Testing device for detecting thermal runaway gas production rate of lithium battery

Abstract

The utility model relates to the technical field of lithium battery combustion detection, in particular to a test device for detecting the thermal runaway gas production rate of a lithium battery, which comprises a support and a test box, the test box is fixedly connected onto the support, a speed regulation air pump is fixedly connected onto the test box, a top cover is hinged to the top of the test box, and a collecting assembly is arranged on the support. The collecting assembly comprises an air cylinder, a connecting pipe, a telescopic rubber pipe and a fixing plate, the air cylinder is fixedly connected to the support, the connecting pipe is fixedly connected between the test box and the air cylinder, the telescopic rubber pipe is fixedly connected to the air cylinder, the fixing plate is fixedly connected to the telescopic rubber pipe, and a marking assembly is arranged on the fixing plate; the marking assembly comprises a motor, a pen holder and a marking pen; according to the utility model, the lithium battery can be combusted under a conventional atmospheric pressure condition, and the relationship between the gas production rate and the time of the lithium battery is recorded in the process, so that the gas production rate of the lithium battery at any time or time period can be calculated.

Description

Technical Field

[0001] The utility model relates to the technical field of lithium battery combustion detection, in particular to a test device for detecting the gas production rate of lithium battery thermal runaway. Background Technique

[0002] In recent years, accidents of lithium batteries in electric vehicles burning during charging and causing casualties have occurred frequently. In order to avoid such accidents, a new test index has been added to the production process of lithium batteries, that is, the rate of harmful gas generation when the lithium battery is short-circuited or burned.

[0003] A patent with the publication number CN212083152U discloses a test device for detecting the gas production rate of lithium battery thermal runaway, which includes a sealed test chamber, a selection valve, a vacuum pump, and a control system; the selection valve is a three-way valve, one end is connected to the atmosphere, one end is connected to the test chamber, and the other end is connected to the vacuum pump; wherein, a pressure gauge is provided on the passage connecting the selection valve and the vacuum pump; a temperature sensor, a pressure sensor and wires for connecting the lithium battery are provided in the vacuum chamber, and the wires are conducted to the outside of the test chamber; the control system serves as a control center and is signal-connected to the pressure sensor and the temperature sensor. This device can effectively suppress secondary disasters such as battery combustion or explosion in electric vehicle charging and swapping stations and battery energy storage stations; by detecting the gas production rate of combustible gas in lithium-ion batteries, the time to reach the lower explosion limit in the energy storage system or other places where lithium batteries are installed can be estimated, so as to calculate the safety time margin of lithium battery thermal runaway and provide scientific guidance for the disposal of such accidents.

[0004] However, in this device, the method of calculating the gas production rate of lithium battery combustion utilizes the change in air pressure, and the change in air pressure will make the combustion environment of the lithium battery different from the natural environment. Therefore, the change in air pressure itself will affect the combustion rate of the lithium battery. At this time, the obtained gas production rate of lithium battery combustion cannot represent the gas production rate when the lithium battery burns during daily use. For this reason, a new device is needed to solve the problem. Content of the Utility Model

[0005] In order to solve the above technical problems, the utility model provides a test device for detecting the gas production rate of lithium battery thermal runaway, which can enable the lithium battery to burn under normal atmospheric pressure conditions, record the relationship between the gas production volume and time of the lithium battery during the process, and then can calculate the gas production rate of the lithium battery at any time or time period.

[0006] The technical solution for achieving the object of the present utility model is: a test device for detecting the gas production rate of a lithium battery during thermal runaway, comprising a bracket and a test chamber. The test chamber is fixedly connected to the bracket. A speed-regulating air pump is fixedly connected to the test chamber. The top of the test chamber is hinged with a top cover. A collection assembly is arranged on the bracket. The collection assembly includes a cylinder, a connecting pipe, a telescopic rubber tube, and a fixing plate. The cylinder is fixedly connected to the bracket. The connecting pipe is fixedly connected between the test chamber and the cylinder. The telescopic rubber tube is fixedly connected to the cylinder. The fixing plate is fixedly connected to the telescopic rubber tube. A marking assembly is arranged on the fixing plate. The marking assembly includes a motor, a pen holder, and a marking pen. The motor is fixedly connected to the fixing plate. The pen holder is fixedly connected to the output shaft of the motor. The marking pen is arranged on the pen holder.

[0007] Preferably, the collection assembly further includes a fixing sleeve and a telescopic rod. The fixing sleeve is fixedly connected to the inner wall of the cylinder. The telescopic rod is slidably connected to the inside of the fixing sleeve, and one end of the telescopic rod is fixedly connected to the fixing plate.

[0008] Preferably, the inside of the cylinder is communicated with the inside of the telescopic rubber tube. The fixing sleeve and the telescopic rod penetrate through the inside of the telescopic rubber tube.

[0009] Preferably, the pen holder is provided with a threaded hole. The surface of the marking pen is provided with threads. The marking pen is threadedly connected to the pen holder.

[0010] Preferably, the marking assembly further includes a fixing ring and an inner ring. The fixing ring is fixedly connected to the bracket. The inner ring is fixedly connected to the inside of the fixing ring.

[0011] Compared with the prior art, the remarkable advantages of the present utility model are:

[0012] The present utility model can record the gas increase amount of the lithium battery during combustion through the telescopic rubber tube, and use the marking pen to record the curve of the change of the gas increase amount with time. By processing the curve, the relatively accurate gas production rate of the lithium battery during combustion can be calculated.

[0013] When establishing a coordinate system with the curve obtained on the cardboard, the vertical change amount is the elongation distance of the telescopic rubber tube. Combining with the diameter of the telescopic rubber tube and calculating, the vertical unit of the curve can represent the gas increase amount L of the lithium battery during combustion. The horizontal change amount of the curve is the arc length when the marking pen rotates. Combining with the rotation speed of the motor and calculating, the horizontal unit of the curve can represent the time t.

[0014] Since the rotational speed of the motor will vary according to the actual situation during the test, in the above calculation process, the unit of t is not fixed at 1 second and may be several seconds. Therefore, when calculating, the actual value of t to be substituted needs to be determined according to the actual situation. Since the curve on the cardboard is not a standard parabola, when calculating the gas production rate of the lithium battery at a certain time point, it is necessary to first collect several points near this time point on the curve to obtain a parabola that approximates the curve near this time point, and then obtain the equation of this parabola, that is, a function equation about L and t. The real-time gas production rate of the lithium battery can be calculated by taking the derivative of this function about L and t. Since all variables are not fixed during the actual test, the above process only provides the calculation method, and the final result is calculated by substituting the specific values of each variable in the real test process. Brief Description of the Drawings

[0015] The present utility model will be further explained below in conjunction with the drawings and embodiments:

[0016] Figure 1 is a three-dimensional structural schematic diagram of the present utility model;

[0017] Figure 2 is a sectional view of the internal structure of the present utility model;

[0018] Figure 3 is an effect diagram of the use of the fixing ring, inner ring and cardboard in the present utility model;

[0019] Figure 4 is an unfolded view of the cardboard after use in the present utility model.

[0020] Description of the reference numerals in the drawings:

[0021] 1, bracket; 2, test chamber; 3, top cover; 4, speed-regulating air pump; 5, collection assembly; 51, cylinder; 52, connecting pipe; 53, telescopic rubber tube; 54, fixing plate; 55, fixing sleeve; 56, telescopic rod; 6, marking assembly; 61, motor; 62, pen holder; 6,3, marking pen; 64, fixing ring; 65, inner ring; 66, cardboard. Detailed Embodiment

[0022] The present utility model will be described in detail below. The technical solutions in the embodiments of the present utility model will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0023] The present utility model provides an experimental device for detecting the gas production rate of a lithium battery during thermal runaway by making improvements. The technical solution of the present utility model is as follows:

[0024] As Figures 1-4 shown, an experimental device for detecting the gas production rate of a lithium battery during thermal runaway includes a bracket 1 and a test chamber 2. The test chamber 2 is fixedly connected to the bracket 1. A speed-regulating air pump 4 is fixedly connected to the test chamber 2. A top cover 3 is hinged to the top of the test chamber 2. A collection assembly 5 is arranged on the bracket 1. The collection assembly 5 includes a cylinder 51, a connecting pipe 52, a telescopic rubber tube 53 and a fixing plate 54. The cylinder 51 is fixedly connected to the bracket 1. The connecting pipe 52 is fixedly connected between the test chamber 2 and the cylinder 51. The telescopic rubber tube 53 is fixedly connected to the cylinder 51. The fixing plate 54 is fixedly connected to the telescopic rubber tube 53. A marking assembly 6 is arranged on the fixing plate 54. The marking assembly 6 includes a motor 61, a pen holder 62 and a marking pen 63. The motor 61 is fixedly connected to the fixing plate 54. The pen holder 62 is fixedly connected to the output shaft of the motor 61. The marking pen 63 is arranged on the pen holder 62. The speed-regulating air pump 4 is used to inject air into the test chamber 2 for the lithium battery to burn. A pressure gauge can be additionally arranged in the test chamber 2 to record the real-time air pressure in the test chamber 2 and cooperate with the speed-regulating air pump 4 to keep the air pressure in the test chamber 2 always near the standard atmospheric pressure, so that the environment in the test chamber 2 is approximately similar to the natural environment.

[0025] Furthermore, the collection assembly 5 further includes a fixed sleeve 55 and a telescopic rod 56. The fixed sleeve 55 is fixedly connected to the inner wall of the cylinder 51. The telescopic rod 56 is slidably connected to the inside of the fixed sleeve 55, and one end of the telescopic rod 56 is fixedly connected to the fixing plate 54. The arrangement of the fixed sleeve 55 and the telescopic rod 56 enables the telescopic rubber tube 53 to only elongate along the vertical direction, avoiding the telescopic rubber tube 53 from being skewed and bent, thereby facilitating the calculation of the gas increase amount in the telescopic rubber tube 53.

[0026] Furthermore, the inside of the cylinder 51 is communicated with the inside of the telescopic rubber tube 53. The fixed sleeve 55 and the telescopic rod 56 penetrate through the inside of the telescopic rubber tube 53.

[0027] Furthermore, the pen holder 62 is provided with a threaded hole, and the surface of the marking pen 63 is provided with a thread. The marking pen 63 is threadedly connected to the pen holder 62.

[0028] Furthermore, the marking assembly 6 further includes a fixed ring 64 and an inner ring 65. The fixed ring 64 is fixedly connected to the bracket 1. The inner ring 65 is fixedly connected to the inside of the fixed ring 64. Before the test, a hard paper 66 can be curled into a cylindrical shape and clamped in the gap between the inner ring 65 and the fixed ring 64. The marking pen 63 can adjust its own position in a spiral manner to ensure that it can draw a clear curve on the hard paper 66 during the rising process.

[0029] The specific working method is as follows: First, prepare a piece of hard paper 66, bend the hard paper 66 into a circle, and then insert the hard paper 66 into the gap between the fixed ring 64 and the inner ring 65. Open the top cover 3, put the lithium battery for testing and the related devices used to make the lithium battery burn or short-circuit into the test chamber 2. At the same time, put a barometer in it and make the lithium battery start to burn. During the burning process of the lithium battery, use the speed-regulating air pump 4 to send the outside air into the test chamber 2 for the lithium battery to burn. During the burning process of the lithium battery, according to the reading of the barometer, adjust the air delivery speed of the speed-regulating air pump 4 so that the air pressure in the test chamber 2 always remains near the atmospheric pressure, thus making the environment in the test chamber 2 approximate to the natural environment. During the burning process of the lithium battery, a large amount of harmful gases will be generated, and the amount of gas in the test chamber 2 will increase. While maintaining the atmospheric pressure in the test chamber 2, the increase in the amount of gas will be filled into the cylinder 51 through the connecting pipe 52, and then into the telescopic rubber tube 53. At this time, the telescopic rubber tube 53 will extend upward. Since the internal space of the telescopic rubber tube 53 is approximately cylindrical, by measuring the diameter of the telescopic rubber tube 53 in advance, the increase in the amount of gas can be calculated according to the upward extension length of the telescopic rubber tube 53.

[0030] Before the lithium battery burns, start the motor 61. The rotation speed of the motor 61 is relatively low. At the same time, install the marker pen 63 on the pen holder 62. According to the inner diameter of the circle formed by the previous hard paper 66, adjust the position of the marker pen 63. Then, during the upward extension process of the telescopic rubber tube 53, the fixed plate 54 will move upward together with the motor 61 and the marker pen 63. During the upward movement of the marker pen 63, it will also rotate with the start of the motor 61. Therefore, the marker pen 63 that moves upward and rotates at the same time will draw a curve on the hard paper 66. When the telescopic rubber tube 53 extends upward an appropriate distance, stop the test, take down the hard paper 66, and unfold the hard paper 66. Since the burning intensity of the lithium battery will gradually increase during combustion, the gas production rate must gradually increase. Therefore, the curve trajectory on the hard paper 66 will ultimately be as Figure 4 shown, approximately a parabola.

[0031] When establishing a coordinate system with the curve obtained on the hard paper 66, the vertical change amount is the elongation distance of the telescopic rubber tube 53. By coordinating with the diameter of the telescopic rubber tube 53 and calculating, the vertical unit of this curve can represent the increase in the amount of gas L during the burning of the lithium battery. The horizontal change amount of the curve is the arc length when the marker pen 63 rotates. By coordinating with the rotation speed of the motor 61 and calculating, the horizontal unit of the curve can represent the time t.

[0032] Since the rotational speed of the motor 61 will vary according to the actual situation during the test, in the above calculation process, the unit of t is not fixed at 1 second and may be several seconds. Therefore, when calculating, the actual value of t substituted finally needs to be determined according to the actual situation. Since the curve on the cardboard 66 is not a standard parabola, when calculating the gas production rate of the lithium battery at a certain time point, it is necessary to first collect several points near this time point on the curve to obtain a parabola that approximates the curve near this time point, and then obtain the equation of this parabola, that is, a function equation about L and t. The real-time gas production rate of the lithium battery can be calculated by taking the derivative of this function about L and t. Since all variables are not fixed during the actual test, the above process only provides the calculation method, and the final result is calculated by substituting the specific values of each variable in the actual test process.

[0033] The technical means disclosed in the solution of the present utility model are not limited to the technical means disclosed in the above technical means, but also include the technical solutions composed of equivalent substitutions of the above technical features. The matters not described in detail in the present utility model are common general knowledge in the art.

Claims

1. An experimental device for detecting the gas production rate of thermal runaway of a lithium battery, comprising a bracket (1) and a test chamber (2), wherein the test chamber (2) is fixedly connected to the bracket (1), and is characterized in that: A speed-regulating air pump (4) is fixedly connected to the test chamber (2). A top cover (3) is hinged to the top of the test chamber (2). A collection assembly (5) is arranged on the support (1). The collection assembly (5) includes a cylinder (51), a connecting pipe (52), a telescopic rubber tube (53), and a fixing plate (54). The cylinder (51) is fixedly connected to the support (1). The connecting pipe (52) is fixedly connected between the test chamber (2) and the cylinder (51). The telescopic rubber tube (53) is fixedly connected to the cylinder (51). The fixing plate (54) is fixedly connected to the telescopic rubber tube (53). A marking assembly (6) is arranged on the fixing plate (54). The marking assembly (6) includes a motor (61), a pen holder (62), and a marking pen (63). The motor (61) is fixedly connected to the fixing plate (54). The pen holder (62) is fixedly connected to the output shaft of the motor (61). The marking pen (63) is arranged on the pen holder (62).

2. The test device for detecting the gas generation rate of thermal runaway of a lithium battery according to claim 1, wherein: The collection assembly (5) further includes a fixed sleeve (55) and a telescopic rod (56). The fixed sleeve (55) is fixedly connected to the inner wall of the cylinder (51). The telescopic rod (56) is slidably connected to the inside of the fixed sleeve (55), and one end of the telescopic rod (56) is fixedly connected to the fixing plate (54).

3. The test device for detecting the gas generation rate of thermal runaway of a lithium battery according to claim 2, characterized in that: The inside of the cylinder (51) is communicated with the inside of the telescopic rubber tube (53). The fixed sleeve (55) and the telescopic rod (56) penetrate through the inside of the telescopic rubber tube (53).

4. The test device for detecting the gas generation rate of thermal runaway of a lithium battery according to claim 1, wherein: Threaded holes are formed in the pen holder (62). Threads are provided on the surface of the marking pen (63). The marking pen (63) is threadedly connected to the pen holder (62).

5. The test device for detecting the gas production rate of thermal runaway of a lithium battery according to claim 1, wherein: The marking assembly (6) further includes a fixed ring (64) and an inner ring (65). The fixed ring (64) is fixedly connected to the support (1). The inner ring (65) is fixedly connected to the inside of the fixed ring (64).

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