Battery early warning test system and method using characteristic gas concentration threshold

Abstract

The invention provides a battery early warning test system and method using a characteristic gas concentration threshold. The battery thermal runaway test system comprises a data recorder, a voltage wire, a battery temperature acquisition part, a tank body, an in-tank pressure acquisition part connected with the tank body, an in-tank gas concentration acquisition part connected with the tank body, an excitation source assembly connected with the tank body, a gas collection pipeline connected with the tank body, and a vacuum pipeline connected with the tank body, the inert gas pipeline is connected with the tank body; the battery temperature acquisition piece, the in-tank pressure acquisition piece, the in-tank gas concentration acquisition piece and the voltage line are all connected with the data recorder; the excitation source assembly comprises an electric excitation source assembly or a heat excitation source assembly, the electric excitation source assembly comprises an electric excitation source and a connecting wire which are connected with each other, and the heat excitation source assembly comprises a heat excitation source, a heating wire and an electric heating sheet which are connected with each other. According to the method, the concentration threshold of each characteristic gas for early warning can be determined, potential risks can be found in time before thermal runaway occurs, accidents are prevented, and the safety of the battery is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and in particular relates to a battery early warning test system and method using characteristic gas concentration thresholds. Background Art

[0002] Lithium-ion batteries, due to their high energy density, long cycle life, and lack of memory, are considered the optimal next-generation energy storage device. However, with their widespread use, safety issues have gradually surfaced, becoming a major obstacle to their further development. In recent years, numerous lithium-ion battery-related safety incidents have occurred worldwide, many resulting in casualties and significant property damage. These incidents are all caused by thermal runaway in lithium-ion batteries. Thermal runaway is a major obstacle to the widespread adoption of electric vehicles. Thermal runaway in lithium-ion batteries is a process of internal heat accumulation and the generation of high-temperature, flammable gases. High battery temperatures are primarily caused by external stimulation, which triggers spontaneous reactions within the battery. This process results in a sharp increase in temperature, a sudden drop in voltage, and the generation of large amounts of toxic and hazardous gases. Furthermore, while various new battery technologies on the market are currently striving for higher energy density, these batteries, once exposed to external stimulation, not only have low critical temperatures for thermal runaway but also react violently, making them susceptible to fire and explosion. Therefore, a comprehensive understanding of the thermal runaway characteristics of lithium-ion batteries under different external stimulus sources, including but not limited to the temperature and voltage signals throughout the thermal runaway process, as well as the amount and composition of gases generated by the battery, will contribute to the development of high-safety battery products, the formulation of corresponding battery explosion warning strategies, and emergency prevention and control measures. In addition, most existing battery thermal runaway test systems only meet the stimulation of a single stimulus source, and the collected parameters are relatively limited, making it impossible to fully understand the thermal runaway characteristics of the battery. More importantly, the existing battery thermal runaway test methods are mainly used to assess the safety of batteries under extreme abuse conditions and to observe whether fires, explosions, and other phenomena will occur. However, these test methods mainly focus on the performance after thermal runaway occurs, and are unable to capture subtle changes in the early stages of thermal runaway. Their test results cannot be directly used to achieve early warning.

[0003] In view of this, developing a battery thermal runaway test system that can not only break through the stimulation of a single excitation source but also help achieve early warning has become an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of the present invention is to solve the difficulties existing in the above-mentioned prior art and provide a battery early warning test system and method using characteristic gas concentration thresholds. The system not only supports multiple stimulus sources (thermal stimulus sources, electrical stimulus sources), but also supports real-time acquisition of multiple parameters (temperature, voltage, gas concentrations, gas quantities, and gas components).

[0005] One of the objectives of the present invention is to provide a battery early warning test system using characteristic gas concentration thresholds, including a data recorder, a voltage line, a battery temperature collection component, a tank body, and a tank pressure collection component connected to the tank body, a tank gas concentration collection component connected to the tank body, an excitation source component connected to the tank body and used to stimulate thermal runaway of a battery to be tested, a gas collecting pipeline connected to the tank body and used to collect gas in the tank body, a vacuum pipeline connected to the tank body and used to provide a vacuum degree for the tank body, and an inert gas pipeline connected to the tank body and used to introduce inert gas into the tank body; the battery temperature collection component, the tank pressure collection component, the tank gas concentration collection components, and the voltage line are all connected to the data recorder; the excitation source component includes an electric excitation source component or a thermal excitation source component, the electric excitation source component includes a connected electric excitation source and a connecting line, and the thermal excitation source component includes a connected thermal excitation source, a heating line, and an electric heating plate.

[0006] In a preferred embodiment of the present invention,

[0007] The can body is a sealed metal can; and / or,

[0008] The battery temperature collecting component is a thermocouple, the measuring end of the thermocouple is arranged inside the tank body, and the free end of the thermocouple is arranged outside the tank body; and / or,

[0009] The tank pressure collection component is a pressure gauge; and / or,

[0010] The gas concentration collecting components in the tank are gas sensors, and the measuring ends of the gas sensors are arranged inside the tank body.

[0011] In a preferred embodiment of the present invention,

[0012] The battery temperature collecting member is connected to the top surface of the tank; and / or,

[0013] The tank internal pressure collection member is connected to the top surface of the tank body; and / or,

[0014] Each gas concentration collecting element in the tank is connected to the top surface of the tank body; and / or,

[0015] The voltage line is connected to the side surface of the tank body.

[0016] In a preferred embodiment of the present invention,

[0017] The battery early warning test system using characteristic gas concentration thresholds further includes a gas collection bag; the gas collection pipeline is connected to the bottom surface of the tank, and the other end of the gas collection pipeline is connected to the gas collection bag; and / or,

[0018] The battery early warning test system using characteristic gas concentration thresholds further includes a vacuum pump; the vacuum pipeline is connected to the top surface of the tank, and the other end of the vacuum pipeline is connected to the vacuum pump; and / or,

[0019] The battery early warning test system using characteristic gas concentration thresholds further includes an inert gas storage tank; the inert gas pipeline is connected to the bottom surface of the tank body, and the other end of the inert gas pipeline is connected to the inert gas storage tank.

[0020] In a preferred embodiment of the present invention, the gas in the inert gas pipeline is argon or nitrogen.

[0021] In a preferred embodiment of the present invention,

[0022] A gas collecting valve is provided on the gas collecting pipeline; and / or,

[0023] A vacuum valve is provided on the vacuum pipeline; and / or,

[0024] An inert gas valve is provided on the inert gas pipeline.

[0025] A second object of the present invention is to provide a battery early warning test method using characteristic gas concentration thresholds, which is performed using the battery early warning test system using characteristic gas concentration thresholds described in the first object of the present invention, and includes the following steps:

[0026] Step 1: Place the electric heating plate on the first largest surface of the battery to be tested, connect the electric heating plate to a heating wire, and the other end of the heating wire is located outside the tank and connected to a heat source; connect the measuring end of the battery temperature acquisition component to the second largest surface of the battery to be tested; and connect two voltage wires to the positive and negative electrodes of the battery to be tested, respectively;

[0027] Step 2: vacuum the tank;

[0028] Step 3: Fill the tank with inert gas;

[0029] Step 4: Start the heat source. When the pressure in the tank drops below the pressure threshold and the temperature rise rate of the battery under test exceeds the temperature rise threshold, turn off the heat source.

[0030] Step 5: Draw a graph showing the temperature of the battery to be tested and the concentration of each gas in the tank changing with time; and obtain the concentration thresholds of each characteristic gas for early warning based on the graph.

[0031] In a preferred embodiment of the present invention,

[0032] In step 1, the heat source is a constant current power supply; and / or,

[0033] In step 2, the vacuum degree in the tank is not greater than -0.1 MPa, preferably -0.09 to -0.10 MPa; and / or,

[0034] In step 3, the pressure inside the tank is not less than 1.00 MPa, preferably 1.00 to 1.20 MPa; and / or;

[0035] In step 4, the pressure threshold is 0V and the temperature rise threshold is 1°C / s.

[0036] A third object of the present invention is to provide another battery early warning test method using characteristic gas concentration thresholds, which is performed using the battery early warning test system using characteristic gas concentration thresholds described in the first object of the present invention, and includes the following steps:

[0037] S1: Connect the electric source to the positive and negative electrodes of the battery under test; connect the measuring end of the battery temperature acquisition component to the second largest surface of the battery under test; connect two voltage lines to the positive and negative electrodes of the battery under test respectively;

[0038] S2: Vacuum the tank;

[0039] S3: Fill the tank with inert gas;

[0040] S4: Turn on the electric excitation source to overcharge or over-discharge the battery under test; when the pressure in the tank drops below the pressure threshold and the temperature rise rate of the battery under test exceeds the temperature rise threshold, turn off the electric excitation source;

[0041] S5: Draw a graph showing the temperature of the battery to be tested and the concentration of each gas in the tank changing with time; and obtain the concentration thresholds of each characteristic gas for early warning based on the graph.

[0042] In a preferred embodiment of the present invention,

[0043] In S1, the electric excitation source is a constant current power supply; and / or,

[0044] In S2, the vacuum degree in the tank is not greater than -0.1 MPa, preferably -0.09 to -0.10 MPa; and / or, in S3, the pressure in the tank is not less than 1.00 MPa, preferably 1.00 to 1.20 MPa; and / or;

[0045] In S4, the pressure threshold is 0V and the temperature rise threshold is 1°C / s.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The battery early warning test system of the present invention utilizes characteristic gas concentration thresholds, and is equipped with gas concentration collection elements within the tank to quantitatively monitor battery gas production in real time. By combining the temporal changes of the battery gas production collected by the gas concentration collection elements within the tank and the temperature of the battery temperature collection element, the characteristic gas concentration thresholds for early warning can be determined. The setting of the characteristic gas concentration thresholds helps to timely detect potential risks before thermal runaway occurs, prevent accidents, improve battery safety, and reduce property losses and casualties. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 Schematic diagram of the structure of the battery early warning test system using characteristic gas concentration thresholds in the present invention;

[0049] Figure 2 Schematic diagram of the battery early warning test system using characteristic gas concentration thresholds in the present invention (same as Figure 1 );

[0050] Figure 3 A schematic diagram of a battery early warning test method using characteristic gas concentration thresholds according to the present invention;

[0051] Figure 4 Schematic diagram of a battery early warning test method using characteristic gas concentration thresholds in the present invention (same as Figure 3 );

[0052] Figure 5 A schematic diagram of a battery early warning test method using characteristic gas concentration thresholds according to the present invention;

[0053] Figure 6 Schematic diagram of a battery early warning test method using characteristic gas concentration thresholds in the present invention (same as Figure 5 );

[0054] Figure 7 A graph showing changes in the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank 1, and the gas pressure in the tank 1 over time;

[0055] Figure 8 A graph showing the temperature of the battery to be tested and the concentration of hydrogen in the tank 1 changing with time (partial time period);

[0056] Figure 9 A graph showing the temperature of the battery to be tested and the concentrations of carbon dioxide and carbon monoxide in the tank 1 changing with time (partial time period);

[0057] In the figure, 1-tank body; 2-battery temperature collection component; 3-tank internal pressure collection component; 4-tank internal gas concentration collection component; 5-voltage line; 6-data recorder; 7-vacuum pump; 8-inert gas storage tank; 9-gas collection bag; 10-electric heating plate; 11-heating wire; 12-constant current power supply. DETAILED DESCRIPTION

[0058] The present invention is further described in detail below with reference to the accompanying drawings:

[0059] like Figure 1 and Figure 2 As shown, the present invention provides a battery early warning test system using characteristic gas concentration thresholds, including a data recorder 6, a voltage line 5, a battery temperature acquisition component 2, a tank body 1 and a tank pressure acquisition component 3 connected to the tank body 1, a tank gas concentration acquisition component 4 connected to the tank body 1, an excitation source component connected to the tank body 1 and used to stimulate thermal runaway of the battery to be tested, a gas collecting pipeline connected to the tank body 1 and used to collect gas in the tank body 1, a vacuum pipeline connected to the tank body 1 and used to provide vacuum for the tank body 1, and an inert gas pipeline connected to the tank body 1 and used to introduce inert gas into the tank body 1; the battery temperature acquisition component 2, the tank pressure acquisition component 3, the tank gas concentration acquisition components 4, and the voltage line 5 are all connected to the data recorder 6; the excitation source component includes an electric excitation source component or a thermal excitation source component, the electric excitation source component includes a connected electric excitation source and a connecting line, and the thermal excitation source component includes a connected thermal excitation source, a heating wire 11, and an electric heating plate 10.

[0060] Those skilled in the art know that when conducting a battery thermal runaway test, the battery to be tested must be placed in the tank body 1 for testing, so the tank body 1 is a storage device for the battery to be tested. The tank pressure collection component 3 and the tank gas concentration collection component 4 connected to the tank body 1 are used to collect the pressure in the tank body 1 and the gas concentration in the tank body 1 respectively. When conducting a battery thermal runaway test, the voltage line 5 and the battery temperature collection component 2 both need to be connected to the battery to be tested to collect the pressure of the battery to be tested and the temperature of the battery to be tested respectively; when the battery thermal runaway test is completed, the connection between the voltage line 5 and the battery to be tested and the connection between the battery temperature collection component 2 and the battery to be tested can be disconnected. It should be noted that the voltage line 5 itself does not have the function of measuring voltage, but because it is connected to the data recorder 6, the combination of the two has the function of measuring voltage. This is a prior art and will not be described in detail here. Furthermore, "the battery temperature acquisition component 2, the tank pressure acquisition component 3, the tank gas concentration acquisition component 4, and the voltage line 5 are all communicatively connected to the data recorder 6." Therefore, the data recorder 6 is used to receive the temperature of the battery under test, the pressure of the battery under test, the pressure within the tank body 1, and the concentrations of the gases within the tank body 1. Based on the temporal changes of these two parameters, the temperature of the battery under test and the concentrations of the gases within the tank body 1, the characteristic gas concentration thresholds for early warning are determined, thereby facilitating early warning of battery thermal runaway. The gas collection pipeline is used to collect gaseous products released by the battery under test during thermal runaway testing for subsequent analysis. The vacuum pipeline is used to ensure that the vacuum level within the tank body 1 meets preset requirements. The inert gas pipeline is used, firstly, to exhaust air from the tank body 1 and create an inert gas atmosphere within the tank body 1, so that the gas products collected by the gas collection pipeline are not affected by air components. Secondly, it is used to enhance the inert gas atmosphere within the tank body 1, making subsequent analysis of the gas products more accurate.

[0061] In a preferred embodiment of the present invention, the tank body 1 is a sealed metal tank, which utilizes its sealing, high temperature resistance and pressure resistance properties to ensure the safety and accuracy of the test process; and / or, the battery temperature collection component 2 is a thermocouple, the measuring end of the thermocouple is located in the tank body 1 and is connected to the battery to be tested during the test, and is used to collect the surface temperature of the test battery, and utilizes its fast response speed and wide measurement range to ensure the real-time and accuracy of the test process, and the free end of the thermocouple is located outside the tank body 1; and / or, the tank pressure collection component 3 is a pressure gauge, which is used to collect the pressure in the tank body 1 on the one hand, and to calculate the total gas production of the battery to be tested based on the difference between the steady-state air pressure and the atmospheric pressure after the experiment; and / or, the tank gas concentration collection component 4 is a gas sensor, the measuring end of which is located in the tank body 1, and is used to collect the concentration of each gas in the tank body 1; the tank gas concentration collection component 4 is a conventional commercially available product.

[0062] In a preferred embodiment of the present invention, the battery temperature collection component 2 is connected to the top surface of the tank body 1; and / or, the tank pressure collection component 3 is connected to the top surface of the tank body 1; and / or, the gas concentration collection components 4 in the tank are connected to the top surface of the tank body 1; and / or, the voltage line 5 is connected to the side of the tank body 1; and / or, the battery early warning test system using characteristic gas concentration thresholds also includes a gas collection bag, the gas collection pipeline is connected to the bottom surface of the tank body 1, and the other end of the gas collection pipeline is connected to the gas collection bag 9 to collect the gas products released by the battery to be tested during the thermal runaway test for subsequent analysis; and / or, the battery early warning test system using characteristic gas concentration thresholds The early warning test system also includes a vacuum pump 7, the vacuum pipeline is connected to the top surface of the tank body 1, and the other end of the vacuum pipeline is connected to the vacuum pump 7, so that the vacuum degree in the tank body 1 meets the preset requirements; and / or, the battery early warning test system using characteristic gas concentration thresholds also includes an inert gas storage tank 8, the inert gas pipeline is connected to the bottom surface of the tank body 1, and the other end of the inert gas pipeline is connected to the inert gas storage tank 8. On the one hand, it can discharge the air in the tank body 1 and form an inert gas atmosphere in the tank body 1, so that the gas products collected by the gas collection bag 9 are not affected by the air components. On the other hand, it can effectively improve the inert gas atmosphere in the tank body 1, so that the subsequent analysis of gas products is more accurate. Preferably, the gas in the inert gas pipeline is argon or nitrogen.

[0063] In a preferred embodiment of the present invention, a gas collecting valve is provided on the gas collecting pipeline to control whether the gas in the tank body 1 enters the gas collecting pipeline and then enters the gas collecting bag 9; and / or, a vacuum valve is provided on the vacuum pipeline to jointly control with the vacuum pump 7 whether the gas in the tank body 1 is extracted and thus adjust the vacuum degree in the tank body 1; and / or, an inert gas valve is provided on the inert gas pipeline to control whether the inert gas in the inert gas storage tank 8 enters the tank body 1.

[0064] Those skilled in the art know that during the actual process of battery thermal runaway testing, multiple gases are generated, and the time at which the multiple gases are generated is not the same, and there may be interactions between different gases. The existing technology collects gases through a gas collection bag 9, and then uses a gas chromatography thermal conductivity detector (GC-WLD) method to analyze the collected gases; therefore, the existing technology can only analyze the proportion of different gases under steady-state conditions after the battery thermal runaway. The warning for the battery to be tested is based on the gas products after the battery thermal runaway, and it is impossible to achieve early warning of battery thermal runaway. The present invention sets up gas concentration collection components 4 in the tank to quantitatively monitor the gas production of the battery in real time. Combining the battery gas production of each gas concentration collection component 4 in the tank with the real-time temperature of the battery temperature collection component 2, it is possible to determine the characteristic gas concentration threshold for early warning. The setting of this characteristic gas concentration threshold helps to timely detect potential risks before thermal runaway occurs, prevent accidents, improve battery safety, and reduce property losses and casualties. In addition, the gas concentration collection components 4 in the tank will not affect the pressure collection of the voltage line 5.

[0065] The present invention also provides a battery early warning test method using characteristic gas concentration thresholds, which includes two types: the first battery early warning test method using characteristic gas concentration thresholds uses a thermal excitation source as the excitation method, and the second battery early warning test method using characteristic gas concentration thresholds uses an electrical excitation source as the excitation method. Figure 3 and Figure 4 As shown, the following steps are included:

[0066] Step 1: Place the electric heating plate 10 on the first largest surface of the battery to be tested. The electric heating plate 10 is connected to the heating wire 11. The other end of the heating wire 11 is located outside the tank body 1 and connected to the heat source. For example, the heat source is a constant current power supply 12, and the heating wire 11 is connected to the constant current power supply 12 (220V power supply). Connect the measuring end of the battery temperature acquisition component 2 to the second largest surface of the battery to be tested. The other end of the battery temperature acquisition component 2 is located outside the tank body 1 and connected to the data recorder 6. Connect one end of the two voltage lines 5 to the positive and negative poles of the battery to be tested respectively, and the other end is located outside the tank body 1 and both are connected to the data recorder 6. Connect each gas concentration acquisition component 4 in the tank to the tank body 1 and set its measuring end inside the tank body 1. The other end of each gas concentration acquisition component 4 in the tank is located outside the tank body 1 and connected to the data recorder 6. The tank pressure collection device 3 is connected to the tank body 1 with its measuring end located inside the tank body 1. The other end of the tank pressure collection device 3 is located outside the tank body 1 and connected to the data recorder 6. It should be noted that during the subsequent testing process, the data recorder 6 continuously receives the temperature and pressure of the battery under test, the concentration of various gases in the tank body 1, and the air pressure in the tank body 1.

[0067] Step 2: Confirm that the gas collection valve and the inert gas valve are closed. Open the vacuum valve and vacuum pump 7 to start evacuating the tank body 1. When the pressure inside the tank body 1 is no greater than -0.1 MPa (i.e., the reading on the tank pressure collection unit 3 is no greater than -0.1 MPa), close the vacuum valve and vacuum pump 7.

[0068] Step three, connect the inert gas pipeline to the inert gas storage tank 8, open the inert gas valve, and fill the tank body 1 with inert gas. When the pressure in the tank body 1 is not less than 1.00MPa (i.e. the reading of the pressure collecting part 3 in the tank is not less than 1.00MPa), close the inert gas valve. Preferably, "open the inert gas valve and fill the tank body 1 with inert gas" is repeated twice to ensure that the air in the tank body 1 is completely removed. It should be noted that, Figure 4 The gas stored in the inert gas storage tank 8 is argon. This is only an exemplary description and does not constitute a limitation on the inert gas. Other inert gases can be used in specific implementations.

[0069] Step 4: Start the heat source and begin heating. Observe and record the temperature of the battery under test, the pressure of the battery under test, the pressure inside tank 1, and the concentrations of the various gases inside tank 1. When the pressure inside tank 1 drops below 0V and the temperature rise rate of the battery under test exceeds 1°C / s for more than 3 seconds, disconnect the heating wire 11 from the heat source (i.e., disconnect the heating wire 11 from the 220V power supply), turn off the heat source, and stop heating.

[0070] Step 5: Based on the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1, and the air pressure in the tank body 1, a graph is drawn showing the changes in the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1, and the air pressure in the tank body 1 over time, and based on the graph, the concentration thresholds of each characteristic gas for early warning are obtained.

[0071] Step 6: After the temperature of the battery under test begins to drop and the reading on the pressure collection unit 3 in the tank stabilizes, open the gas collection valve to collect gas. This gas is analyzed using gas chromatography to determine the gas components that indicate thermal runaway in the battery under test. After the experiment is complete, exhaust the remaining flue gas.

[0072] Those skilled in the art know that commercial batteries are all equipped with safety valves. When the internal pressure of the battery is too high, the safety valve ruptures and produces gas, which occurs before the battery thermal runaway. There is a period of time between the monitoring of the gas concentration from the rupture of the safety valve to the occurrence of thermal runaway of the battery. If emergency measures are taken during this period of time, it can play an early warning role, prevent accidents, and improve the safety of the battery. The present invention plots a graph of the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1, and the air pressure in the tank body 1 over time, and obtains the threshold value of each characteristic gas concentration based on the graph; therefore, emergency measures can be set according to the threshold value of each characteristic gas concentration before the battery thermal runaway occurs, which is used for safety prevention and control work in real scenarios. In other words, in actual application, the sensor that can monitor the concentration of each gas is interlocked with the emergency measures (such as alarm, fire extinguishing). When the real-time concentration of a characteristic gas exceeds its characteristic gas concentration threshold, the emergency measures are activated to prevent the battery from thermal runaway and then causing a fire. It should be noted that, generally speaking, the characteristic gas concentration platform before the temperature of the battery to be tested rises is selected as the characteristic gas concentration threshold; the "characteristic gas concentration platform" here means that the concentration of various gases changes very little within a certain period of time, so that it almost forms a platform in the curve graph.

[0073] The second battery early warning test method using characteristic gas concentration thresholds uses an electric excitation source as the excitation method. Figure 5 and Figure 6 As shown, the following steps are included:

[0074] S1: Connect the electric source to the positive and negative electrodes of the battery under test via connecting wires (illustratively, the connecting wires can be cables). Different electric source operating conditions can be set, such as overcharge electric source operating conditions, overdischarge electric source operating conditions, etc. Exemplarily, the electric source can be a constant current power supply 12. Connect the measuring end of the battery temperature acquisition component 2 to the second largest surface of the battery under test. The other end of the battery temperature acquisition component 2 is located outside the tank body 1 and connected to the data recorder 6. Connect two voltage lines 5 to the positive and negative electrodes of the battery under test respectively. The other ends are located outside the tank body 1 and connected to the data recorder 6. Connect the gas concentration acquisition components 4 in the tank to the tank body 1, with their measuring ends located inside the tank body 1. The other ends of the gas concentration acquisition components 4 in the tank are located outside the tank body 1 and connected to the data recorder 6. Connect the tank pressure acquisition component 3 to the tank body 1, with its measuring end located inside the tank body 1. The other end of the tank pressure acquisition component 3 is located outside the tank body 1 and connected to the data recorder 6. It should be noted that, during the subsequent testing process, the data recorder 6 continuously receives the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1 , and the gas pressure in the tank body 1 .

[0075] S2: Confirm that the gas collection valve and the inert gas valve are both closed. Open the vacuum valve and vacuum pump 7 to start evacuating the tank body 1. When the pressure in the tank body 1 is no greater than -0.1 MPa (i.e., the reading on the tank pressure collection unit 3 is no greater than -0.1 MPa), close the vacuum valve and vacuum pump 7.

[0076] S3, connect the inert gas pipeline to the inert gas storage tank 8, open the inert gas valve, and fill the tank body 1 with argon gas, repeat twice. When the pressure in the tank body 1 is not less than 1.00MPa (i.e. the reading on the tank pressure collection unit 3 is not less than 1.00MPa), close the inert gas valve. Figure 6 The gas stored in the inert gas storage tank 8 is argon. This is only an exemplary description and does not constitute a limitation on the inert gas. Other inert gases can be used in specific implementations.

[0077] S4: Turn on the electric source to overcharge or overdischarge the battery under test. Observe and record the temperature of the battery under test, the pressure of the battery under test, the pressure inside tank 1, and the concentration of each gas inside tank 1. When the pressure inside tank 1 drops below 0V and the temperature rise rate of the battery under test exceeds 1°C / s for more than 3 seconds, disconnect the cable from the constant current power supply 12 and stop heating.

[0078] S5: Based on the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1, and the air pressure in the tank body 1, a graph is drawn showing the changes of the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1, and the air pressure in the tank body 1 over time, and based on the graph, the concentration threshold values of each characteristic gas for early warning are obtained.

[0079] S6: After the temperature of the battery under test begins to drop and the reading on the pressure collection unit 3 in the tank stabilizes, open the gas collection valve to collect gas. This gas is analyzed using gas chromatography to determine the gas components that indicate thermal runaway in the battery under test. Exhaust the remaining flue gas after the experiment is complete.

[0080] Example 1

[0081] The battery under test is tested for thermal runaway using the aforementioned battery early warning test system utilizing characteristic gas concentration thresholds. The system includes a data recorder 6, a voltage line 5, a battery temperature sensor 2, a tank body 1, and a tank pressure sensor 3, tank gas concentration sensor 4, connected to the tank body 1, a gas collection line, a vacuum line, and an inert gas line. The battery temperature sensor 2, tank pressure sensor 3, tank gas concentration sensor 4, and voltage line 5 are all connected to the data recorder 6. The tank body 1 is a sealed metal tank; the battery temperature collection component 2 is connected to the top surface of the tank body 1, specifically a thermocouple, the measuring end of the thermocouple is located inside the tank body 1, and the free end of the thermocouple is located outside the tank body 1; the tank internal pressure collection component 3 is connected to the top surface of the tank body 1, specifically a pressure gauge; the tank internal gas concentration collection component 4 is connected to the top surface of the tank body 1, specifically a gas sensor, and its measuring end is located inside the tank body 1; the voltage line 5 is connected to the The side is connected; the gas collecting line is connected to the bottom surface of the tank body 1, and the other end of the gas collecting line is connected to the gas collecting bag 9, and the gas collecting line is provided with a gas collecting valve; the vacuum line is connected to the top surface of the tank body 1, and the other end of the vacuum line is connected to the vacuum pump 7, and the vacuum line is provided with a vacuum valve; the inert gas line is connected to the bottom surface of the tank body 1, and the other end of the inert gas line is connected to the inert gas storage tank 8, and the inert gas line is provided with an inert gas valve. The inert gas storage tank 8 is an argon cylinder, so the gas in the inert gas line is argon. The parameters of the battery to be tested are shown in Table 1.

[0082] Table 1 Parameters of the battery under test

[0083] Battery parameter cathode materials Lithium iron phosphate (LFP) Anode materials Graphite (C) Nominal capacity 50Ah Nominal voltage 3.2V Cut-off voltage 3.65V / 2.5V Internal resistance 0.7mΩ size 185mm×135mm×29mm weight 1395±50g

[0084] The battery thermal runaway excitation method of this embodiment is a method using a thermal excitation source, which includes the following steps:

[0085] Step 1: Place the electric heating plate 10 on the first largest surface of the battery to be tested. The electric heating plate 10 is connected to the heating wire 11. The other end of the heating wire 11 is located outside the tank body 1 and connected to the constant current power supply 12. Connect the measuring end of the battery temperature acquisition component 2 to the second largest surface of the battery to be tested. The other end of the battery temperature acquisition component 2 is located outside the tank body 1 and connected to the data recorder 6. Connect one end of the two voltage lines 5 to the positive and negative poles of the battery to be tested respectively, and the other ends are located outside the tank body 1 and are both connected to the data recorder 6. Connect the gas concentration acquisition components 4 in the tank to the tank body 1 and have their measuring ends located inside the tank body 1. The other ends of the gas concentration acquisition components 4 in the tank are located outside the tank body 1 and are connected to the data recorder 6. Connect the tank pressure acquisition component 3 to the tank body 1 and have its measuring end located inside the tank body 1. The other end of the tank pressure acquisition component 3 is located outside the tank body 1 and is connected to the data recorder 6.

[0086] Step 2: Confirm that the gas collection valve and the inert gas valve are closed. Open the vacuum valve and vacuum pump 7 to start evacuating the tank body 1. When the pressure in the tank body 1 reaches -0.1 MPa (i.e., the reading on the tank pressure collection unit 3 is -0.1 MPa), close the vacuum valve and vacuum pump 7.

[0087] Step 3: Connect the inert gas pipeline to the inert gas storage tank 8, open the inert gas valve, and fill the tank body 1 with argon. Repeat this process twice. When the pressure in the tank body 1 reaches 1.01 MPa (i.e., when the pressure measurement unit 3 shows 1.01 MPa), close the inert gas valve.

[0088] Step 4: Start the constant current power supply 12 and begin heating. Observe and record the temperature of the battery under test, the pressure of the battery under test, the pressure inside tank 1, and the concentration of each gas inside tank 1. When the pressure inside tank 1 drops below 0V and the temperature rise rate of the battery under test exceeds 1°C / s for more than 3 seconds, disconnect the heating wire 11 from the constant current power supply 12, turn off the constant current power supply 12, and stop heating.

[0089] Step 5: Based on the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1 and the pressure in the tank body 1, a graph is drawn showing the temperature of the battery to be tested, the pressure of the battery to be tested, the concentration of each gas in the tank body 1 and the pressure in the tank body 1 changing with time (e.g. Figure 7 As shown in FIG, the concentration thresholds of each characteristic gas for early warning are obtained based on the curve diagram.

[0090] Depend on Figure 7 It can be seen that the temperature of the battery under test rises significantly when the test time is about 1200s. Before the temperature of the battery under test rises significantly, the hydrogen concentration reaches a plateau in the test time range of 550-700s. The curves of the temperature and hydrogen concentration of the battery under test over time during this period are listed separately. The results are as follows: Figure 8 As shown. Figure 8 It can be seen that the concentration of hydrogen changes little within 610 to 625 seconds. In practical applications, the corresponding gas concentration of 3132ppm can be used as the characteristic gas concentration threshold of hydrogen in early warning. When the real-time hydrogen concentration exceeds the characteristic gas concentration threshold of hydrogen, emergency measures are initiated to prevent thermal runaway of the battery and fire. Similarly, before the temperature of the battery to be tested rises significantly, the specific test time is in the range of 850 to 1200 seconds, and the concentrations of carbon dioxide and carbon monoxide have a platform. The curves of the temperature of the battery to be tested and the concentrations of carbon dioxide and carbon monoxide changing with time during this time period are listed separately, and the results are as follows. Figure 9 As shown. Figure 9 It can be seen that the concentration of carbon dioxide changes little between 1075 and 1175 seconds, and the concentration of carbon monoxide changes little between 1000 and 1100 seconds. In practical applications, the gas concentration corresponding to the carbon dioxide platform, 8288 ppm, can be used as the characteristic gas concentration threshold for carbon dioxide in early warning, and the gas concentration corresponding to carbon monoxide, 6314 ppm, can be used as the characteristic gas concentration threshold for carbon monoxide in early warning. Emergency measures are initiated when the real-time carbon dioxide concentration exceeds the characteristic gas concentration threshold for carbon dioxide, or when the real-time carbon monoxide concentration exceeds the characteristic gas concentration threshold for carbon monoxide, to prevent battery thermal runaway and fire.

[0091] Step 6: After the temperature of the battery under test begins to drop and the reading on the pressure collection unit 3 in the tank stabilizes, open the gas collection valve to collect gas. This gas is analyzed using gas chromatography to determine the gas components that indicate thermal runaway in the battery under test. After the experiment is complete, exhaust the remaining flue gas.

[0092] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection; mechanical connection, electrical connection; direct connection, or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0093] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0094] The above technical solution is only one embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A battery early warning test system using characteristic gas concentration thresholds, characterized in that: It includes a data recorder, a voltage line, a battery temperature collection component, a tank body, and a tank pressure collection component connected to the tank body, a tank gas concentration collection component connected to the tank body, an excitation source component connected to the tank body and used to excite thermal runaway of the battery to be tested, a gas collecting pipeline connected to the tank body and used to collect the gas in the tank body, a vacuum pipeline connected to the tank body and used to provide vacuum for the tank body, and an inert gas pipeline connected to the tank body and used to introduce inert gas into the tank body; the battery temperature collection component, the tank pressure collection component, the tank gas concentration collection components, and the voltage line are all connected to the data recorder; the excitation source component includes an electric excitation source component or a thermal excitation source component, the electric excitation source component includes a connected electric excitation source and a connecting line, and the thermal excitation source component includes a connected thermal excitation source, a heating line, and an electric heating plate.

2. The battery early warning test system using characteristic gas concentration threshold according to claim 1, characterized in that: The can body is a sealed metal can; and / or, The battery temperature collecting component is a thermocouple, the measuring end of the thermocouple is arranged inside the tank body, and the free end of the thermocouple is arranged outside the tank body; and / or, The tank pressure collection component is a pressure gauge; and / or, The gas concentration collecting components in the tank are gas sensors, and the measuring ends of the gas sensors are arranged inside the tank body.

3. The battery early warning test system using characteristic gas concentration threshold according to claim 1, characterized in that: The battery temperature collecting member is connected to the top surface of the tank; and / or, The tank internal pressure collection member is connected to the top surface of the tank body; and / or, Each gas concentration collecting element in the tank is connected to the top surface of the tank body; and / or, The voltage line is connected to the side surface of the tank body.

4. The battery early warning test system using characteristic gas concentration threshold according to claim 1, characterized in that: The battery early warning test system using characteristic gas concentration thresholds further includes a gas collection bag; the gas collection pipeline is connected to the bottom surface of the tank, and the other end of the gas collection pipeline is connected to the gas collection bag; and / or, The battery early warning test system using characteristic gas concentration thresholds further includes a vacuum pump; the vacuum pipeline is connected to the top surface of the tank, and the other end of the vacuum pipeline is connected to the vacuum pump; and / or, The battery early warning test system using characteristic gas concentration thresholds further includes an inert gas storage tank; the inert gas pipeline is connected to the bottom surface of the tank body, and the other end of the inert gas pipeline is connected to the inert gas storage tank.

5. The battery early warning test system using characteristic gas concentration threshold according to claim 1, characterized in that: The gas in the inert gas pipeline is argon or nitrogen.

6. The battery early warning test system using characteristic gas concentration threshold according to claim 1, characterized in that: A gas collecting valve is provided on the gas collecting pipeline; and / or, A vacuum valve is provided on the vacuum pipeline; and / or, An inert gas valve is provided on the inert gas pipeline.

7. A battery early warning test method using characteristic gas concentration threshold, characterized in that: The battery early warning test system using characteristic gas concentration thresholds according to any one of claims 1 to 6 is used, comprising the following steps: Step 1: Place the electric heating plate on the first largest surface of the battery to be tested, connect the electric heating plate to a heating wire, and the other end of the heating wire is located outside the tank and connected to a heat source; connect the measuring end of the battery temperature acquisition component to the second largest surface of the battery to be tested; and connect two voltage wires to the positive and negative electrodes of the battery to be tested, respectively; Step 2: vacuum the tank; Step 3: Fill the tank with inert gas; Step 4: Start the heat source. When the pressure in the tank drops below the pressure threshold and the temperature rise rate of the battery under test exceeds the temperature rise threshold, turn off the heat source. Step 5: Draw a graph showing the temperature of the battery to be tested and the concentration of each gas in the tank changing with time; and obtain the concentration thresholds of each characteristic gas for early warning based on the graph.

8. The battery early warning test method using characteristic gas concentration threshold according to claim 7, characterized in that: In step 1, the heat source is a constant current power supply; and / or, In step 2, the vacuum degree in the tank is not greater than -0.1 MPa, preferably -0.09 to -0.10 MPa; and / or, In step 3, the pressure inside the tank is not less than 1.00 MPa, preferably 1.00 to 1.20 MPa; and / or; In step 4, the pressure threshold is 0V and the temperature rise threshold is 1°C / s.

9. A battery early warning test method using characteristic gas concentration threshold, characterized in that: The battery early warning test system using characteristic gas concentration thresholds according to any one of claims 1 to 6 is used, comprising the following steps: S1: Connect the electric source to the positive and negative electrodes of the battery under test; connect the measuring end of the battery temperature acquisition component to the second largest surface of the battery under test; connect two voltage lines to the positive and negative electrodes of the battery under test respectively; S2: Vacuum the tank; S3: Fill the tank with inert gas; S4: Turn on the electric excitation source to overcharge or over-discharge the battery under test; when the pressure in the tank drops below the pressure threshold and the temperature rise rate of the battery under test exceeds the temperature rise threshold, turn off the electric excitation source; S5: Draw a graph showing the temperature of the battery to be tested and the concentration of each gas in the tank changing with time; and obtain the concentration thresholds of each characteristic gas for early warning based on the graph.

10. The battery early warning test method using characteristic gas concentration threshold according to claim 9, characterized in that: In S1, the electric excitation source is a constant current power supply; and / or, In S2, the vacuum degree in the tank is not greater than -0.1 MPa, preferably -0.09 to -0.10 MPa; and / or, In S3, the pressure inside the tank is not less than 1.00 MPa, preferably 1.00 to 1.20 MPa; and / or; In S4, the pressure threshold is 0V and the temperature rise threshold is 1°C / s.

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