Gas collection device for internal short circuit of lithium battery and testing method

Abstract

The present application relates to the technical field of battery testing, and provides a lithium battery internal short circuit gas production collecting device and a testing method. The lithium battery internal short circuit gas production collecting device comprises a first shell, a pressing assembly and a collecting assembly. The first shell has a containing cavity for containing a lithium battery. The pressing assembly comprises two pressing heads arranged on the inner walls of the opposite sides of the first shell. The two pressing heads are respectively in abutment with the opposite sides of the lithium battery. The two pressing heads are movable relative to or away from each other to adjust the pressing force of the lithium battery. The first shell is provided with a gas outlet which is in communication with the collecting assembly. The present application sets the gas outlet on the first shell, and the gas outlet is in communication with the collecting assembly. Under the action of the pressing force of the pressing assembly, the gas produced by the lithium battery in the first shell enters the collecting assembly through the gas outlet. The present application can effectively collect the gas produced by the lithium battery, which is conducive to the accurate evaluation of the actual gas produced in the lithium battery in the later stage and improves the safety of the lithium battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of battery testing, in particular to a lithium battery internal short circuit gas collection device and testing method. BACKGROUND

[0002] Lithium batteries have been widely used in various fields such as portable electronic devices, electric vehicles and large-scale energy storage systems due to their high energy density, excellent cycle life and extremely low self-discharge rate. However, under abnormal working conditions such as overcharging, overdischarging, mechanical damage or internal short circuit, lithium batteries may experience thermal runaway, resulting in gas generation, leakage and even explosion, posing a serious threat to personnel and equipment safety.

[0003] Particularly noteworthy is the problem of internal short circuit caused by melting of the heated separator or penetration of foreign matter, which has become a major challenge in lithium battery safety management due to its concealment and suddenness. Compared with external short circuit or conventional overcharge and overdischarge tests, gas generation caused by internal short circuit is often more difficult to predict and prevent because it can be caused by various factors such as small defects in the lithium battery manufacturing process, mechanical damage during use or battery aging.

[0004] Currently, in the process of simulating internal short circuit, traditional methods such as external needle piercing can simulate the occurrence of internal short circuit, but due to the operation mode, the generated gas is easy to escape and difficult to collect, thus the actual gas generation inside the lithium battery cannot be accurately evaluated. SUMMARY

[0005] The present application provides a lithium battery internal short circuit gas collection device and testing method to solve the problem of difficulty in collecting internal short circuit gas in the prior art, which leads to inaccurate evaluation of the actual gas generation inside the battery and low safety.

[0006] The present application provides a lithium battery internal short circuit gas collection device, comprising: a first housing having a receiving cavity for accommodating the lithium battery; an extrusion assembly comprising two extrusion heads, the two extrusion heads being arranged on the inner walls of the opposite sides of the first housing, the two extrusion heads respectively abutting the opposite sides of the lithium battery, and the two extrusion heads being movable relative to or away from each other to adjust the extrusion force of the lithium battery; and a collection assembly, the first housing being provided with a gas outlet, the gas outlet being in communication with the collection assembly.

[0007] According to the lithium battery internal short circuit gas collection device provided by the present application, the collection assembly comprises a gas storage bin and a first control valve, the gas outlet is in communication with the gas storage bin through a pipeline, and the first control valve is arranged on the pipeline to control the communication and disconnection of the gas outlet and the gas storage bin.

[0008] The lithium battery internal short circuit gas collection device provided by the application further comprises a vacuum pump, which is communicated with the gas storage bin.

[0009] The lithium battery internal short circuit gas collection device provided by the application further comprises a control assembly, and the first control valve and the vacuum pump are electrically connected with the control assembly respectively.

[0010] The lithium battery internal short circuit gas collection device provided by the application further comprises a drive motor, at least one of the pressing heads is connected with the drive motor, and the drive motor is used for controlling the two pressing heads to move close to or away from each other; the lithium battery internal short circuit gas collection device further comprises a pressure sensor, which is used for acquiring the pressing force of the lithium battery; and the drive motor and the pressure sensor are electrically connected with the control assembly respectively.

[0011] The lithium battery internal short circuit gas collection device provided by the application further comprises a temperature sensor, which is arranged in the first shell and is used for acquiring temperature information in the first shell; and the temperature sensor is electrically connected with the control assembly.

[0012] The lithium battery internal short circuit gas collection device provided by the application further comprises a liquid injection assembly, the first shell is further provided with a liquid inlet, the liquid injection assembly is communicated with the liquid inlet through a liquid injection pipe, a second control valve is arranged on the liquid injection pipe, the second control valve is used for controlling the communication and closing of the liquid inlet and the liquid injection assembly; and the second control valve is electrically connected with the control assembly.

[0013] The lithium battery internal short circuit gas collection device provided by the application further comprises a heating assembly, the heating assembly comprises a heating piece and a heating power supply, the heating piece is arranged in the first shell, and the heating power supply is electrically connected with the heating piece; and the heating power supply is electrically connected with the control assembly.

[0014] The lithium battery internal short circuit gas collection device provided by the application further comprises a charge-discharge power supply, and the positive electrode and the negative electrode of the lithium battery are electrically connected with two ends of the charge-discharge power supply respectively.

[0015] The lithium battery internal short circuit gas collection device provided by the application further comprises a second shell and a gas sensor, the first shell is arranged in the second shell; the gas sensor is arranged in the second shell, the second shell is provided with a pressure relief port, a pressure relief valve is arranged in the pressure relief port, and the gas sensor and the pressure relief valve are electrically connected with the control assembly respectively.

[0016] The application further provides a lithium battery internal short circuit test method based on the lithium battery internal short circuit gas production collecting device.

[0017] According to the lithium battery internal short circuit test method provided by the application, the voltage drop of the lithium battery is greater than or equal to a preset value by controlling the extrusion assembly to extrude the lithium battery or controlling the heating assembly to heat the lithium battery, and the method comprises the following steps: controlling the extrusion assembly to extrude at an extrusion rate less than or equal to 0.2 mm / s until the voltage drop of the lithium battery is greater than or equal to the preset value; or, controlling the heating assembly to heat at a temperature rising rate less than or equal to 5 ℃ / min to the melting point of the cell diaphragm until the voltage drop of the lithium battery is greater than or equal to the preset value.

[0018] The lithium battery internal short circuit gas production collecting device and the test method provided by the application can effectively collect the gas produced by the lithium battery, which is beneficial to accurately evaluate the actual gas produced in the lithium battery in the later period and improve the safety of the lithium battery. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] Figure 1 Fig. 1 is a structural schematic diagram of the lithium battery internal short circuit gas production collecting device provided by the application;

[0021] Figure 2 Fig. 2 is a flow schematic diagram of the lithium battery internal short circuit test method provided by the application;

[0022] Reference signs:

[0023] 1, first shell; 2, extrusion head; 3, drive motor; 4, lithium battery; 5, gas storage warehouse; 6, vacuum pump; 7, first control valve; 8, three-way valve; 9, temperature sensor; 10, liquid injection assembly; 11, second control valve; 12, heating element; 13, heating power supply; 14, charge and discharge power supply; 15, pressure relief valve; 16, second shell. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the present application clearer, the following will be a clear and complete description of the technical solutions in the present application in conjunction with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0025] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0026] In the description of the embodiments of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0027] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0028] The embodiments of the present application will be described in detail below, and the examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as limiting the present application.

[0029] The disclosure that follows provides many different embodiments, or examples, for implementing different structures of the application. For the purpose of simplicity, the elements and settings of the particular examples below are described in some instances in particular combinations. Of course, it is not intended that the application be limited to such combinations. Indeed, many of the elements and settings described can be combined in a variety of ways and / or combined with other elements and settings not expressly described in order to realize the application. In addition, the disclosure provides examples of various specific processes and materials that can be used in the application. However, it is contemplated that other processes and / or materials can be used in place of, or in combination with, those disclosed.

[0030] The following detailed description is presented in connection with Figures 1 to 2 A lithium battery internal short circuit gas collection device and testing method are described.

[0031] The lithium battery internal short circuit gas collection device provided by the embodiment of the application comprises a first shell 1, an extrusion assembly and a collection assembly. The first shell 1 has a containing cavity for containing a lithium battery 4. The extrusion assembly comprises two extrusion heads 2, which are arranged on the inner walls of opposite sides of the first shell 1 and abut against the opposite sides of the lithium battery 4 respectively. The two extrusion heads 2 can move towards or away from each other to adjust the extrusion force of the lithium battery 4. The first shell 1 is provided with a gas outlet, which is in communication with the collection assembly.

[0032] The first shell 1 is provided with a fixing structure for limiting the position of the lithium battery 4. For example, a clamping groove is arranged on the inner wall of the first shell 1, and the lithium battery 4 is clamped in the clamping groove to prevent the lithium battery 4 from moving randomly. The first shell 1 in the embodiment of the application can be a steel shell or an aluminum shell. The top of the first shell 1 is provided with an opening, and an end cover sealing cover is arranged at the opening (as shown by the dashed line in FIG. 1), so that the user can open the end cover to place the lithium battery 4 in the containing cavity. Figure 1

[0033] The extrusion assembly comprises two extrusion heads 2, namely a first extrusion head and a second extrusion head, which are arranged on opposite sides of the inner wall surface of the first shell 1. The first extrusion head and the second extrusion head can move towards each other, and abut against the outer wall surfaces of the opposite sides of the lithium battery 4 respectively to apply an extrusion force to the lithium battery 4. The first extrusion head and the second extrusion head move away from each other to reduce the extrusion force. Under the action of the extrusion force, the lithium battery 4 generates gas due to internal short circuit.

[0034] The extrusion head 2 in the embodiment of the application can be a cylindrical extrusion head 2. In one embodiment, the extrusion head 2 is hemispherical, and the diameter of the sphere is 3-5 mm, which can be 3 mm, 4 mm, 5 mm or the like. The spherical surface abuts against the outer wall surface of the lithium battery 4. The extrusion head 2 in the embodiment of the application can be made of tungsten steel. ​

[0035] As shown in the figure, the first shell 1 is provided with an air outlet, and the air outlet is in communication with the collecting assembly. Figure 1 The gas generated by the lithium battery 4 under the extrusion effect enters the collecting assembly, which facilitates the analysis of the composition of the gas and the change of the internal system of the lithium battery 4 in the later period, and improves the safety of the lithium battery 4.

[0036] The lithium battery internal short-circuit gas collecting device provided by the embodiment of the present application further comprises a detection assembly for detecting the gas composition in the gas storage chamber.

[0037] The lithium battery internal short-circuit gas collecting device provided by the embodiment of the present application can effectively collect the gas generated by the lithium battery 4, which is conducive to the accurate evaluation of the actual gas generated in the lithium battery 4 in the later period, and improves the safety of the lithium battery 4.

[0038] The collecting assembly provided by the embodiment of the present application further comprises a gas storage chamber 5 and a first control valve 7, the air outlet is in communication with the gas storage chamber 5 through a pipeline, and the first control valve 7 is arranged on the pipeline and used for controlling the communication and disconnection of the air outlet and the gas storage chamber 5.

[0039] The collecting assembly provided by the embodiment of the present application further comprises a vacuum pump 6, which is in communication with the gas storage chamber 5 and used for vacuumizing the gas storage chamber 5.

[0040] The present application realizes the communication through a three-way valve 8. Specifically, the three-way valve 8 has three valve ports, namely a first valve port, a second valve port and a third valve port, the first valve port is in communication with the air outlet, the second valve port is in communication with the gas storage chamber 5, and the third valve port is in communication with the vacuum pump 6.

[0041] The lithium battery internal short-circuit gas collecting device provided by the embodiment of the present application further comprises a control assembly, and the first control valve 7, the three-way valve 8 and the vacuum pump 6 are respectively electrically connected with the control assembly.

[0042] The control assembly controls the first control valve 7 to be closed, controls the three-way valve 8 to make the vacuum pump 6 communicate with the gas storage chamber 5, controls the vacuum pump 6 to be started, and performs vacuumizing treatment on the gas storage chamber 5, controls the vacuum pump 6 to be closed when the gas storage chamber 5 reaches the target vacuum degree, and controls the three-way valve 8 to make the vacuum pump 6 be disconnected with the gas storage chamber 5. When the parameters of the lithium battery 4 reach the target requirement, the control assembly controls the first control valve 7 to be opened, and controls the three-way valve 8 to make the pipeline communicate with the gas storage chamber 5, at this time, the gas in the first shell 1 enters the gas storage chamber 5 under the action of negative pressure.

[0043] The extrusion assembly provided by the embodiment of the present application comprises two extrusion heads 2 and a driving motor 3, at least one extrusion head 2 is connected with the driving motor 3, and the driving motor 3 is used for controlling the two extrusion heads 2 to be close to or far away from each other. In an embodiment, the first extrusion head is connected with the driving end of the driving motor 3, the second extrusion head is arranged on the inner side wall of the first shell 1, the first extrusion head and the second extrusion head are oppositely arranged, the lithium battery 4 is located between the first extrusion head and the second extrusion head, the driving motor 3 is started to drive the first extrusion head to move towards the second extrusion head, the first extrusion head and the second extrusion head respectively abut against the two side walls of the lithium battery 4, and the extrusion force of the lithium battery 4 is increased; the driving assembly drives the first extrusion head to move away from the second extrusion head, and the extrusion force of the lithium battery 4 is reduced.

[0044] In another embodiment, one of the first extrusion head and the second extrusion head is connected with the driving end of the first driving motor 3, and the other is connected with the driving end of the second driving motor 3, so as to control the first extrusion head and the second extrusion head to be close to or far away from each other.

[0045] It should be noted that the first shell 1 is provided with a avoiding hole, the driving motor 3 is connected with the extrusion head 2 in the first shell 1 through the avoiding hole, and the driving motor 3 is sealingly attached to the inner wall surface of the avoiding hole.

[0046] Further, the lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a pressure sensor, and the pressure sensor is used for acquiring the extrusion force of the lithium battery 4. In an embodiment, the pressure sensor is arranged between the driving motor 3 and the extrusion head 2, and the pressure sensor can acquire the current extrusion force data when the driving motor 3 drives the extrusion head 2 to perform the pressurizing action. In another embodiment, the pressure sensor can be arranged between the extrusion head 2 and the lithium battery 4 to acquire the current extrusion force data of the lithium battery 4.

[0047] Further, the driving motor 3 and the pressure sensor are respectively electrically connected with the control assembly, and the control assembly is used for acquiring the pressure data of the pressure sensor and controlling the operating parameters of the driving motor 3 based on the pressure data.

[0048] Further, the lithium battery internal short circuit gas collection device further comprises a temperature sensor 9 arranged in the first shell 1 and used to obtain temperature information in the first shell 1; the temperature sensor 9 is electrically connected with the control assembly, and the control assembly is used to obtain the temperature information obtained by the temperature sensor 9; based on the temperature information of the temperature sensor 9 and the gas collected by the collection assembly, the relationship between the lithium battery 4 gas production and the temperature in the first shell 1 can be analyzed, so that the safety standard of the lithium battery 4 is improved, and the occurrence of safety accidents is reduced.

[0049] The lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a liquid injection assembly 10, the first shell 1 is further provided with a liquid inlet, the liquid injection assembly 10 is communicated with the liquid inlet through a liquid injection pipe, a second control valve 11 is arranged on the liquid injection pipe, and the second control valve 11 is used to control the communication and closing of the liquid inlet and the liquid injection assembly 10; the second control valve 11 is electrically connected with the control assembly.

[0050] Specifically, the control assembly controls the second control valve 11 to open, the liquid injection assembly 10 is communicated with the first shell 1, and the liquid injection assembly 10 injects electrolyte into the first shell 1, so as to prepare for the formation of the lithium battery 4. The amount of electrolyte is determined according to the lithium battery 4, and the control assembly controls the second control valve 11 to close when the target requirement is reached. The second control valve 11 can be an electromagnetic valve.

[0051] In addition, heating can also trigger the internal short circuit of the lithium battery 4. The lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a heating assembly, the heating assembly comprises a heating piece 12 and a heating power supply 13, the heating piece 12 is arranged in the first shell 1, and the heating power supply 13 is electrically connected with the heating piece 12; the heating power of the heating piece 12 can be adjusted by adjusting the output voltage of the heating power supply 13, so as to adjust the temperature in the first shell 1. The heating piece 12 can be made of alloy, silicon carbide, graphite, PTC material, silica gel, mica, stainless steel and ceramic, etc., and the heating piece can be fixed to the inner wall of the first shell 1 or the outer wall surface of the lithium battery 4 by external pressure.

[0052] It should be noted that the first shell 1 is provided with a through hole, the heating power supply 13 is electrically connected with the heating piece 12 in the first shell 1 through a cable, that is, the cable passes through the through hole, and the cable and the through hole are sealed, for example, by filling a sealing piece, to prevent internal gas from flowing out.

[0053] The heating piece 12 in the embodiment of the present application can be an armored thermocouple.

[0054] Further, the heating power supply 13 is electrically connected with the control assembly. Specifically, the control assembly controls the parameters of the heating power supply 13, including the output voltage of the heating power supply 13, based on the temperature information obtained by the temperature sensor 9, adjusts the heating power of the heating piece 12, and further adjusts the temperature in the first shell 1.

[0055] The lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a charge-discharge power supply 14, and the positive electrode and the negative electrode of the lithium battery 4 are electrically connected to two ends of the charge-discharge power supply.

[0056] Specifically, the end of the first shell is provided with an outlet end, which is fixed on the first shell in the form of welding or flange sealing, and the outlet end is arranged on the inner and outer sides of the first shell, and the positive electrode and the negative electrode of the lithium battery 4 are connected to the two ends of the charge-discharge power supply through the outlet end.

[0057] The lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a voltage detection member, which is connected to the lithium battery in correspondence and can obtain the current voltage of the lithium battery, and the change of the current voltage is helpful to determine whether the lithium battery is short-circuited. The voltage detection member can be a voltmeter.

[0058] The lithium battery internal short circuit gas collection device provided by the embodiment of the present application further comprises a second shell 16 and a gas sensor, and the first shell 1 is arranged in the second shell 16; the gas sensor is arranged in the second shell 16, the second shell 16 is provided with a pressure relief port, a pressure relief valve 15 is installed in the pressure relief port, and the gas sensor and the pressure relief valve 15 are electrically connected to a control assembly respectively.

[0059] Specifically, the gas sensor is used to detect whether there is gas in the second shell 16, that is, to determine whether the gas generated in the first shell 1 leaks into the second shell 16 through the gas sensor. The control assembly is electrically connected to the gas sensor and is used to receive the data information obtained by the gas sensor; the control assembly is also used to control the opening and closing of the pressure relief valve 15.

[0060] The gas sensor in the embodiment of the present application can be a hydrogen, carbon monoxide and methane gas sensor.

[0061] It should be noted that the second shell 16 is provided with a through hole in correspondence, which facilitates the communication of the gas outlet with the collection assembly, the communication of the liquid inlet with the liquid injection assembly 10, the connection of the extrusion head 2 with the driving motor 3, the electrical connection of the heating member 12 with the heating power supply 13, and the connection of the lithium battery 4 with the charge-discharge power supply. Moreover, the through hole is sealed to prevent the gas in the first shell 1 from leaking.

[0062] For example, the control assembly can be a single-chip microcomputer. Figure 2As shown, based on the lithium battery internal short circuit gas collection device in any of the above embodiments, the embodiment of the application also provides a lithium battery internal short circuit test method, comprising: step 100, performing formation treatment on the lithium battery; step 200, charging the lithium battery by the charge-discharge power supply to make its parameters reach the target parameters. Step 300, control the extrusion assembly to extrude the lithium battery or control the heating assembly to heat the lithium battery, so that the voltage drop value of the lithium battery is greater than or equal to the preset value; specifically, control the extrusion assembly to extrude at an extrusion rate less than or equal to 0.2mm / s until the voltage drop value of the lithium battery is greater than or equal to the preset value; or, control the heating assembly to heat to the melting point of the cell separator at a heating rate less than or equal to 5℃ / min until the voltage drop value of the lithium battery is greater than or equal to the preset value. Step 400, in the case that the lithium battery remains in the extrusion state or the duration of the preset temperature is greater than or equal to the preset duration, control the first control valve to open, and the gas in the first housing enters the collection assembly. Step 500, detect the gas in the collection assembly.

[0063] Specifically, the cell of the lithium battery is sealed and fixed in the first housing, and the positive and negative electrodes are connected with the lead-out end on the first housing, so that the lithium battery is sealed in the first housing. The first housing containing the lithium battery is placed in a vacuum glove box, and the liquid inlet on the first housing is communicated with the liquid injection assembly, and the gas outlet on the first housing is closed, and the preparation before liquid injection is completed.

[0064] Further, control the second control valve to open, and according to the requirements of the lithium battery, a certain amount of electrolyte is injected into the first housing. After completion, control the second control valve to close, and be static for a certain duration, such as more than 6h, such as 7h, etc. After the static is completed, the first housing is removed from the vacuum glove box, and the charge-discharge power supply is turned on to perform formation treatment on the lithium battery.

[0065] Further, the first housing containing the lithium battery is sealed in the second housing, and the gas outlet is communicated with the collection assembly, the heating member is electrically connected with the heating power supply, the extrusion head is electrically connected with the driving motor, and the lithium battery is electrically connected with the charge-discharge power supply. Control the relevant parameters of the lithium battery to reach the target parameters by the standard charging method, and then be static for a certain duration, such as 1h.

[0066] In one embodiment, the short circuit of the lithium battery is triggered by extrusion to generate gas. Specifically, the driving motor is controlled to drive two extrusion heads to approach each other, so that the two extrusion heads extrude the outer wall surface of the lithium battery, and the extrusion rate is below 0.2 mm / s, such as 0.2 mm / s, 0.1 mm / s, etc., until the voltage drop of the lithium battery is greater than or equal to a preset value, such as 50 mV (short circuit occurs in the lithium battery when the initial voltage of the lithium battery drops by 50 mV), and the drop is 50 mV, 60 mV, etc. After the short circuit occurs, the extrusion is stopped and the extrusion state is maintained. In the case where the maintenance duration is greater than or equal to a preset duration, the first control valve is controlled to be opened to allow the generated gas to enter the collection assembly.

[0067] In another embodiment, the short circuit of the lithium battery is triggered by heating to generate gas. Specifically, the heating power supply is controlled to be started, and the temperature in the first shell is raised at a temperature rise rate of not higher than 5℃ / min, such as 5℃ / min, 3℃ / min, until the temperature reaches the melting point of the cell separator, and then the temperature is maintained until the voltage drop of the lithium battery is greater than or equal to a preset value, such as 50 mV, and the drop is 50 mV, 60 mV, etc. The first control valve is controlled to be opened to allow the generated gas in the first shell to enter the collection assembly.

[0068] Further, the detection assembly is used to detect the gas in the collection assembly, such as the composition of the gas, etc.

[0069] It should be noted that during the process of collecting the gas, attention should be paid to the change of the gas sensor in the second shell to ensure that there is no gas leakage during the process and to improve safety. After the temperature in the first shell reaches room temperature and stabilizes for a period of time, such as 30 minutes, the disassembly can be performed.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A short-circuit gas collection device for lithium batteries, characterized in that, include: A first housing, having a sealed cavity for accommodating the lithium battery; The extrusion assembly includes two extrusion heads, which are respectively disposed on the inner walls of opposite sides of the first housing. The two extrusion heads abut against opposite sides of the lithium battery, and the two extrusion heads can move relative to each other or in opposite directions to adjust the extrusion force of the lithium battery. The first housing has a gas outlet, which is connected to the collection component and is used to collect the gas generated by the short circuit in the lithium battery within the sealed cavity to the collection component.

2. The lithium battery internal short-circuit gas collection device according to claim 1, characterized in that, The collection assembly includes a gas storage chamber and a first control valve. The gas outlet is connected to the gas storage chamber via a pipeline. The first control valve is located on the pipeline and is used to control the connection and disconnection between the gas outlet and the gas storage chamber.

3. The lithium battery internal short-circuit gas collection device according to claim 2, characterized in that, The collection assembly also includes a vacuum pump, which is connected to the gas storage chamber.

4. The lithium battery internal short-circuit gas collection device according to claim 3, characterized in that, It also includes a control component, with the first control valve and the vacuum pump respectively electrically connected to the control component.

5. The lithium battery internal short-circuit gas collection device according to claim 4, characterized in that, The extrusion assembly further includes a drive motor, at least one of the extrusion heads is connected to the drive motor, and the drive motor is used to control the two extrusion heads to move closer to each other or further apart; the lithium battery internal short-circuit gas collection device further includes a pressure sensor for acquiring the extrusion force of the lithium battery; The drive motor and the pressure sensor are electrically connected to the control component.

6. The lithium battery internal short-circuit gas collection device according to claim 4, characterized in that, The short-circuit gas collection device in the lithium battery also includes a temperature sensor, which is located inside the first housing and is used to acquire temperature information inside the first housing. The temperature sensor is electrically connected to the control component.

7. The lithium battery internal short-circuit gas collection device according to claim 4, characterized in that, It also includes a liquid injection assembly. The first housing is further provided with a liquid inlet. The liquid injection assembly is connected to the liquid inlet through a liquid injection pipe. A second control valve is provided on the liquid injection pipe. The second control valve is used to control the connection and closure between the liquid inlet and the liquid injection assembly. The second control valve is electrically connected to the control assembly.

8. The lithium battery internal short-circuit gas collection device according to claim 4, characterized in that, It also includes a heating assembly, which includes a heating element and a heating power source. The heating element is disposed inside the first housing, and the heating power source is electrically connected to the heating element. The heating power supply is electrically connected to the control component.

9. The lithium battery internal short-circuit gas collection device according to claim 1, characterized in that, It also includes a charging and discharging power supply, wherein the positive and negative terminals of the lithium battery are electrically connected to the two ends of the charging and discharging power supply, respectively.

10. The lithium battery internal short-circuit gas collection device according to claim 4, characterized in that, It also includes a second housing and a gas sensor, with the first housing disposed inside the second housing; the gas sensor is disposed inside the second housing, the second housing has a pressure relief port, and a pressure relief valve is installed inside the pressure relief port; the gas sensor and the pressure relief valve are respectively electrically connected to the control component.

11. A method for testing internal short circuits in lithium batteries, based on the internal short circuit gas collection device for lithium batteries as described in any one of claims 1 to 10, characterized in that, The internal short-circuit test methods for lithium batteries include: Formation treatment is performed on lithium batteries; The lithium battery is charged using a charging and discharging power supply until its parameters reach the target parameters. The extrusion assembly is controlled to extrude the lithium battery, or the heating assembly is controlled to heat the lithium battery, so that the voltage drop of the lithium battery is greater than or equal to a preset value. When the lithium battery is kept in a compressed state or at a preset temperature for a period of time greater than or equal to a preset time, the first control valve is opened, and the gas in the first housing enters the collection component. Detect the gas inside the collection component.

12. The lithium battery internal short-circuit test method according to claim 11, characterized in that, Controlling the extrusion assembly to extrude the lithium battery or controlling the heating assembly to heat the lithium battery, so that the voltage drop of the lithium battery is greater than or equal to a preset value, including: The extrusion assembly is controlled to extrude at an extrusion rate of less than or equal to 0.2 mm / s until the voltage drop of the lithium battery is greater than or equal to a preset value. Alternatively, the heating component can be controlled to heat to the cell separator melting point at a heating rate of less than or equal to 5°C / min until the voltage drop of the lithium battery is greater than or equal to a preset value.

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