Thermal insulation box for lithium manganate single cell low-temperature test, test method and device

Abstract

The invention relates to the technical field of lithium battery production, in particular to a heat preservation box for low-temperature testing of a lithium manganate single battery cell, a testing method and a device. The heat preservation box comprises a shell used for containing the lithium manganate single battery cell, and the shell at least covers a main body area, except for an external electric connection part, of the battery cell; the lining layer is arranged on the inner surface of the shell and is made of an aerogel material; the shell layer is arranged on the outer side of the lining layer and is made of plastic or a composite foaming material. According to the invention, the normal form of a traditional single-cell low-temperature test is fundamentally changed, a heat insulation environment similar to the interior of the Pack is constructed for the single cell by introducing the aerogel heat preservation box, and spontaneous heat generated when the cell works can be effectively accumulated. Therefore, the thermal behavior of the Pack is accurately simulated on the single cell level, and the temperature deviation between the traditional test and the practical application is thoroughly avoided.

Description

Technical Field

[0001] This invention relates to the field of lithium battery production technology, and in particular to an insulation box, testing method and apparatus for low-temperature testing of lithium manganese oxide single cells. Background Technology

[0002] Lithium-ion batteries suffer from severe performance degradation at low temperatures, primarily manifested as slow electrochemical reaction kinetics, reduced lithium-ion diffusion rates, increased polarization, and loss of effective capacity. This is particularly pronounced in lithium manganese oxide (LiMn2O4) batteries, where electrolyte viscosity is extremely sensitive to temperature.

[0003] Currently, common solutions for improving low-temperature performance include external heating, phase change energy storage material coating, or high-power pulse preheating. However, these methods generally suffer from problems such as complex structure, high energy consumption, and slow response, making it difficult to achieve accurate temperature simulation and energy retention in the single-cell experimental stage. In actual battery modules (packs), the stacking structure between individual cells causes self-heating to accumulate within a certain range, forming a temperature rise effect that indirectly improves low-temperature performance.

[0004] Therefore, designing a simple and efficient thermal management method for lithium manganese oxide single cells that can simulate the internal thermal accumulation characteristics of the module, so as to improve the accuracy and performance of its low-temperature testing, has become a key research direction that urgently needs to be addressed. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention discloses an insulation box, testing method, and apparatus for low-temperature testing of lithium manganese oxide single cells. This invention fundamentally changes the paradigm of traditional single-cell low-temperature testing. By introducing an aerogel insulation box, it constructs an insulating environment for the single cell that closely resembles the internal environment of the battery pack, effectively accumulating the self-heating generated during cell operation. This allows for precise simulation of the battery pack's thermal behavior at the single-cell level, thereby completely avoiding temperature deviations between traditional testing and practical applications.

[0006] The technical solution of this invention is implemented as follows:

[0007] In a first aspect, the present invention provides an insulation box for low-temperature testing of lithium manganese oxide single cells, comprising:

[0008] A housing for accommodating a lithium manganese oxide single cell, the housing at least covering the main body area of ​​the cell except for its external electrical connection parts;

[0009] An inner liner layer disposed on the inner surface of the housing, the inner liner layer being composed of an aerogel material;

[0010] An outer shell layer disposed on the outside of the inner liner layer, the outer shell layer being made of plastic or composite foam material.

[0011] In some embodiments, the thermal conductivity of the aerogel material of the liner layer is not higher than 0.02 W / (m·K).

[0012] In some embodiments, the thickness of the inner liner is 0.5-5 mm; and / or, the thickness of the outer shell is 5-20 mm.

[0013] In some embodiments, the aerogel material of the liner is selected from at least one of silica aerogel felt, ceramic aerogel felt, polymer aerogel felt, or carbon aerogel felt.

[0014] In some embodiments, the plastic material of the outer shell layer is selected from at least one of polycarbonate, ABS plastic, and PP plastic; or the composite foaming material of the outer shell layer is selected from at least one of EVA / EPE composite foaming material, EPP foaming composite material, or PU foaming composite material.

[0015] In some embodiments, the inner lining layer accounts for 30-50% of the mass of the insulated box, and the outer shell layer accounts for 50-70% of the mass of the insulated box.

[0016] Secondly, the present invention provides a method for testing the low-temperature performance of a lithium manganese oxide single cell, using the insulation box provided in the first aspect, and including the following steps:

[0017] Provides single-cell lithium manganese oxide battery cells;

[0018] The single lithium manganese oxide battery cell is placed inside the insulation box, and the insulation box at least covers the main body area of ​​the battery cell except for its external electrical connection parts, so as to form an insulation space;

[0019] The insulation box containing the battery cells is placed in a low-temperature environment;

[0020] The battery cell is subjected to charge and discharge tests. The Joule heat and reaction heat generated by the battery cell itself are used to create a temperature rise inside the battery cell under the heat preservation effect of the heat preservation box, so as to simulate the heat accumulation environment in the battery module and test its discharge performance under the low temperature environment.

[0021] In some embodiments, the low-temperature environment is -40°C to 0°C; and / or, by adjusting the insulation performance of the insulation box and the operating current of the battery cell, the internal temperature of the battery cell is made 5-15°C higher than the external ambient temperature.

[0022] In some embodiments, during the charge-discharge test, temperature changes inside the cell are monitored by temperature probes located at the external electrical connection points and / or large surfaces of the cell.

[0023] Thirdly, the present invention provides a lithium manganese oxide single-cell testing device, including the insulation box provided in the first aspect, as well as equipment and temperature monitoring components for charge and discharge testing.

[0024] The beneficial technical effects of the present invention are as follows:

[0025] In terms of structural design, the high strength of the outer shell layer is combined with the flexible filling of the inner liner layer, which ensures overall impact resistance while providing effective vibration damping protection for the battery cell. The two layers are tightly bonded, which significantly reduces contact thermal resistance. The inner liner layer, as the main insulation layer, isolates most of the heat conduction, while the outer shell layer, by using low thermal conductivity materials, weakens the thermal bridging effect. This synergistic design achieves efficient heat preservation and physical protection.

[0026] In terms of thermal management mechanisms and core innovations, this invention fundamentally changes the paradigm of traditional single-cell low-temperature testing. Traditional direct testing methods cannot simulate the self-heating accumulation effect generated by cell stacking within a battery pack, resulting in significant thermal deviations between the testing environment and real-world applications. This invention introduces an aerogel insulation box, creating an adiabatic environment for each cell similar to that inside the pack. This effectively accumulates the self-heating generated during cell operation, resulting in a stable temperature rise of 5–15°C. This innovation makes it possible to accurately simulate the thermal behavior of the pack at the single-cell level, thus completely avoiding the temperature discrepancy between traditional testing and actual application. The resulting experimental data accurately reflects the cell's performance in the final usage scenario, greatly enhancing the data's reference value and design guidance significance.

[0027] In terms of comprehensive application characteristics, the aerogel material used has both low density and good flame retardancy, and can achieve a high-efficiency heat insulation layer without significantly increasing the weight. The whole solution has a simple structure and is safe and reliable. It is not only very suitable for the accurate evaluation of the low-temperature performance of single cells in laboratory scenarios, but also provides a direct and feasible path for the integrated application of this structure as an scalable local thermal management module in future battery modules. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram showing the assembly state of the battery cell and the insulation box of the present invention.

[0030] Figure 2 This is an exploded view of the battery cell and insulation box of the present invention;

[0031] Figure 3 This is a magnified view of a portion of the assembly of the battery cell and the insulation box.

[0032] The attached figures are labeled as follows:

[0033] 1. Insulated box; 11. Outer shell layer; 12. Inner lining layer; 2. Battery cell; 3. External electrical connection parts. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used in the detailed description is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0036] In the description of specific embodiments of the present invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, "multiple" means two or more, unless otherwise explicitly defined.

[0037] In this invention, the reference to "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described in this invention can be combined with other embodiments.

[0038] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, in this invention, the character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0039] Throughout this invention, numerical values ​​represent approximate measurements or limits of a range to cover minute deviations from a given value, as well as embodiments with approximately the mentioned value and embodiments with the exact mentioned value. Except for the working examples provided at the end of the detailed description, all numerical values ​​of parameters (e.g., quantities or conditions) in this specification (including the appended claims) should be understood to be modified in all cases by the term “about,” regardless of whether “about” actually appears before the numerical value. “About” indicates that the stated numerical value allows for some minor inaccuracy (approaching the exact value in some way; approximately or reasonably approaching the value; almost). If the inaccuracy provided by “about” is not otherwise understood in this general sense in the art, then “about” as used in this invention at least indicates a variation that can be produced by common methods of measuring and using such a parameter. For example, “about” may include a variation less than or equal to 5%, optionally less than or equal to 4%, optionally less than or equal to 3%, optionally less than or equal to 2%, optionally less than or equal to 1%, optionally less than or equal to 0.5%, and in some respects, optionally less than or equal to 0.1%.

[0040] Additionally, the disclosure of the range includes the disclosure of all values ​​across the entire range and the disclosure of further subdivided ranges, including the endpoints and subranges given for these ranges.

[0041] Lithium-ion batteries suffer from severe performance degradation at low temperatures, primarily manifested as slow electrochemical reaction kinetics, reduced lithium-ion diffusion rates, increased polarization, and loss of effective capacity. This is particularly pronounced in lithium manganese oxide (LiMn2O4) batteries, where electrolyte viscosity is extremely sensitive to temperature.

[0042] Currently, common solutions for improving low-temperature performance include external heating, phase change energy storage material coating, or high-power pulse preheating. However, these methods generally suffer from problems such as complex structure, high energy consumption, and slow response, making it difficult to achieve accurate temperature simulation and energy retention in the single-cell experimental stage. In actual battery modules (packs), the stacking structure between individual cells causes self-heating to accumulate within a certain range, forming a temperature rise effect that indirectly improves low-temperature performance.

[0043] Therefore, designing a simple and efficient thermal management method for lithium manganese oxide single cells that can simulate the internal thermal accumulation characteristics of the module, so as to improve the accuracy and performance of its low-temperature testing, has become a key research direction that urgently needs to be addressed.

[0044] To address the aforementioned technical problems, this invention discloses an insulation box, testing method, and apparatus for low-temperature testing of lithium manganese oxide single cells. This invention fundamentally changes the paradigm of traditional single-cell low-temperature testing. By introducing an aerogel insulation box, it constructs an insulating environment for the single cell that closely resembles the internal environment of the battery pack, effectively accumulating the self-heating generated during cell operation. This allows for precise simulation of the battery pack's thermal behavior at the single-cell level, thereby completely avoiding temperature deviations between traditional testing and practical applications.

[0045] Firstly, such as Figures 1-3 The present invention provides an insulation box for low-temperature testing of lithium manganese oxide single cells, comprising:

[0046] A housing for accommodating a lithium manganese oxide single cell 1, the housing at least covering the main body area of ​​the cell 1 except for its external electrical connection portion 3;

[0047] The inner liner 12 disposed on the inner surface of the housing is made of aerogel material;

[0048] The outer shell layer 11 is disposed on the outside of the inner liner layer, and the outer shell layer is made of plastic or composite foam material.

[0049] In terms of structural design, the high strength of the outer shell layer is combined with the flexible filling of the inner liner layer, which ensures overall impact resistance while providing effective vibration damping protection for the battery cell. The two layers are tightly bonded, which significantly reduces contact thermal resistance. The inner liner layer, as the main insulation layer, isolates most of the heat conduction, while the outer shell layer, by using low thermal conductivity materials, weakens the thermal bridging effect. This synergistic design achieves efficient heat preservation and physical protection.

[0050] In terms of thermal management mechanisms and core innovations, this invention fundamentally changes the paradigm of traditional single-cell low-temperature testing. Traditional direct testing methods cannot simulate the self-heating accumulation effect generated by cell stacking within a battery pack, resulting in significant thermal deviations between the testing environment and real-world applications. This invention introduces an aerogel insulation box, creating an adiabatic environment for each cell similar to that inside the pack. This effectively accumulates the self-heating generated during cell operation, resulting in a stable temperature rise of 5–15°C. This innovation makes it possible to accurately simulate the thermal behavior of the pack at the single-cell level, thus completely avoiding the temperature discrepancy between traditional testing and actual application. The resulting experimental data accurately reflects the cell's performance in the final usage scenario, greatly enhancing the data's reference value and design guidance significance.

[0051] In terms of comprehensive application characteristics, the aerogel material used has both low density and good flame retardancy, and can achieve a high-efficiency heat insulation layer without significantly increasing the weight. The whole solution has a simple structure and is safe and reliable. It is not only very suitable for the accurate evaluation of the low-temperature performance of single cells in laboratory scenarios, but also provides a direct and feasible path for the integrated application of this structure as an scalable local thermal management module in future battery modules.

[0052] In some embodiments, the thermal conductivity of the aerogel material of the inner liner 12 is not higher than 0.02 W / (m·K). The present invention does not impose any limitation on the selection of any value within this range for the thermal conductivity of the selected aerogel material.

[0053] In some embodiments, the thickness of the inner liner 12 is 0.5-5 mm; and / or, the thickness of the outer shell layer is 5-20 mm.

[0054] In specific applications, the thickness of the inner lining layer 12 can be 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, etc.; and / or, the thickness of the outer shell layer 11 can be 5mm, 10mm, 15mm, 20mm, etc. The above values ​​are for illustrative purposes only and are not intended to be limiting; appropriate selections can be made based on specific needs in actual applications.

[0055] In some embodiments, the aerogel material of the inner liner 12 is selected from at least one of silica aerogel felt, ceramic aerogel felt, polymer aerogel felt, or carbon aerogel felt.

[0056] In some embodiments, the plastic material of the outer shell layer 11 is selected from at least one of polycarbonate, ABS plastic, and PP plastic; or the composite foaming material of the outer shell layer is selected from at least one of EVA / EPE composite foaming material, EPP foaming composite material, or PU foaming composite material.

[0057] In this invention, "at least one" means selecting one of the listed materials, or selecting a mixture of two or more materials. Those skilled in the art can freely choose within the scope of their understanding. This invention does not impose any limitations in this regard.

[0058] In some embodiments, the inner lining layer 12 accounts for 30-50% of the mass of the insulated box, and the outer shell layer 11 accounts for 50-70% of the mass of the insulated box.

[0059] In specific applications, the inner lining layer 12 can account for 30%, 35%, 40%, 45%, 50% of the total mass of the insulated box, etc.; the outer shell layer 11 can account for 50%, 55%, 60%, 65%, 70% of the total mass of the insulated box, etc. The above values ​​are for illustrative purposes only and are not intended to be limiting. In actual applications, appropriate choices can be made according to specific needs.

[0060] Secondly, the present invention provides a method for testing the low-temperature performance of a lithium manganese oxide single cell, using the insulation box provided in the first aspect, and including the following steps:

[0061] Provide 2 single-cell lithium manganese oxide battery cells;

[0062] The single lithium manganese oxide cell 2 is placed inside the insulation box 1, and the insulation box 1 covers at least the main body area of ​​the cell except for its external electrical connection part 3, to form an insulation space.

[0063] The insulation box 1, which is equipped with the battery cell 2, is placed in a low-temperature environment;

[0064] The battery cell is subjected to charge and discharge tests. The Joule heat and reaction heat generated by the battery cell itself are used to create a temperature rise inside the battery cell under the heat preservation effect of the heat preservation box, so as to simulate the heat accumulation environment in the battery module and test its discharge performance under the low temperature environment.

[0065] In some embodiments, the low-temperature environment is -40°C to 0°C; and / or, by adjusting the insulation performance of the insulation box and the operating current of the battery cell, the internal temperature of the battery cell is made 5-15°C higher than the external ambient temperature.

[0066] In specific applications, the low-temperature environment can be selected as -40℃, -30℃, -20℃, -10℃, 0℃, etc. Specifically, the insulation performance of the insulation box can be adjusted by optimizing parameters such as the thickness and mass ratio of the aerogel material in the inner lining layer. The temperature difference between the internal temperature of the battery cell and the external environment can be 5℃, 8℃, 10℃, 12℃, 15℃, etc. The above values ​​are for illustrative purposes only and are not intended to be limiting; appropriate selections can be made based on specific needs in actual applications.

[0067] In some embodiments, during the charge-discharge test, the internal temperature change of the battery cell is monitored by a temperature probe arranged at the external electrical connection portion 3 and / or the large surface of the battery cell.

[0068] In this application, the term "external electrical connection portion" refers to the portion of a single battery cell used to achieve electrical connection with an external circuit, including test tabs or temporary connecting pieces that are additionally attached for testing.

[0069] In some specific embodiments, before testing, a thin metal test tab (or temporary connecting tab) is welded to the positive and negative terminals of the individual battery cell to facilitate clamping or welding with the wires of the testing equipment. When the insulation box 1 is used to cover the battery, an outlet or space needs to be reserved for this external electrical connection part 3.

[0070] In some specific embodiments, to ensure both insulation effectiveness and the convenience and accuracy of temperature monitoring, the shell of the insulation box 1 has an opening on one side corresponding to the battery cell terminal or external electrical connection point. The size of this opening is configured to: on the one hand, allow the electrical connection point of the battery cell (such as a test tab) to extend for connection to external charge / discharge testing equipment; on the other hand, provide a physical channel for inserting a temperature probe (such as a thermocouple or thermistor) into the insulation box, allowing its sensing element to directly contact or be close to the outer surface of the battery cell shell (especially the large surface area or near the tab area) for temperature measurement. This design enables direct and accurate monitoring of the operating temperature of the battery cell under test while minimizing disruption to the overall insulation structure of the insulation box.

[0071] In some specific embodiments, various temperature sensing and monitoring schemes can be employed to accurately monitor the temperature changes of the battery cells inside the insulation box. The temperature monitoring component includes, but is not limited to, any combination of one or more of the following:

[0072] Embedded direct temperature measurement: Miniature thermocouples (such as K-type or T-type) or thin-film platinum resistance thermometers (such as PT100) are pre-embedded in specific locations inside the battery cell during the cell assembly process (such as near the tabs, in the center of the cell, etc.), or implanted through subsequent drilling, to directly measure the temperature of the core area of ​​the battery cell. This method provides the most direct and accurate data, but may cause slight invasiveness to the battery cell.

[0073] Surface mount temperature measurement: A surface mount thermistor (NTC), surface mount thermocouple, or flexible thin-film temperature sensor is attached to the center of the largest surface area (i.e., the area near the tabs) of the battery cell housing using high thermal conductivity adhesive. To reduce the influence of the insulation box lining on temperature measurement, miniature temperature-conducting holes can be made at corresponding locations within the insulation box, allowing the sensor probe to make close contact with the battery cell surface while ensuring the integrity of the insulation box's main structure. This method is non-invasive, simple to operate, and one of the most commonly used methods in laboratories.

[0074] Contact temperature measurement via electrode tabs: Since the electrode tabs are one of the main heat-generating components during battery cell operation, and their temperature is related to the internal temperature, a clamp-on thermocouple or a temperature sensor with a spring probe can be directly clamped or brought into close contact with the test electrode tabs (external electrical connection points) of the battery cell. By monitoring the temperature changes of the electrode tabs, the internal thermal state of the battery cell can be indirectly reflected. This method requires no modification to the battery cell or insulation box and is extremely convenient.

[0075] Infrared non-contact temperature measurement and thermal imaging: Infrared transmission windows (such as germanium windows or specific polymer films) are used on the inner wall of the insulation box facing the large surface of the battery cell, or observation ports are directly reserved in the outer shell layer. The temperature distribution on the surface of the battery cell shell is measured non-contactly using an external infrared thermometer or thermal imager. This method can be used to study the overall temperature field uniformity of the battery cell within the insulation box, but the accuracy is affected by the window material and surface emissivity.

[0076] Thirdly, the present invention provides a lithium manganese oxide single-cell testing device, including the insulation box provided in the first aspect, as well as equipment and temperature monitoring components for charge and discharge testing.

[0077] In some embodiments, the testing device is a dedicated system that integrates functions such as heat preservation, charge and discharge excitation, temperature monitoring, and data acquisition.

[0078] In some implementations, the testing device mainly consists of three functional modules: an insulation box module, a charge / discharge excitation module, and a temperature monitoring module. The core logical relationship is as follows: the insulation box module serves as the carrier and thermal environment controller for the tested battery cell; the charge / discharge excitation module provides the operating current to the battery cell and records its electrical parameters; and the temperature monitoring module senses temperature changes in key parts of the battery cell in real time. All modules are connected via electrical and signal cables and work collaboratively.

[0079] The embodiments of the present invention will be described in more detail below through examples and comparative examples. All examples and comparative examples are lithium-ion battery sample groups prepared using the same process.

[0080] To demonstrate the advantages of the present invention in a clear and comprehensive manner, all embodiments and comparative examples have been recorded or tested as follows: discharge capacity test, polarization voltage at the end of discharge, and capacity retention rate.

[0081] It should be noted that the embodiments of the present invention are not limited to these examples.

[0082] Example 1

[0083] A 56Ah lithium manganese oxide (LiMn2O4) / graphite prismatic battery cell 2 was selected as the research object. The cell was placed in an insulated box 1. The outer shell layer 11 was made of polycarbonate, accounting for 60% of the mass of the insulated box 1, and the inner liner layer 12 was made of silica aerogel felt, accounting for 40% of the mass of the insulated box. The thickness of the outer shell layer 11 and the inner liner layer 12 was 5mm. The insulated box 1 containing the battery cell 2 was placed in a test environment at -20℃. Discharge was performed at a rate of 0.5C, and the external ambient temperature and the internal temperature of the battery cell were recorded simultaneously (external electrical connection part 3, i.e., test tab contact temperature measurement). The internal temperature of the battery cell was on average about 10℃ higher than the external temperature. During this discharge process, the heat generated by the battery cell itself accumulated inside the insulated box, forming a stable temperature rise.

[0084] Example 2

[0085] The battery cell system and method used in Example 1 are the same. The difference from Example 1 is that EVA foam cotton is used for the inner liner. The test results show that the internal temperature of the battery cell is on average about 5°C higher than the external temperature.

[0086] Example 3

[0087] The battery cell system and method used in Example 1 are the same. The difference from Example 1 is that the inner liner uses PU foam material. The test results show that the internal temperature of the battery cell is on average about 6°C higher than the external temperature.

[0088] Comparative Example 1

[0089] The difference from Example 1 is that the lithium manganese oxide cell does not use an insulation box, and the test results show that the internal temperature of the cell is the same as the external temperature.

[0090] Comparative Example 2

[0091] The battery cell system and method used in Example 1 are the same. The difference from Example 1 is that the insulation box does not use an inner lining layer, but is made of only outer shell polycarbonate material. The test results show that the internal temperature rise of the battery cell is not significant (below 1°C).

[0092] Comparative Example 3

[0093] The battery cell system and method used in Example 1 are the same. The difference from Example 1 is that the insulation box does not use an outer shell layer, but is only made of inner lining aerogel felt material. The test results show that the internal temperature rise of the battery cell is not significant (below 2°C).

[0094] The batteries prepared in Examples 1-3 and Comparative Examples 1-3 were tested as follows.

[0095] Low-temperature discharge capacity test:

[0096] Environmental pretreatment: The battery cell to be tested, equipped with an insulation box and temperature probe, is placed in a constant temperature chamber or temperature-controlled chamber that has been set to the target test temperature (e.g., -20℃).

[0097] Temperature equilibration: Allow to stand for 2 to 5 hours to allow the constant temperature chamber environment, the insulation box shell, and the battery cell itself to reach sufficient thermal equilibrium. Equilibration is considered complete when the monitored temperature data confirms that the battery cell temperature change is within ±1℃ / 30 minutes.

[0098] Test parameter settings: Using a battery testing system, the test program is set as follows:

[0099] Discharge mode: Constant current discharge.

[0100] Discharge current: 0.5C (calculated based on the nominal capacity of the cell, for example, 28A corresponds to a 56Ah cell).

[0101] Discharge termination voltage: 2.5V.

[0102] Charging steps (preliminary steps for capacity calibration, performed at room temperature): At room temperature of 25°C, fully charge the battery cell using a standard procedure (e.g., first charge at a constant current of 0.5C to 4.2V, then charge at a constant voltage of 4.2V until the current drops to 0.05C).

[0103] Polarization voltage at the end of discharge:

[0104] The polarization voltage at low temperature is obtained by extracting the voltage at the end of the discharge from the original data and comparing the voltage at the end of the discharge at different temperatures.

[0105] Capacity retention rate:

[0106] At room temperature: Charge at a constant current of 0.5C to the upper limit voltage of 4.2V, then switch to a constant voltage of 4.2V until the current drops below 0.05C, at which point it is considered fully charged. After full charging, let it stand for at least 30 minutes. Discharge at a constant current of 0.5C to the termination voltage of 2.5V.

[0107] The result is obtained by dividing the discharge capacity at low temperature by the discharge capacity at room temperature.

[0108] The results are shown in the table below.

[0109]

[0110] As shown in the table above, compared with Comparative Examples 1-3, the insulation box prepared using aerogel as the inner lining layer can more effectively maintain the cell operating temperature and improve low-temperature discharge performance. Under low-temperature conditions, it can significantly reduce heat loss and improve the stability of battery energy output. Specifically, compared with Comparative Example 1, which did not employ any insulation measures, Example 1, using the insulation box of this invention, showed an increase in discharge capacity of approximately 46.9%. Compared with Examples 2 or 3, which only used ordinary insulation materials, Example 1 showed an increase in capacity of approximately 9.7%-16.7%.

[0111] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A heat preservation box for low-temperature testing of lithium manganese oxide single cells, characterized in that, include: A housing for accommodating a lithium manganese oxide single cell, the housing at least covering the main body area of ​​the cell except for its external electrical connection parts; An inner liner layer disposed on the inner surface of the housing, the inner liner layer being composed of an aerogel material; An outer shell layer disposed on the outside of the inner liner layer, the outer shell layer being made of plastic or composite foam material.

2. The insulated box according to claim 1, characterized in that, The thermal conductivity of the aerogel material in the inner lining layer is no higher than 0.02 W / (m·K).

3. The insulated box according to claim 1, characterized in that, The thickness of the inner lining layer is 0.5-5 mm; and / or, The thickness of the outer shell layer is 5-20 mm.

4. The insulated box according to claim 1, characterized in that, The aerogel material of the inner lining layer is selected from at least one of silica aerogel felt, ceramic aerogel felt, polymer aerogel felt or carbon aerogel felt.

5. The insulated box according to claim 1, characterized in that, The plastic material of the outer shell layer is selected from at least one of polycarbonate, ABS plastic, and PP plastic; or the composite foaming material of the outer shell layer is selected from at least one of EVA / EPE composite foaming material, EPP foaming composite material, or PU foaming composite material.

6. The insulated box according to claim 1, characterized in that, The inner lining layer accounts for 30-50% of the mass of the insulated box, and the outer shell layer accounts for 50-70% of the mass of the insulated box.

7. A method for testing the low-temperature performance of a lithium manganese oxide single cell, characterized in that, Using the insulated box as described in any one of claims 1 to 6, and including the following steps: Provides single-cell lithium manganese oxide battery cells; The single lithium manganese oxide battery cell is placed inside the insulation box, and the insulation box at least covers the main body area of ​​the battery cell except for its external electrical connection parts, so as to form an insulation space; The insulation box containing the battery cells is placed in a low-temperature environment; The battery cell is subjected to charge and discharge tests. The Joule heat and reaction heat generated by the battery cell itself are used to create a temperature rise inside the battery cell under the heat preservation effect of the heat preservation box, so as to simulate the heat accumulation environment in the battery module and test its discharge performance under the low temperature environment.

8. The test method according to claim 7, characterized in that, The low-temperature environment is -40°C to 0°C; and / or, By adjusting the heat preservation performance of the heat preservation box and the working current of the battery cell, the internal temperature of the battery cell can be made 5-15℃ higher than the external ambient temperature.

9. The test method according to claim 7, characterized in that, During the charge-discharge test, temperature changes inside the battery cell are monitored by temperature probes placed on the external electrical connection points and / or large surfaces of the battery cell.

10. A testing device for a single lithium manganese oxide cell, characterized in that, It includes the heat preservation box as described in any one of claims 1 to 6, as well as the equipment and temperature monitoring components for charge and discharge testing.

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