CN103837834B - The method of testing of battery thermal runaway characteristic - Google Patents

Abstract

The invention provides a method for testing the thermal runaway characteristics of a battery, comprising: selecting a simulant; placing the simulant in the calorimeter; calibrating the calorimeter to obtain calibration data, and after the calibration is completed , take out the simulant; put the battery sample to be tested into the calorimeter, and use the calibration data to conduct a thermal runaway test on the battery sample to be tested.

Description

Test method for battery thermal runaway characteristics

technical field

The invention belongs to the technical field of batteries, and in particular relates to a test method for the thermal runaway characteristics of batteries.

Background technique

Under the dual pressure of energy crisis and environmental pollution, electrification of vehicle power system has gradually become the mainstream of future vehicle technology development. One of the main characteristics of the electrification of the vehicle power system is to use the power battery as the main energy supply source of the vehicle. However, in recent years, fire and explosion accidents have occurred frequently due to thermal runaway of power batteries. The safety problem of power batteries not only seriously threatens the safety of people's lives and property, but also hinders the large-scale industrialization of electric vehicles. The research on the thermal runaway behavior of power batteries, especially the research on the thermal runaway behavior of large-capacity power batteries, is of great significance to solve the safety problems of power batteries. Conduct research to find out the key factors to solve the thermal runaway of the power battery, or design the battery safety protection device of the electric vehicle according to the thermal runaway behavior of the power battery to avoid the occurrence of thermal runaway of the power battery, etc.

One of the ways to evaluate the thermal runaway behavior of a battery is thermal runaway testing using an accelerating calorimeter. Accelerated calorimeter can provide an adiabatic environment in the battery thermal runaway test, so the heat released by the battery during the thermal runaway process can be accurately obtained. During the test, the battery sample to be tested is heated rapidly by the calorimeter until the self-generated heat of the battery sample to be tested is detected. During the rapid heating process of the calorimeter, a time interval is set, and within this time interval, the calorimeter suspends the rapid heating of the battery sample to be tested, and observes whether the surface temperature of the battery sample to be tested rises spontaneously. If the surface temperature of the battery sample to be tested rises spontaneously, it means that the battery sample to be tested has self-generated heat. The temperature at which the battery sample to be tested just begins to generate heat is called the starting point of heat release of the battery sample to be tested. After the self-heating of the battery sample to be tested occurs, the calorimeter stops the rapid heating of the battery sample to be tested, but starts to provide an insulating environment around the battery sample to be tested, so that all the heat generated by the battery sample to be tested is used for its own temperature rise. Obtaining an adiabatic environment needs to meet a core condition, that is, the temperature of the surface of the battery sample to be tested is always equal to the temperature of the inner wall of the calorimeter chamber of the calorimeter.

The temperature of the surface of the battery sample to be tested and the temperature of the inner wall of the calorimetric chamber are respectively measured by a first temperature sensor and a second temperature sensor. After the calorimeter finds the temperature difference between the first temperature sensor and the second temperature sensor, it eliminates the temperature difference by adding heat. However, because different temperature sensors are different, when the actual temperature is equal, the temperature sensor analog value read by the calorimeter may be different. In order to make up for this difference, the calorimeter will mistakenly add excess heat or less Supplementing the energy not only makes it impossible for the calorimeter to accurately find the exothermic starting point of the battery sample to be tested during the rapid temperature rise stage, but also fails to provide an adiabatic calorimetric environment for the battery sample to be tested. The analog value of the temperature sensor refers to an output signal that the temperature sensor intuitively responds to changes in temperature. For example, when the temperature sensor is a thermal resistance sensor, the analog value of the temperature sensor refers to a resistance value that varies with temperature.

Therefore, the calorimeter needs to be calibrated before use to eliminate the differences in the analog quantities measured by different sensors. However, in the usual calibration method, there is no sample inside the calorimeter, and in actual testing, especially in the testing process of large-capacity power batteries, the heat absorption of the battery sample to be tested will cause the surface temperature of the sample to be lower than that during the calibration process. Therefore, in the actual thermal runaway test process, the surface temperature of the sample will gradually drop during the time interval of stopping heating. This drop will cover the self-generated heat of the sample itself, making it impossible to accurately find the temperature of the sample during the experiment. The starting point of heat release, which marks the beginning of self-heating of the battery sample to be tested, is of great significance for the analysis of thermal runaway characteristics.

Contents of the invention

In view of this, it is indeed necessary to provide a test method that can accurately obtain the thermal runaway characteristics of the battery.

The invention provides a method for testing the thermal runaway characteristics of a battery, comprising:

A simulant is selected, and the relative error between the product of the mass of the simulant and the specific heat capacity and the product of the mass of the battery sample to be tested and the specific heat capacity is less than or equal to 10%;

placing the simulant in a calorimeter;

Calibrate the calorimeter, obtain calibration data, and take out the simulant after the calibration is completed;

The battery sample to be tested is put into the calorimeter, and the thermal runaway test is performed on the battery sample to be tested by using the calibration data.

Compared with the prior art, the test method for the thermal runaway characteristics of the battery provided by the present invention can complete accurate calibration work during the use of the calorimeter, so that the starting point of heat release of the battery can be accurately tested in the thermal runaway test The thermal runaway characteristics can provide an accurate reference for the research on the thermal runaway principle of power batteries and the design of electric vehicle battery safety protection devices.

Description of drawings

FIG. 1 is a schematic structural diagram of a calorimeter used in the battery thermal runaway characteristic test method provided by the present invention.

Fig. 2 is a flow chart of the test method for the thermal runaway characteristics of the battery provided by the present invention.

Fig. 3 is a calibration curve chart recorded during the calibration process of the calorimeter according to the embodiment of the present invention.

Fig. 4 is a thermal runaway test curve of the battery sample to be tested according to the embodiment of the present invention.

Fig. 5 is an enlarged view near the starting point of heat release in the thermal runaway test curve of the battery sample to be tested according to the embodiment of the present invention.

Explanation of main component symbols

Calorimeter 100

Calorimetry chamber 110

Top cover 120

first temperature sensor 130

Second temperature sensor 140

Fixed bracket 150

Screw 152

Nut 154

First top plate 156

Second Top Plate 158

Simulator 200

The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings.

detailed description

The method for testing the thermal runaway characteristics of the battery provided by the present invention will be further described in detail below in conjunction with specific embodiments and accompanying drawings.

Referring to Fig. 1, a calorimeter 100 includes a calorimetric cavity 110, a top cover 120, a first temperature sensor 130 and a second temperature sensor 140, and the first temperature sensor 130 is used to monitor the battery sample to be tested The temperature of the surface, the second temperature sensor 140 is used to monitor the temperature of the calorimetric cavity 110 . In the embodiment of the present invention, a large-scale accelerated calorimeter EV-ARC produced by British THT Company is used to conduct a thermal runaway test.

The calorimeter further includes a fixing bracket 150 for fixing the battery sample to be tested, and the fixing bracket 150 can be hoisted on the top cover 120 . The fixing bracket 150 includes a plurality of screw rods 152, a plurality of nuts 154, a first top plate 156 and a second top plate 158, and the first top plate 156 and the second top plate 158 can be fixed on the set by the nuts 154. On the screw 152 , the first top plate 156 and the second top plate 158 can be arranged opposite to each other, and can move up and down along the screw 158 .

Please refer to Figure 1 and Figure 2 together, a test method for thermal runaway characteristics of power batteries, including:

S1, select a simulant 200;

S2, placing the simulant 200 in the calorimeter 100;

S3. Calibrate the calorimeter 100 to obtain calibration data, and take out the simulant 200 after the calibration is completed;

S4, putting the battery sample to be tested into the calorimeter, and performing a thermal runaway test on the battery sample to be tested by using the calibration data.

In step S1, the simulant 200 is used to simulate the temperature field distribution of the battery sample to be tested during the calibration process, so that more accurate calibration data can be obtained in step S3. Preferably, the relative error between the product of the mass of the simulant 200 and the specific heat capacity and the product of the mass of the battery sample to be tested and the specific heat capacity may be less than or equal to 10%, so that the simulant 200 can more accurately simulate the Describe the temperature field distribution of the battery sample to be tested. More preferably, the relative error between the product of the mass and specific heat capacity of the simulant 200 and the product of the mass and specific heat capacity of the battery sample to be tested may be less than or equal to 5%. More preferably, the product of the mass and specific heat capacity of the simulant 200 may be the same as the product of the mass and specific heat capacity of the battery sample to be tested. The specific heat capacity of the sample to be tested can be measured by a common test method in the prior art.

Further, the shape of the simulant 200 may be the same as that of the battery sample to be tested. The shape can be characterized by multiple shape parameters, for example, when the shape is a cuboid, the cuboid can be characterized by length, width and height. Preferably, the relative error between each shape parameter of the simulant 200 and the corresponding shape parameter of the battery sample to be tested may be less than or equal to 10%. For example, when the battery sample to be tested is a cuboid, the simulant 200 may be It is a cuboid, and the relative error between the length, width or height of the simulant 200 and the corresponding length, width or height of the battery sample to be tested can be less than or equal to 10%, so that the simulant 200 can be more accurate The temperature field distribution of the battery sample to be tested is simulated. More preferably, the shape of the simulant 200 is the same as that of the battery sample to be tested, and the shape parameters are also the same. More preferably, the product of the mass of the simulant 200 and the specific heat capacity is the same as the product of the mass of the battery and the specific heat capacity, and the shape of the simulant 200 is the same as that of the battery sample to be tested, and the shape parameters are also the same, so that Make the temperature field distribution of the simulant 200 exactly the same as the temperature field distribution of the battery sample to be tested.

In the embodiment of the present invention, the mass of the battery sample to be tested is 0.72 kg, the specific heat capacity is 1100 J/(kg·K), the shape of the battery sample to be tested is a cuboid, and the length, width and height of the battery sample to be tested are respectively 146mm, 92mm and 26mm; the material of the simulant is an aluminum block, the mass is 0.91kg, the specific heat capacity of aluminum is 903J/(kg K), the shape of the simulant is a cuboid, and the length, width and height of the simulant are 150mm respectively , 90mm and 25mm. The relative error of the mass and specific heat capacity product of the simulant and the battery sample to be tested is 4%. The relative errors of the length, width and height of the simulant and the battery sample to be tested are 3%, 2% and 4% respectively.

In step S2, when placing the simulant 200 in the calorimeter 100, the simulant 200 can be suspended in the calorimeter 100 to ensure that the simulant 200 is not in contact with the calorimeter 100. The side walls of the thermal chamber 110 and the top cover 120 are in contact with each other. The simulant 200 can be hoisted on the top cover 120 so that the simulant 200 is suspended in the air. Preferably, the simulant 200 can be further fixed by using the fixing bracket 150 . The simulant 200 can be clamped by the first top plate 156 and the second top plate 158 so that the simulant 200 is fixed and suspended in the calorimeter 100 .

In step S3, before calibrating the calorimeter 100, it may further include clamping the first temperature sensor 130 between the simulant 200 and the first top plate 156 or the simulant 200 A fixing step is performed between the second top plate 158 so that the first temperature sensor 130 will not be detached from the simulant 200 during the calibration process.

In step S3, when calibrating the calorimeter 100, a calibration algorithm provided with the calorimeter 100 may be used for calibration. When performing calibration, the calorimeter 100 heats up, and maintains a temperature platform every other temperature interval, and records and calculates the analog values of the first temperature sensor 140 and the second temperature sensor 150 under different temperature platforms. difference. The temperature interval can be set by itself before calibration. Preferably, the temperature interval can be 5 to 25°C. The range of this temperature interval can enable the calibration to be completed in a short time, and can obtain more differences under different temperature platforms, which improves the calibration temperature. Data Accuracy. After obtaining the difference values under different temperature platforms, the calorimeter uses its own algorithm such as linear fitting to process the difference values, and thus obtain the first temperature sensor and the second temperature sensor at all temperatures. The difference of the analog value of the temperature sensor is the calibration data. Fig. 3 is a calibration curve recorded during the calibration process of the embodiment of the present invention. In the embodiment of the present invention, the temperature interval is 25°C.

In step S4, when the battery sample to be tested is placed in the calorimeter 100, the battery sample to be tested can be suspended in the calorimeter 100 to ensure that the battery sample to be tested not in contact with the calorimetric cavity 110 and the top cover 120 . The fixing bracket 150 can be further used to fix the battery sample to be tested. The battery sample to be tested can be clamped between the first top plate 156 and the second top plate, so that the battery sample to be tested can be fixed and hoisted in the calorimeter 100 .

When performing the thermal runaway test, it may further include clamping the first temperature sensor 130 between the battery sample to be tested and the first top plate 156 or between the battery sample to be tested and the second top plate 156. The step of fixing between the top plates 158 is to avoid that in the prior art, when the first temperature sensor 130 is pasted on the surface of the battery sample to be tested by tape, the tape will be damaged due to poor high temperature tolerance during the thermal runaway test. The adhesive tape falls off from the surface of the battery sample to be tested or the battery sample to be tested due to temperature rise and expansion, so that the first temperature sensor 130 can no longer reflect the temperature of the surface of the battery sample to be tested. question. The thermal runaway test procedure of the calorimeter can be used to test the thermal runaway characteristics of the battery sample to be tested. FIG. 4 is a thermal runaway test curve of the battery sample to be tested according to the embodiment of the present invention, and FIG. 5 is an enlarged view near the starting point of heat release in FIG. 4 . It can be seen from Figure 4 and Figure 5 that the starting point of self-generated heat of the battery sample to be tested is 85°C, and the battery sample to be tested is completely thermally out of control at about 200°C and explodes.

Compared with the prior art, the test method for the thermal runaway characteristics of the battery provided by the present invention can complete accurate calibration work during the use of the calorimeter, so that the starting point of heat release of the battery can be accurately tested in the thermal runaway test The thermal runaway characteristics can provide an accurate reference for the research on the thermal runaway principle of power batteries and the design of electric vehicle battery safety protection devices.

Claims (10)

1. a method of testing for battery thermal runaway characteristic, comprising:

Choose analogies, the quality of the sum of products mesuring battary sample of the quality of described analogies and specific heat capacityBe less than or equal to 10% with the relative error of the product of specific heat capacity;

Described analogies are positioned in a calorimeter;

Described calorimeter is calibrated, obtained calibration data, after calibration, described analogies are taken out;

Described mesuring battary sample is put into calorimeter, utilize described calibration data, to described mesuring battarySample carries out thermal runaway test.

2. the method for testing of battery thermal runaway characteristic as claimed in claim 1, is characterized in that, described analogiesThe sum of products of quality and specific heat capacity described in the quality of mesuring battary sample identical with the product of specific heat capacity.

3. the method for testing of the battery thermal runaway characteristic as described in claim 1 and 2 any one, is characterized in that,The shape of described analogies is identical with the shape of described mesuring battary sample.

4. the method for testing of battery thermal runaway characteristic as claimed in claim 3, is characterized in that, described analogiesWhile sign by multiple form parameters with the shape of mesuring battary sample, each shape of described analogiesThe relative error of the parameter form parameter corresponding with described mesuring battary sample is all less than or equal to 10%.

5. the method for testing of battery thermal runaway characteristic as claimed in claim 3, is characterized in that, described analogiesWhile sign by multiple form parameters with the shape of mesuring battary sample, each shape of described analogiesThe parameter form parameter corresponding with described mesuring battary sample is all identical.

6. the method for testing of battery thermal runaway characteristic as claimed in claim 1, is characterized in that, described calorimeterComprise a top cover, a calorimetric chamber, one first temperature sensor and one second temperature sensor, described firstTemperature sensor is for monitoring the surface temperature of described analogies or described mesuring battary sample, described secondTemperature sensor is for monitoring the temperature in described calorimetric chamber.

7. the method for testing of battery thermal runaway characteristic as claimed in claim 6, is characterized in that, to described amountWhen hot instrument is calibrated, described calorimeter is heated up, and maintain a temperature every a temperature intervalPlatform, and mould to described the first temperature sensor and described the second temperature sensor under different temperatures platformIntend numerical quantity and record and ask difference.

8. the method for testing of battery thermal runaway characteristic as claimed in claim 7, is characterized in that, obtains differenceAfter described difference under temperature platform, described calorimeter is processed described difference, obtains all temperatureUnder described the first temperature sensor and the difference of the analog quantity numerical value of described the second temperature sensor, this isFor described calibration data.

9. the method for testing of battery thermal runaway characteristic as claimed in claim 6, is characterized in that, described calorimetricInstrument further comprises a fixed support, and described fixed support is lifted on described top cover, described fixed supportComprise one first top board and one second top board, described the first top board and described the second top board are oppositely arranged, instituteState analogies or described mesuring battary sample by being clamped between described the first top board and described the second top boardBe fixed on described fixed support.

10. the method for testing of battery thermal runaway characteristic as claimed in claim 9, is characterized in that, calibration orThermal runaway when test, will described the first temperature sensor be clamped in described analogies or described sample battery andBetween described the first top board or described the second top board, be fixed.