Lithium ion battery thermal runaway test device and test method

Abstract

The invention relates to the technical field of lithium ion battery thermal runaway tests, in particular to a lithium ion battery thermal runaway test device and test method. The test device comprises a shell and an inner cylinder which are placed in the shell, and a test area of a lithium ion battery is formed on the inner side of the inner cylinder; a heat preservation layer is arranged in a gap between the shell and the inner cylinder; the top cover can be connected with the top wall of the inner cylinder in a fastened mode so as to seal the inner cylinder and the gap. The thermal insulation performance of a test area can be well ensured through the three-layer structure of the inner cylinder, the thermal insulation layer and the shell, so that thermal runaway tests can be carried out at different test temperatures by adjusting the temperature control device to obtain more comprehensive test data; meanwhile, the gas in the test area can be collected at each thermal runaway stage through the gas collection port, so that the aim of synchronously acquiring temperature data and gas production conditions at each thermal runaway stage is fulfilled, and reliable data support is provided for subsequent analysis.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal runaway testing of lithium ion batteries, and in particular to a thermal runaway testing device and a testing method for lithium ion batteries. Background Art

[0002] At present, there is no commercially available thermal runaway test device for lithium-ion batteries on the market, and only a few have conducted tests on thermal runaway of lithium-ion batteries under needle puncture conditions under laboratory conditions. There is a lack of corresponding test equipment for thermal runaway caused by short circuits in the working state of 18650 general-purpose batteries.

[0003] The general lithium-ion battery thermal runaway test device usually consists of a test cylinder, a sensor, and a cover plate. Usually, only the temperature or pressure changes of a single lithium-ion battery under thermal runaway can be studied. However, the thermal runaway state of lithium ions may be different under different temperature environments. If the internal temperature of the cylinder cannot be stably controlled, it is difficult to accurately obtain thermal runaway test data of lithium-ion batteries under different temperature environments. In addition, there are different stages of thermal runaway of lithium-ion batteries (electrolyte decomposition stage, positive electrode material decomposition stage, negative electrode material decomposition stage, etc.). In order to obtain more comprehensive test data, it is necessary to collect the test temperature and gas in the test area of ​​lithium-ion batteries at different stages of thermal runaway to conduct a thermal runaway hazard analysis. If the test temperature is greatly affected by the outside world, the test temperature and gas production of lithium-ion batteries at different stages of thermal runaway may be affected by the external environment, making it difficult to ensure the reliability of the test results. Summary of the invention

[0004] The present invention provides a lithium-ion battery thermal runaway test device, which can better ensure the thermal insulation performance of the test area through the three-layer structure of the inner tube, the thermal insulation layer and the outer shell, so that the thermal runaway test can be carried out at different test temperatures by adjusting the temperature control device to obtain more comprehensive test data. In addition, during the test, the more accurate surface temperature obtained by the thermocouple sensor can determine the current thermal runaway stage of the lithium-ion battery, and at the same time, the gas in the test area can be collected at each thermal runaway stage through the gas collection port, so as to achieve the purpose of synchronously obtaining the temperature data and gas production conditions at each thermal runaway stage, and provide reliable data support for subsequent test analysis.

[0005] The present invention adopts the following technical solution to solve the problem: In a first aspect, the present invention provides a lithium ion battery thermal runaway test device, comprising: shell, An inner cylinder is placed in the outer shell, and a test area is formed in the inner cylinder; a thermal insulation layer is arranged in the gap between the outer shell and the inner cylinder; A top cover, used to cover the top of the inner cylinder to close the test area and the gap; A battery holder is arranged in the test area, the battery holder is used to place lithium-ion batteries, and the battery holder is also provided with a heating mechanism for heating the lithium-ion batteries; A thermocouple sensor is disposed on the battery support; the thermocouple sensor is used to be disposed close to the surface of the lithium-ion battery so as to obtain the surface temperature of the lithium-ion battery in real time during the process of the heating mechanism heating the lithium-ion battery; A temperature sensor is disposed at the bottom wall of the top cover, and the temperature sensor is used to obtain the real-time temperature of the test area; A temperature control device, disposed on the inner cylinder, for adjusting the temperature of the test area according to the real-time temperature; A gas collection port is provided on the top cover, and is used to open for a preset time when the surface temperature of the lithium-ion battery reaches various preset temperatures, so as to collect gas in the test area at various stages of thermal runaway of the lithium-ion battery.

[0006] Optionally, a gasket is provided on the top wall of the inner cylinder, and the top cover is fastened to the gasket by bolts.

[0007] Optionally, the inner cylinder and the top cover are made of stainless steel, and the gasket is made of silicone.

[0008] Optionally, the insulation layer comprises insulation foam.

[0009] Optionally, the heating mechanism includes a heating rod or a heating wire.

[0010] Optionally, a pressure sensor is further provided at the bottom wall of the top cover, and the pressure sensor is used to obtain the real-time pressure of the test area.

[0011] Optionally, it also includes: The explosion-proof glass passes through the outer shell and the heat-insulating layer and is fixed on the side wall of the inner tube, and the test area can be observed through the explosion-proof glass.

[0012] Optionally, the shell includes a bottom plate and a plurality of shell plates erected on the bottom plate.

[0013] Optionally, the lithium-ion battery is a 18650 lithium-ion battery.

[0014] In a second aspect, the present invention provides a lithium ion battery thermal runaway test method, which is performed using the lithium ion battery thermal runaway test device, and comprises the following steps: Step S1: placing the lithium-ion battery to be tested on a battery holder in the test area; Step S2: fastening the top cover to the top wall of the inner tube, and checking the air tightness of the test area; Step S3: controlling the temperature control device to adjust the temperature of the test area until the real-time temperature measured by the temperature sensor reaches a preset test temperature; Step S4: controlling the heating mechanism to heat the lithium-ion battery; Step S5: when the lithium-ion battery is heated to a surface temperature reaching a preset value, a gas collection port is opened to collect gas in the test area of ​​the current thermal runaway stage within a preset time; Step S6: the temperature control device sequentially adjusts the temperature of the test area to another preset test temperature, and repeats steps S4 and S5 to obtain test data at each preset test temperature.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention can better isolate the test area in the inner tube from the external environment through the three-layer structure of the outer shell, the inner tube and the insulation layer, thereby improving the safety and thermal insulation of the test area. Under the premise of ensuring the safety of the test, the test personnel can observe the thermal runaway process of the battery in situ during the thermal runaway of the lithium-ion battery. Under the premise of ensuring that the temperature of the test area is less affected by the external environment, the real-time temperature of the test area can be obtained more accurately at each stage of the thermal runaway of the battery through the temperature sensor and the thermocouple sensor, and the gas in the test area can be collected at each stage of thermal runaway through the gas collection port to analyze the gas production situation. In addition, the present invention can control the test temperature through the temperature control device, so as to carry out the thermal runaway test of the lithium-ion battery under different temperature environments to obtain more comprehensive test data. The entire test device of the present invention has a complete and reliable structure, which can realize the synchronous collection of temperature data, pressure data and gas production conditions of the thermal runaway test, and provide reliable data support for subsequent test analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic structural diagram of a lithium-ion battery thermal runaway test device in Example 1; Figure 2 for Figure 1 A cross-sectional schematic diagram of; Figure 3 for Figure 1 Schematic diagram of the structure of the middle inner tube; Figure 4 for Figure 1 A schematic diagram of the structure of the middle top cover; Figure 5 for Figure 2 Schematic diagram of the structure of the middle gasket; Figure 6 for Figure 2Schematic diagram of the structure of the midsole plate; Figure 7 It is a schematic structural diagram of a housing plate provided with an observation window in Example 2; In the figure, 1. gas collection port; 2. pressure sensor interface; 3. temperature sensor interface; 4. heating mechanism; 5. temperature control device; 6. top cover; 7. gasket; 8. inner tube; 9. outer shell; 10. insulation layer; 11. bottom plate; 12. battery bracket; 13. lithium-ion battery; 14. explosion-proof glass; 15. outer shell plate; 16. observation window. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0018] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention. Example 1

[0019] Combination Figure 1 This embodiment provides a lithium-ion battery thermal runaway test device, which includes: a shell 9, an inner tube 8, a top cover 6 and a battery bracket 12; Figure 2, the inner cylinder 8 is placed in the outer shell 9, and the inner side of the inner cylinder 8 forms a test area for the lithium-ion battery 13; in this embodiment, the lithium-ion battery 13 is a 18650 lithium-ion battery. The main body of the test device in this embodiment is a two-layer structure of the outer shell 9 and the inner cylinder 8, which can better improve the safety so that the test personnel can observe the test situation at a closer distance. An insulation layer 10 is arranged in the gap between the outer shell 9 and the inner cylinder 8; in this embodiment, the insulation layer 10 can ensure that the temperature of the test area is not affected by the outside world as much as possible, so as to ensure that the accuracy of the subsequent temperature-related test data is better. In a specific embodiment, the insulation layer 10 includes insulation foam, and the insulation foam is composed of rubber and plastic cotton.

[0020] The top cover 6 can be fastened to the top wall of the inner tube 8 to close the inner tube 8 and the gap where the insulation layer 10 is arranged. Figures 3 to 5 In this embodiment, a gasket 7 can be arranged at the top wall of the inner tube 8, and the gasket 7 can be used as the outer edge of the top wall of the inner tube 8 and fixedly connected with the top cover 6 by bolts. In a specific embodiment, the outer shell 9, the inner tube 8 and the top cover 6 are all made of 304 stainless steel to improve the safety of the entire test device. The gasket 7 is made of silicone material, which can not only ensure the connection between the inner tube 8 and the top cover 6, but also ensure that the test area maintains better airtightness after the top cover 6 closes the inner tube 8.

[0021] In this embodiment, the battery holder 12 is arranged in the inner tube 8. The battery holder 12 is used to place the lithium-ion battery 13. The battery holder 12 is also provided with a heating mechanism 4 for heating the lithium-ion battery 13 to be tested. The battery holder 12 is also provided with a thermocouple sensor, which is used to be arranged close to the surface of the lithium-ion battery 13 to obtain the surface temperature of the battery in real time during the heating process of the heating mechanism 4. In a specific embodiment, the heating mechanism 4 includes a heating rod or a heating wire. If a heating rod is used as the heating mechanism 4, the heating rod can be close to the lithium-ion battery 13. If a heating wire is used as the heating mechanism 4, the heating wire can be wound around the lithium-ion battery 13, so as to obtain a better heating effect.

[0022] A temperature sensor is also provided at the bottom wall of the top cover 6, and the temperature sensor is used to obtain the real-time temperature of the test area. A temperature control device 5 is also provided at the inner tube 8, and the temperature control device 5 is used to adjust the temperature of the test area according to the real-time temperature measured by the temperature sensor. A gas collection port 1 is also provided on the top cover 6, and the gas collection port 1 is used to open for a preset time when the surface temperature of the lithium-ion battery 13 reaches each preset temperature, so as to collect the gas in the test area at each thermal runaway stage and analyze the gas production situation. After the gas collection port is opened for a preset time, the collected gas is released into a container with a label for storage, and the gas production situation of the corresponding thermal runaway stage is analyzed and determined.

[0023] The heating process of the lithium-ion battery 13 has at least the following stages: the initial heating stage (the internal resistance of the battery increases, the internal resistance generates heat, and the temperature rises), the electrolyte decomposition stage (the electrolyte begins to decompose, the decomposition produces gas and heat, and the battery may expand or swell), the positive electrode material decomposition stage (the positive electrode material decomposes and further releases heat and gas), the negative electrode material decomposition stage (the negative electrode material reacts with the electrolyte to generate more heat and gas), and the thermal runaway stage (the entire battery system loses control, and violent heat and gas release occurs). The preset temperatures corresponding to different stages can be set or calibrated according to actual conditions, so as to accurately obtain the corresponding test data and corresponding gas products of each stage of thermal runaway of the lithium-ion battery 13.

[0024] In conjunction with the specific test method, a specific test method of the thermal runaway test device for the lithium-ion battery 13 in the present embodiment includes: step S1: placing the lithium-ion battery 13 to be tested on the battery holder 12 in the test area; step S2: fastening the top cover 6 to the top wall of the inner tube 8; step S3: controlling the temperature control device 5 to adjust the temperature of the test area until the real-time temperature measured by the temperature sensor reaches the preset test temperature; step S4: controlling the heating mechanism 4 to heat the lithium-ion battery 13; step S5: when the lithium-ion battery 13 is heated to a surface temperature that reaches a preset value, opening the gas collection port 1 to collect gas in the test area at the current thermal runaway stage; step S6: the temperature control device 5 adjusts the temperature of the test area to each preset test temperature in turn, and repeats steps S4 and S5 to record test data at different test temperatures.

[0025] Through the above steps, this embodiment uses a double-layer structure of the outer shell 9 and the inner tube 8 with the insulation layer 10 between the two layers, which can better isolate the test area from the external environment, not only improving the thermal insulation performance of the test area, but also ensuring the safety of the test. Under the premise that the thermal insulation performance of the test area is good, the test personnel can more accurately obtain the test data of each stage of thermal runaway of the lithium-ion battery 13 at different test temperatures through the temperature control device 5, the temperature sensor, and the thermocouple sensor. The obtained test data is accurate and comprehensive, thereby providing reliable data support for subsequent test analysis.

[0026] In a specific embodiment, in order to obtain more comprehensive test data, a pressure sensor is also provided at the bottom wall of the top cover 6, and the pressure sensor is used to obtain the real-time pressure of the test area. The pressure sensor can obtain the pressure data of each thermal runaway stage of the lithium-ion battery 13, so as to cooperate with the temperature data and the collected gas to conduct a more detailed analysis of the thermal runaway of the lithium-ion battery 13. This embodiment can synchronously collect the temperature, pressure and gas production conditions in each stage of the thermal runaway process of the lithium battery under the premise of ensuring safety through the above test method.

[0027] In this embodiment, combined with Figure 2 and Figure 6 The shell 9 includes a base plate 11 and a plurality of shell plates 15 erected on the base plate 11. The shell plate 15 is fixed to the base plate 11 by bolts, and is convenient to disassemble and assemble. The thermocouple sensor and the heating mechanism 4 in this embodiment are connected to the external communication terminal through the interface provided on the shell plate 15. The shell plate 15 is provided with a plurality of open grooves, and the corresponding positions on the inner tube 8 are also provided with openings. Thermocouple interfaces and heating rod interfaces are respectively installed in each open groove on the shell plate 15. In this embodiment, the insulating layer 10 is also provided with openings at positions corresponding to the thermocouple interfaces and the heating rod interfaces to ensure that the interfaces can connect the thermocouples and the heating rods in the inner tube. Similarly, the top cover 6 is also provided with a temperature sensor interface 3 and a pressure sensor interface 2 to connect with the external communication terminal. Example 2

[0028] The difference between this embodiment and the embodiment 1 is that: in this embodiment, under the premise of ensuring the safety of the test device, Figure 7The test device further includes explosion-proof glass 14, which is fixed on the side wall of the inner tube 8 through the outer shell 9 and the thermal insulation layer 10, and the test area can be observed through the explosion-proof glass 14. An observation window 16 is provided on at least one outer shell plate 15, and an opening is also provided at a corresponding position of the inner tube 8. The explosion-proof glass 14 is installed and fixed on the inner tube 8 through the observation window 16, the thermal insulation layer 10 and the opening on the inner tube 8, so that the test personnel can directly observe the thermal runaway process of the lithium-ion battery.

[0029] Through the above test method, this embodiment can synchronously collect the temperature, pressure and gas production conditions in each stage of the thermal runaway process of the lithium battery under the premise of ensuring safety, and observe the test conditions in real time through the explosion-proof glass 14.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A lithium-ion battery thermal runaway test device, characterized in that: include: Housing (9), An inner cylinder (8) is placed inside the outer shell (9), and a test area is formed inside the inner cylinder (8); a thermal insulation layer (10) is arranged in the gap between the outer shell (9) and the inner cylinder (8); A top cover (6) is used to cover the top of the inner cylinder (8) to close the test area and the gap; A battery holder (12) is disposed in the test area, the battery holder (12) is used to place a lithium-ion battery (13), and a heating mechanism (4) for heating the lithium-ion battery (13) is also provided on the battery holder (12); a thermocouple sensor disposed on the battery support (12); the thermocouple sensor is used to be disposed close to the surface of the lithium-ion battery (13) so as to obtain the surface temperature of the lithium-ion battery (13) in real time during the process of the heating mechanism (4) heating the lithium-ion battery (13); A temperature sensor is arranged on the bottom wall of the top cover (6), and is used to obtain the real-time temperature of the test area; A temperature control device (5) is provided on the inner cylinder (8) and is used to adjust the temperature of the test area according to the real-time temperature; A gas collection port (1) is provided on the top cover (6), and the gas collection port (1) is used to open for a preset time when the surface temperature of the lithium ion battery (13) reaches various preset temperatures, so as to collect gas in a test area at various stages of thermal runaway of the lithium ion battery (13).

2. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: A gasket (7) is provided on the top wall of the inner cylinder (8), and the top cover (6) is fastened to the gasket (7) by bolts.

3. A lithium-ion battery thermal runaway test device according to claim 1, characterized in that: The inner cylinder (8) and the top cover (6) are made of 304 stainless steel, and the gasket (7) is made of silicone rubber.

4. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: The thermal insulation layer (10) comprises thermal insulation foam.

5. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: The heating mechanism (4) comprises a heating rod or a heating wire.

6. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: A pressure sensor is also provided on the bottom wall of the top cover (6), and the pressure sensor is used to obtain the real-time pressure of the test area.

7. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: Also includes: An explosion-proof glass (14) passes through the outer shell (9) and the thermal insulation layer (10) and is fixed to the side wall of the inner tube (8), and the test area can be observed through the explosion-proof glass (14).

8. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: The housing (9) comprises a bottom plate (11) and a plurality of housing plates (15) erected on the bottom plate (11).

9. The lithium-ion battery thermal runaway test device according to claim 1, characterized in that: The lithium ion battery (13) is a 18650 type lithium ion battery.

10. A lithium-ion battery thermal runaway test method, characterized in that: The method is carried out using the lithium ion battery thermal runaway test device according to any one of claims 1 to 9, which comprises the following steps: Step S1: placing a lithium-ion battery (13) to be tested on a battery holder (12) within a test area; Step S2: placing the top cover (6) on the inner tube (8), and checking the air tightness of the test area to ensure that the air tightness is intact; Step S3: controlling the temperature control device (5) to adjust the temperature of the test area until the real-time temperature measured by the temperature sensor reaches a preset test temperature; Step S4: controlling the heating mechanism (4) to heat the lithium-ion battery (13); Step S5: when the lithium-ion battery (13) is heated until the surface temperature reaches each preset value, the gas collection port (1) is opened to collect gas in the test area at each thermal runaway stage at a preset time; Step S6: the temperature control device (5) adjusts the temperature of the test area to another preset test temperature, and repeats steps S4 and S5.

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