The present application first performs formation activation on the sodium-nickel battery module at a certain temperature, and records the initial battery capacity of the sodium-nickel battery module, and then performs multiple freeze-thaw treatments on the sodium-nickel battery module and records the final battery capacity, the freeze-thaw treatment is used to simulate the impact of extreme environment on the battery, and finally the temperature stability of the sodium-nickel battery module to be tested is judged by calculating the battery capacity retention rate of the sodium-nickel battery module before and after freeze-thaw, and then the working performance of the sodium-nickel battery module is judged; that is, the test method of the present application evaluates or tests the temperature stability of the sodium-nickel battery module by testing the change in battery capacity before and after multiple freeze-thaws of the sodium-nickel battery module, and the test cycle is shorter than that of the existing traditional method, so that the temperature stability performance of the sodium-nickel battery module can be quickly and effectively tested, and the test efficiency can be improved while providing a guarantee for the quality of the sodium-nickel battery; therefore, the test method of the present application can achieve a rapid and accurate evaluation of the temperature stability and reliability of the sodium-nickel battery module, and solve the existing deficiencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Flow chart of a temperature stability testing method for a sodium-nickel battery module provided in an embodiment of the present invention.

[0032] Figure 2 This is an overall schematic diagram of a sodium-nickel battery module provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its application.

[0034] like Figure 1 As shown, a temperature stability test method of a sodium-nickel battery module provided in this embodiment includes the following steps:

[0035] S1, placing the sodium-nickel battery module in a heating device and gradually heating it to a target temperature and then keeping it warm, and the insulation time is preferably 2 hours; during the heating process or the insulation process, performing a formation activation treatment on the sodium-nickel battery module, and recording the initial battery capacity C1 of the current sodium-nickel battery module;

[0036] like Figure 2As shown, it is a schematic diagram of the overall structure of a sodium-nickel battery module provided in this embodiment, which is composed of a plurality of sodium-nickel battery cells connected in series. Of course, according to the actual needs of the battery capacity, the sodium-nickel battery cells can also be connected in parallel; the heating device is preferably a resistance heating furnace;

[0037] This step is used to preliminarily heat and activate the sodium-nickel battery, wherein the heating is performed by gradually increasing the temperature, which can avoid thermal shock and ensure the safety of the battery module. In this embodiment, the heating device is preferably gradually heated to the target temperature at a heating rate of 0.3-1°C / min, and the target temperature is 285±10°C;

[0038] Preferably, the formation activation operation is performed during the heat preservation process, during which the heating device has been heated to the target temperature, which can significantly improve the chemical reaction efficiency and ion conductivity of the sodium-nickel battery module, thereby optimizing the capacity and performance of the sodium-nickel battery module;

[0039] In this embodiment, the specific steps of the formation activation operation include:

[0040] S11, charging the sodium-nickel battery module at a current of 0.2 or 0.5C until a constant voltage is reached, and stopping charging when the charging current of the battery module drops to 0.1-0.5A; in this embodiment, the constant voltage needs to be determined according to the model of the sodium-nickel battery module, etc., and is preferably 2.67V*n in this embodiment, where n is the number of sodium-nickel battery cells connected in series; the purpose of controlling the charging current to 0.1-0.5A is to avoid overcharging and improve charging safety;

[0041] S12, standing for 2-6 minutes, preferably 5 minutes;

[0042] S13, discharging the sodium-nickel battery module at a current of 0.2C or 0.5C until the termination voltage, and recording the battery capacity C2 of the sodium-nickel battery; in this embodiment, the termination voltage needs to be determined according to the model of the sodium-nickel battery module, etc., and in this embodiment, it is preferably 2.0V*n, where n is the number of sodium-nickel battery cells connected in series;

[0043] S2, after the heat preservation time is reached, the heating device stops heating and cools the sodium-nickel battery module until the room temperature of the sodium-nickel battery module is less than or equal to 80° C.;

[0044] This step is used to cool the heated sodium-nickel battery module to create a temperature difference and simulate an extreme environment.

[0045] S3, gradually heating the heating device to the target temperature and then keeping it warm;

[0046] This step is used to reheat the sodium-nickel battery. The heating method and target temperature used are the same as those in S1 above, that is, the heating device is gradually heated to the target temperature at a heating rate of 0.3-1°C / min, and the target temperature is 285±10°C.

[0047] S4, repeating the above steps S2 and S3 20-25 times to achieve multiple freeze-thaw operations.

[0048] S5, discharging the sodium-nickel battery module again to a termination voltage, and recording its final battery capacity C2;

[0049] This step is used to obtain the battery capacity of the sodium-nickel battery module after multiple freeze-thaw treatments;

[0050] In this embodiment, the sodium-nickel battery module is preferably discharged at a current of 0.2C to a termination voltage, and then the battery capacity C2 of the sodium-nickel battery module is recorded. The termination voltage is preferably 2.0*n, where n is the number of sodium-nickel battery cells connected in series.

[0051] S6, calculating the battery capacity retention rate of the sodium-nickel battery module according to the initial battery capacity C1 and the final battery capacity C2 and determining whether it is within a preset range;

[0052] Specific calculation formula:

[0053] In this embodiment, the value of the preset range is set according to actual needs and is not specifically limited in this embodiment.

[0054] According to the calculated battery capacity retention rate, the change of capacity retention rate and performance attenuation trend of sodium-nickel battery module under extreme environment can be analyzed, and then the performance stability of sodium-nickel battery module can be judged and analyzed;

[0055] If the retention rate is within the preset range, it indicates that the sodium-nickel battery module performs well during the freeze-thaw cycle, has high temperature stability, and can meet the design or application requirements;

[0056] If the calculated battery capacity retention rate is not within a preset range, multiple battery cells in the sodium-nickel battery module are tested separately to locate abnormal sodium-nickel battery cells, and the abnormal battery cells in the current sodium-nickel battery module are replaced to ensure that the sodium-nickel battery module can be in a normal state and improve the quality of the sodium-nickel battery module; wherein, the test of the abnormal sodium-nickel battery cell can adopt at least one of a capacity test, a voltage test, a temperature test and an internal resistance test.

[0057] The above is the overall fluid of the test method of this embodiment. Through the above analysis, it can be seen that in the entire process, multiple freeze-thaw cycles take the longest time. Since the heating rate, insulation time and number of repetitions are known each time, it can be seen from calculations that the test method of this embodiment can obtain the test results in about one week, which significantly shortens the test cycle compared to existing conventional test methods.

[0058] In this embodiment, two test groups are selected. The sodium-nickel battery modules in the two test groups are normal batteries. After testing using the test method described in this embodiment, the data described in Table 1 are obtained:

[0059] C1 / Ah C2 / Ah γ Experimental Group A 46.454 46.387 99.85％ Test Group B 46.495 46.414 99.825％

[0060] Table 1

[0061] According to the above table, after testing the two test groups using the temperature stability test method of the sodium-nickel battery module in this embodiment, it was found that the battery capacity retention rates of the sodium-nickel battery modules in test group A and test group B were 99.85% and 99.825%, respectively, which are relatively close; it can be seen that multiple freeze-thaw treatments will affect the actual capacity of the sodium-nickel battery module to a certain extent, and it is feasible to reflect the temperature stability of the sodium-nickel battery module by the battery capacity retention rate, and the test method in this embodiment can realize the test of the sodium-nickel battery module, and the test accuracy is high, which meets the requirements of this embodiment.

[0062] In summary, the test method of this embodiment evaluates or tests the temperature stability of the sodium-nickel battery module by testing the change in battery capacity before and after multiple freeze-thaw cycles of the sodium-nickel battery module, and the test cycle is shorter than that of the existing traditional method, thereby achieving rapid and effective testing of the temperature stability performance of the sodium-nickel battery module, improving the test efficiency while providing a guarantee for the quality of the sodium-nickel battery; therefore, the test method of this embodiment can achieve rapid and accurate evaluation of the temperature stability and reliability of the sodium-nickel battery module, solving the existing deficiencies.

[0063] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several improvements can be made without departing from the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of the claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A method for testing the temperature stability of a sodium-nickel battery module, characterized in that: The following steps are included: S1, placing the sodium-nickel battery module in a heating device and gradually heating it to a target temperature and then keeping it warm; during the heating process or the keeping warm process, performing a formation activation treatment on the sodium-nickel battery module, and recording the initial battery capacity C1 of the current sodium-nickel battery module; S2, after the heat preservation time is reached, the heating device stops heating and cools the sodium-nickel battery module until the room temperature of the sodium-nickel battery module is less than or equal to 80° C.; S3, gradually heating the heating device to the target temperature and then keeping it warm; S4, repeating the above steps S2 and S3 20-25 times; S5, discharging the sodium-nickel battery module again to a termination voltage, and recording its final battery capacity C2; S6, calculating the battery capacity retention rate of the sodium-nickel battery module according to the initial battery capacity C1 and the final battery capacity C2 and determining whether it is within a preset range.

2. The temperature stability testing method of a sodium-nickel battery module according to claim 1, characterized in that: In step S1, the specific method of performing formation treatment on the sodium-nickel battery module comprises: S11, charging the sodium-nickel battery module until a constant voltage is reached, and stopping charging when the charging current of the battery module drops to 0.1-0.5A; S12, let stand for 2-6 minutes; S13, discharging the sodium-nickel battery module until a termination voltage is reached, and recording the battery capacity C2 of the sodium-nickel battery.

3. The temperature stability testing method of a sodium-nickel battery module according to claim 2, characterized in that: The sodium-nickel battery module is charged or discharged using a 0.2C or 0.5C current.

4. The temperature stability testing method of a sodium-nickel battery module according to claim 1, characterized in that: In step S1 and step S3, the heating device is gradually heated to a target temperature at a heating rate of 0.3-1°C / min, and the target temperature is 285±10°C.

5. The temperature stability testing method of a sodium-nickel battery module according to claim 1, characterized in that: In step S6, when the calculated battery capacity retention rate is not within a preset range, multiple sodium-nickel battery cells in the sodium-nickel battery module are tested respectively to locate abnormal sodium-nickel battery cells, and the abnormal sodium-nickel battery cells in the sodium-nickel battery module are replaced.

6. The temperature stability testing method of a sodium-nickel battery module according to claim 5, characterized in that: The test method for abnormal sodium-nickel battery cells includes: at least one of a capacity test, a voltage test, a temperature test and an internal resistance test.

7. The temperature stability testing method of a sodium-nickel battery module according to claim 1, characterized in that: The insulation time is 1-2h.

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