Method for testing cluster fire spreading of lithium ion battery with good safety performance

Abstract

The invention discloses a lithium ion battery cluster fire spreading test method with good safety performance. The method comprises the following steps: S1, building a test model, building a cabin body, and installing a pressure release valve on the cabin body; three clusters of battery packs are arranged in the cabin body, each cluster comprises eight battery packs, the middle cluster is a solid pack, the second pack counted from bottom to top is a heating experiment pack, the left side and the right side of the heating experiment pack are solid battery packs, and the other two clusters are non-solid empty packs. The test process can be accurately controlled, and the accident risk is reduced; sufficient data support is provided for fire behavior analysis; the industrial research and engineering application requirements are met; the analysis result can directly guide battery cluster safety design and fire extinguishing system optimization, and the application prospect is wide.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cluster fire spread testing technology, and in particular to a test method for lithium-ion battery cluster fire spread with good safety performance. Background Technology

[0002] With the large-scale application of lithium-ion batteries in energy storage power stations, thermal runaway fire accidents at the battery cluster level are gradually increasing. These fires spread rapidly and release large amounts of heat, easily causing major safety accidents. Therefore, conducting fire spread tests at the battery cluster level to understand the laws of thermal runaway propagation and fire evolution characteristics is crucial to improving the safety performance of battery clusters.

[0003] Existing testing methods have the following shortcomings: First, safety protection measures are inadequate, with most tests lacking precise pressure relief devices, which can easily lead to a sudden increase in chamber pressure and trigger an explosion; second, the monitoring dimensions are limited, focusing only on temperature data and lacking simultaneous monitoring of heat flow, combustible gas concentration, and spatiotemporal changes in flames, making it difficult to comprehensively analyze fire evolution; third, the testing procedures are not standardized, with vague criteria for determining thermal runaway and unclear division of responsibilities among personnel, resulting in poor repeatability of test results; and fourth, the battery pack layout is unreasonable, failing to distinguish the roles of solid and empty packs, interfering with the accurate identification of thermal runaway propagation paths.

[0004] Therefore, there is an urgent need for a safe, comprehensive, and standardized test method for the spread of cluster fires in lithium-ion batteries to address the shortcomings of existing technologies. To this end, we propose a safe test method for the spread of cluster fires in lithium-ion batteries. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a safe and effective test method for the spread of fire in lithium-ion batteries.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A test method for the safe spread of cluster fires in lithium-ion batteries includes the following steps: S1. Build the test model and the chamber. Install a pressure relief valve on the chamber. Arrange 3 clusters of battery packs inside the chamber, with 8 battery packs in each cluster. The middle cluster is a solid pack, the second pack from the bottom is set as a heating test pack, and the packs on the left and right sides are solid battery packs. The other two clusters are non-solid empty packs. S2. Configure heating and ignition devices, select heating blocks with a power of 1000W or more, and place them in the middle of the heating test pack; place one ignition needle on each of the shelves on the left and right sides of the heating test pack and 30cm in front of the pressure relief port, for a total of 3 ignition needles; S3. Deploy a monitoring system, including temperature monitoring, gas monitoring, and flame monitoring equipment. Temperature monitoring uses K-type thermocouples. 1mm diameter K-type thermocouples are placed inside the battery pack, totaling 29 thermocouples inside the heating test pack, inserted from the top into the gaps between the battery cells. 2mm diameter K-type thermocouples are placed outside the battery pack, with 3 thermocouples on each side of the bottom left, center, and right of each battery pack, for a total of 9 thermocouples per pack. For gas monitoring, CO and H2 combustible gas detectors are placed on the left and right sides of the third pack from the top of the target battery pack. For flame monitoring, a thermal imager and camera are placed 5 meters directly in front of the target battery pack, with the main unit facing the battery cluster. S4. Pre-test preparation: calibrate the time of all data acquisition devices; charge the battery modules, charging the target battery pack to 100% SOC and the remaining physical packs to 80% SOC, and let them stand for at least 30 minutes after charging; configure the test personnel, including 1 operator of the heating equipment switch, 1 person to start the fire extinguishing device, 1 person to issue a command, 1 person to record data, and 1 person on standby. S5. Execute the test. After the starter notifies each post to prepare, start the heating device to heat the test package and induce thermal runaway of the battery by overcharging. If thick smoke comes out of the pressure relief port but does not catch fire, start the ignition needle to ignite it manually and turn off the heating device at the same time. S6. Data Acquisition and Recording: Keep the acquisition and imaging equipment running throughout the process, record the first open flame layer number and location, cross-layer propagation time including layer number and time, peak flame height time and overflow direction, and heat flow meter peak value and time of occurrence; simultaneously save the temperature of the thermocouples on the front and back of the battery, the temperature point of the upper edge of the flame, and the voltage curve of each channel. S7. Post-test processing: organize test data, analyze thermal runaway propagation path, fire propagation speed and heat flow path, and generate test report.

[0007] Preferably, the cabin in step S1 is constructed with reference to T / CES373-2020 "Technical Specification for Fire Protection of Prefabricated Lithium Iron Phosphate Battery Energy Storage Power Station", and the length, width and height of the cabin are 6058mm×2438mm×2896mm.

[0008] Preferably, in step S1, the battery pack has a cell specification of 314Ah and a battery pack specification of 1P48S, 48.230KWh.

[0009] Preferably, in step S1, the pressure relief valve is a mechanical pressure relief valve with a pressure relief of 11 kPa ± 50 Pa.

[0010] Preferably, in step S3, the connector of the K-type thermocouple needs to be arranged outside the battery pack to avoid thermal runaway inside the battery pack damaging the K-type thermocouple connector and affecting temperature data acquisition.

[0011] Preferably, step S3 further includes a heat flow monitoring device, which is a heat flow meter arranged in a 5-point array, at the same height as the safety valve and 50cm in front of it.

[0012] Preferably, in step S5, thermal runaway is determined when any one of the following conditions is met: "battery pack temperature exceeds 150°C", "three consecutive temperature rise rates ≥ 3°C / s", "fire", or "explosion".

[0013] Preferably, in step S7, after the thermal runaway of the physical package occurs 2 hours later or after all test data has been collected, a standby system is used to extinguish the fire. The standby system includes an internal water system and an external compressed air foam extinguishing system.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the triple protection of mechanical pressure relief valve, standby fire extinguishing system and clear division of labor effectively avoids the risk of explosion and fire spread during the test process; the multi-condition judgment of thermal runaway and flexible ignition design can accurately control the test process and reduce unexpected risks.

[0015] 2. In this invention, multi-dimensional monitoring data of temperature, gas, flame, heat flow, and voltage are integrated to fully cover the entire process of fire evolution from "thermal runaway triggering to flame spread to heat flow transfer", providing sufficient data support for fire behavior analysis.

[0016] 3. In this invention, the experimental model construction, process execution, and data recording all refer to industry standards. At the same time, the operational details of each step are clearly defined to ensure that the experimental results are repeatable and comparable, meeting the needs of industry research and engineering applications.

[0017] 4. This invention can simulate two typical thermal runaway triggering modes: heating and overcharging. The test object and cabin size are close to the actual energy storage scenario. The analysis results can directly guide the safety design of battery clusters and the optimization of fire protection systems, and have broad application prospects. Attached Figure Description

[0018] Figure 1 This is a flowchart of a test method for preventing the spread of cluster fires in lithium-ion batteries with good safety performance, as proposed in this invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Reference Figure 1 A test method for preventing the spread of cluster fires in lithium-ion batteries with good safety performance includes the following steps: S1. Build the test model and the chamber. Install a pressure relief valve on the chamber. Arrange 3 clusters of battery packs inside the chamber, with 8 battery packs in each cluster. The middle cluster is a solid pack, the second pack from the bottom is set as a heating test pack, and the packs on the left and right sides are solid battery packs. The other two clusters are non-solid empty packs. S2. Configure heating and ignition devices, select heating blocks with a power of 1000W or more, and place them in the middle of the heating test pack; place one ignition needle on each of the shelves on the left and right sides of the heating test pack and 30cm in front of the pressure relief port, for a total of 3 ignition needles; S3. Deploy a monitoring system, including temperature monitoring, gas monitoring, and flame monitoring equipment. Temperature monitoring uses K-type thermocouples. 1mm diameter K-type thermocouples are placed inside the battery pack, totaling 29 thermocouples inside the heating test pack, inserted from the top into the gaps between the battery cells. 2mm diameter K-type thermocouples are placed outside the battery pack, with 3 thermocouples on each side of the bottom left, center, and right of each battery pack, for a total of 9 thermocouples per pack. For gas monitoring, CO and H2 combustible gas detectors are placed on the left and right sides of the third pack from the top of the target battery pack. For flame monitoring, a thermal imager and camera are placed 5 meters directly in front of the target battery pack, with the main unit facing the battery cluster. S4. Pre-test preparation: calibrate the time of all data acquisition devices; charge the battery modules, charging the target battery pack to 100% SOC and the remaining physical packs to 80% SOC, and let them stand for at least 30 minutes after charging; configure the test personnel, including 1 operator of the heating equipment switch, 1 person to start the fire extinguishing device, 1 person to issue a command, 1 person to record data, and 1 person on standby. S5. Execute the test. After the starter notifies each post to prepare, start the heating device to heat the test package and induce thermal runaway of the battery by overcharging. If thick smoke comes out of the pressure relief port but does not catch fire, start the ignition needle to ignite it manually and turn off the heating device at the same time. S6. Data Acquisition and Recording: Keep the acquisition and imaging equipment running throughout the process, record the first open flame layer number and location, cross-layer propagation time including layer number and time, peak flame height time and overflow direction, and heat flow meter peak value and time of occurrence; simultaneously save the temperature of the thermocouples on the front and back of the battery, the temperature point of the upper edge of the flame, and the voltage curve of each channel. S7. Post-test processing: organize test data, analyze thermal runaway propagation path, fire propagation speed and heat flow path, and generate test report.

[0021] When constructing the cabin in step S1, the fire protection technical specifications for prefabricated lithium iron phosphate battery energy storage power stations (T / CES373-2020) were used as a reference. The length, width, and height of the cabin are 6058mm×2438mm×2896mm.

[0022] In step S1, the battery pack has a cell specification of 314Ah and a battery pack specification of 1P48S, 48.230KWh.

[0023] In step S1, the pressure relief valve is a mechanical pressure relief valve with a pressure relief of 11 kPa ± 50 Pa.

[0024] In step S3, the connector of the K-type thermocouple needs to be placed outside the battery pack to avoid thermal runaway inside the battery pack damaging the K-type thermocouple connector and affecting temperature data acquisition.

[0025] Step S3 also includes a heat flow monitoring device, which is a heat flow meter arranged in a 5-point array, at the same height as the safety valve and 50cm in front of it.

[0026] In step S5, thermal runaway is determined when any of the following conditions are met: "battery pack temperature exceeds 150°C", "three consecutive temperature rise rates ≥ 3°C / s", "fire", or "explosion".

[0027] In step S7, two hours after the thermal runaway of the solid package or after all test data has been collected, the standby system is used for fire extinguishing. The standby system includes an internal water system and an external compressed air foam fire extinguishing system.

[0028] Working principle: Experimental model setup: A 20-foot standard container (6058mm×2438mm×2896mm) was selected, and a mechanical pressure relief valve with a pressure relief of 11KPa±50Pa was installed. Three battery packs (314Ah, 1P48S, 48.230KWh) were arranged inside the compartment, with eight batteries in each pack. The middle pack was a solid pack (the second one from the bottom was the heating test pack), and the packs on both sides were empty packs. Installation of heating and ignition devices: The heating block is selected as 1200W (compliant with GB / T 36276-2023 requirements) and placed in the middle of the heating test pack; 3 ignition needles are fixed on the left and right shelves of the heating test pack and the bracket 30cm in front of the pressure relief port, respectively, and connected to a 24V power supply; Monitoring system deployment: 29 K-type thermocouples with a diameter of 1mm are inserted into the heating test pack (entering the gap between the cells at the top), and 9 K-type thermocouples with a diameter of 2mm are arranged at the bottom of each battery pack; CO / H2 detectors are installed on the left and right sides of the third layer of the target pack; thermal imager and camera are placed 5 meters directly in front of the target pack, with the main unit facing the middle cluster, and heat flow meters arranged in a 5-point array; Preparation before the test: Use a time synchronizer to calibrate the time of all equipment (error ≤ 1s); charge the battery pack (target pack 100% SOC, other physical packs 80% SOC), and let it stand for 40 minutes; complete the battery module pretreatment according to GB / T 36276-2023 (such as visual inspection, initial voltage test); all personnel are in place, and the starter is clear about the test procedure; Test execution: After the starter issues the start command, the heating equipment operator starts the heating block and triggers the overcharge system at the same time; the data recorder monitors the temperature in real time, and when the temperature of the heating test package reaches 152℃, it is determined to be thermal runaway; after dense smoke comes out of the pressure relief port, the fire extinguishing device operator manually starts the ignition needle to ignite the dense smoke and shuts off the heating block at the same time; Data acquisition: Cameras and thermal imagers captured the entire process, recording the location of the first open flame, the time it took to move from one floor to another, the peak flame height, and the peak value of the heat flow meter; temperature and voltage curves of each thermocouple were saved simultaneously. Post-test procedures: After all physical packages have experienced thermal runaway, wait 2 hours before standby personnel activate the fire suppression system (spraying water inside the packages and compressed air foam outside); compile the data, analyze the thermal runaway propagation path and the average fire spread rate; and generate a test report including battery cluster parameters, monitoring equipment parameters, and the above analysis results.

[0029] The method described in this embodiment safely and efficiently completes the lithium-ion battery cluster fire spread test. The complete data obtained can be directly used for battery cluster safety protection optimization, verifying the practicality and reliability of this method.

[0030] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A test method for the spread of cluster fire in lithium-ion batteries with good safety performance, characterized in that, Includes the following steps: S1. Build the test model and the chamber. Install a pressure relief valve on the chamber. Arrange 3 clusters of battery packs inside the chamber, with 8 battery packs in each cluster. The middle cluster is a solid pack, the second pack from the bottom is set as a heating test pack, and the packs on the left and right sides are solid battery packs. The other two clusters are non-solid empty packs. S2. Configure heating and ignition devices, select heating blocks with a power of 1000W or more, and place them in the middle of the heating test pack; place one ignition needle on each of the shelves on the left and right sides of the heating test pack and 30cm in front of the pressure relief port, for a total of 3 ignition needles; S3. Deploy a monitoring system, including temperature monitoring, gas monitoring, and flame monitoring equipment. Temperature monitoring uses K-type thermocouples. 1mm diameter K-type thermocouples are placed inside the battery pack, totaling 29 thermocouples inside the heating test pack, inserted from the top into the gaps between the battery cells. 2mm diameter K-type thermocouples are placed outside the battery pack, with 3 thermocouples on each side of the bottom left, center, and right of each battery pack, for a total of 9 thermocouples per pack. For gas monitoring, CO and H2 combustible gas detectors are placed on the left and right sides of the third pack from the top of the target battery pack. For flame monitoring, a thermal imager and camera are placed 5 meters directly in front of the target battery pack, with the main unit facing the battery cluster. S4. Pre-test preparation: calibrate the time of all data acquisition devices; charge the battery modules, charging the target battery pack to 100% SOC and the remaining physical packs to 80% SOC, and let them stand for at least 30 minutes after charging; configure the test personnel, including 1 operator of the heating equipment switch, 1 person to start the fire extinguishing device, 1 person to issue a command, 1 person to record data, and 1 person on standby. S5. Execute the test. After the starter notifies each post to prepare, start the heating device to heat the test package and induce thermal runaway of the battery by overcharging. If thick smoke comes out of the pressure relief port but does not catch fire, start the ignition needle to ignite it manually and turn off the heating device at the same time. S6. Data acquisition and recording: Keep the acquisition and shooting equipment running throughout the process, and record the first open flame appearance floor number and location, cross-floor propagation time including floor number and time, peak flame height time and overflow direction, and heat flow meter peak value and appearance time. Simultaneously save the thermocouple temperatures on the front and back of the battery, the temperature point of the upper edge of the flame, and the voltage curves of each channel; S7. Post-test processing: organize test data, analyze thermal runaway propagation path, fire propagation speed and heat flow path, and generate test report.

2. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, The cabin in step S1 was constructed with reference to T / CES373-2020 "Technical Specification for Fire Protection of Prefabricated Lithium Iron Phosphate Battery Energy Storage Power Station". The length, width and height of the cabin are 6058mm×2438mm×2896mm.

3. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, In step S1, the battery pack has a cell specification of 314Ah and a battery pack specification of 1P48S, 48.230KWh.

4. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, In step S1, the pressure relief valve is a mechanical pressure relief valve with a pressure relief pressure of 11 kPa ± 50 Pa.

5. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, In step S3, the connector of the K-type thermocouple needs to be placed outside the battery pack to avoid thermal runaway inside the battery pack damaging the K-type thermocouple connector and affecting temperature data acquisition.

6. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, Step S3 also includes a heat flow monitoring device, which is a heat flow meter arranged in a 5-point array, at the same height as the safety valve and 50cm in front of it.

7. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, In step S5, thermal runaway is determined when any of the following conditions are met: "battery pack temperature exceeds 150°C", "three consecutive temperature rise rates ≥ 3°C / s", "fire", or "explosion".

8. The test method for the spread of cluster fire in a lithium-ion battery with good safety performance according to claim 1, characterized in that, In step S7, after the thermal runaway of the physical package for 2 hours or after all test data has been collected, the standby system is used to extinguish the fire. The standby system includes an internal water system and an external compressed air foam extinguishing system.

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